[Federal Register Volume 61, Number 158 (Wednesday, August 14, 1996)]
[Proposed Rules]
[Pages 42318-42354]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-20592]
[[Page 42317]]
_______________________________________________________________________
Part II
Environmental Protection Agency
_______________________________________________________________________
40 CFR Parts 261, 271, and 302
Hazardous Waste Management System; Identification and Listing of
Hazardous Waste; Solvents; CERCLA Hazardous Substance Designation and
Reportable Quantities; Proposed Rule
Federal Register / Vol. 61, No. 158 / Wednesday, August 14, 1996 /
Proposed Rules
[[Page 42318]]
ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 261, 271, and 302
[SWH-FRL-5551-3]
RIN 2050-AD84
Hazardous Waste Management System; Identification and Listing of
Hazardous Waste; Solvents; CERCLA Hazardous Substance Designation and
Reportable Quantities
AGENCY: Environmental Protection Agency.
ACTION: Notice of proposed rulemaking.
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SUMMARY: After extensive study of 14 chemicals potentially used as
solvents, characterization of the wastes generated from solvent uses,
and a risk assessment evaluating plausible mismanagement scenarios for
these wastes, the U.S. EPA is proposing not to list those additional
wastes from solvent uses as hazardous waste under 40 CFR Part 261. This
action is proposed under the authority of Sections 3001(e)(2) and
3001(b)(1) of the Hazardous and Solid Waste Amendments (HSWA) of 1984,
which direct EPA to make a hazardous waste listing determination for
solvent wastes.
The determinations in this proposed rule are limited to specific
solvent wastes, and are made pursuant to the current regulatory
structure that classifies wastes as hazardous either through a specific
listing or as defined under the more generic hazardous waste
characteristics. Many of the solvent wastes addressed in this proposed
rule are already regulated as hazardous wastes due to their
characteristics. It is important to note that the proposal not to list
these solvent wastes as hazardous wastes is not a determination that
these chemicals are nontoxic. It is a determination only regarding the
need for specifically adding these solvent wastes to the lists of
hazardous waste.
DATES: EPA will accept public comments on this proposed rule until
October 15, 1996. Comments postmarked after this date will be marked
``late'' and may not be considered. Any person may request a public
hearing on this proposal by filing a request with Mr. David Bussard,
whose address appears below, by August 28, 1996.
ADDRESSES: The official record for this proposed rulemaking is
identified by Docket Number F-96-SLDP-FFFFF and is located at the
following address. The public must send an original and two copies of
their comments to: RCRA Information Center, U.S. Environmental
Protection Agency (5305W), 401 M Street, SW, Washington, D.C., 20460.
Although the mailing address for the RCRA Information Center has
not changed, the office was physically moved in November 1995.
Therefore, hand-delivered comments should be taken to the new address:
1235 Jefferson Davis Highway, First Floor, Arlington, Virginia. Copies
of materials relevant to this proposed rulemaking are located in the
docket at the address listed above. The docket is open from 9:00 a.m.
to 4:00 p.m., Monday through Friday, excluding Federal holidays. The
public must make an appointment to review docket materials by calling
(703) 603-9230. The public may copy 100 pages from the docket at no
charge; additional copies cost $0.15 per page.
EPA is asking prospective commenters to voluntarily submit one
additional copy of their comments on labeled personal computer
diskettes in ASCII (TEXT) format or a word processing format that can
be converted to ASCII (TEXT). It is essential to specify on the disk
label the word processing software and version/edition as well as the
commenter's name. This will allow EPA to convert the comments into one
of the word processing formats utilized by the Agency. Please use
mailing envelopes designed to protect physically the submitted
diskettes. EPA emphasizes that submission of comments on diskettes is
not mandatory, nor will it result in any advantage or disadvantage to
the commenter. Rather, EPA is experimenting with this procedure as an
attempt to expedite our internal review and response to comments. This
expedited procedure is in conjunction with the Agency ``Paperless
Office'' campaign. For further information on the submission of
diskettes, contact the Waste Identification Branch at the phone number
listed below.
Requests for a hearing should be addressed to Mr. David Bussard at:
Office of Solid Waste, Hazardous Waste Identification Division (5304W),
U.S. Environmental Protection Agency, 401 M Street, SW, Washington,
D.C. 20460, (703) 308-8880.
FOR FURTHER INFORMATION CONTACT: The RCRA/Superfund Hotline toll-free,
at (800) 424-9346, or at (703) 920-9810 in the Washington, D.C.
metropolitan area. The TDD Hotline number is (800) 553-7672 (toll-free)
or (703) 486-3323 in the Washington, D.C. metropolitan area. For
technical information or questions regarding the submission of
diskettes, contact Mr. Ron Josephson, U.S. EPA Office of Solid Waste,
Waste Identification Branch (5304W), 401 M St., SW, Washington, D.C.
20460, (703) 308-8890.
SUPPLEMENTARY INFORMATION: There are no regulated entities as a result
of this action.
I. Background
A. Statutory and Regulatory Authorities
B. Existing Solvent Listings and the Regulatory Definition of
Solvent
II. Today's Action
A. Summary of Today's Action
B. EPA's Evaluation of Solvent Use
1. Development of Study Universe
2. Applicability to National Use
C. Description of Health and Risk Assessments
1. Human Health Criteria and Effects
2. Risk Assessment
a. Selection of Waste Management Scenarios
b. Exposure Scenarios
c. Risk Assessment Methodology
d. Consideration of Damage Cases
e. Risk Assessment Results
D. Acetonitrile
1. Industry Identification
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
E. 2-Methoxyethanol (2-ME)
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
F. Methyl Chloride
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
G. Phenol
1. Industry Identification
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
[[Page 42319]]
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
H. 2-Ethoxyethanol Acetate (2-EEA)
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
I. Furfural
1. Industry Identification
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
J. Cumene
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Response
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
K. Cyclohexanol
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
L. Isophorone
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
M. 2-Methoxyethanol Acetate (2-MEA)
1. Industry Identification
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses
b. Physical/Chemical Properties and Toxicity
c. Waste Generation, Characterization, and Management
3. Basis for Proposed No-List Determination
a. Risk Assessment
b. Environmental Damage Incidents
c. Conclusion
N. Chemicals Not Used as Solvents
1. p-Dichlorobenzene
2. Benzyl Chloride
3. Epichlorohydrin
4. Ethylene Dibromide
O. Relationship to RCRA Regulations and Other Regulatory
III. Waste Minimization
IV. State Authority
A. Applicability of Rule in Authorized States
B. Effect on State Authorizations
V. CERCLA Designation and Reportable Quantities
VI. Regulatory Impacts
A. Executive Order 12866
VII. Environmental Justice
VIII. Regulatory Flexibility Act
IX. Paperwork Reduction Act
X. Unfunded Mandates Reform Act
XI. Compliance and Implementation
I. Background
A. Statutory and Regulatory Authorities
This investigation and listing determination was conducted under
the authority of Sections 2002(a), 3001(b) and 3001(e)(2) of the Solid
Waste Disposal Act (42 U.S.C. 6912(a), and 6921 (b) and (e)(2)), as
amended (commonly referred to as RCRA).
Section 102(a) of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), 42 U.S.C. 9602(a), is
the authority for the CERCLA aspects of this proposed rule.
Section 3001(e)(2) of RCRA (42 U.S.C. 6921(e)(2)) requires EPA to
determine whether to list as hazardous several specified wastes,
including solvent wastes.
The Environmental Defense Fund (EDF) and EPA entered into a consent
decree to resolve most of the issues raised in a civil action
undertaken by the Environmental Defense Fund (EDF v. Browner, Civ. No.
89-0598 (D.D.C.)), in which the Agency agreed, among other things, to a
schedule for making a listing determination on spent solvents. The
consent decree was approved by the court on December 9, 1994. As
modified, the consent decree provides that the listing determination is
scheduled to be proposed for public comment on or before July 31, 1996;
upon notification to EDF, this date may be extended for up to 15 days.
Under the agreement, EPA must promulgate the final rule on or before
May 31, 1997. This listing determination includes the following spent
solvents, still bottoms from the recovery of the following solvents,
and spent solvent mixtures thereof: cumene, phenol, isophorone,
acetonitrile, furfural, epichlorohydrin, methyl chloride, ethylene
dibromide, benzyl chloride, p-dichlorobenzene, 2-methoxyethanol, 2-
methoxyethanol acetate, 2-ethoxyethanol acetate, and cyclohexanol.
For an additional set of solvents, EPA agreed to conduct a study,
in lieu of a listing determination, and issue a final report. The study
is scheduled to be issued by August 30, 1996. This study is to discuss
the wastes associated with the use of the materials as solvents, the
toxicity of the wastes, and a description of the management practices
for the wastes. These additional chemicals are: diethylamine, aniline,
ethylene oxide, allyl chloride, 1,4-dioxane, 1,1-dichloroethylene, and
bromoform.
As part of its regulations implementing Section 3001(e) of RCRA,
EPA published a list of hazardous wastes that includes hazardous wastes
generated from nonspecific sources and a list of hazardous wastes from
specific sources. These lists have been amended several times and are
published in 40 CFR 261.31 and 40 CFR 261.32, respectively. In today's
action, EPA is proposing not to amend 40 CFR 261.31 to add wastes from
nonspecific sources generated during the use of the 14 solvents. This
is not a determination that these chemicals are nontoxic. Many of these
solvent wastes are, in fact, already regulated as hazardous waste
because they exhibit a hazardous waste characteristic under 40 CFR 261
Subpart B, and/or because they are mixed with other solvent wastes that
are, themselves, listed hazardous waste. Rather, this is a
determination only regarding the need for adding these specific wastes
to the RCRA hazardous waste listings based on the specific criteria in
the listing regulations. Although the consent decree does not require a
listing determination for the solvents covered by the study, the Agency
may decide to make a listing determination for those solvents in a
future rulemaking.
B. Existing Solvent Listings and the Regulatory Definition of Solvent
Five hazardous waste listings for solvents have been promulgated to
date
[[Page 42320]]
(40 CFR 261.31(a)): F001, F002, F003, F004, and F005. EPA has defined
the universe of wastes covered by today's listing determination to
include only those wastes generated as a result of a solvent being used
for its ``solvent'' properties. This approach is consistent with the
existing solvent listings (50 FR 53316; December 31, 1985); this is
also consistent with the term ``spent'' in the Consent Decree.
This definition of ``solvent use'' was included in the RCRA 3007
Solvent Use Questionnaire used to obtain information to support today's
proposed rulemaking.
Solvents are used for their ``solvent'' properties--to
solubilize (dissolve) or mobilize other constituents. Examples of
such solvent use include degreasing, cleaning, and fabric scouring,
use as diluents, extractants, and reaction and synthesis media, and
for other similar uses. A chemical is not used as a solvent if it is
used only for purposes other than those described above.
Spent solvents are solvents that have been used and are no longer
fit for use without being regenerated, reclaimed, or otherwise
processed (50 FR 53316, December 31, 1985). The listing investigation
undertaken to support today's proposal covered spent solvents, still
bottoms from the recovery of spent solvents, and mixtures of spent
solvents after use with other solid wastes. The Agency also
investigated the residuals generated by processes that use the solvents
of interest. Residuals include spent solvents, residuals generated
during solvent recovery, and any residuals generated after the solvent
has been introduced into the process that might include some
concentration of spent solvent. The existing solvent listings in 40 CFR
261.31 apply to spent solvents that contain at least 10 percent (by
volume), before use, of the listed solvents are used for their
``solvent properties,'' as defined in the December 31, 1985 Federal
Register (50 FR 53316). In evaluating spent solvent wastes for today's
determination, however, EPA considered all reported solvent uses,
including those reported to be below the 10% threshold.
EPA's listing investigation did not consider processes where the
constituents of interest are used as raw materials or principally sold
as commercial products (i.e., where the constituent is not used for its
solvent properties) because the materials used as raw materials or
products are not generally considered wastes under RCRA. This also is
discussed in the December 31, 1985 FR, (``* * * process wastes where
solvents were used as reactants or ingredients in the formulation of
commercial chemical products are not covered by the listing''). EPA
could examine the wastes from such nonsolvent uses, if deemed
necessary. However, with a backlog of listing determinations to
complete under court-ordered deadlines, EPA has focussed its current
efforts on those determinations required by law. An example of the use
of solvents as ingredients is the use of solvents contained in paints,
coatings, or photoresist.
EPA solvent listings are distinct from most other hazardous waste
listings in 40 CFR Part 261 Subpart D because they cover hazardous
wastes from the use of, rather than the production of, specified
chemicals. As noted above, the Agency has used the same approach in
this listing determination as in previous listings. EPA believes that
applying this definition of spent solvent in today's rulemaking is a
reasonable approach. RCRA 3001(e)(2) directs EPA to make a listing
determination on ``solvents,'' but provides no further direction on the
meaning of that term. EPA therefore has the discretion to reasonably
define the scope of the listing determination. The Consent Decree
identifies a subset of solvent wastes that are potential candidates for
listing, and specifies that the listing determination applies to
``spent solvents.'' Use of the definition has allowed the Agency to
place reasonable limits on the scope of its listing investigation for
this rulemaking. Given the ubiquity of ``solvents'' in general, the
Agency cannot take a census of a particular industry for a study (as
other recent listing determinations have done) to arrive at a
regulatory determination. Instead, the Agency has used the existing
definition of solvent use and attempted to identify facilities and
industries that use these chemicals as solvents.
For this listing determination, this definition proved particularly
useful as many of the chemicals (where used as solvents) are rather
specialized in their solvent uses. The Agency has, therefore, retained
the interpretations used in the past to define ``solvent use'' and
``spent solvent'' waste generation.
Finally, in a previous proposed hazardous waste listing for wastes
from the production of dyes and pigments (59 FR 66072, December 22,
1994) EPA presented the general approach the Agency uses for
determining whether to list a waste as hazardous pursuant to 40 CFR
261.11(a)(3). The discussion focussed on the selection of waste
management scenarios used in assessing risk and the use of information
on risk levels in making listing determinations. This approach was
further developed in EPA's proposed listing for petroleum refining
process wastes (60 FR 57747, November 20, 1995). EPA is employing the
same general approach in today's proposal. Readers are referred to
these notices for a description of EPA's listing policy. Also, Section
II.C.2., ``Risk Assessment,'' contains a discussion of how elements of
EPA's listing policy were applied in today's listing determination.
II. Today's Action
A. Summary of Today's Action
This action proposes not to list as hazardous wastes from solvent
uses of the following 14 chemicals from the EDF consent decree:
acetonitrile, 2-ethoxyethanol acetate, 2-methoxyethanol, 2-
methoxyethanol acetate, cyclohexanol, cumene, phenol, furfural,
isophorone, methyl chloride, 1,4-dichlorobenzene, benzyl chloride,
epichlorohydrin, and ethylene dibromide. The Agency has determined that
these wastes do not meet the criteria for listing set out in 40 CFR
261.11. Sections II.D through II.M of this preamble present waste
characterization, waste management, mobility, persistence, and risk
assessment data that are the bases for the Agency's proposal not to
list these wastes.
For the first 10 chemicals, EPA found that the management of
residuals from the use of these chemicals as solvents does not pose a
risk to human health and the environment under the plausible
mismanagement scenarios. The data used as the bases for these
determinations are presented in Sections II.F through II.M of today's
proposal. Detailed information is presented in the background documents
supporting today's proposal, which are available in the docket (see
ADDRESSES).
For the last four chemicals, the decision not to list residuals
from the use of these chemicals as solvents is due to EPA's belief that
these chemicals are extremely unlikely to be used as solvents based on
a lack of data indicating widespread solvent use for these chemicals.
These chemicals were originally put on the list in the consent decree
because of initial indications that some solvent use may have existed.
However, EPA did not find significant solvent use for these chemicals.
One of the chemicals (p-dichlorobenzene) is a solid at room
temperature, and the other three (benzyl chloride, epichlorohydrin, and
ethylene dibromide) are relatively reactive chemicals not well suited
to solvent use. EPA's information shows that the reported use of these
four chemicals as solvents is linked to bench-scale or experimental
laboratory
[[Page 42321]]
settings, and no significant solvent uses were found.
In short, the Agency is proposing not to list as hazardous benzyl
chloride, epichlorohydrin, ethylene dibromide, and p-dichlorobenzene as
hazardous spent solvents because these chemicals are extremely unlikely
to be used as solvents. For more detailed Agency findings on these
chemicals, see Sections II.N through II.Q of today's proposal and the
background document supporting today's proposal. The Agency requests
comment for new information on other solvent uses not covered in this
proposal. If the Agency receives new data during the comment period,
the Agency may use these data to revise risk assessment methodology and
assumptions.
B. EPA's Evaluation of Solvent Use
1. Development of Study Universe
Spent solvents differ from other listed wastes among EPA's waste
listings in that they are not principal waste streams generated by
manufacturing processes. Rather, they are used in a host of
manufacturing and allied applications, such as cleaning, degreasing,
extraction, purification, etc.
As part of the solvent use study, the Agency researched uses for
all 14 chemicals being considered in this listing determination (See
Section II.B). Following the data gathering, the Agency sent out almost
1,500 preliminary questionnaires in an attempt to characterize
industrial solvent use. After compiling the data and conducting follow
up phone calls to facilities, the Agency mailed out 156 questionnaires
to facilities to further characterize solvent uses. Summary information
from these questionnaires forms part of the basis of the listing
determination and may be found in the background document supporting
today's proposal.
The solvents listing investigation focuses on facilities using
specific chemicals for their solvent properties. At the outset of this
investigation, EPA set out to identify probable solvent uses for these
chemicals. The Agency conducted a thorough literature search to
characterize the potential solvent uses. This search is fully described
in the background document supporting today's proposal. The Agency
identified industrial processes known or suspected of using the 14
chemicals being investigated as solvents through such sources as
chemical engineering and industrial manufacturing reference books. Also
central to the results of the literature search was the location of
four to ten years of abstracts from scientific publications that
referenced the use of the 14 chemicals of concern as solvents. From
these sources, the Agency developed profiles of known, suspected, and
potential uses of these 14 chemicals as solvents.
The solvent uses identified were correlated with specific
industries, using Standard Industrial Classification (SIC) Codes. The
list of SIC codes developed was cross-referenced, by solvent, with
other Agency data sources, including the Toxic Release Inventory (TRI)
reporters list, Office of Water facility lists, and other sources to
obtain a final list of facilities that might reasonably be expected to
use one of the 14 chemicals as a solvent. The other sources utilized
included (1) the mailing list for EPA's RCRA 3007 Petroleum Industry
Questionnaire, (2) EPA's effluent guidelines questionnaire recipients
for the Pharmaceuticals and Organic Chemicals, Plastics, and Synthetic
Fibers industries, (3) facilities included in the Agency's National Air
Toxics Inventory of Chemical Hazards (NATICH) database, and (4) pulp
and paper mills studied during an investigation of pulp and paper mill
sludge disposal. Additional facilities were included that were
identified by EPA's Office of Pollution Prevention and Toxics (OPPT)
during an evaluation of solvents. The Agency also met with trade groups
representing pharmaceutical, chemical, synthetic organic chemical, and
semiconductor manufacturers.
Where a suspected use of a chemical would affect industries other
than those discussed above, EPA refined the facility mailing list
through the use of publicly available industrial address books and
product manufacturer listings. This approach to developing a mailing
list is discussed in detail in the background document to support
today's proposed rule.
The Agency used a preliminary questionnaire to prescreen for
solvent use by facilities on the mailing list. The RCRA 3007
Preliminary Questionnaire of Solvent Use was mailed to 1,497 facilities
in May 1993. Facilities were asked to provide the quantity of the
chemical used as a solvent in 1991 and 1992. As a result of the
preliminary questionnaire, the Agency removed more than 900 facilities
from further analysis because they reported no use of the 14 chemicals
as solvents.
The Agency attempted to refine the results of the preliminary
questionnaire further before sending out the full 3007 survey. Several
hundred of the facilities were contacted to confirm and clarify the
information reported. Some facilities misreported the use of a solvent
(i.e., reported methyl chloride when methylene chloride was used), and
such errors were corrected. (Telephone logs for these contacts are
contained in the docket to today's rule.) Further, because EPA
estimated that very little useful information would be gained from
smaller facilities, EPA eliminated from further consideration those
facilities that used less than a combined total of 1,200 kilograms of
all of the chemicals of concern. The Agency chose this cutoff because
it represents the maximum annual quantity of waste that would be
generated by a conditionally exempt small quantity generator (i.e., one
that generates less than 100 kilograms per month of a hazardous waste).
Further, EPA's data collection effort showed that most facilities (90%)
reporting less than 1,200 kg/year were in fact using significantly less
than 1,200 kg/year, i.e., 120 kg/year or less. In all the Agency
eliminated approximately 400 facilities from further study, either due
to reporting errors, discontinued use, or use of small quantities of
the solvents. As a result of this refinement, 156 facilities received a
RCRA 3007 Questionnaire of Solvent Use.
EPA believes that the elimination of most small quantity users does
not significantly affect the risk assessment, because the volumes used
were small compared to the larger volume users that were sent the full
survey. The risk assessment results are based on the highest waste
volumes (and solvent loadings) reported for each management practice
(see section II.C.2), therefore any significant risks would be found in
EPA's evaluation of the larger quantity users.
The Agency did not conduct a sampling and analysis program for the
spent solvent wastes. EPA found that obtaining representative samples
would be almost impossible due to potential use of these solvents in a
variety of different industries. The cost of such a program would have
been prohibitive to the Agency.
2. Applicability to National Use
For the solvents under review, the Agency believes that the
industry study results obtained through the methodology described above
accurately characterize solvent uses of the chemicals mandated for
review. In addition, the industry study completed gives the Agency an
accurate idea of the nationwide uses of these chemicals, whether or not
the chemicals are used in large or small quantities as solvents. The
Agency is confident that the collected information on solvent use
covers the large solvent users.
[[Page 42322]]
Once the industry study was completed, the resulting data for each
of the 14 chemicals was evaluated to determine whether or not large
users may have reasonably been missed during the RCRA Sec. 3007 survey
process. Several considerations were evaluated for this review,
including:
the scope of anticipated solvent use obtained during the
extensive literature search prior to pre-questionnaire mailing list
development;
whether or not the chemical was required to be reported in
the 1990 Toxics Release Inventory;
the number of facilities and type of solvent use
eventually identified and characterized in the full RCRA Sec. 3007
survey; and
comparison of Sec. 3007 survey solvent use quantities with
total chemical production volume and, where available, volume of the
chemical used as a non-solvent.
Three chemicals under evaluation (cyclohexanol, isophorone, and
furfural) were not TRI chemicals in 1990, a primary data source for the
RCRA Sec. 3007 pre-questionnaire mailing list. However, EPA believes
that large users of these chemicals were captured through other data
sources. Literature searches suggested limited solvent uses for these
chemicals across several industries. Results from the full RCRA
Sec. 3007 questionnaire confirmed limited solvent uses of greater than
1,200 kg/year for two chemicals: a single facility for cyclohexanol and
four facilities for isophorone. The one cyclohexanol facility was a
petroleum refinery and all identified petroleum refineries were sent a
pre-questionnaire.
Isophorone solvent use was identified at four facilities across
four SIC codes. Three of these facilities used isophorone as a solvent
in a similar process (in the coating industry). As with cyclohexanol,
no TRI data existed for isophorone to identify specific facilities.
Furfural was used in large quantities as a solvent, however nearly
all of the solvent use (>99.9%) was found in the petroleum industry,
which EPA surveyed. Given that the major use of this solvent was very
specialized (e.g., extraction of lube oil), the Agency believes that
the collected information on solvent use covers all large solvent
users.
A detailed description of the methodology used to evaluate the
coverage of the Agency's industry study for the 14 chemicals of concern
is contained in the background document contained in the docket for
today's rule (Hazardous Waste Listing Determination Background Document
for Solvents). Statistics on production and solvent use for each
solvent are also summarized in the discussions of the listing
determination for each respective chemical (Sections II.D through
II.N). The Agency requests comment on the use of these chemicals as
solvents EPA may not have uncovered in its data collection efforts.
3. Comparison of Questionnaire and Prequestionnaire Data
After the receipt of responses to the RCRA 3007 Questionnaire of
Solvent Use, EPA compared the 1992 solvent use reported in the
Preliminary Questionnaire with the solvent use reported in the 1993
Questionnaire. With the exception of acetonitrile, for which a slight
increase in solvent use is noted, the reported use of the remaining 13
chemicals decreased. For all of the chemicals, the solvent use reported
in the preliminary questionnaire included amounts of wastes containing
the chemicals reported as managed by commercial treatment, storage, and
disposal facilities (TSD). In some cases, such as benzyl chloride,
ethylene dibromide and p-dichlorobenzene, nearly all quantities
reported as used in 1992 were actually wastes received by TSDs. Other
apparent decreases resulted from incorrect reporting of chemicals used,
or because further review by EPA showed that the use did not meet EPA's
definition of solvent use (see below). In addition to apparent changes
that resulted from corrections to the data base, there were decreases
in actual quantities used for some solvents. Specifically, significant
decreases were noted for glycol ethers (e.g., 2-ethoxyethanol acetate,
2-methoxyethanol, and 2-methoxyethanol acetate), because facilities
were phasing out their use as solvents. Additional decreases were
attributable to plant closures and other discontinued use.
Based on a detailed review of the full Questionnaire responses, the
Agency determined that certain uses reported in 1992 did not meet EPA's
definition of solvent use. For example, further reductions from
quantities reported in 1992 are attributable to the elimination from
consideration of the use of a solvent as an ingredient in a photoresist
in semiconductor and printed circuit board manufacture, and use of a
solvent as a component of a paint or coating. (For example, for
photoresist uses, Agency staff determined that such uses did not
comport with the definition of ``solvent use'' as described earlier
because the chemicals were not carriers, reaction media, extractants,
etc. Rather, they were used in a way that suggested they were
components of the manufacturing process.) Finally, variations in usage
are to be expected. For many solvents, facilities reported either
increases or decreases in use between 1992 and 1993 that indicate
changes in production schedule or product slate. Additional details on
these changes, on a solvent-by-solvent basis, are presented in the
Background Document for today's rulemaking. EPA believes that all large
users of the 14 solvents were identified and surveyed as part of
today's determination because of the specialized nature of solvent use
for such chemicals as observed in its literature search. EPA also notes
that users of small amounts of one solvent were captured in many cases
because they are large users of another solvent. For example, one
refinery uses a large amount of phenol but also was captured as an
acetonitrile user.) Further, the Agency believes that the solvent use
reported in response to the full Questionnaire provides a more accurate
characterization of solvent use patterns than the Preliminary
Questionnaire because of the greater level of detail provided by the
respondents.
C. Description of Health and Risk Assessments
In determining whether waste generated from the use of these 14
chemicals as solvents meets the criteria for listing a waste as
hazardous as set out at 40 CFR 261.11, the Agency evaluated the
potential toxicity of the solvents, the fate and mobility of these
chemicals, the likely exposure routes, and the current waste management
practices.
1. Human Health Criteria and Effects
The Agency uses health-based levels, or HBLs, as a means for
evaluating the level of concern of toxic constituents in various media.
In the development of HBLs, EPA first must determine exposure levels
that are protective of human health and then apply standard exposure
assumptions to develop media-specific levels. EPA uses the following
hierarchy for evaluating health effects data and health-based standards
in establishing chemical-specific HBLs:
Use the Maximum Contaminant Level (MCL) or proposed MCL
(PMCL), when it exists, as the HBL for the ingestion of the constituent
in water. MCLs are promulgated under the Safe Drinking Water Act (SDWA)
of 1984, as amended in 1986, and consider technology and economic
feasibility as well as health effects.
Use Agency-verified Reference Doses (RfDs) or Reference
Concentrations (RfCs) in calculating HBLs for noncarcinogens and
verified
[[Page 42323]]
carcinogen slope factors (CSFs) in calculating HBLs for carcinogens.
Agency-verified RfDs, RfCs, and CSFs and the bases for these values are
presented in the EPA's Integrated Risk Information System (IRIS).
Use RfDs, RfCs, or CSFs that are calculated by standard
methods but not verified by the Agency. These values can be found in a
number of different types of Agency documents and EPA uses the
following hierarchy when reviewing these documents: Health Effects
Assessment Summary Tables (HEAST); Human Health Assessment Group for
Carcinogens; Health Assessment Summaries (HEAs) and Health and
Environmental Effects Profiles (HEEPs); and Health and Environmental
Effects Documents (HEEDs).
Use RfDs or CSFs that are calculated by alternative
methods, such as surrogate analysis, including structure activity
analysis and toxicity equivalency.
All HBLs and their bases for this listing determination are
provided in the risk assessment background document entitled Assessment
of Risks from the Management of Used Solvents, which can be found in
the RCRA docket for this rule at EPA Headquarters (see ADDRESSES
section). That document also includes the evaluation of acute toxicity
data, such as lethal doses for the oral and dermal routes, and lethal
concentrations for the inhalation route.
2. Risk Assessment
The risk characterization approach follows the recent EPA Guidance
on Risk Characterization (Browner, 1995) and Guidance for Risk
Assessment (EPA Risk Assessment Council, 1991). The guidance specifies
that EPA risk assessments will be expected to include (1) the central
tendency and high-end portions of the risk distribution, (2) important
subgroups of the populations such as highly susceptible groups or
individuals, if known, and (3) population risk. In addition to the
presentation of results, the guidance also specifies that the results
portray a reasonable picture of the actual or projected exposures with
a discussion of uncertainties. These documents are available in the
public docket for this action (see ADDRESSES section).
Individual Risk
Individual risk descriptors are intended to convey information
about the risk borne by individuals within a specified population and
subpopulations. These risk descriptors are used to answer questions
concerning the affected population and the risk for individuals within
a population of interest. The risk methodology section specifies the
process used by EPA to assess individual risk for these solvents.
Due to the unique circumstances of this listing determination
(e.g., variety of industries using solvents, limitations of the
available data), EPA was unable to assess population risks. The generic
management scenarios devised for this risk assessment were not
industry-specific and EPA did not have sufficient data to allow for
specific population risk assessment; such an assessment would have
required inappropriate assumptions and with little accuracy in results.
There is no need to conduct population risk assessment, however (even
were it feasible), for today's action, because EPA did not find any
significant individual risks of concern for any of the 14 chemicals
examined.
Uncertainties Associated With the Risk Assessment
One source of uncertainty derives from the generically constructed
management scenarios used; EPA had to make a variety of assumptions in
order to model releases and exposures. Due to data limitations, as
noted above, EPA was also not able to characterize actually exposed
populations. Another uncertainty stems from the assumptions of
plausible mismanagement, as described below in the following section.
The Agency completed an enormous task in the data gathering effort.
These data helped EPA to identify the major waste generators, and the
quantities of solvent waste most likely to pose a risk to human health
and the environment. The questionnaire asked for detailed information
on waste generation, management, and disposal for these chemicals when
used as solvents. By closely examining facilities that use these
chemicals as solvents, the Agency identified where these chemicals are
used as solvents, and where wastes of interest are generated and
managed. The Agency then used this information to focus on the
appropriate exposure scenarios. Because EPA relied on the data provided
from the questionnaires, the resulting analysis is dependent on the
quality of the data collected.
a. Selection of Waste Management Scenarios. EPA's regulations at
261.11(a)(3)(vii) require the Agency to consider the risk associated
with ``the plausible types of improper management to which the waste
could be subjected'' because exposures to wastes (and therefore the
risks involved) will vary by waste management practice. The choice of
which ``plausible management scenario'' (or scenarios) to use in a
listing determination depends on a combination of factors which are
discussed in general terms in EPA's policy statement on hazardous waste
listing determinations contained in the Dyes and Pigments Listing
Determination (59 FR 24530, December 22, 1994). EPA applied this
policy, with some specific modifications that reflect unique
characteristics of the industry, in the petroleum refining listing
determination (60 FR 57747, November 20, 1995). The general use of the
policy described in the dyes and pigments listing determination and
applied in the petroleum rule is continued here.
The following discussion explains the selection of plausible
management scenarios for the solvents listing determination. EPA's
basic approach to selecting which waste management scenarios to model
for risk analysis in listing determinations is to examine current
management practices and assess whether or not other practices are
available and would reasonably be expected to be used. Where a practice
is actually reported in use, that practice is generally considered
``plausible'' and may be considered for potential risk. EPA then
evaluates which of these current or projected management practices for
each wastestream are likely to pose significant risk based on an
assessment of exposure pathways of concern associated with those
practices. There are common waste management practices, such as
landfilling, which the Agency generally presumes may be plausible for
solid wastes and will evaluate it for potential risk. There are other
practices which are less common, such as land treatment, where EPA will
consider them plausible only where the disposal methods have been
reported to be practiced. In some situations, potential trends in waste
management for a specific industry suggest the Agency will need to
project ``plausible'' mismanagement even if it is not currently in use
in order to be protective of potential changes in management and
therefore in potential risk.
As experience is gained in listing determinations, the Agency
recognizes the need to more specifically describe its approach to
plausible management selection for the circumstances related to each
listing. EPA believes it necessary to do so here, in part because of
the unique nature of the solvents listing determination.
Selection of plausible management scenarios can better be described
by noting that there are three important elements of this selection
that must be considered in the risk assessment process: selection of
the management practice(s) considered ``plausible'',
[[Page 42324]]
selection of waste volumes evaluated as going to each plausible
practice, and selection of exposure pathways for each practice
evaluated.
The first element is selection of plausible management practices.
As described above, plausible practices are ones that are reported by
generators and can also be ones that are common practices, such as
landfilling. EPA may project less common or unreported practices as
plausible if there are compelling reasons for doing so. For the
solvents listing determination, all practices EPA considers common were
reported.
In general, solvent wastes were wastewaters, high concentration
organic wastes, or treatment residuals. Facilities also had losses of
solvents gases due to process vents, flares, or other air releases, but
these releases are not typically considered spent solvent wastes
because they are process-related. Wastewaters were typically fairly
dilute and are generally managed in a biological wastewater treatment
system or sent to a Publicly Owned Treatment Works (POTW). In most
cases, wastewater treatment occurred in tanks, however, some treatment
in surface impoundments did occur. Wastewaters for one solvent
(acetonitrile) were reported to go to underground injection wells,
however, essentially all (>99.99%) such discharges were to Subtitle C
hazardous waste injection wells.
Questionnaire data show that a high percentage of the high organic
nonwastewaters go to thermal treatment in incinerators, industrial
boilers, or fuel blenders. Because many of these solvent wastes are
either characteristic hazardous wastes (primarily due to ignitability)
and/or are mixed with listed hazardous wastes, the vast majority of
these wastes are handled as hazardous. The other major category of
nonwastewaters was treatment residuals (e.g., wastewater treatment
sludges, incinerator ash) and were typically landfilled.
The Agency evaluated potential risk for the following practices:
storage, combustion, wastewater treatment tanks and surface
impoundments, and underground injection wells. There were no compelling
reasons for projecting other practices as plausible.
Second, there is the selection of the volumes of each wastestream
the Agency considers could be disposed of in that management practice.
(Note that EPA must also consider the ``loading'' of waste going to
disposal sites. The ``loading'' is the amount of the solvent itself
contained in the volume of the wastestream reported.) Here the Agency
must determine what the volume of a wastestream is or could be going to
a selected plausible management practice. Because different volumes are
reported by generators, the Agency most often puts these reported
volumes into a distribution and selects a high percentile volume to be
representative of a reasonable volume that could go to the disposal
scenario, usually a volume falling at or above the 90th percentile of
volumes reported. That volume is then used as the volume input
parameter for the risk assessment model. For solvents, EPA used the
highest reported volumes (and loadings) going to the different
management practices, because the number of volumes (and loadings) were
limited to a few data points in many cases. The Agency did not attempt
to project higher volumes than those reported in this listing
determination for the following reasons:
Use of these solvents is mostly specialized. The volume
distribution was often skewed by one or two very high volume users. EPA
used these higher volumes in its risk assessment modeling and therefore
believes the conservative high volumes were in fact modeled.
For purposes of this listing determination, the Agency has
assumed that wastestreams reported to be managed as hazardous waste
will continue to be managed in that way in the future. In this listing
determination in particular, that assumption is considered reasonable
because solvent use most often requires very high concentrations of
chemical. Spent solvent as initially generated is therefore often very
high concentration waste, meaning that the wastestreams are often and
will continue to be characteristically hazardous for ignitability. In
addition, many solvents are often used as mixtures containing other
solvents that are listed as hazardous when spent (i.e., the F001
through F005 listings), or exhibit a characteristic (e.g.,
ignitability). Such wastestreams would have to continue to be managed
as hazardous, and stringent requirements are in place to ensure that
hazardous wastes do not pose a threat to human health or the
environment. This also means that certain waste management practices
could not be employed. It would be unreasonable to assume that large
amounts of such concentrated organic wastestreams would be shifted from
combustion or recycling to waste management practices for which they
were not reported, such as landfilling, especially when the
concentrated organic waste streams are already hazardous wastes subject
to the land disposal restriction rules.
Spent solvents with relatively high value are also
recovered by onsite distillation/fractionation in a closed-loop recycle
stream. These residuals would not usually be considered wastes (see 40
CFR 261.2), and, therefore, these volumes (if reported) were not used
in the risk assessment modeling.
Investment by industry in waste management practices
suggests that dramatic changes in reported volumes going to specific
waste management practices would not occur. For example, it would be
unreasonable to assume that a generator with a large investment in a
wastewater treatment plant would abandon that management practice for
another.
For these reasons, the Agency has concluded that the use of
reported volumes of solvent wastestreams going to specific waste
management practices is a reasonable way to project potential risk from
spent solvent waste management.
The third element in selecting plausible management scenarios is
the selection of the actual exposure pathways that could be expected to
be created via that management practice. The exposure scenarios
examined are discussed in the following section.
b. Exposure Scenarios. For each management scenario, EPA chose the
pathways through which the solvents could affect human health or the
environment. EPA initially considered a wide range of direct and
indirect exposure pathways, including direct inhalation, ingestion of
groundwater, inhalation of soil and dust, ingestion of soil, ingestion
of surface water, ingestion of crops, ingestion of animal/dairy
products, and ingestion of fish and shellfish. Exposure through the
ingestion of fish and shellfish were not quantitatively evaluated
because the solvents are nearly all highly water soluble, and therefore
are not expected to be absorbed or bioaccumulated. Vapor phase releases
will have little tendency to deposit to soil or surface water and,
thus, little tendency to enter the food chain or crops.
Based on the physical and chemical properties of the constituents
of concern and current management practices, direct inhalation was
identified as the primary exposure route of concern. EPA also evaluated
the groundwater pathway, where appropriate. Given the plausible waste
management practices and the physical properties of the solvents, the
following exposure scenarios were evaluated.
[[Page 42325]]
------------------------------------------------------------------------
Management practice Pathway Exposure route
------------------------------------------------------------------------
Combustion..................... Air............... Inhalation of
emissions from
combustion.
Storage Tanks.................. Air............... Inhalation of
volatilized
solvents.
Wastewater treatment tanks..... Air............... Inhalation of
volatilized
solvents.
Wastewater treatment surface Air and Inhalation of
impoundments. Groundwater. volatilized
solvents;
ingestion of
groundwater
contaminated by
solvents leaching.
------------------------------------------------------------------------
To assess the risks posed by thermal treatment, EPA chose to model
potential releases from a boiler as a plausible management practice.
For preliminary screening, wastes currently managed in permitted
hazardous waste management units (e.g., incinerators) were assumed to
be managed in similar types of non-hazardous waste management units
(e.g., Subtitle D industrial boiler). This approach results in risk
estimates that are quite conservative, since the non-hazardous units
are less protective than their hazardous counterparts. In addition, EPA
modeled possible air releases from an open accumulation tank, because
many solvent wastes are reported to be stored before treatment; for
this analysis, EPA assumed that any waste that was thermally treated
could be stored prior to treatment. To model potential air releases
from wastewater treatment, EPA modeled aerated tanks and surface
impoundments.
EPA evaluated two scenarios, landfills and deepwell injection, and
found that modeling was not necessary to determine that risks from
these pathways would not be significant, as discussed below. A third
scenario, treatment of wastewaters in surface impoundments, also did
not require extensive analysis to determine that risks from potential
releases to groundwater would not be significant (see below).
The data from the 3007 Survey show that wastes that were sent to
landfills contained negligible amounts of solvent; landfilling of
wastes high in solvent content did not occur. As noted previously,
solvent wastes are generally wastes with high organic content (spent
solvent liquids, residuals from recycling), or dilute wastewaters. The
vast majority of concentrated solvent wastes are hazardous due to
characteristic or mixing with other listed wastes, and could not be
landfilled, but are thermally treated. Therefore, organic or aqueous
liquid wastes are not expected to be managed in a landfill. Few solids
were generated that contained any residual solvent. The total loading
of all solvents reported going to landfills was <500 kg per year, and
nearly all went to Subtitle C landfills. Treatment residuals
(wastewater treatment sludges and incineration residuals) were reported
to be landfilled; however, they had negligible solvent levels. The lack
of solvent in treatment residuals is expected because these solvents
are efficiently treated by combustion and in wastewater treatment
systems. Therefore, because the wastes that reported to go to landfills
contained little or no solvent, and considering that nonwastewaters
with any appreciable solvent content are generally hazardous and thus
are managed as hazardous waste already, the Agency had no reason to
model the landfill scenario.
EPA also considered the potential for groundwater risks posed by
treatment in surface impoundments for all solvents that had wastewater
going to surface impoundments for treatment. EPA found that these
wastes are diluted by the flow of other dilute wastewaters (i.e., at
the ``headworks''). EPA gathered data on headworks flow in the 3007
Survey, and this allowed EPA to estimate headworks concentrations of
all solvents going to surface impoundments based on the loading of
solvent in each waste and the total wastewater flow to the headworks.
Solvent levels were generally found to be below the HBLs at the
headworks. Thus, no modeling was needed to ``bound out'' nearly all
reported impoundment practices for possible groundwater risks. EPA
closely examined the few remaining cases for which solvent levels might
enter impoundments above HBLs, and completed bounding analysis when
appropriate. Potential risks from surface impoundment treatment are
discussed in more detail in the specific sections for each solvent.
The practice of deep-well injection was reported to occur for only
one solvent (acetonitrile); nearly all of it was hazardous waste
(except for wastes containing 2 kg of solvent), and all went to
Subtitle C wells. Given that nearly all of the waste was hazardous and
was disposed of in RCRA permitted units, the waste is adequately
regulated. EPA found no evidence of any disposal in nonhazardous
deepwells. Therefore, EPA did not evaluate this practice further.
Finally, even though EPA could not find scenarios that could lead
to significant releases to ground water, the Agency also considered
whether the spent solvent wastes had the potential to form non-aqueous
phase liquids (NAPLs) that might move as a separate phase either above
or below the ground water table. These NAPLs may present special
problems, especially in assessing their transport and potential impact.
However, EPA found that nearly all solvents under consideration are
miscible or very soluble in water and are not likely to form NAPLs in
groundwater. One chemical with some solvent use, cumene, is only
slightly soluble in water. However, EPA found no significant land
disposal of cumene wastes. The solubilities of the solvents are given
in the section specific to each solvent.
Potential Risks From Spills
The Agency considers significant risk from spillage of spent
solvents to be unlikely for several reasons. First, most of the actual
volume of residuals reported were low concentration wastestreams, i.e.,
wastewaters and treatment residuals. Their ``loading'' or mass of
constituent in the reported waste is typically very low. These low
reported concentrations (often reported as ``trace'' concentrations)
were due to both treatment efficiencies of the spent solvents in
wastewater treatment systems and dilution in the treatment system
itself. Spills of such dilute wastestreams would not be of concern in
terms of risk. The high concentration spent solvent wastes would be of
most concern, but EPA found the vast majority to be already subject to
hazardous waste management requirements as characteristically hazardous
waste, or due to use or mixing with other listed solvents.
c. Risk Assessment Methodology. The general approach used for this
risk assessment involved successive iterations of risk screening. At
each step, risk from waste management scenarios was compared to these
levels of concern: for non-carcinogens, a hazard quotient exceeding
1.0, and for carcinogens, a lifetime cancer risk factor in the range of
1 x 10-6 to 1 x 10-4. For further explanation of levels of
concern, see ``EPA's Hazardous Waste Listing Determination Policy'' in
59 FR 66073 (December 22, 1994). The overall risk assessment was
conducted in three steps, as outlined below. The results of
[[Page 42326]]
the risk assessment for each solvent are described in Sections II.D to
II.M.
First Phase of Risk Screening--Bounding Analysis: For each of the
scenarios evaluated, EPA applied a screening methodology to arrive at
``bounding'' estimates of risk. These estimates gauge the risk posed by
the particular scenario under worst-case conditions: i.e., risk to the
most exposed populations under the most conservative assumptions about
releases, transport, and exposure. Bounding estimates therefore
purposely overestimate the exposure for the purpose of screening out
those scenarios which cannot pose any significant risk under any real-
life conditions. The scenarios that did not pose a significant risk
under a bounding analysis were considered to have been screened out,
and were not studied any further.
Second Phase of Risk Screening--High-End and Central Tendency
Analysis: For each scenario where bounding analysis risk was above a
level of concern, EPA estimated the high-end and central tendency
risks. High-end risk describes the individual risk for those persons at
the upper end (above the 90th percentile) of the risk distribution;
central tendency represents the typical risk using average or median
values for all exposure parameters. For this analysis, high-end
estimates were determined by identifying the two most sensitive
exposure parameters and then using maximum (or near-maximum) values for
these parameters. Median or average values were used for all other
parameters.
Third Phase of Risk Screening--Wastes Already Regulated as
Hazardous: As stated above, EPA noted that many of the waste streams
were already hazardous wastes; they were either characteristically
hazardous (generally because of ignitability), or mixed with listed
solvents (either during use or after waste generation). Current
requirements for managing these wastes mean that they will not pose a
threat to human health and the environment.
Therefore, EPA applied a third phase of risk screening to those
wastes which had not screened out in either of the first two phases.
This third phase consisted of a bounding analysis restricted to
wastestreams that could plausibly be managed as nonhazardous waste.
d. Consideration of Damage Cases. EPA investigated damage incidents
that contained reports of the 14 chemicals under evaluation as
contaminants at the site. Sources for this investigation included the
Record of Decision Database, the Damage Incident Database, and a
literature search. The Record of Decision (ROD) is generated by EPA to
document how the Agency plans to clean up a Superfund Site, and
contains the results of a detailed study of the contamination at the
site. Unlike industry studies in which wastes under study are generated
from set processes that are site-specific, in the solvent's industry
study it was not possible to determine a contaminant was used as a
solvent meeting EPA's definition of solvent use. Wastes disposed at
many sites were categorized only in broad terms as ``oily wastes,''
``pesticide wastes,'' ``organic wastes,'' or ``solvent wastes;'' the
uses of specific wastes prior to disposal were not identified.
Furthermore, sites were typically contaminated by a wide variety of
chemicals, many of which are widely used F-listed solvents, and wastes
containing these chemicals are more likely to represent any vaguely
identified ``solvent wastes.'' In other damage incidents, waste
categorization for buried drums or landfilled hazardous materials was
not possible. Based on a review of identified damage instances, no
single instance of damage was identified that could be tied to use of
the target chemicals as a solvent.
Most of the damage cases found for these solvents resulted from
disposal that took place many years ago, typically well before 1980.
Waste management regulations have changed dramatically since the RCRA
regulations were first promulgated (1980), and the damage cases appear
to reflect management practices that are no longer legal or likely.
Therefore, these cases do not provide a useful guide to current or
future disposal practices that may occur.
Also, many of the 14 chemicals are produced in relatively large
volumes, and only small percentages of most are used as a solvent. Some
of the chemicals have been widely used as chemical intermediates (e.g.,
phenol) or as ingredients in products (e.g., cumene in paint and 2-
methoxyethanol in jet fuel). The presence of others may often be traced
to their occurrence as an impurity in other chemicals (e.g., p-
dichlorobenzene is a common impurity in the listed solvent 1,2-
dichlorobenzene). Therefore, EPA believes that reported contamination
is more likely to arise from nonsolvent uses. Furthermore, the solvent
uses identified for the target chemicals studied were typically limited
to a few industries, and none of these sectors were represented by
facilities reported in the damage case databases.
Many of the damage cases arose from mismanagement at older
municipal or industrial landfills, and it is difficult to determine how
a chemical may have been used prior to disposal. These sites invariably
accepted a wide variety of wastes and were contaminated with many
different chemicals. Some of the target chemicals are possible
breakdown products from the degradation of other contaminants (e.g.,
phenol, methyl chloride). Therefore, because the ROD database does not
specifically cite the uses of any of the wastes found at the site, the
cases did not provide any direct evidence that contamination by any
other chemicals evaluated in this listing determination was linked to
disposal of spent solvents.
Finally, the 3007 Survey showed that high percentages of most of
the nonwastewater residuals reported are classified as hazardous, and
are subject to strict regulation under RCRA. Thus, the solvent wastes
currently generated generally could not be legally managed in the
manner that led to the damage cases (e.g., landfills). Therefore, EPA
did not find that the damage cases provided any relevant information on
the potential risks posed by solvent wastes. The sections for each
target chemical presents a more specific discussion for the damage
cases identified.
e. Risk Assessment Results. Sections II.D to II.N present a more
specific analysis by each solvent of the waste generation and
management information to justify the individual regulatory
determinations. Risk assessment evaluations were not conducted for the
four chemicals (benzyl chloride, epichlorohydrin, ethylene dibromide,
and p-dichlorobenzene) for which EPA found no significant solvent use.
The risk tables for each of the remaining 10 constituents indicate the
estimated health risk associated with the current and plausible
management scenarios. For greater detail, see the listing and risk
assessment background documents available in the docket to this
rulemaking proposal.
EPA requests comment on all aspects of its listing determinations,
including comments pertinent to the adequacy of the data base and the
methodology used to evaluate the data, and comments regarding the
extent to which EPA has adequately characterized solvent uses, users of
the solvents and management practices for the solvent waste streams.
EPA is also soliciting comment on the risk assessment methodology and
assumptions, including the Agency's rationale for choosing plausible
management scenarios.
Comments suggesting changes to the Agency's data base or risk
assessment methodology, or to the Agency's listing determination for
any of the 14 solvent waste streams, should be accompanied by any
relevant data or supporting
[[Page 42327]]
information. If EPA receives new data or information during the comment
period, EPA may use this information to augment its data base or revise
its methodology or assumptions for purposes of the final rule. If EPA
receives relevant new information during the comment period on solvent
uses, users or management practices for any of the specific solvent
wastes addressed in this rulemaking, EPA may revise its individual
listing determinations based on this information.
In particular, EPA notes that while a number of these solvents
might cause an unacceptable groundwater risk if significant volumes
were land disposed in concentrated form, such a scenario does not
appear to be plausible. Much of EPA's assessment of the risks from the
use of these solvents derives from evidence that such wastes are not
likely to be discarded on the land in significant concentrations. Nine
of these chemicals are already listed as commercial chemical products
and thus cannot be legally land disposed in their unused form without
treatment; furthermore, they would be subject to manifesting and other
RCRA controls when discarded. Many of the more concentrated wastes are
ignitable as generated, or already covered by an existing hazardous
waste listing, and are thus subject to RCRA regulation. Solid treatment
residuals appear to contain negligible or very low concentrations of
these solvents, because of the efficacy of treatment. Wastewaters do
not pose significant risk to groundwater or air, because the
wastewaters are generated in relatively dilute form, are further
diluted in integrated wastewater treatment systems, and then
effectively treated in those systems.
If EPA receives comments that leads it to conclude that unregulated
land disposal of concentrated wastestreams from the use of these
solvents is likely, EPA will consider promulgating a listing to address
those concerns. However, EPA currently believes that such a listing
should be limited to those circumstances in which significant
concentrations causing significant risk are plausible, such as listing
only wastes with high concentrations of solvents. EPA would consider
that approach in this case, given the analysis presented in this
proposal indicating that the existing or plausible waste management
scenarios do not pose significant risk. In particular, EPA believes
that it may be inappropriate to list the full range of wastes that
might otherwise be brought under regulation through application of the
mixture and derived-from rule to such waste. EPA invites comment on
such an approach.
D. Acetonitrile
1. Industry Identification
Almost all acetonitrile is manufactured as an acrylonitrile by-
product. U.S. production of acetonitrile is estimated to be between 8
and 11 million kilograms per year, of which more than 60 percent is
believed to be used in solvent applications and about 40 percent in
non-solvent applications.
Acetonitrile may be used for many non-solvent purposes such as the
production of nitrogen-containing compounds, including amides, amines,
higher molecular weight mono- and dinitriles, ketones, isocyanates, and
heterocyclic compounds. However, acetonitrile finds its primary use as
a solvent in various industries, particularly in the pharmaceutical
industry where it is used in the production of drugs and medicinal
chemicals.
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses. In response to the RCRA
3007 Preliminary Survey of Solvent Use, 178 facilities reported the use
of 5.8 million kilograms of acetonitrile as a solvent in 1992. The full
RCRA 3007 Survey of Solvent Use Questionnaire was sent to the 74
largest users of the 178 facilities that reported 1992 use of
acetonitrile. Most (>94%) of the respondents to the preliminary survey
that were not sent the full questionnaire reported using less than 120
kg per year of acetonitrile as a solvent. Some of the facilities sent
the 3007 survey used small quantities of acetonitrile, but were
included because the total amount of target solvents used was above
1200 kg. The facilities responding to the full 3007 survey reported a
1993 use of 9.3 million kilograms of acetonitrile as a solvent.
Literature searches indicate that acetonitrile is a common,
versatile, polar solvent often used as an extraction medium or a
recoverable reaction medium. Its high dielectric strength and dipole
moment make it an excellent solvent for both inorganic and organic
compounds, including polymers. RCRA 3007 Questionnaire responses
indicate that acetonitrile is used across a broad range of industries
as: a product and equipment wash; the mobile phase in high pressure
liquid chromatography (HPLC) at laboratory, pilot, and production
scale; a reaction, crystallization, or synthesis medium; an extractant
or extractive distillation medium; a diluent; and a dissolution medium.
Its largest use is in the pharmaceutical industry for the
production of drugs and medicinal chemicals, where its applications
range from laboratory use to pilot production in Food and Drug
Administration drug trials to full-scale batch product preparation. It
also is used in the organic chemicals industry as an extraction medium
and in the petrochemical industry for the separation of butadiene from
C4 hydrocarbons by extractive distillation. Literature searches
indicated that acetonitrile may be used in electroplating operations,
however, this use was not confirmed.
A detailed discussion of the processes in which acetonitrile is
employed is presented in the background document for today's proposal,
which is available in the docket (see ADDRESSES section).
b. Physical/Chemical Properties and Toxicity. Acetonitrile is a
relatively polar compound and is completely miscible in water. Because
of its miscibility, it is not expected to form a nonaqueous phase layer
in groundwater (NAPL). It has a relatively low boiling point (82
deg.C), and it has a moderate evaporation rate from water, as evidenced
by its Henry's Law Constant (2.007 x 10-5 atm-m3/mole).
Acetonitrile has a high vapor pressure at ambient temperature, and is
also flammable and ignitable, with a flash point of 6 deg.C.
Therefore, concentrated residuals from the use of acetonitrile as a
solvent are expected to exhibit the characteristic of ignitability.
The octanol-water partition coefficient (Log Kow) for
acetonitrile is -0.34; this indicates that acetonitrile has a low
tendency to sorb to soil organic matter, and is not expected to
bioaccumulate in organisms.
Acetonitrile is not classified as a carcinogen. The chemical has an
RfC of 0.05 mg/m3 and an RfD of 0.006 mg/kg/day; these correspond
to an air HBL of 0.05 mg/m3, and a water HBL of 0.2 mg/L.
c. Waste Generation, Characterization, and Management. The
respondents to the RCRA 3007 Survey of Solvent Use Questionnaire
reported a combined total of greater than 9.15 billion kilograms of
residuals generated from processes using acetonitrile as a solvent. The
vast majority of the residuals, 9.13 billion kilograms, were
wastewaters usually containing low to negligible concentrations of
acetonitrile (average concentrations less than 1%). The remaining
residuals, a combined total of greater than 15.0 million kilograms, are
nonwastewaters containing widely varying levels of acetonitrile. Some
[[Page 42328]]
nonwastewaters usually have low to negligible solvent concentrations,
such as filter-related materials, containers, and wastewater treatment
sludges; other nonwastewaters, such as spent solvents and heavy ends
from solvent recovery operations, typically have high levels of
acetonitrile and/or other organic wastes.
Nearly all wastewater residuals (98.4% by waste volume, and 79% by
loading) are managed in on-site wastewater treatment systems; treatment
in most cases included biological treatment in tanks, with a small
amount (0.1% by loading, or 294 kg total) reported to be sent to
surface impoundments. Some wastewaters (1.6% by volume, or 21% by
loading) also went to Subtitle C deepwell injection as a hazardous
waste. Very small quantities were reported to be discharged to Publicly
Owned Treatment Works (POTWs).
In 1993, more than 67 percent by volume of all nonwastewater
residuals containing acetonitrile were classified as hazardous waste.
However this percentage is skewed by one large volume (4.2 million kg,
or 30% of nonwastewaters) of nonhazardous wastewater treatment sludge
that had negligible acetonitrile concentration (see discussion below).
Nonwastewaters with high organic content, such as spent solvent and
heavy ends/distillates, were managed by some form of thermal treatment,
including incineration, energy recovery in a BIF, or blending for fuel
for future energy recovery.
Based on the reported waste volumes and concentrations of the
acetonitrile in the wastes, loadings of acetonitrile in the waste were
calculated by multiplying the volume (in kilograms) by the
concentration (in percent) and dividing by 100 (percent conversion).
This calculation provides the total loading of acetonitrile in the
waste that is available for potential release via management. Table 1
presents the reported volumes and acetonitrile loadings by management
practice for the wastes that contain spent acetonitrile from use as a
solvent.
EPA believes that the waste management practices reported in the
questionnaires by industry capture the plausible management scenarios
of concern for acetonitrile wastes. The full RCRA 3007 Questionnaire
was sent to 74 facilities, and information was obtained concerning the
management of over 250 wastestreams. The Agency believes that this
sample of facilities revealed likely waste management practices that
are or could be used in the management of these wastes. Therefore, EPA
does not think it is warranted to project other management practices
that could be employed. Further, the Agency anticipates the loadings to
these different practices will not change significantly over time.
To assess the potential risks for management of acetonitrile
wastes, EPA selected several management practices for modeling. To
represent the thermal treatment process (incineration, industrial
boilers, fuel blending, critical oxidation), EPA chose an industrial
boiler. To account for risks from the accumulation of residuals for
thermal treatment, EPA modeled an uncovered storage tank. To assess
risks arising from wastewater treatment, EPA modeled treatment in an
aerated wastewater treatment tank.
The Agency considered potential risks that might arise from the
land-based management of acetonitrile wastes, i.e., deepwell injection,
landfills, and surface impoundments. EPA does not believe that these
management practices present significant risk for the following
reasons.
Concerning deepwell injection, as noted above, all of the disposal
by this method occurs in Subtitle C units that are permitted to accept
hazardous waste. Therefore, EPA does not believe that these wastes
present any significant risk. Nearly all of the wastes sent to deepwell
injection were classified as hazardous waste; only a total of 97 kg of
wastes (containing 2 kg of solvent) sent to deepwell injection were
nonhazardous. Thus, the Agency believes that future disposal of nearly
all of these wastes will continue to be in a permitted unit, and EPA
did not evaluate this practice further.
EPA examined the practice of landfilling acetonitrile wastes and
found that only four out of the 254 waste streams containing spent
acetonitrile were reported to go to landfills. Of these four wastes,
three were sent to Subtitle C landfills (2 after treatment, and 1 was
small volume of filter material), and one wastewater treatment sludge
was sent to a Subtitle D landfill. While the volume of the one waste
sent to the Subtitle D landfill was relatively large (4.2 million kg),
the sludge was reported to contain only a ``trace'' of miscellaneous
organics. This specific sludge, and wastewater treatment residuals in
general, are unlikely to contain significant levels of acetonitrile,
because the chemical is removed by such treatment due to its volatility
and susceptibility to biodegradation (>98%; see the U.S. EPA RREL
Treatability Database). EPA also considered whether the practice of
landfilling spent acetonitrile wastes was likely to increase, but could
find no evidence to support this. To the contrary, the facility that
had been sending the largest acetonitrile loading to a Subtitle C
landfill (454 kg loading, 45,400 kg volume), indicated that it had
ceased this practice during 1993 and started sending the waste for
thermal treatment because of the waste's fuel value.
Only three wastes with spent acetonitrile were reported to go to
surface impoundments, and these were impoundments that were part of a
wastewater treatment train. In all cases the annual loadings were very
small (294 kg total), and acetonitrile levels would be negligible
(i.e., orders of magnitude below the health-based level) after mixture
with other wastewaters at the headworks prior to entering an
impoundment. (For example, the largest loading reported treated in a
surface impoundment, 230 kg per year, was mixed into a wastewater flow
of more than 30 million gallons a day; thus, the estimated
concentration at the headworks would be less than 0.04 ppm, well below
the health-based level of 0.2 ppm.) Furthermore, acetonitrile is
removed during wastewater treatment, such that any acetonitrile in
treatment impoundments would be further reduced. Except for these three
wastes, all reported wastewater treatment of acetonitrile wastes occurs
in tanks. EPA has no reason to believe this practice would change,
given the capital and regulatory costs associated with siting a new
surface impoundment, and the investments already made in tank-based
treatment systems.
Overall, EPA concludes that nonwastewaters with all but negligible
acetonitrile loadings are usually managed as hazardous under Subtitle C
(because of the ignitability of these wastes, and/or the common
practice of mixing with other hazardous solvent wastes), or recycled
onsite. Wastewaters are primarily handled either as hazardous through
deepwell injection, or treated in tank-based wastewater treatment
systems.
[[Page 42329]]
Table 1.--Generation Statistics for Acetonitrile
----------------------------------------------------------------------------------------------------------------
# of # of Total volume Total
Management Practice facilities streams (kg) loading (kg)
----------------------------------------------------------------------------------------------------------------
Incineration.......................................... 33 79 \1\ <6,000,000 \1\ <700,000
BIF................................................... 11 73 2,410,944 1,650,764
Fuel Blending......................................... 19 46 622,870 337,437
WWT--Tank............................................. 15 29 8,988,222,016 206,159
WWT--Surface Impoundment.............................. 3 3 95,118 294
POTW.................................................. 4 6 16,911 16
Landfill, Subtitle C.................................. 2 3 72,755 459
Landfill, Subtitle D.................................. 1 1 4,181,818 trace
Deepwell Injection, Hazardous......................... 4 8 150,123,631 54,706
Critical Oxidation.................................... 1 2 315,000 18,900
Distillation/Fractionation............................ 3 4 771,966 429,300
----------------------------------------------------------------------------------------------------------------
\1\ Exact value is withheld because some of the data for this practice are claimed as confidential business
information.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 2.
Using bounding assumptions, the Agency estimated that management of
acetonitrile residuals in a boiler could result in an inhalation HQ of
0.0000006. Risk based on bounding assumptions for the other plausible
mismanagement scenarios (an aerated tank and on site accumulation)
exceeded an inhalation HQ of 1, and EPA then conducted high end and
central tendency risk analyses for these scenarios.
The estimated high-end risk assessment with plausible mismanagement
of acetonitrile wastes in an aerated tank is an inhalation HQ of 0.002,
which indicates minimal risk through the inhalation pathway for this
scenario. However, the high-end risk estimate for the plausible
mismanagement of acetonitrile wastes through on site accumulation
resulted in an inhalation HQ of 200; the central tendency HQ was 0.09.
This was the only management scenario with a high-end HQ greater than
1.
EPA then conducted a third phase of risk screening on these
acetonitrile wastes modeled in accumulation tanks. The 3007 survey data
showed that the vast majority of these wastes are either
characteristically hazardous (generally ignitable) or co-managed with
other listed hazardous wastes. Since these wastes are already regulated
under RCRA Subtitle C, this third phase of risk screening focused on
the risk from waste streams that are not currently being managed as
hazardous. A bounding analysis of these wastes resulted in an HQ of
0.44, revealing risks below the HQ level of concern.
Since all the other acetonitrile waste streams also showed hazard
quotients below 1, EPA concluded that the risks from the portion of
wastes that are nonhazardous are not significant. EPA also believes
that the risk assessment overstates the risks from tank storage because
the bounding and high end risk analyses assumed that all of the stored
solvent would volatilize from the tank; such an assumption is very
conservative because these wastes are being accumulated for thermal
treatment or fuel blending.
Table 2.--Risk Assessment Results for Acetonitrile
----------------------------------------------------------------------------------------------------------------
Hazard quotient (HQ)
-------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Wastewaters:
Treatment in Aerated Tanks............................. 0.00002 2.4 0.002
Nonwastewaters:
On Site Accumulation:
--Phase I & II (all wastes)................................. 0.09 346 200
--Phase III (nonhazardous wastes)........................... ............ 0.44 ............
Boiler................................................. ............ 0.00000061 ............
----------------------------------------------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk assessment methodology and results, see
the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. Acetonitrile has been identified
as a constituent of concern at one site investigated using the Hazard
Ranking System (HRS). However, there are no sites that have undergone a
Record of Decision (ROD) that identify acetonitrile as a constituent.
In no instances has the use of acetonitrile as a solvent been linked to
environmental damage in either the ROD or HRS databases.
c. Conclusion. EPA believes that acetonitrile does not satisfy the
criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of acetonitrile as a solvent should
not be listed as hazardous waste under 40 CFR 261.31. While risk
analyses indicate some potential risk from air releases of acetonitrile
stored in open tanks, EPA believes that this risk would not be
significant for these residuals because most of the nonwastewater
residuals stored are regulated as hazardous waste. Some of those wastes
are already listed; others are regulated as hazardous waste because of
their characteristics (generally ignitability). EPA believes
[[Page 42330]]
that regulating the wastes this way is protective of human health and
the environment. The wastes which are regulated as characteristically
hazardous are being managed through incineration, an efficient
mechanism for destroying the hazardous constituents. EPA believes that
it is implausible that these wastes will be managed in an unsafe manner
(as explained in section II-D-2-c). Regulations controlling air
releases from storage of hazardous waste have recently been
promulgated. (See December 6, 1994 at 59 FR 62896, and February 9, 1996
at 61 FR 4903). These regulations address volatile organic compounds at
levels much less (i.e., 100 ppm) than those that yielded the potential
risks for acetonitrile. Furthermore, EPA believes that the risk
assessment overstated the risks presented by storage in tanks because
the scenario assumed that all of the stored solvent would escape; this
seems unlikely if the waste is being stored expressly to send for
further treatment or fuel blending. Therefore, given that nearly all of
the nonwastewater acetonitrile residuals are either already being
handled as hazardous, or contain negligible amounts of the solvent, EPA
believes that spent solvent residuals are not likely to pose a
significant hazard to human health and the environment.
E. 2-Methoxyethanol (2-ME)
1. Industry Identification
In 1993, 24 million kilograms of 2-methoxyethanol, also known as
ethylene glycol monomethyl ether, or 2-ME, were produced. Data on
imports and exports are not available. 2-Methoxyethanol is widely used
as a jet fuel additive to inhibit icing in fuel systems, with 76
percent consumed for this purpose. It is used as a chemical
intermediate (9 percent in 1993) in the production of the specialty
plasticizer di-(2-methoxyethyl) phthalate (DMEP); as a chemical
intermediate in the manufacture of esters such as 2-methoxyethyl
acetate; and in the synthesis of the dimethyl ethers of ethylene
glycol.
The remaining 14 percent of 2-ME is used in a variety of
applications, including the solvents use discussed in greater detail
below.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 111 facilities reported the use of
15.4 million kilograms of 2-methoxyethanol as a solvent in 1992. Of the
111 facilities reporting use in 1992, 47 were sent the RCRA 3007
Solvent Use Questionnaire (nearly all of the remaining facilities used
less than 100 kg). In the RCRA 3007 Questionnaire, 35 facilities
reported the use of 3.7 million kilograms of 2-methoxyethanol, a
decline from the previous year. This is primarily attributable to the
elimination of use of 2-methoxyethanol at 12 facilities, and a large
drop in use at five other facilities. In addition, EPA determined from
the responses to the full questionnaire that some uses reported in the
semiconductor industry and by TSDs were not solvent uses.
Information from the RCRA 3007 Questionnaire indicates that 2-
methoxyethanol is used for cleaning purposes, including removal of
product buildup from tanks and removal of polymer film during the
production of integrated circuits. 2-Methoxyethanol is used as a
reaction medium for the production of various products. It can be used
as a diluent in the production of lacquers and coating formulations
that subsequently are applied to a substrate, which may be aluminum,
metal, or nonwoven fiber. It also is a diluent in the production of
specialty chemicals. Additionally, 2-methoxyethanol is used in
specialized laboratory analyses.
2-Methoxyethanol is used in the formulation of a photoresist system
used in the semiconductor manufacturing industry. Where the 2-
methoxyethanol is part of the formulation of purchased photoresist, its
use does not constitute solvent use. However, in at least one case, 2-
methoxyethanol is used as a solvent for cleaning the edge of the
semiconductor wafer after application of the photoresist; this use does
meet the RCRA definition of solvent use. Discussions with the
semiconductor industry and engineering site visits to many of these
facilities leads EPA to believe that the use of 2-methoxyethanol, along
with other lower order glycol ethers, is being phased out.
Literature searches indicated that 2-methoxyethanol has the
potential for use as a solvent in: the manufacture of polymeric
materials, composite membranes, resins, and recording materials; the
preparation of specialty chemicals; electroplating; and dye processing.
However, the Agency could find no confirmation of these uses from the
RCRA 3007 Questionnaire. In light of the Agency's extensive
investigation of actual solvent use in connection with the 3007 Survey,
EPA believes it is reasonable to consider only those solvent uses
actually confirmed by he survey results.
b. Physical/Chemical Properties and Toxicity. 2-Methoxyethanol is
miscible in water, and is useful as a solvent for polar and nonpolar
chemicals. 2-Methoxyethanol is flammable when exposed to heat or open
flame, and is ignitable, with a flash point of 39.4 deg.C. Residuals
with high concentrations of 2-methoxyethanol are expected to exhibit
the characteristic of ignitability. With a vapor pressure of 6.2 mm Hg
at 20 deg.C, 2-methoxyethanol is volatile, and the Henry's Law Constant
for 2-methoxyethanol is 2.9 x 10-3 atm-m3/mole, indicating
that 2-methoxyethanol rapidly evaporates from water.
The Log Kow for 2-methoxyethanol is -0.77, indicating that 2-
methoxyethanol has a low tendency to sorb to soil organic matter and
bioaccumulate in organisms. In the atmosphere, 2-methoxyethanol is
subject to photodegradation, with a half-life of less than one day.
2-Methoxyethanol is not classified as a carcinogen. The chemical
has an RfC of 2 x 10-2 mg/m3 and a provisional reference dose
(RfD) of 5.7 x 10-3 mg/kg/day. The corresponding air HBL is
2 x 10-2 mg/m3 and the provisional water HBL is 0.2 mg/L.
c. Waste Generation, Characterization, and Management. Twenty-three
facilities reported a total of 3.14 billion kg of waste generated in
1993. The vast majority (>99%) of the residuals generated are
wastewaters contaminated with relatively low concentrations of 2-
methoxyethanol (average concentration of 0.01%). These wastes also
include 2.1 million kg of nonwastewaters, containing variable amounts
of 2-methoxyethanol, including spent solvents, sludges, and containers
and rags. Where 2-methoxyethanol is incorporated into the final
product, wastes may include off-specification materials and tank
cleanout wastes.
In 1993, over 96% percent by volume of nonwastewaters were reported
to be hazardous. A large fraction (70%) of the nonwastewaters was
recovered through distillation or fractionation, and most of the rest
(29%) was managed by some type of thermal treatment, either by
incineration, energy recovery in a boiler, or fuel blending. The
wastewaters containing spent 2-methoxyethanol were all reported to be
treated in tank-based wastewater treatment systems.
Based on the reported waste volumes and concentration of the 2-
methoxyethanol in the wastes, loadings of 2-methoxyethanol were
calculated by multiplying the volume (in kilograms) by the
concentration (in percent) and dividing by 100 (percent conversion).
This calculation provides the quantity of 2-methoxyethanol in the waste
that is available for potential release via management. Table 3
presents the
[[Page 42331]]
reported volumes and 2-methoxyethanol loadings by management practice
for the wastes that contain spent 2-methoxyethanol.
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios of concern
for 2-methoxyethanol. EPA surveyed all significant users of this
solvent, and collected information on the waste management practices
for 54 wastestreams. The Agency believes that these facilities provide
a good indication of all likely waste management practices.
Furthermore, with the use of this chemical as a solvent declining, new
management practices are unlikely to occur.
To assess the potential risks for management of 2-methoxyethanol
wastes, EPA selected several management practices for modeling. To
represent thermal treatment (incineration, industrial boilers, fuel
blending), EPA chose an industrial boiler. To account for risks from
the accumulation of residuals in tanks, EPA modeled an uncovered
storage tank. Finally, to assess risks arising from wastewater
treatment, EPA modeled treatment in an aerated wastewater treatment
tank.
None of the 56 wastestreams were reported to go to land disposal in
landfills or impoundments. Solids containing spent solvent are
incinerated, and wastewaters are all treated in tanks. Wastewater
treatment sludges generated do not contain significant levels of 2-
methoxyethanol, because the chemical is efficiently removed by such
treatment due to its volatility. In the face of the existing practices,
EPA finds it implausible that high organic wastes or aqueous liquids
currently sent to thermal treatment would be managed in a landfill.
Essentially all of the nonwastewater residuals that contain spent 2-
methoxyethanol are thermally treated or recovered, and more than 96% of
this treatment is as a hazardous waste. The large percentage of spent
2-methoxyethanol wastes that are already hazardous are precluded from
land disposal in Subtitle D units, and no evidence exists to suggest
that any wastes containing spent 2-methoxyethanol would be placed in a
landfill. Any change from the current practice of treatment of
wastewaters in tanks to treatment in
Table 3.--Waste Statistics for 2-Methoxyethanol
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration........................................... 11 20 297,522 52,839
Energy Recovery........................................ 6 13 129,369 57,760
Fuel Blending.......................................... 5 11 224,530 104,444
WWT-Aerated Tanks...................................... 6 6 3,139,049,350 452,030
WWT-Other Tanks........................................ 2 2 2,558 486
Fractionation/Distillation............................. 1 2 1,463,068 14,631
Storage (for unspecified offsite hazardous treatment).. 2 2 14,802 704
----------------------------------------------------------------------------------------------------------------
Impoundments also seems unlikely given the associated costs for
such a change. As noted above, however, this solvent is easily removed
from wastewaters by volatilization, therefore even if treatment in an
aerated impoundment occurred, it would be expected to rapidly remove
the solvent and make any releases to groundwater unlikely.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 4.
Using bounding assumptions, the Agency estimated that management of
2-methoxyethanol wastewater in an aerated tank could result in an
inhalation HQ of 0.98 and management of nonwastewater in a boiler could
result in an inhalation HQ of 6 x 10-\8\. Risk based on bounding
assumptions for the other plausible mismanagement scenario (on site
accumulation) exceeded an inhalation HQ of 1, and EPA then conducted
high end and central tendency risk analyses for these scenarios.
The estimated high-end risk assessment for plausible mismanagement
of 2-methoxyethanol wastes through on site accumulation is an
inhalation HQ of 16. This was the only management scenario where the
high-end HQ was higher than 1.
EPA then conducted a third phase of risk screening on these 2-
methoxyethanol wastes in open accumulation tanks. Since wastestreams
which are hazardous are already being regulated under RCRA Subtitle C,
this third phase of risk screening focused on the risk from waste
streams that are not currently being managed as hazardous.
EPA's data showed no waste streams in this management scenario
which were nonhazardous; all of the waste streams were already being
managed under RCRA Subtitle C. Since all the other 2-methoxyethanol
waste streams showed hazard quotients below 1, EPA concluded that there
was insignificant risk reduction which could be gained by listing 2-
methoxyethanol as a hazardous waste. EPA also believes that the risk
assessment overstates the risks from tank storage because the bounding
and high end risk analyses assumed that a large fraction of the stored
solvent would volatilize from the tank; such an assumption is very
conservative because these wastes are being accumulated for thermal
treatment or fuel blending.
Table 4.--Risk Assessment Results for 2-Methoxyethanol
------------------------------------------------------------------------
Hazard quotient (HQ)
--------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
------------------------------------------------------------------------
Wastewaters:
Treatment in Aerated
Tanks....................... 3 x 10-9 0.98 ...........
[[Page 42332]]
Nonwastewaters:
On Site Accumulation
--Phase I & II (all
wastes)................. 0.007 59 16
--Phase III (non-haz
wastes)................. ........... None
Incineration............. ........... 6 x 105-\8\ ...........
------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk
assessment methodology and results, see the background document
Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. 2-Methoxyethanol has been
detected at three Superfund sites, however, based on a review of
identified damage instances, no single instance of damage was
identified that could be tied to use of 2-methoxyethanol as a solvent.
The RODs report that 2 methoxyethanol was detected, however, no
concentrations were provided for any of the three sites. Two of the
sites were landfills that accepted a wide variety of industrial and
municipal wastes. One landfill ceased operation in 1980, and received
liquid wastes (including latex and ``spent organic solvents'') from
1968-1972. The other landfill received municipal wastes from 1969 until
1984, and drummed industrial wastes between 1973 and 1975. The use of
the 2-methoxyethanol prior to disposal at these landfills is impossible
to ascertain. In both cases a wide variety of other contaminants were
found. The third facility was a used oil recycling site that ceased
operations in 1981, and was primarily contaminated by oil, PCBs,
metals, and VOCs. 2-methoxyethanol has been used as a jet fuel
additive, and it is likely that 2-methoxyethanol is present in used oil
from this source.
The solvent uses identified for 2-methoxyethanol (e.g.,
pharmaceutical manufacturing, coatings and lacquers, electronics,
photographic chemicals, and laboratory use) are not represented in any
of the facilities identified as having 2-methoxyethanol contamination.
Therefore, it is not likely that the damage incidents identified were
the result of mismanagement of 2-methoxyethanol following use as a
solvent, and the Agency did not consider the damage incidents relevant
to the listing determination. In addition, disposal of the wastes that
are the potential sources of 2-methoxyethanol occurred well before RCRA
regulations were in place. The vast majority of the nonwastewater
solvent wastes identified in the 3007 Survey were reported to be
hazardous waste, and are now subject to strict regulation. Therefore,
the kind of disposal that led to these Superfund sites cannot occur for
nearly all nonwastewaters resulting from solvent use of 2-
methoxyethanol.
c. Conclusion. EPA believes that 2-methoxyethanol does not satisfy
the criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of 2-methoxyethanol as a solvent
should not be listed as hazardous waste under 40 CFR 261.31. While risk
analyses indicate some potential risk from air releases of 2-
methoxyethanol stored in open tanks, EPA believes that this risk from
residuals that are currently regulated hazardous waste would not be
significant because all of the nonwastewater residuals were stored as
regulated hazardous waste. Therefore, these wastes are already
hazardous, and listing is not necessary. Regulations controlling air
releases of volatile organics from storage of hazardous waste have
recently been promulgated. (See 59 FR 62896, December 6, 1994, and
February 9, 1996 at 61 FR 4903). Furthermore, EPA believes that the
risk assessment overstated the risks presented by storage in tanks
because the scenario assumed that a large fraction of the stored
solvent would escape; this seems unlikely if the waste is being stored
expressly to send for further treatment or fuel blending. For the
foregoing reasons, spent solvent residuals are not likely to pose a
significant hazard to human health and the environment.
F. Methyl Chloride
1. Industry Identification
In 1993, U.S. production of methyl chloride was estimated to be
218.8 million kilograms, of which 78 percent was used as an
intermediate in the manufacture of chlorosilanes; 16 percent was used
in the production of quaternary ammonium compounds, agricultural
chemicals, and methycellulose; approximately 3 percent was exported;
and the remainder is used for other purposes, including use as a
solvent.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 32 facilities reported the use of a
combined total of 1.04 million kilograms of methyl chloride in 1992. In
the RCRA 3007 Questionnaire, seven facilities reported the use of
623,645 kilograms of methyl chloride as a solvent. This reduction
occurred because EPA determined from responses to the full
questionnaire that methyl chloride was not used as a solvent in some
facilities. Of the seven facilities, three reported the use of small
quantities in laboratories, primarily for liquid/liquid extraction. The
major use was reported by two butyl rubber manufacturers, which
accounted for greater than 99% of the solvent use of methyl chloride.
Literature searches indicated that methyl chloride may be used
commercially as a liquid (under pressure) and has solvent applications
in the production of butyl rubbers, which was confirmed by the
Questionnaire respondents. Other potential solvent uses include the
dealumination of aluminosilicates; a polymerization medium; a blowing
agent for Styrofoam; a medium for the synthesis of tert-chlorine-ended
polyisobutylenes with allyltrimethyl-silane; and a specialty solvent in
laboratory applications. These uses were not confirmed by the RCRA 3007
Questionnaire respondents.
b. Physical/Chemical Properties and Toxicity. Methyl chloride has a
moderate solubility in water of 0.648 percent by weight at 30 deg.C.
Methyl chloride is a gas under ambient conditions, and will have a high
rate of evaporation from water to air, as evidenced by its Henry's Law
Constant of 4.5 x 10-2 atm-m3/mole. It has a Log KOW of
0.91, indicating that methyl chloride has a low potential for
absorption to soil and bioaccumulation in organisms.
[[Page 42333]]
Methyl chloride can biodegrade anaerobically. It will also
hydrolyze in water to give methanol; at ambient temperatures, the half
life in water is estimated to be about one year. Just considering
hydrolysis alone, this means that in less than 10 years the
concentration of methyl chloride would be decreased by a thousand-fold.
Methyl chloride is a suspected carcinogen. Using an oral carcinogen
slope factor (CSF) of 1.3x10-2 (mg/kg/day) -1, EPA calculated
that exposure to a water concentration of 0.003 mg/L for 70 years would
correspond to a cancer risk of 1 x 10-6. The inhalation CSF is
1.8 x 10-6 (ug/m\3\) -1, which corresponds to a 10-6
risk HBL in air of 6 x 10-4 mg/m3.
c. Waste Generation, Characterization, and Management. Seven
respondents to the RCRA 3007 Questionnaire reported the generation of
more than 1.19 billion kg of residuals resulting from the use of methyl
chloride as a solvent; nearly all of the waste from the production of
butyl rubber. The vast majority of this volume was wastewaters (1.1
billion kg), with relatively low solvent concentrations. The remaining
wastes included residuals generated from treatment of the wastewaters
(89 million kg of wastewater treatment sludge and 6.6 million kg of
sludge/ash from further treatment of the sludge), and 0.52 million kg
of spent solvent.
The wastewaters were all sent to wastewater treatment systems,
which included aeration/biological treatment in tanks or surface
impoundments. The vast majority (89 million kg) of the nonwastewaters
were further treated and ultimately landfilled (6.6 million kg). The
balance of the nonwastewaters (0.52 million kg) were managed by thermal
treatment (incineration or energy recovery in a boiler/industrial
furnace).
Based on the reported waste volumes and concentration of the methyl
chloride in the wastes, loadings of methyl chloride to the environment
were calculated by multiplying the volume (in kilograms) by the
concentration (in percent) and dividing by 100 (percent conversion).
This calculation provides the quantity of methyl chloride in the waste
that is available for potential release via management. Table 5
presents the reported volumes by management practice, and the amount of
methyl chloride contained in the wastes.
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios for spent
methyl chloride wastes. Nearly all of the solvent use of this chemical
was accounted for by the two facilities that produce butyl rubber. The
other facilities that reported any waste containing methyl chloride
reported corresponding loadings that were extremely small (2 kg total
loading). One company owns both butyl rubber plants, and is the sole
producer of butyl rubber in the country. Given this highly specialized
solvent use of this chemical, the Agency is confident that no other
significant waste management practice for the associated wastes exists.
To assess the potential risks associated with the management of
these wastes, EPA chose to model an industrial boiler to represent the
thermal treatment practices (incineration and fuel blending). To
account for storage prior to thermal treatment, EPA modeled the
accumulation of spent methyl chloride in an open storage tank. To
assess risks from wastewater treatment, EPA also modeled potential
releases from wastewater treatment in a surface impoundment.
Table 5.--Waste Statistics for Methyl Chloride Residuals
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration........................................... 4 4 89,296,310 2
Energy Recovery (BIFs)................................. 1 1 225,000 2,250
Land Disposal.......................................... 1 2 6,550,550 <5.5
WWT--Tanks............................................. 1 1 60,000,000 600
WWT--SI................................................ 1 1 1,036,517,000 175,000
----------------------------------------------------------------------------------------------------------------
EPA considered the potential risks that might arise from the land-
based management of methyl chloride wastes in landfills and surface
impoundments. EPA does not believe that these management practices
present a significant risk for the following reasons.
Two wastes were reported sent to Subtitle D landfills. The larger
volume waste (6.55 million kg) is a residual from a sludge treatment
unit, which includes an incinerator, that was sent off-site for
stabilization and placement in a landfill. The residual was reported to
have only a ``trace'' of hydrocarbons. Methyl chloride is readily
treated by biodegradation and volatilization in an aerated system with
activated sludge. Removal efficiencies for methyl chloride from
industrial wastewater treatment systems are reported to be high
(greater than 98.9%; see the U.S. EPA RREL Treatability Database).
Therefore, it is unlikely that any appreciable level of the chemical
remains in this treatment residual. The other waste sent to a landfill
was a small volume of spent desiccant (550 kg), containing relatively
little solvent (<5.5 kg). Neither of these wastes is expected to
present any significant risk due to negligible amounts of solvent
present.
One other major wastestream (89 million kg) was reported as
wastewater treatment sludge, however, as noted previously, this waste
was actually the waste that entered the sludge treatment unit, where it
was treated to give the 6.55 million kg sludge/ash wastestream noted
above. For the reasons described previously, EPA believes that these
very low-concentration wastes are typical of the types of wastes that
are likely to be landfilled. Therefore, EPA believes that no
significant risks are likely to arise from landfills for methyl
chloride wastes. Furthermore, methyl chloride will also undergo
hydrolysis in water with a half-life of less than one year, and
hydrolysis would be significant for any methyl chloride reaching the
groundwater. For example, over a ten year period (which would
correspond to rapid movement off-site from a landfill in groundwater),
the concentration of methyl chloride would drop to less than 0.001 of
the level leaving the landfill.
The two wastewater streams reported were sent to wastewater
treatment systems; one included treatment in tanks, the other used
treatment in an aerated surface impoundment. The wastewater sent to the
impoundment was reported to contain relatively high amounts of methyl
chloride (175,000 kg); thus, EPA examined this process in detail for
risks from possible releases to air and groundwater. Using the
[[Page 42334]]
estimated loading of methyl chloride reaching the surface impoundment,
EPA modeled the potential risks from air releases (see risks given in
the next section). The Agency does not believe that risks are likely to
arise from releases to groundwater because the impoundment is reported
in the 3007 survey to be a permitted hazardous waste management unit.
EPA confirmed that the unit is regulated under RCRA. The unit is
subject to the applicable regulations in 40 CFR 264 including:
groundwater monitoring, corrective action, and closure requirements.
Therefore, EPA does not believe that methyl chloride wastewaters in
this unit present any significant risk via groundwater releases.
Furthermore, methyl chloride is readily treated by biodegradation and
volatilization in wastewater treatment systems in general; the
impoundment in question is an aerated system with activated sludge that
should efficiently remove methyl chloride. Removal efficiencies for
methyl chloride from industrial wastewater treatment systems are
reported to be high (greater than 98.9%; see the U.S. EPA RREL
Treatability Database).
EPA also considered the possibility that the combustion of methyl
chloride might lead to formation of toxic products of incomplete
combustion (PICs) due to its chlorine content. The amount of methyl
chloride in the wastes that go to incineration is relatively low. The
actual loading in the wastes incinerated was reported to be 2 kg, and
these wastes were reported to go to hazardous waste incineration. The
waste sent offsite for combustion in a BIF had a higher loading (2,250
kg), however this waste was hazardous due to ignitability (due to high
levels of hydrocarbons such as hexane present) and the toxicity
characteristic (due to the presence of benzene). Therefore, the wastes
sent to combustion that contained an appreciable level of methyl
chloride were burned as a hazardous waste. EPA recently proposed rules
to address releases from hazardous waste combustion units (see 61 FR
17358, April 19, 1996). Therefore, EPA does not believe that combustion
products are likely to be of concern for the thermal treatment of
methyl chloride wastes.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a risk for each plausible mismanagement scenario.
Methyl chloride is a suspected carcinogen, and EPA used cancer risk
estimations rather than hazard quotients (the latter are used to
measure the risk for non-carcinogenic effects). Where the risk exceeds
10-6 and approaches 10-4 , exposure poses risks of concern to
human health and the environment. The results of these analyses, given
in terms of the increase in life-time cancer risk, over are shown in
Table 6.
Using bounding assumptions, the Agency estimated that management of
methyl chloride residuals in a boiler could result in an inhalation
risk of 3.3 x 10-14. Risk based on bounding assumptions for the
onsite accumulation mismanagement scenario exceeded an inhalation risk
of 10-6, and EPA then conducted high end and central tendency risk
analyses for this scenario. The estimated high end risk assessment with
plausible mismanagement of methyl chloride wastes by onsite
accumulation in an uncovered tank resulted is an inhalation risk of
4 x 10-6. The estimated high end risk assessment exceeds
1 x 10-6 only with the pairing of two high end parameters for (1)
the waste stream and receptor distance and (2) the waste stream and
storage duration. The estimated central tendency risk was
2 x 10-10. EPA believes that the risk assessment overstates the
risks from tank storage because the bounding and high end risk analyses
assumed that all of the stored solvent would volatilize from the tank;
such an assumption is very conservative because these wastes are being
accumulated for fuel blending.
Risk for air releases from an aerated impoundment were estimated
using bounding-type assumptions, in addition to the relatively large
size of the one impoundment in question. EPA estimated the risk from
the aerated impoundment to be 7 x 10-6. The Agency did not attempt
to calculate a high end risk for the impoundment, because the use of
more realistic parameters was expected to reduce the risk level below
levels of concern. For example, the closest residence to the only
impoundment in question is 2300 feet, far beyond the bounding
assumption distance of 100 meters. In addition, the surface impoundment
is regulated as a hazardous waste management unit, and is therefore
subject to the recently promulgated regulations limiting releases from
impoundments (see Subpart CC in 40 CFR Part 264).
Table 6.--Risk Assessment Results for Methyl Chloride
----------------------------------------------------------------------------------------------------------------
Risk
----------------------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Nonwastewaters:
On Site Accumulation.................... 2 x 10-10 1.8 x 10-5 4 x 10-6
Incineration............................ .............. 3.3 x 10-14 ...........
Wastewaters:
Surface Impoundment..................... .............. 7 x 10-6 ...........
----------------------------------------------------------------------------------------------------------------
All risks are cancer risk for direct inhalation. For a complete description of the risk assessment methodology
and results, see the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. Methyl chloride has been
detected at three Superfund sites. Two of the sites (a gravel pit and a
landfill) ceased operation before 1980, and therefore disposal occurred
prior to promulgation of the RCRA regulations. The third site was a
manufacturing facility which was in operation from 1902 to 1982,
indicating that all but a limited amount of disposal predated the RCRA
controls. The major activities at this third site included milling,
refrigeration, circuit board manufacturing, and photo processing. The
primary constituents of concern at all three sites are a variety of
volatile organic compounds, and it is possible that methyl chloride may
be a degradation product from other chlorinated chemicals. The ROD
database indicates that methyl chloride has contaminated the ground
water at two of the sites (no information on
[[Page 42335]]
concentration levels or affected media is available for the third
site).
Wastes deposited at the manufacturing site were reported to include
cleaning solvents used in circuit board manufacturing processes, but
the ROD database does not cite the uses of any of the wastes found at
the site. Most important, however, this site was also used as a
refrigeration plant, and methyl chloride was used as a refrigeration
agent in the past. Because methyl chloride is a gas under ambient
conditions, EPA does not believe that it is likely that wastes at these
sites were derived from the use of methyl chloride as a solvent. The
3007 Survey indicated that the only significant use of this chemical as
a solvent is in the butyl rubber industry, and none of the damage cases
were from that industry. Furthermore, the vast majority of methyl
chloride is used as a synthetic reactant in industrial chemical
processes, with very little used as a solvent. Therefore, EPA did not
consider these damage cases in its listing decision for methyl
chloride.
c. Conclusion. EPA believes that methyl chloride does not satisfy
the criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of methyl chloride as a solvent
should not be listed as hazardous waste under 40 CFR 261.31. Under
certain circumstances, the risk assessment indicates some potential
risk from onsite accumulation of methyl chloride residuals. However,
the estimated high-end cancer risk was 4 x 10-6. This risk is at
the low end of EPA's range of concern for listing (10-6 to
10-4). Furthermore, EPA believes that the risk assessment
overstated the risks presented by storage in tanks because the scenario
assumed that all of the stored solvent would escape; this seems
unlikely if the waste is being stored expressly to send for further
treatment or fuel blending. In addition, EPA believes that this risk
would not be significant for these residuals because they are regulated
hazardous wastes. The air release from aerated wastewater treatment
basins is a more plausible occurrence, and EPA calculated a bounding
risk of 7 x 10-6, also at the low-risk end of the Agency's range
of concern. However, as noted previously, the wastewaters generating
the potential risk due to aeration in an impoundment are going to a
unit that is a permitted hazardous waste management unit. Thus, in both
cases, the recently promulgated regulations limiting air releases from
storage tanks and impoundments would apply (see Subpart CC, 40 CFR Part
264).
Furthermore, potential air releases of methyl chloride from the key
waste generators are being addressed by other EPA programs. Under the
authority of the Clean Air Act, the Agency investigated air releases of
methyl chloride by butyl rubber manufacturers. EPA proposed standards
(see Standards for HAP Emissions from Process Units in the Elastomers
Manufacturing Industry, 60 FR 30801, June 12, 1995) that address
releases from these facilities, including storage tanks and wastewater
treatment systems. The Agency believes that air regulations that result
from this activity can lead to a more integrated control of risks than
the limited hazardous waste regulations that could be imposed. For all
of these reasons, therefore, the Agency has made a determination that
wastes resulting from the use of methyl chloride as a solvent should
not be listed as hazardous waste under 40 CFR 261.31.
G. Phenol
1. Industry Identification
In 1993, U.S. production of synthetic phenol was estimated to be
1.6 billion kilograms, of which 34 percent was consumed in the
production of phenolic resins (particularly phenol-formaldehyde
resins), 34 percent was consumed in the production of bisphenol-A, 15
percent was consumed in the production of caprolactam and adipic acid,
3 percent was consumed in the production of aniline, 5 percent was
consumed in the production of alkyl phenols, and 5 percent was consumed
in the production of xylenols. Five percent was exported and the
remaining 2 percent was used in other ways, including as a solvent.
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses. In response to the RCRA
Sec. 3007 Prequestionnaire of Solvent Use, 99 facilities indicated that
2.21 million kg of phenol were used as a solvent at the site in 1992.
Thirty-one facilities reported a 1993 combined use of 1.43 billion
kilograms of phenol as a solvent in response to the RCRA 3007
Questionnaire of Solvent Use. This large increase was due to a change
in reporting by one facility resulting in an increased use of over one
billion kilograms. The facility produces its own phenol for use and did
not report this use correctly in the Prequestionnaire. This facility (a
petroleum refining facility) reported the production of native phenol
as a byproduct of other processes. This native phenol is not reflected
in the synthetic phenol production totals, although its use is
reflected in 1993 totals. EPA surveyed all petroleum refineries and is
confident that additional quantities of native phenol are not produced
and subsequently used as a solvent in this industry.
Literature searches indicated that phenol may be used as an
extraction solvent in petroleum refining, especially in the processing
of lubricating oils; in biological applications; in other chemical
industry and laboratory processes; and as a reagent in chemical
analysis. Minor uses may include use as a general disinfectant, either
in solution or mixed with slaked lime, etc., for toilets, stables,
cesspools, floors, drains, etc.; for the manufacture of colorless or
light-colored artificial resins, and in many medical and industrial
organic compounds and dyes.
According to the respondents to the RCRA 3007 Questionnaire of
Solvent Use, phenol is used as a solvent for four primary purposes: as
an extraction medium in the production of lube oil stock using the
``Duo-Sol'' process; as a coating remover in the microelectronic and
automotive industries; as a reaction or synthesis medium; and as a
solvent in laboratory analysis.
The vast majority (>99.9%) of the solvent use of phenol is in the
petroleum industry. The Duo-Sol process is used widely in the
extraction of lube stock and fuel from crude oil residuals. In this
process, phenol acts as an extraction medium to separate the extract
(subsequently sent to fuels refining) and the raffinate (subsequently
sent to a dewaxing unit). The extract and raffinate enter a second set
of extraction units, where phenol is removed. The phenol is dried and
forwarded to the first extractor along with makeup phenol and crude
residual. The Duo-Sol solvent does not become spent. Losses are
attributable to attrition to product and minor loss to wastewater.
Phenolic wastewater is removed from the system and forwarded to waste
management.
Although the industries are quite different, the use of phenol as a
coating remover by the microelectronic and automotive industry is
similar. Phenol is used to remove photoresist in the production of
semiconductors. In the automotive industry, phenol is used in
combination with other solvents to remove coatings from automotive
wheels. It is also used (in conjunction with other solvents) in the
aircraft maintenance industry for depainting purposes.
Finally, much smaller uses are attributable to the use of phenol as
a reaction or synthesis medium in the
[[Page 42336]]
organic chemicals industry and as a laboratory solvent across a variety
of industries.
b. Physical/Chemical Properties and Toxicity. Phenol is a solid at
room temperature. It has a solubility in water of 80 grams per liter at
25 deg.C, indicating that it is highly soluble. With a vapor pressure
of 35 mm Hg at 25 deg.C, phenol is moderately volatile at ambient
temperatures. The Henry's Law Constant of 1.3 x 10-6 atm-m\3\/mole
for phenol indicates that phenol has a relatively low evaporation rate
from water. The Log Kow for phenol is 1.46, indicating that it has
a relatively low tendency to sorb to soil organic matter, and a low
tendency to bioaccumulate in organisms.
Phenol rapidly biodegrades to CO2 and water in soil, sewage,
fresh water, and sea water. This biodegradation will slow under
anaerobic conditions, but still occurs in groundwater.
Phenol is a Class D carcinogen and no carcinogen slope factor has
been developed. Phenol has an provisional RfC of 2 x 10-2 mg/
m3 and an RfD of 6 x 10-1 mg/kg/day; these correspond to an
air HBL of 2 x 10-2 mg/m3 and a water HBL of 20 mg/L. These
health-based numbers are provisional and have not undergone external
peer review. The Agency plans to complete an external peer review of
these health-based numbers prior to issuing a final determination. EPA
requests comments on the appropriateness of the provisional numbers,
and seeks any additional data on the toxicity of phenol.
c. Waste Generation, Characterization, and Management. Twenty-four
facilities reported the generation of residuals from the use of phenol
as a solvent totaling 52.5 million kilograms. The largest portion of
these wastes, 52.3 million kilograms, or 99.6 percent, were phenolic
wastewaters containing from 0.01% to almost 8 percent phenol. The
remaining nonwastewater residuals were high organic wastes, primarily
spent solvent (197,000 kg), and small volumes of filter media, spent
carbon, and debris containing low levels of phenol. In 1993, 92 percent
of the nonwastewaters were classified as hazardous waste, and 8 percent
was classified as nonhazardous.
Facilities generating high-volume wastewaters managed these wastes
via wastewater treatment. These facilities consist predominantly of
petroleum refineries and have sophisticated wastewater treatment
systems in place that include primary treatment, biological treatment,
and off-site secondary treatment. Facilities managed nonwastewaters
through some form of thermal treatment, either blending of the residual
for fuel or burning in a boiler or incinerator.
Based on reported waste volumes and concentration of phenol in the
wastes, loadings of phenol to each waste management practice were
calculated. Table 7 presents the total volumes of wastes and total
solvent content for the waste management practices.
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios for spent
phenol wastes. Nearly all of the solvent use of this chemical (>99.9%)
was attributed the petroleum industry, which EPA surveyed. Furthermore,
other minor uses were also examined in detail. Given that the major
uses of this solvent were very specialized (e.g., extraction of lube
oil), the Agency is confident that no other significant waste
management practices for the associated wastes are likely to exist.
To assess the potential risks for management of phenol wastes, EPA
selected several management practices for modeling. To represent the
thermal treatment process (incineration, industrial boilers, fuel
blending), EPA chose an industrial boiler. To account for risks from
the accumulation of residuals for thermal treatment, EPA modeled an
uncovered storage tank. To assess risks arising from wastewater
treatment, EPA modeled treatment in an aerated wastewater treatment
tank.
Table 7.--Waste Statistics for Phenol Residuals
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration............................................. 14 28 103,055 23,110
Fuel Blending............................................ 4 4 97,526 12,764
Energy Recovery (BIFs)................................... 1 1 9 <0.001
Storage.................................................. 1 1 153 92
WWT--Tanks............................................... 1 1 40,000,000 3,600
WWT--SI.................................................. 3 3 12,323,813 355,758
----------------------------------------------------------------------------------------------------------------
The Agency considered potential risks that might arise from the
land-based management of phenol wastes, i.e., landfills, and surface
impoundments. EPA does not believe that these management practices
present significant risk for the following reasons.
None of the 38 wastestreams containing spent phenol were reported
to go to a landfill. This is not surprising given that there are few
phenol wastes that are generated as solids. The only waste solids that
contained any significant level of phenol was spent carbon, and this
was sent for regeneration or incineration. EPA also could find no
reason to suggest that the practice of landfilling was likely to
increase. Wastewater treatment residuals may be landfilled, but are
unlikely to contain significant levels of phenol, because the chemical
is removed by such treatment due to its susceptibility to
biodegradation (>99%; see the U.S. EPA RREL Treatability Database).
Wastes with higher organic content were thermally treated, and most
(about 92%) of the thermal treatment was in hazardous waste units or
fuel blending. Therefore, none of the wastes with significant phenol
concentration are likely to be placed in a landfill.
Three wastewaters with spent phenol were reported to go to surface
impoundments, and these were impoundments that were part of a
wastewater treatment train. In two of these cases, the phenol
concentration was below the water health-based level after mixing at
the headworks, prior to reaching the surface impoundment. The phenol
concentration for one wastewater sent to an off-site wastewater
treatment system was reported to range from the HBL (20 mg/L) up to an
order of magnitude higher (180 mg/L) at the headworks. However, as
noted above, this level of phenol is expected to be efficiently treated
(>99%) by the activated sludge, such that little phenol would be
available for release to the groundwater. In general, facilities have
effluent limitations for chemicals such as phenol, so that treatment
must occur
[[Page 42337]]
prior to discharge. In addition, any phenol is quite susceptible to
biodegradation, so that any of the chemical released to the groundwater
is expected to undergo biodegradation, further reducing any potential
risk. Information on the specific surface impoundment receiving the
phenol wastewater of concern also indicates that groundwater releases
from the unit are not likely to be significant. The ground water in the
immediate area was reported to be a class 3 aquifer, which is not
considered a potential source of drinking water, and the closest
private or public well was reported to be 4,900 feet from the unit.
Therefore, due to the dilution at the headworks, the susceptibility of
phenol to biodegradation, and the specific facts related to the surface
impoundment of concern, EPA does not believe that the treatment of
phenol wastes in surface impoundments presents a significant risk.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 8.
Using bounding assumptions, the Agency estimated that management of
phenol residuals in a boiler could result in an inhalation HQ of
1.1 x 10-5. Risk based on bounding assumptions for the other
plausible mismanagement scenarios (an aerated tank and on site
accumulation) exceeded an inhalation HQ of 1, and EPA then conducted
high end and central tendency risk analyses for these scenarios.
The estimated high-end risk assessment with plausible mismanagement
of phenol wastes in an aerated tank is an inhalation HQ of 0.002, and
on site accumulation is an inhalation HQ of 0.5. These results indicate
minimal risk through the inhalation pathway for these scenarios.
Table 8.--Risk Assessment Results for Phenol
------------------------------------------------------------------------
Hazard quotient (HQ)
---------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
------------------------------------------------------------------------
Wastewaters
Treatment in
Aerated Tanks.............. 2 x 10-7 3.3 0.002
Nonwastewaters:
On Site
Accumulation............... 0.005 12 0.5
Incineration....... ........... 1.1 x 10-5 ............
------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk
assessment methodology and results, see the background document
Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. EPA investigated damage
incidents at which phenol was an identified contaminant at the site.
Based on a review of identified damage instances, no single instance of
damage was identified that could be tied to use of phenol as a solvent.
Phenol is identified as a contaminant at 25 sites in the ROD database,
however, ``phenol'' is often listed as a class of compounds. Listings
where the contaminant was listed as ``phenols'' or ``phenolics'' were
not considered by EPA further, unless a specific concentration of
phenol was identified.
Furthermore, most of the damage cases found for phenol were for
sites at which disposal took place many years ago. Only seven
facilities identified with phenol contamination appeared to have
operated since the RCRA regulations were first promulgated (1980), and
even at these sites, disposal typically occurred decades before 1980
and ceased in the early 1980's. These seven cases included: two
landfills, three chemical manufacturers (including a pesticide
manufacturer and a textile dye manufacturer), one cement production
facility, and one chemical waste storage and processing facility.
Levels of phenol reported at these seven sites showed maximum
concentrations of 20 ppm in soils, 8 ppm in groundwater, and 0.47 ppm
in surface water. However, a wide variety of chemicals were present at
these sites, and it is possible that the phenol present may have been a
contaminant or degradation product of these other chemicals. No damage
case was identified that could be tied to use of phenol as a solvent.
In addition, phenol is produced in relatively large volumes, and only a
very small fraction is used as a solvent, except for the specialized
use of phenol in the petroleum industry (none of these sites were
related to the petroleum industry). The solvent uses identified for
phenol were limited to several types of industries (petroleum refining,
electronics, and automotive industries), and none of these sectors were
represented by facilities identified as having phenol contamination on
site.
The 3007 Survey showed that, of the phenol nonwastewater residuals
reported to be generated in 1993, 92% were classified as hazardous.
Therefore, most of the wastes currently generated from use of phenol as
a solvent could not be legally managed under RCRA in the same manner as
the wastes were at the contaminated sites. For all of the above
reasons, therefore, EPA does not believe that the damage cases provide
any relevant information on the potential risks posed by phenol solvent
wastes.
c. Conclusion
EPA believes that phenol does not satisfy the criteria for listing
in 40 CFR 261.11(a)(3). Therefore, EPA is proposing that wastes from
the use of phenol as a solvent should not be listed as hazardous waste
under 40 CFR 261.31. The Agency's risk assessment indicates that spent
phenol residuals are not considered to pose a substantial risk under
the plausible management scenarios assessed. Thus, these residuals do
not appear to be managed in a manner that poses a threat to human
health and the environment. High-end analysis revealed air risks from
wastewater treatment and storage tanks were below levels of concern.
Furthermore, some of the assumptions made in these assessments are
likely to have resulted in an overestimation of risk. For example, the
storage tank scenario assumed the phenol would volatilize; this seems
somewhat unlikely if the waste is being accumulated for subsequent
incineration or fuel blending. Also, wastes with higher organic content
were thermally treated, and most (92%) treatment was in hazardous waste
units or fuel blending.
[[Page 42338]]
H. 2-Ethoxyethanol Acetate (2-EEA)
1. Industry Identification
The 1993, U.S. production of 2-ethoxyethanol acetate, also known as
ethylene glycol monoethyl ether acetate, was 22.3 million kilograms.
Data indicate a rapidly declining market for 2-ethoxyethanol acetate.
In 1983, total estimated use was 59.5 million kilograms. By 1987, that
had dropped to 36.8 million kilograms and dropped again in 1988 to 31.8
million kilograms. Exports have increased steadily and now represent 79
percent of the production in 1993. 2-Ethoxyethanol acetate is used
primarily for its solvent properties. Its most extensive use, until
recently, has been in the formulation of photoresist used in the
manufacture of semiconductors. While the formulators of photoresist
would be considered solvent users for the purposes of this study,
photoresist users generally are not. Semiconductor manufacturers may
fall within the scope of this industry study if they use 2-
ethoxyethanol acetate to clean the edges of semiconductors. However,
the use of a formulation that contains a solvent, such as photoresist,
does not constitute use of the solvent.
The use of 2-ethoxyethanol acetate in the semiconductor industry is
being phased out. Other solvents, including n-methyl pyrollidone, n-
butyl acetone, and higher order glycol ethers, such as propylene glycol
ethers, are being used as substitutes.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 121 facilities reported the use of
1.16 million kilograms of 2-ethoxyethanol acetate. In the RCRA 3007
Questionnaire, 22 facilities reported the use of 0.27 million kilograms
of 2-ethoxyethanol acetate. This decrease reflects the elimination from
further analysis of 14 facilities that are semiconductor manufacturers
whose sole use of 2-ethoxyethanol acetate is due to its presence in
photoresist. Semiconductor manufacturers who reported the use of 2-
ethoxyethanol acetate as an edge cleaner or for other cleaning purposes
were included in the use study. One additional facility was eliminated
from study because its sole use of 2-ethoxyethanol acetate was due to
its presence in a paint used in coating operations.
The facilities who reported the use of 2-ethoxyethanol acetate in
the RCRA 3007 Questionnaire use it most often for tank cleaning or
degreasing in conjunction with processes that incorporate the solvent
into the products. 2-Ethoxyethanol acetate is used for tank cleaning at
three facilities between batch manufacturing operations in which 2-
ethoxyethanol is one of the materials in the formulation. At one
facility, the tank clean out is incorporated into the next product
batch, thus reducing losses to waste. Another facility uses 2-
ethoxyethanol acetate to clean filter housings.
2-Ethoxyethanol acetate is used to adjust the viscosity of
adhesives applied during the manufacture of circuit boards. A mixture
of 2-ethoxyethanol acetate and methylene chloride (already regulated as
Hazardous Waste Numbers F001 and F002) is used to clean curtain coating
equipment in the same process. A small number of facilities in the
semiconductor manufacturing sector use 2-ethoxyethanol acetate for
thinning of photo lithographic materials. This 2-ethoxyethanol acetate
is not part of the formulation of prepurchased photoresist and, thus,
meets the Agency's definition of solvent.
2-Ethoxyethanol acetate also is used as a reaction, synthesis, or
dissolution medium for raw materials in the chemical manufacturing
sector. Finally, 2-ethoxyethanol acetate is used to a small extent in
laboratories for specialty analyses. Literature searches suggested
other uses for 2-ethoxyethanol acetate, however these uses were not
confirmed by the industry study, and were not considered in EPA's
listing analysis.
b. Physical/Chemical Properties and Toxicity. 2-Ethoxyethanol
acetate has a solubility in water of 22.9 wt. percent in water,
indicating that the solvent is highly water soluble. With a vapor
pressure of 2.0 mm Hg at 20 deg.C, 2-ethoxyethanol acetate is highly
volatile and can be expected to volatilize to air from open tanks and
containers. The Henry's Law Constant for 2-ethoxyethanol acetate is
1.9 x 10-6 atm-m3/mole, indicating that it has a moderate
rate of evaporation from water. The Log Kow for 2-ethoxyethanol
acetate is not known, however, given its high water solubility, the
chemical is not expected to sorb to soils or bioaccumulate in
organisms.
2-Ethoxyethanol acetate is not classified as a carcinogen. The
chemical has an RfC of 7 x 10-2 mg/m\3\ and a RfD of 2 x 10-2
mg/kg/day. These values correspond to an air HBL of 7 x 10-2 mg/
m3 and a water HBL of 0.7 mg/L.
c. Waste Generation, Characterization, and Management. The 22
facilities reported the generation of 1.2 million kilograms of
residuals from the use of 2-ethoxyethanol acetate as a solvent. The
residuals include 0.95 million kilograms of nonwastewaters containing
variable levels of 2-ethoxyethanol acetate. These facilities also
reported the generation of 0.25 million kilograms of wastewaters
containing 2 percent or less of 2-ethoxyethanol acetate.
Essentially all (99.8%) of the nonwastewaters in 1993 were reported
to be characteristically hazardous or mixed with listed hazardous
waste, and therefore were managed as hazardous waste through some form
of thermal treatment (fuel blending or combustion in a boiler or
incinerator). The wastewaters were managed in aerated tanks, quiescent
tanks, and through discharge to a Publicly Owned Treatment Works
(POTWs).
Based on reported waste volumes and concentrations of 2-
ethoxyethanol acetate in the waste, loadings of 2-ethoxyethanol acetate
were calculated. Table 9 presents the total volumes of wastes and total
solvent content for the different waste management practices.
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios for spent
2-ethoxyethanol acetate wastes. The use of 2-ethoxyethanol acetate has
been decreasing dramatically in recent years, thus, other generators of
this solvent waste are unlikely to exist. To assess the potential risks
for management of 2-ethoxyethanol acetate wastes, EPA selected several
management practices for modeling. To represent the thermal treatment
process (incineration, industrial boilers, fuel blending), EPA chose an
industrial boiler. To account for risks from the accumulation of
residuals for thermal treatment, EPA modeled an uncovered storage tank.
To assess risks arising from wastewater treatment, EPA modeled
treatment in an aerated wastewater treatment tank.
None of the 38 wastestreams were reported to go to land disposal in
landfills or impoundments. Solids (rags, containers, lab wastes)
containing spent solvent were all incinerated, and wastewaters are all
treated in tanks. In the face of the existing practices, EPA finds it
implausible that high organic wastes or aqueous liquids currently sent
to thermal treatment would be managed in a landfill. The large
percentage of spent 2-ethoxyethanol acetate wastes that are already
hazardous is precluded from land disposal in Subtitle D units, and no
evidence exists to suggest that any wastes containing spent 2-
ethoxyethanol acetate would be placed in a landfill. Any change from
the current practice of treatment of wastewaters in tanks to treatment
in impoundments also seems unlikely given the associated costs for such
a
[[Page 42339]]
change. However, this solvent is removed from wastewaters by
volatilization, therefore even if the practice occurred, treatment in
an aerated impoundment would be expected to rapidly remove the solvent
and make any releases to groundwater unlikely.
Table 9.--Waste Statistics for 2-Ethoxyethanol Acetate Residuals
----------------------------------------------------------------------------------------------------------------
Total
Management Practice Number of Number of Total loading
facilities streams volume (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration................................................ 9 14 641,275 23,239
Energy Recovery (BIFs)...................................... 7 13 167,547 146,554
Fuel Blending............................................... 8 9 146,612 8,569
WWT--Tanks.................................................. 2 2 3,161 3
POTW........................................................ 1 1 243,500 4,871
----------------------------------------------------------------------------------------------------------------
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 10.
Using bounding assumptions, the Agency estimated that management of
2-ethoxyethanol acetate residuals in a boiler could result in an
inhalation HQ of 2.2 x 10-8 and management in an aerated tank
could result in an HQ of 0.006. Risk based on bounding assumptions for
the other plausible mismanagement scenario (on site accumulation)
exceeded an inhalation HQ of 1, and EPA then conducted high end and
central tendency risk analyses for this scenario.
The estimated high-end risk assessment with plausible management of
2-ethoxyethanol acetate wastes in an uncovered onsite accumulation tank
yielded an inhalation HQ of 0.7. This result indicates minimal risk
through the inhalation pathway for this scenario.
Table 10.--Risk Assessment Results for 2-Ethoxyethanol Acetate
------------------------------------------------------------------------
Hazard quotient (HQ)
---------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
------------------------------------------------------------------------
Wastewaters:
Treatment in
Aerated Tanks.............. ........... 0.006
Nonwastewaters:
On Site
Accumulation............... 0.003 9 0.7
Incineration....... ........... 2.2 x 10-8
------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk
assessment methodology and results, see the background document
Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. 2-Ethoxyethanol acetate has been
detected at one Superfund site. The ROD database indicates that 2-
ethoxyethanol acetate has contaminated the soil, sediments, and ground
water at the site, although no information on the concentration level
is available. Wastes deposited at the landfill site include industrial
and municipal waste, including what was termed spent organic solvents.
However, no disposal occurred at the site after 1980, and the site
would reflect management practices that may no longer be
representative. Essentially all of the nonwastewater solvent wastes
identified in the 3007 Survey were reported to be hazardous waste, and
are subject to strict regulation. Furthermore, the ROD database does
not specifically cite the uses of any of the wastes found at the site.
Therefore, EPA did not factor this damage case into its listing
determination.
c. Conclusion. EPA believes that 2-ethoxyethanol acetate does not
satisfy the criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA
is proposing that wastes from the use of 2-ethoxyethanol acetate as a
solvent should not be listed as hazardous waste under 40 CFR 261.31.
The use of 2-ethoxyethanol is declining rapidly in industry, and the
Agency believes that this trend will continue. As discussed above, risk
bounding estimates indicate that 2-ethoxyethanol acetate spent solvent
residuals are not considered to pose a substantial risk or potential
hazard to human health and the environment through the pathways and
plausible mismanagement scenarios assessed. Furthermore, essentially
all of the nonwastewaters are already incinerated as hazardous waste or
sent to fuel blending. Risks from wastewater treatment were low and
this practice bounded out. Thus, these residuals do not appear to be
managed in a manner that poses a threat to human health and the
environment.
I. Furfural
1. Industry Identification
In 1993, U.S. production of furfural was estimated to be 39.5
million kilograms. An estimated 85 percent was consumed as an
intermediate in the production of furfural alcohol and as an
intermediate in the production of tetrahydrofuran. Other non-solvent
uses of furfural may include the manufacture of cold-molded grinding
wheels, where phenol and furfural react to form fusible, soluble resins
that may be thermally set in the presence of hexamethylenetetramine.
Less than 1 percent of furfural produced in 1993 was exported. The
remaining 14 percent is used for other purposes, including 4 percent
identified as solvent use by Questionnaire respondents.
[[Page 42340]]
2. Description of Solvent Usage and Resulting Wastes
a. Solvent Use and Questionnaire Responses. In response to the RCRA
3007 Prequestionnaire, 32 facilities indicated that 3.87 million kg of
furfural were used as a solvent at their site in 1992. Eight facilities
reported use of furfural as a solvent in response to the 3007
Questionnaire of Solvent Use, with a total 1993 use of 2.46 million
kilograms. This apparent decrease was due to large volumes reported in
the prequestionnaire that EPA determined from the full questionnaire
were not used as a solvent
Based on the responses to the Questionnaire, essentially all
(>99.99%) of the use of furfural as a solvent is in the petroleum
industry for lube oil extraction. The furfural refining process,
developed by Texaco, Inc., involves extraction of raw lubricating stock
with furfural at temperatures generally below 121 deg.C to yield
refined oil extract. The undesirable aromatic and olefinic components
of the oil are selectively dissolved by furfural and separated from the
desired paraffinic and naphthionic components. In practice, oil enters
near the bottom of a countercurrent extraction column, and furfural is
applied at the point near the top. The extract is removed from the
bottom of the column with the bulk of the furfural. Furfural is
separated from the extracted material and recovered for reuse by flash
distillation followed by steam distillation. Furfural-water mixtures
from the steam distillation are readily separated in a decanter by
drawing off the lower layer which consists of about 92 percent furfural
and 8 percent water. This layer is subsequently dried for reuse.
Furfural losses are generally 0.03 percent or less per cycle. EPA
believes that the trend for furfural use is not favorable. The industry
is moving toward the use of n-methyl pyrollidone for lube oil
extraction. The remaining solvent use reported was in specialty
applications in laboratory analyses.
Literature searches indicated other potential uses for furfural,
however Questionnaire responses did not indicate use of furfural for
these purposes.
b. Physical/Chemical Properties and Toxicity. Furfural has a
solubility in water of 83 grams per liter at 20 deg.C, indicating that
it is highly soluble in water. Furfural has a vapor pressure of 1 mm Hg
at 20 deg.C indicating that furfural is highly volatile. The Henry's
Law Constant for furfural is 8.1 x 10-5 atm-m3/mole,
indicating that furfural has a moderate evaporation rate from water.
The Log Kow is not available at this time, but the high water
solubility suggests that furfural is not likely to sorb strongly to
soils or bioaccumulate in organisms. However, the aldehyde functional
group in furfural is fairly reactive and may lead to oxidation and
degradation in the environment.
Furfural is not classified as a carcinogen. It has an RfC of 0.05
mg/m3 and an RfD of 0.003 mg/kg/day. These values correspond to
HBLs of 0.05 mg/m3 for air, and 0.1 mg/L for water.
c. Waste Generation, Characterization, and Management. The seven
responding facilities reported a combined volume of just under 177.5
million kilograms of waste, containing less than 0.1 percent furfural,
generated from processes using furfural as a solvent. Furfural wastes,
as reported in the RCRA 3007 Questionnaire of Solvent Use, are
predominantly (>99.9%) wastewaters that are managed in wastewater
treatment systems. These high-volume wastes are not likely to be
managed in another manner. One facility has a surface impoundment in
their wastewater treatment system and two treat the wastewater in
tanks. Much smaller quantities of nonwastewater furfural wastes were
reported and these were incinerated as hazardous waste.
Based on reported waste volumes and concentration of furfural in
the wastes, loadings of furfural to each waste management practice were
calculated. Table 11 presents the total volumes of wastes and total
solvent content for the waste management practices.
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios for spent
furfural wastes. Nearly all of the solvent use of this chemical
(>99.9%) was attributed to the petroleum industry, which EPA surveyed.
Given that the major use of this solvent was very specialized (e.g.,
extraction of lube oil), the Agency is confident that no other
significant waste management practices for the associated wastes are
likely to exist.
To assess the potential risks for management of phenol wastes, EPA
selected several management practices for modeling.
Table 11.--Waste Statistics for Furfural Residuals
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Wastewater Treatment--Surface Impoundment................ 1 2 24,732,124 15,940
Wastewater Treatment--Tank............................... 3 3 152,738,784 165,848
Incineration............................................. 1 2 6,220 0.07
----------------------------------------------------------------------------------------------------------------
To represent the thermal treatment process (incineration), EPA
chose an industrial boiler. To account for risks from the accumulation
of residuals for thermal treatment, EPA modeled an uncovered storage
tank. To assess risks arising from wastewater treatment, EPA modeled
treatment in an aerated wastewater treatment tanks and surface
impoundments.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure may pose a risk to human
health and the environment. The results of these analyses are shown in
Table 12.
Using bounding assumptions, the Agency estimated that management of
furfural residuals in a boiler could result in an inhalation HQ of
2.4 x 10-14 and on site accumulation could result in an inhalation
HQ of 1.2 x 10-5. For management of furfural wastewater in a
surface impoundment using bounding assumptions (e.g., no
biodegradation), the Agency estimated an inhalation HQ of 0.69, and an
ingestion HQ of 0.8.1 Risk based on bounding assumptions for the
other plausible mismanagement scenario (an aerated wastewater treatment
tank) exceeded an inhalation HQ of 1, and EPA then conducted high
[[Page 42341]]
end and central tendency risk analyses for these scenarios.
---------------------------------------------------------------------------
\1\ The bounding estimate for ingestion of contaminated
groundwater from a surface impoundment assumed a leachate factor of
1, a dilution and attenuation factor of 10, and ingestion of 2
liters per day of water and a 70 kilogram body weight. After mixing
with other wastewaters in the offsite treatment system, the initial
concentration of furfural entering the impoundment was 0.80 mg/L.
---------------------------------------------------------------------------
The estimated high end risk assessment with plausible mismanagement
of furfural wastes in an aerated wastewater treatment tank resulted in
an inhalation HQ of 0.0008. This result indicates minimal risk through
the inhalation pathway for this scenario.
Table 12.--Risk Assessment Results for Furfural
----------------------------------------------------------------------------------------------------------------
Hazard quotient (HQ)
-----------------------------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Wastewaters:
Treatment in Aerated Tanks....... 2 x 10-4 7.9................................... 0.0008
Treatment in Surface............. ........... 0.69 (inhalation).....................
Impoundment............................... ........... 0.8 (ingestion).......................
Nonwastewaters:
On Site Accumulation............. ........... 1.2 x 10-5............................
Incineration..................... ........... 2.4 x 10-14...........................
----------------------------------------------------------------------------------------------------------------
All risks are direct inhalation, unless otherwise noted. For a complete description of the risk assessment
methodology and results, see the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. Furfural has been identified as
a constituent of concern at one site investigated using the Hazard
Ranking System (HRS). However, there are no sites with a Record of
Decision (ROD) that identify furfural as a constituent. The reason for
the absence of furfural may be due to its breakdown in the environment
prior to the ROD investigation. In no instance has the use of furfural
as a solvent been linked to environmental damage in either the ROD or
HRS databases.
c. Conclusion. EPA believes that furfural does not satisfy the
criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of furfural as a solvent should not
be listed as hazardous waste under 40 CFR 261.31. Risk analyses
indicate that furfural spent solvent residuals do not pose a
substantial risk or potential hazard through the pathways assessed.
Thus, these residuals do not appear to be managed in a manner that
poses a threat to human health and the environment.
J. Cumene
1. Industry Identification
In 1993, U.S. production and imports of cumene totaled 2.24 billion
kilograms, of which 1.5 percent is exported. The major non-solvent use
of cumene is in the production of phenol and co-product acetone, which
utilizes nearly 95 percent of the available cumene. Three percent is
used either in the production of poly(alpha-methyl styrene) or for
unknown purposes, which may include use as a component in aviation
gasoline to improve the octane rating or use as a solvent.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Response. In the RCRA 3007
Prequestionnaire of Solvent Use, 67 facilities reported the use of 1.19
million kilograms of cumene in 1992. In response to the RCRA
Questionnaire, nine facilities reported the use of a combined total of
0.60 million kilograms of cumene in 1993. Four other facilities were
commercial treatment, storage, and disposal facilities that only
received cumene wastes, and were eliminated from consideration. EPA
also determined that a large amount of cumene reported as solvent use
actually was cumene contained in purchased products.
The major solvent use of cumene is as a reaction medium for
chemical production; this accounted for 82% of the total solvent use.
The other major use of cumene was for de-inking or paint removal in the
commercial printing, automotive, and aviation industries. Solvents used
for de-inking and paint removal generally contain small amounts (1 to
3%) of cumene that are less than the 10 percent before use criterion in
the existing spent solvents regulations (See 40 CFR 261.31(a)).
Finally, cumene is used in small amounts as a reaction medium in
laboratory experiments.
b. Physical/Chemical Properties and Toxicity. Cumene has a
solubility in water of 50 mg/L at 20 deg.C, indicating that it is only
slightly soluble in water. It has a vapor pressure of 3.2 mm Hg at
20 deg.C, indicating that it is highly volatile under ambient
conditions and can become an air pollutant. The Log Kow for cumene
is 3.66, indicating that cumene has a moderate tendency to sorb to
soils and some ability to bioaccumulate in organisms. Cumene is non-
persistent in water due to volatilization, with a half-life of less
than two days.
Cumene is not classified as a carcinogen. It has a water HBL of 1
mg/L, based on a reference dose of 0.04 mg/kg/day. The HBL for air
based on the RfC is 9 x 10-3 mg/m\3\.
Shortly before today's action was published, an industry group (The
Cumene Panel of the Chemical Manufacturers Association) submitted a
letter with information related to the toxicity of cumene. The letter
cited the group's comments on another EPA proposal (Hazardous Waste
Identification Rule; 60 FR 66344, December 21, 1995), which included
extensive technical information concerning the toxicity of cumene. EPA
will evaluate this information, along with information submitted by
commenters, as it relates to this listing determination.
c. Waste Generation, Characterization, and Management. Nine
facilities reported a combined generation of 224 thousand kilograms of
residuals from the use of cumene as a solvent. The majority of these
wastes (>70%; 160 thousand kg) are collected as vapors and sent
directly to on-site combustion; this accounts for the vast majority
(>95%) of the cumene loading in all of the wastes that are generated
from use as a solvent. Other wastes include spent solvent and process
solids that are sent for recovery, incinerated as hazardous, or stored
for fuel blending. Small amounts of process wastewaters are sent to
wastewater treatment systems, and the process sludges are sent to a
landfill.
Based on reported waste volumes and concentration of cumene in the
wastes, loadings of cumene were calculated. Table 13 presents the
volumes and loadings reported for each management practice.
[[Page 42342]]
EPA believes that the waste management practices reported in the
questionnaires represent the plausible management scenarios for spent
cumene. The uses of cumene as a solvent are very limited and other
significant generators of this solvent waste are unlikely to exist.
To assess the potential risks for management of cumene wastes, EPA
selected several management practices for modeling. To represent the
thermal treatment process (incineration, industrial boilers, fuel
blending), EPA chose an industrial boiler. To account for risks from
the accumulation of residuals for thermal treatment, EPA modeled an
uncovered storage tank. To assess risks arising from wastewater
treatment, EPA modeled treatment in an aerated wastewater treatment
tank.
Only one cumene waste was reported to go to a landfill, wastewater
treatment sludges, and the cumene concentration was not reported.
However, the cumene was used in small quantities in this case, so that
the maximum amount of solvent that could be in the sludge would be <28
kg. The amount actually in the sludge is expected to be much less after
wastewater treatment. Such a very small amount of cumene is highly
unlikely to present any risk in a landfill. Furthermore, cumene use in
this case was at a level (1.7%), far below the 10% level used to define
the currently listed solvents, suggesting that this particular waste is
not derived from solvent use per se, but is essentially an impurity in
the solvent mixture being used. Given the limited use of cumene as a
solvent, and the minor volumes reported, EPA believes that the practice
of landfilling will not increase. To the contrary, except for
wastewaters, nearly all wastes generated are being treated as
hazardous, suggesting that any change to Subtitle D landfills is
implausible.
Table 13.--Waste Statistics for Cumene
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total loading
facilities streams volume (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration................................................ 3 3 14,620 2,242
Boiler/Industrial Furnace................................... 1 1 160,088 128,070
Wastewater Treatment-Tank................................... 1 1 (\1\) <28
Wastewater Treatment-Surface Impoundment.................... 1 1 4,738 <47
Landfill.................................................... 1 1 1,631 <28
Storage Only................................................ 1 1 3,670 1,468
Recovery.................................................... 3 2 39,117 1,379
----------------------------------------------------------------------------------------------------------------
\1\ Not reported.
One waste containing spent cumene was reported to go to a surface
impoundment as part of a wastewater treatment train. However, the
annual loading was very small (<47 kg) and cumene levels would be
negligible (i.e., orders of magnitude below the health-based level)
after mixture with other wastewaters at the headworks prior to entering
an impoundment. Furthermore, cumene volatilizes relatively quickly from
water and is efficiently removed during wastewater treatment (>97%; see
U.S. EPA RREL Treatability Database); thus any cumene reaching
treatment impoundments would be further reduced. All wastewaters
generated from use of cumene as a solvent appear to contain very low
levels of cumene, therefore EPA believes treatment in a surface
impoundment is unlikely to present a significant risk, even if the
practice were to increase.
Finally, EPA also considered that spent cumene wastes have the
potential to form non-aqueous phase liquids (NAPLs) that might move as
a separate phase above the ground water table. These NAPLs may present
special problems, especially in assessing their transport and potential
impact. Unlike all the other target solvents that are miscible or very
soluble in water and are not likely to form NAPLs in groundwater,
cumene's water solubility is relatively low, and cumene could
theoretically form NAPLs. However, EPA believes that NAPL formation
from cumene used as a solvent is highly unlikely because such uses are
very limited, and the cumene loading to land-based disposal was minimal
(<28 kg to landfills).
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 14.
Using bounding assumptions, the Agency estimated that management of
cumene residuals in a boiler could result in an inhalation HQ of
2.8 x 10-7, management in an aerated tank could result in an
inhalation HQ of 0.03. Risk based on bounding assumptions for the other
plausible mismanagement scenario (on site accumulation) exceeded an
inhalation HQ of 1, and EPA then conducted high end and central
tendency risk analyses for these scenarios.
The estimated high end risk assessment with plausible mismanagement
of cumene wastes by on site accumulation in an uncovered tank resulted
is an inhalation HQ of 0.2. This result indicates minimal risk through
the inhalation pathway for this scenario.
Table 14.--Risk Assessment Results for Cumene
----------------------------------------------------------------------------------------------------------------
Hazard quotient (HQ)
-----------------------------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Wastewaters:
Treatment in Aerated Tanks......... ........... 0.03................................
Nonwastewaters:
On Site Accumulation............... 0.02 3..................................... 0.2
[[Page 42343]]
Boiler............................. ........... 2.8 x 10-7............................ ...........
----------------------------------------------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk assessment methodology and results, see
the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. Of the three facilities
identified with cumene contamination in the Record of Decision
Database, only one was reported to be in operation after 1980. This
facility was a landfill that operated from 1960 until 1984, when it was
abandoned. The facility reportedly received a variety of wastes from
1972 to 1974, including waste paints, painting sludges, and spent
solvents. Therefore, the disposal of the potential wastes of concern
appears to have occurred well before 1980. The specific solvents
disposed at the facility are not identified, making it difficult to
link cumene contamination to spent solvents. However, eleven solvents
currently listed as hazardous wastes were found as contaminants at the
site and may account for the reporting of spent solvent wastes.
Furthermore, cumene is a common additive to paint formulations and may
be present at the site as a result of the waste paints and painting
sludges. Given the limited uses of cumene as a solvent identified in
the 3007 Survey, and the likelihood that cumene was present as an
ingredient in paint wastes, EPA does not believe that the damage cases
are relevant to its listing decision.
c. Conclusion. EPA believes that cumene does not satisfy the
criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of cumene as a solvent should not be
listed as hazardous waste under 40 CFR 261.31. Cumene has some limited
use as a solvent, however, data indicate that the concentration of
cumene before its use as a solvent is relatively low for the most
prevalent use, deinking. As discussed above, risk bounding estimates
indicate that cumene spent solvent residuals are not considered to pose
a substantial risk or potential hazard to human health and the
environment through the pathways assessed. Furthermore, essentially all
of the cumene in the solvent wastes generated are thermally treated as
hazardous or recovered. Thus, these residuals do not appear to be
managed in a manner that poses a threat to human health and the
environment.
K. Cyclohexanol
1. Industry Identification
The combined production and import data show 10.0 million kilograms
of available cyclohexanol, based on 1990 production and 1993 import
data. Non-solvent uses of cyclohexanol include cyclohexamine production
(54 percent) and pesticide production (14 percent). An unknown amount
is used in the oxidation of cyclohexanol to adipic acid (a key
ingredient in nylon 66) and cyclohexanol can be used in the production
of caprolactam. Some cyclohexanol was reported as solvent use by RCRA
3007 Questionnaire respondents within the petroleum industry. There is
no evidence of significant use of cyclohexanol as a solvent outside the
petroleum industry.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 37 facilities reported the use of
cyclohexanol as a solvent, with a total 1992 use of greater than 100
thousand kg. In the RCRA 3007 Questionnaire, six facilities reported
the use of cyclohexanol in 1993, with a total of greater than 1,000 kg
and less than 20,000 kg (the exact volume used is confidential business
information). The Agency removed a film manufacturer from further study
because it was determined that the facility actually uses
cyclohexanone, a portion was also found to be reported by a TSD, and
other firms responding to the prequestionnaire in 1992 discontinued or
reduced use in 1993.
According to data collected in the RCRA 3007 Questionnaire, the
major solvent use of cyclohexanol is as an extraction solvent in the
production of cyclohexane; however, the cyclohexanol used in this
fashion was reported to be recycled in the process. Therefore, wastes
generated arose primarily from smaller amounts of cyclohexanol used in
specialized laboratory settings.
b. Physical/Chemical Properties and Toxicity. Cyclohexanol has a
solubility in water of 56,700 mg/L at 15 deg.C, indicating that it is
highly soluble in water. With a vapor pressure of 1 mm Hg at 20 deg.C,
cyclohexanol is moderately volatile. The Log Kow for cyclohexanol
is 1.23, indicating that cyclohexanol has a low potential for sorbing
to soil. The Henry's Law Constant is 4.5 x 10\6\ atm-m\3\/mole
indicates that cyclohexanol has a low evaporation rate from water.
Data on the health effects of cyclohexanol are limited. Provisional
values for the RfD and RfC have been calculated from one study. The
provisional RfC is 6 x 10-5 mg/m\3\ and the RfD is 1.7 x 10-5
mg/kg/day. These correspond to HBLs of 6 x 10-5 mg/m\3\ for air
and 0.0006 mg/L for water. These health-based numbers are provisional
and have not undergone external peer review. The Agency plans to
complete an external peer review of these health-based numbers prior to
issuing a final determination. EPA requests comments on the
appropriateness of the provisional numbers, and seeks any additional
data on the toxicity of cyclohexanol.
c. Waste Generation, Characterization, and Management. Six
facilities initially reported a combined generation of greater than 9
million kilograms of residuals from the use of cyclohexanol as a
solvent. However, essentially all of this volume was treatment
residuals reported by one facility. This facility reported details for
the treatment train that led to a misleading volume as follows. Spent
solvent (5,000 kg containing 11 kg of cyclohexanol) is sent to an
onsite incinerator; the scrubber water from this hazardous waste
incinerator (320 million kg containing no solvent) is then treated in a
wastewater treatment system (as hazardous waste) to produce
biotreatment sludge (9 million kg containing no solvent). After
incineration all subsequent treatment residuals are expected to contain
negligible amounts of cyclohexanol. Therefore, only the initial volume
going to the incinerator contained cyclohexanol, and this was the only
volume from this treatment process that was considered further. The
corrected volume of waste generated that contained spent cyclohexanol
is actually 44,110 kg, consisting of 43,360
[[Page 42344]]
kg of spent solvent (containing 16 kg of cyclohexanol), and 750 kg of
filter media reported to contain a ``negligible'' concentration of
cyclohexanol. Table 8 presents the waste volumes and loadings of
cyclohexanol for the management practices reported.
In 1993, 98.3 percent of the wastes generated with spent
cyclohexanol were treated as hazardous, and the remaining 750 kg of
filter media as nonhazardous. Table 15 summarizes that volumes and
loadings estimated for cyclohexanol.
Nearly all of the cyclohexanol wastes were reported to be
incinerated in a hazardous waste BIF. One small wastestream (750 kg) of
filter media was reported to go to a landfill, however the
concentration was negligible and presumed zero. Given the specialized
and limited uses of cyclohexanol as a solvent, EPA does not believe
that other wastes or management practices are likely to be significant.
Therefore, to assess possible risks from management of cyclohexanol
wastes from solvent use, EPA modeled combustion in a boiler to account
for incineration, and storage in an open accumulation tank.
Table 15.--Waste Statistics for Cyclohexanol
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Landfill................................................. 1 1 750 (\1\)
Incineration............................................. 4 5 43,360 16
----------------------------------------------------------------------------------------------------------------
\1\ Negligible.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure may pose a risk to human
health and the environment. The results of these analyses are shown in
Table 16.
Using bounding assumptions, the Agency estimated that management of
cyclohexanol residuals in a boiler could result in an inhalation HQ of
7.2 x 10-9. Risk based on bounding assumptions for the other
plausible mismanagement scenario (on site accumulation) exceeded an
inhalation HQ of 1, and EPA then conducted high end and central
tendency risk analyses for these scenarios.
The estimated high end risk assessment with plausible mismanagement
of cyclohexanol wastes by on site accumulation in an uncovered tank is
an inhalation HQ of 0.3. This result indicates minimal risk through the
inhalation pathway for this scenario.
Table 16.--Risk Assessment Results for Cyclohexanol
----------------------------------------------------------------------------------------------------------------
Hazard quotient (HQ)
-----------------------------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Nonwastewaters:
On Site Accumulation............... 0.01 2..................................... 0.3
Incineration....................... ........... 7.2 x 10-9............................ ...........
----------------------------------------------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk assessment methodology and results, see
the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. Cyclohexanol has been detected
at one Superfund site. The ROD database indicates that cyclohexanol has
contaminated the soil and ground water at the site. The site was
occupied by a waste oil company for ten years, and it was contaminated
by a wide variety of chemicals. The ROD database does not specifically
cite the uses of any of the cyclohexanol found at the site, and given
the rare use of this chemical as a solvent, EPA did not consider this
damage case to be relevant to its decision.
c. Conclusion. EPA believes that cyclohexanol does not satisfy the
criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of cyclohexanol as a solvent should
not be listed as hazardous waste under 40 CFR 261.31. It appears there
is very limited use of cyclohexanol as a solvent. The residuals
generated from the use of cyclohexanol as a solvent contain negligible
levels of cyclohexanol and are generally managed by thermal treatment
as a hazardous waste. As discussed above, risk bounding estimates
indicate that cyclohexanol solvent residuals are not considered to pose
a substantial risk or potential hazard to human health and the
environment during combustion or storage.
L. Isophorone
1. Industry Identification
Production information from 1995 shows 79.3 million kilograms were
produced worldwide. However, only one domestic manufacturer exists. The
non-solvent uses of isophorone include use as a raw material in the
production of isophorone-derived aliphatic diisocyanates; as an
intermediate in the manufacture of 3,5-xylenol-3,3,5-
trimethylcyclohexanol and 3,3,5-trimethyl-cyclohexamine; as a starting
material and/or emulsifier for insecticides, xylenol-formaldehyde
resins, disinfectants, and wood preservatives; and in the synthesis of
vitamin E. Although isophorone may be used as a solvent for such
purposes as commercial preparations of lacquers, inks, vinyl resins,
copolymers, coatings and finishings, ink thinners, and pesticides, and
formulators of these products would be considered solvent users for the
purposes of this study, the use of these products generally is not.
Users of these products may fall within the scope of the industry study
only if they use isophorone for cleaning or other solvent purposes.
[[Page 42345]]
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 30 facilities reported a combined use
of greater than 0.3 million kilograms of isophorone. In the RCRA 3007
Questionnaire, six facilities reported a total use of 0.24 million
kilograms of isophorone as a solvent in 1993. The largest user of
isophorone used a solvent mixture containing significantly less than 10
percent isophorone before use.
Questionnaire respondents indicate that isophorone is used
primarily as a diluent cleaning out tank bottoms, and in coating
processes. At an aluminum manufacturing facility, isophorone-bearing
paint and additional isophorone paint thinner enter the coil coating
operation. The coil is coated and waste paint/thinner is drummed prior
to fuel blending. At a printing facility, isophorone is mixed with ink
and screened onto the material to be printed. The printed material is
dried. Waste ink from the operation is drummed prior to off-site fuel
blending. A pilot plant in the chemical industry uses isophorone in the
coating process, where it is added in the coating steps. Isophorone is
used in the manufacture of magnetic disks during the coating process,
where isophorone and other raw materials are mixed and coated onto the
disk substrate.
b. Physical/Chemical Properties and Toxicity. Isophorone has a
solubility in water of 12,000 mg/L at 25 deg.C, indicating that it is
highly soluble in water. With a vapor pressure of 0.38 mm Hg at
20 deg.C, isophorone is volatile. The Henry's Law Constant of
6.2 x 10-6 atm-m\3\ mole indicates that isophorone has a low to
moderate rate of evaporation from water. It has a Log Kow of 1.70
and it is expected to have limited tendencies to sorb to soils and to
bioaccumulate. Isophorone can biodegrade.
Isophorone is a suspected carcinogen by ingestion. Using an oral
carcinogen slope factor (CSF) of 9.5 x 10-4 (mg/kg/day)-1,
EPA calculated that exposure to a water concentration of 0.04 mg/L for
70 years would correspond to a cancer risk of 1 x 10-6. EPA also
estimated a provisional air HBL of 4 x 10-3 mg/m\3\. These health-
based numbers are provisional and have not undergone external peer
review. The Agency plans to complete an external peer review of these
health-based numbers prior to issuing a final determination. EPA
requests comments on the appropriateness of the provisional numbers,
and seeks any additional data on the toxicity of isophorone.
c. Waste Generation, Characterization, and Management. Six
facilities reported the generation of 0.75 million kilograms of
residuals from the use of isophorone as a solvent. The concentration of
isophorone in all these residuals ranges from 0.1 percent to 8 percent,
except one that was 45 percent. All wastes contained little or no water
and were primarily organic liquids. Because of the primary use of
isophorone as a diluent for tank bottoms or coating processes,
wastewaters were not generated. The solids generated were containers,
rags and similar wastes contaminated with solvent. All isophorone
residuals are managed by some type of thermal treatment, either fuel
blending, energy recovery in a BIF, or incineration.
Based upon reported waste volumes and concentration of isophorone
in the wastes, loadings of isophorone were calculated. Table 17
presents the volumes and loadings for each waste management practice.
All of the wastes identified in the questionnaire are managed as
hazardous. Most are hazardous because of a characteristic (usually
ignitability) or are listed based on other constituents (e.g., F003).
One waste volume generated (705 thousand kg) was not hazardous, but was
sent to a hazardous waste BIF; this waste resulted from the use of
isophorone as a minor ingredient in a diluent to thin heavy end
residuals from waste storage tanks to aid pumping the heavy ends to an
on-site hazardous BIF. This stream also results from use of isophorone
at a concentration of 8.8 percent, which is just below the 10 percent
threshold EPA has used in the past to define solvent use in previous
solvent listings (e.g., F001). However, EPA included this waste in its
evaluation in order to more fully characterize potential risks from
these wastes.
Table 17.--Waste Statistics for Isophorone
----------------------------------------------------------------------------------------------------------------
Total
Management practice Number of Number of Total volume loading
facilities streams (kg) (kg)
----------------------------------------------------------------------------------------------------------------
Incineration............................................. 3 4 12,186 2,248
Boiler/Industrial Furnace................................ 1 2 * 705,180 * 9,873
Fuel Blending............................................ 1 4 36,329 1,816
----------------------------------------------------------------------------------------------------------------
* Based on two wastestreams in 3007 Questionnaire derived from isophorone at a before use concentration of <10%.
Because of the limited uses of isophorone as a solvent, EPA does
not believe that other wastes or management practices are likely to be
significant. Therefore, to assess possible risks from management of
isophorone wastes from solvent use, EPA modeled combustion in a boiler
to account for thermal treatment (incineration, BIFs, and fuel
blending), and storage in an open accumulation tank.
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency performed risk bounding and high end
risk estimates using the approaches described earlier (see Section
II.C) to obtain a hazard quotient (HQ) for each plausible mismanagement
scenario. Where the HQ exceeds 1, exposure is expected to pose a risk
to human health and the environment. The results of these analyses are
shown in Table 18.
Using bounding assumptions, the Agency estimated that management of
isophorone residuals in a boiler could result in an inhalation HQ of
6.2 x 10-8. Risk based on bounding assumptions for the other
plausible mismanagement scenario (on site accumulation) exceeded an
inhalation HQ of 1, and EPA then conducted high end and central
tendency risk analyses for this scenario.
The estimated high end risk assessment with plausible mismanagement
of isophorone wastes by on site accumulation in an uncovered tank
resulted in an inhalation HQ of 0.6. This result indicates minimal risk
through the inhalation pathway for this scenario. Furthermore, this
risk resulted from one large wastestream that was used to mobilize tank
heavy ends for pumping to an onsite hazardous waste BIF. The resulting
waste mixture was not reported stored, and is likely pumped directly to
the BIF for combustion, therefore the scenario appears to be
unrealistic for this wastestream in any case.
[[Page 42346]]
Table 18.--Risk Assessment Results for Isophorone
----------------------------------------------------------------------------------------------------------------
Hazard quotient (HQ)
-----------------------------------------------------------------
Plausible mismanagement practice Central
tendency Bounding High end
----------------------------------------------------------------------------------------------------------------
Nonwastewaters:
On Site Accumulation............... 0.01 14.................................... 0.6
Incineration....................... ........... 6.2 x 10-8 ...........
----------------------------------------------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk assessment methodology and results, see
the background document Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. EPA investigated damage
incidents at which isophorone was an identified contaminant at the
site. Based on a review of identified damage instances, no single
instance of damage was identified that could be tied to use of
isophorone as a solvent. Isophorone was identified as a contaminant at
17 sites in the ROD database, however most of these sites arose from
disposal practices that occurred many years ago, prior to promulgation
of the RCRA regulations. Of the four facilities identified with
isophorone contamination that have operated since 1980, two were
landfills, one a chemical waste storage and processing facility, and
one a pesticide manufacturing facility. All four of these facilities
have also been in operation for many years before 1980, and all sites
were contaminated with a myriad of chemicals. The maximum levels of
isophorone found at the four sites were 0.014 ppm in groundwater, 59
ppm in soil, and 0.13 ppm in surface water. For the landfills and
chemical treatment facility, the use of the isophorone prior to being
found at the site is impossible to ascertain. However, in the case of
the pesticide manufacturer, isophorone has been used as a starting
ingredient in the production of pesticides and insecticides, and
isophorone becomes part of the final product. This would not be
considered a solvent use.
The solvent uses identified for isophorone are limited to only two
industry sectors--agricultural chemicals and coating/printing
operations, and none of these sectors were represented by facilities
identified as having isophorone contamination onsite. Given that the
current use of isophorone appears to be very limited, and considering
that all of the isophorone wastes generated in 1993 were treated as
hazardous, EPA does not believe that these damage cases are relevant to
the listing determination.
c. Conclusion. EPA believes that isophorone does not satisfy the
criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA is
proposing that wastes from the use of isophorone as a solvent should
not be listed as hazardous waste under 40 CFR 261.31. As discussed
above, risk bounding estimates indicate that isophorone solvent
residuals are not considered to pose a substantial risk or potential
hazard to human health and the environment through the inhalation
pathway from burning. Furthermore, all reported residuals were treated
as hazardous waste, and all were sent to thermal treatment. Thus, these
residuals do not appear to be managed in a manner that poses a threat
to human health and the environment.
M. 2-Methoxyethanol Acetate (2-MEA)
1. Industry Identification
In 1992, 2-methoxyethanol acetate (2-MEA) production was estimated
to be approximately 500,000 kilograms based on 1988 data; however, the
Chemical Manufacturers Association reported that production of this
chemical ceased in 1992. It was manufactured only by Union Carbide,
under the trade name Methyl Cellosolve Acetate. The use of 2-
methoxyethanol acetate is reported to be 82,000 kilograms. The demand
for 2-methoxyethanol acetate has declined and current U.S. use is
limited to specialty solvents. Based on industry contacts, EPA believes
that reported use reflects consumption of stockpiled chemicals.
2. Description of Solvent Usage and Resulting Waste
a. Solvent Use and Questionnaire Responses. In the RCRA 3007
Prequestionnaire of Solvent Use, 16 facilities reported the use of 2-
methoxyethanol acetate, with use of greater than 4,000 kilograms in
1992. In the RCRA 3007 Questionnaire, three facilities reported the use
of 1,672 kilograms of 2-methoxyethanol acetate in 1993.
Although limited in use, RCRA 3007 Questionnaire respondents
indicated that 2-methoxyethanol acetate was used as a diluent in a
coating formulation. It also was used as a reaction or synthesis medium
and for dissolution.
Literature searches indicate other past uses for 2-methoxyethanol
acetate, however, these uses were not confirmed by the RCRA 3007
Questionnaire respondents.
b. Physical/Chemical Properties and Toxicity. 2-Methoxyethanol
acetate is completely soluble in water. With a vapor pressure of 1.2 mm
Hg at 20 deg.C, 2-methoxyethanol acetate is moderately volatile. The
Henry's Law Constant is 7.6 x 10-7 atm-m3/mole, indicating
that 2-methoxyethanol acetate has a low rate of evaporation from water.
The Log Kow is -0.76, indicating that 2-methoxyethanol acetate has
a low tendency to sorb to soil organic matter or to bioaccumulate.
2-Methoxyethanol acetate is not classified as a carcinogen. EPA
estimated a provisional RfC of 0.02 mg/m3 and RfD of
5.7 x 10-3 mg/kg/day. These correspond to provisional HBLs of
2 x 10-2 mg/m\3\ for air, and 0.2 mg/L for water. These health-
based numbers are provisional and have not undergone external peer
review. The Agency plans to complete an external peer review of these
health-based numbers prior to issuing a final determination. EPA
requests comments on the appropriateness of the provisional numbers,
and seeks any additional data on the toxicity of 2-methoxyethanol
acetate.
c. Waste Generation, Characterization, and Management. Three
facilities reported the generation of 16,329 kilograms of 2-
methoxyethanol acetate solvent residuals. These residuals include 1,362
kg of debris (i.e., rags and containers), almost 15,000 kg of spent
solvents, and negligible amounts (<1 kg) of process sludges. For the
most part, these residuals had very low (<1 percent) concentrations of
2-methoxyethanol acetate in the residual. Only one residual from one
facility had a higher concentration, in a range of 20-50 percent. Given
the limited uses reported (diluent in coating and reaction media),
wastewaters are not expected and were not reported. Waste management
practices reported were hazardous waste incineration and energy
recovery in a BIF.
Table 19 presents the waste volumes and loadings of 2-
methoxyethanol
[[Page 42347]]
acetate for each waste management practice. All waste went to a
hazardous waste incinerator or BIF. Given the limited and decreasing
use of this chemical as a solvent, EPA believes that these represent
the only significant management practices likely to be found.
Therefore, to assess possible risks from management of 2-methoxyethanol
acetate wastes from solvent use, EPA modeled combustion in a boiler to
account for thermal treatment (incineration, BIFs), and storage in an
open accumulation tank.
Table 19.--Waste Statistics for 2-Methoxyethanol Acetate
----------------------------------------------------------------------------------------------------------------
Number of Number of Total volume Total
Management practice facilities streams (kg) loading (kg)
----------------------------------------------------------------------------------------------------------------
Incineration............................................ 1 3 16,322 963
Boiler/Industrial Furnace............................... 1 3 7 0.07
----------------------------------------------------------------------------------------------------------------
3. Basis for Proposed No-List Determination
a. Risk Assessment. The Agency estimated risk using bounding
assumptions as described earlier (see Section II.C) to obtain a risk
for each plausible mismanagement scenario. Where the HQ exceeds 1,
exposure may pose a risk to human health and the environment. The
results of these analyses are shown inTable 20.
Using risk bounding assumptions, the Agency estimated that
management of 2-methoxyethanol acetate residuals in a boiler could
result in an inhalation HQ of 7.9x10-13 and by onsite accumulation
could result in an inhalation HQ of 0.4. These results indicate minimal
risk through the inhalation pathway for these scenarios.
Table 20.--Risk Assessment Results for 2-Methoxyethanol Acetate
------------------------------------------------------------------------
Hazard quotient (HQ)
Management practice ----------------------------
Bounding
------------------------------------------------------------------------
Nonwastewaters:
On Site Accumulation............ 0.4
Incineration.................... 7.3 x 10-13
------------------------------------------------------------------------
All risks are direct inhalation. For a complete description of the risk
assessment methodology and results, see the background document
Assessment of Risks from the Management of Used Solvents.
b. Environmental Damage Incidents. 2-Methoxyethanol acetate has
been detected at one Superfund site. The ROD database indicates that 2-
methoxyethanol acetate has contaminated the soil, sediments, and ground
water at the site, although no information on the concentration level
is available. Wastes deposited at the municipal landfill site include
drums of industrial waste that were buried either intact, punctured, or
crushed. The ROD database does not specifically cite the uses of any of
the wastes found at the site. Given the declining production and
solvent use of 2-methoxyethanol acetate, and the fact that the small
amount of waste currently generated is treated as hazardous waste, EPA
does not believe this damage case provides any relevant information on
possible future management of the chemical. Therefore, EPA did not
consider this damage case information in the listing determination.
c. Conclusion. EPA believes that 2-methoxyethanol acetate does not
satisfy the criteria for listing in 40 CFR 261.11(a)(3). Therefore, EPA
is proposing that wastes from the use of 2-methoxyethanol acetate as a
solvent should not be listed as hazardous waste under 40 CFR 261.31.
The use of 2-methoxyethanol acetate has been declining in recent years
and does not appear to be manufactured domestically. Further, as
discussed above, risk bounding estimates indicate that 2-methoxyethanol
spent solvent residuals are not considered to pose a substantial risk
or potential hazard to human health and the environment through the
pathways assessed. Residuals from the use of 2-methoxyethanol acetate
as a solvent generally are managed as hazardous waste, typically being
co-managed with other wastes already listed under 40 CFR Part 261.
Thus, these residuals do not appear to be managed in a manner that
poses a threat to human health and the environment.
N. Chemicals With No Significant Use as Solvents
The following four chemicals were not reported to have any
significant uses as solvents: p-dichlorobenzene, benzyl chloride,
epichlorohydrin, and ethylene dibromide. On the 1993 Preliminary
Questionnaire, the major recipients were hazardous waste incinerators,
fuel blenders, or cement kilns who could not tell if the wastes
containing these chemicals had, in fact, solvent use. Except in once
case (for p-dichlorobenzene), all other use reported as a solvent at
any facility was below 10 kg per year. In these cases, reports of
``solvent use'' often turned out to be quantities purchased for a
facility's research laboratory, without regard as to whether the
chemical was actually used as a solvent. The Agency contacted
facilities that reported apparent solvent use of larger quantities of
these chemicals to confirm whether or not solvent use was actually
taking place. In all cases, the facility indicated that solvent use was
not occurring.
One of the chemicals, p-dichlorobenzene, is a solid at room
temperature, which limits its utility as a solvent. The others are
relatively reactive chemicals, which also makes them unsuitable for
most solvent applications. All the chemicals may appear as an
ingredient in product formulations, sometimes as a chemical impurity.
The chemicals are most often used as chemical reactants, pesticides,
sterilizing agents, or in other non-solvent uses. Information collected
by EPA on each of the four chemicals is discussed below.
1. p-Dichlorobenzene
In 1993, U.S. production of p-dichlorobenzene was reported to be
35.9 million kilograms. Data from 1993 indicate that most of the uses
that could be identified were nonsolvent uses, including the production
of polyphenylene sulfide resin, in room deodorant blocks, and in moth
control products. Industry studies indicate that p-dichlorobenzene is
used in very limited amounts as a solvent, but is more typically found
as a contaminant in o-dichlorobenzene, a listed solvent.
In response to the RCRA Sec. 3007 Prequestionnaire of Solvent Use,
the total volume used by 26 Prequestionnaire respondents for 1992 was
greater than 25,000 kilograms. Much of that ``use'' was reported by
facilities that treat waste by incineration or in a cement kiln; its
use was also erroneously reported due to the presence of p-
dichlorobenzene as an impurity in o-dichlorobenzene, a listed solvent.
Six facilities reported the use of 6,288 kilograms of p-dichlorobenzene
as a solvent in response to the RCRA Sec. 3007 Questionnaire of Solvent
Use.
[[Page 42348]]
The chemical was used in very small volumes (<2kg), except for one
facility; this metal finishing facility reported using p-
dichlorobenzene in a solvent mixture to remove coatings from metal
parts in paint stripping tanks. However the facility reported very
little solvent in the resulting wastestreams; furthermore, this
facility indicated in its questionnaire response that it intended to
cease using p-dichlorobenzene and switch to a less toxic solvent. In
general, the data from most industries indicate that the chemical is
primarily used in research and laboratory applications. p-
Dichlorobenzene has a melting point of 54 deg.C and is a solid at room
temperature, limiting possible solvent uses.
Wastes from p-dichlorobenzene use were generated as spent lab
solvents, laboratory wastewaters, spent solvents, and as part of
process wastewaters. Five facilities reported that p-dichlorobenzene
solvent waste was sent to hazardous waste incineration or a BIF; this
includes the facility that used most of the p-dichlorobenzene. One
facility reported discharging process wastewaters to a sanitary sewer
(POTW). The total amount of p-dichlorobenzene reported in the
wastestreams generated from solvent use in 1993 was <17 kg.
No instance of environmental damage relating to the use of p-
dichlorobenzene as a solvent has been identified. This chemical is
relatively common at CERCLA and other environmental damage sites, but
always appears with other contaminants, most often solvents classified
as F001-F005 wastes. p-Dichlorobenzene commonly occurs with high
concentrations of o-dichlorobenzene, probably due to the presence of
the p-isomer as an impurity. Other damage sites at which p-
dichlorobenzene has been detected include former dye manufacturers;
however, a nonsolvent use for p-dichlorobenzene is as an intermediate
in a dye manufacturing process. Given the extremely low solvent use
identified for p-dichlorobenzene, it is not likely that any of the
damage incidents identified were the result of mismanagement of p-
dichlorobenzene used as a solvent.
The Agency proposes that wastes from the use of p-dichlorobenzene
as a solvent should not be listed as hazardous waste under 40 CFR
261.31. The use of p-dichlorobenzene as a solvent appears to be
extremely limited, having specialty applications in laboratories and
little or no industrial solvent use. p-Dichlorobenzene may be present
in wastes generated from use of o-dichlorobenzene as a solvent, because
the para-isomer is an impurity in the o-dichlorobenzene. However, o-
dichlorobenzene is already included in the F002 solvent listing,
therefore, these wastes would already be regulated as hazardous.
Residuals from the use of p-dichlorobenzene as a solvent generally are
very small volumes and the total amount of p-dichlorobenzene in
residuals was only 17 kg in 1993. Given that wastes generated were
either incinerated or sent to a POTW where it would be further diluted
by large volumes of other wastewater and treated, EPA believes that
these wastes present no significant risks to human health and the
environment.
2. Benzyl Chloride
Data from 1993 indicate that U.S. demand for benzyl chloride was
33.2 million kilograms. Nonsolvent applications account for nearly 100
percent of the reported uses of benzyl chloride. There were no
industrial solvent uses of benzyl chloride identified during the
industry study. Monsanto Corporation informed EPA in February 1993 that
it is the only U.S. producer of benzyl chloride and that benzyl
chloride has no current solvent uses.
Data from the RCRA 3007 Prequestionnaire reported the total volume
used by the 12 Prequestionnaire respondents was 21,809 kg in 1992.
Nearly all of that ``use'' was reported by TSD facilities that accepted
the constituent for thermal treatment. Five facilities reported the
1993 use of 6.4 kg of benzyl chloride in response to the RCRA 3007
Questionnaire of Solvent Use; the 1992 solvent use was reported to be
5.9 kg. Data for 1993 indicated that the total amount of benzyl
chloride solvent waste generated by five facilities in 1993 was 36,817
kg, and that these waste contained a total loading of 1.9 kg of benzyl
chloride.
Benzyl chloride hydrolyzes in water and decomposes rapidly in the
presence of most common metals (e.g., iron). The aqueous hydrolysis
rate for benzyl chloride corresponds to a half-life of 14 hours; this
means that the concentration of benzyl chloride in water would decrease
by a factor of 1000 in less than 6 days. Due to its rapid
transformation in environmental media, benzyl chloride is not expected
to be persistent in moist soil or water. Given its high reactivity, it
is highly unlikely that this chemical could find significant use as a
solvent. Of the facilities providing information in the RCRA 3007
Questionnaire, each facility used 1 kg or less of benzyl chloride. The
benzyl chloride solvent waste generated in 1993 were classified as
spent solvents, and all were reported incinerated as hazardous. Given
the extremely low use rates, the concentration of benzyl chloride in
the waste solvents is negligible (<2kg).
Benzyl chloride has been identified as a constituent of concern at
one site investigated using CERCLA. However, there are no sites that
have undergone a ROD that identifies benzyl chloride as a constituent.
The reason for the absence of benzyl chloride may be due to its
breakdown in the environment prior to the ROD investigation. In no
instances has the use of benzyl chloride as a solvent been linked to
environmental damage in either the ROD or HRS databases.
The Agency proposes that waste from the use of benzyl chloride as a
solvent not be listed as hazardous waste under 40 CFR 261.31. The use
of benzyl chloride as a solvent appears to be very limited, having
specialty applications in laboratories and no known industrial solvent
use. Residuals from the apparent use of benzyl chloride as a solvent
generally are very small volumes and contain negligible concentrations
of the solvent. The reactivity of the chemical severely limits any
solvent use. The relatively rapid hydrolysis of benzyl chloride also
indicates that the substance will not persist long enough to present
significant risk even if released to the environment in such small
quantities. Furthermore, all residuals are managed as hazardous waste.
Thus, EPA believes that there are no residuals from solvent use that
pose a threat to human health and the environment.
3. Epichlorohydrin
The estimated U.S. production and import of epichlorohydrin were
229.6 million kilograms, based on 1989 production data and 1993 import
data. Nonsolvent use of epichlorohydrin includes use in the production
of epoxy resins, glycerin, epichlorohydrin elastomers.
In response to the prequestionnaire, 14 facilities indicated that
epichlorohydrin was used as a solvent at their site. These facilities
reported a total use of more than 76,365 kilograms in 1992. Nearly all
of these ``uses'' were either misreported as solvent use (when
epichlorohydrin was, in fact, a chemical reactant) or the use was
reported by a facility that accepted the constituent for thermal
treatment or reclamation. Three facilities reported use 3.4 kilograms
of epichlorohydrin as a solvent in response to the RCRA section 3007
Questionnaire of Solvent Use. The sharp decline reflects the
elimination of a treatment facility from further study, since the use
of the epichlorohydrin as a solvent prior to treatment could not be
confirmed.
[[Page 42349]]
Literature searches indicate that epichlorohydrin has been used as
an ingredient in natural and synthetic resins, gums, cellulose esters
and ethers, paints, varnishes, nail enamels, lacquers, and cement for
celluloid. Finally, epichlorohydrin has been used by the textiles
industry to modify the carboxyl groups of wool, in the preparation of
fibers, and in dyeing fibers.
Three facilities provided data in the section 3007 Questionnaire of
Solvent Use. One facility used only .001 kg in 1993; the wastes
generated (25 kg) were classified as lab wastes and sent off-site to a
hazardous waste incinerator or to a nonhazardous energy recovery
facility. The other two facilities, both pharmaceutical companies, used
1 kg and 2.36 kg of epichlorohydrin, respectively, in 1993. One of the
two pharmaceutical facilities reported the generation of a total of
17,254 kg of spent solvent or lab waste, which was sent off-site for
hazardous waste incineration. The other facility generated 5,000 kg of
spent solvent or lab waste, which was incinerated on-site in a
hazardous waste incinerator. These wastes contained epichlorohydrin in
part per million concentrations.
Epichlorohydrin has not been identified as a constituent of concern
at any sites investigated using the HRS. In addition, there are no
sites that have undergone a ROD that identify epichlorohydrin as a
constituent. The reason for the absence of epichlorohydrin may be due
to its breakdown in the environment prior to the ROD or HRS
investigation. Epichlorohydrin hydrolyzes relatively rapidly in water
with a half-life of 8.2 days. In no instances has the use of
epichlorohydrin as a solvent been linked to environmental damage in
either the ROD or HRS databases.
The Agency proposes that waste from the use of epichlorohydrin as a
solvent not be listed as hazardous waste under 40 CFR 261.31. The use
of epichlorohydrin as a solvent, if it truly occurs, appears to be
limited to specialty applications in laboratories and no known
industrial solvent use. Residuals from the apparent use of
epichlorohydrin as a solvent generally are very small volumes and
contain negligible concentrations of the solvent. The reactivity of the
chemical severely limits any solvent use. The relatively rapid
hydrolysis of epichlorohydrin also indicates that the substance is
unlikely to persist long enough to present significant risk even if
released to the environment in such small quantities. Furthermore, all
of the waste was reported to be incinerated as hazardous waste. Thus,
EPA believes that there are no residuals from solvent use that pose a
threat to human health and the environment.
4. Ethylene Dibromide
The estimated U.S. capacity for ethylene dibromide production and
import totals 61.6 million kilograms for 1993, based on 1981 production
capacity and 1993 import data. However, production has been declining
since 1974, and 1993 production was 11.3 million kg. The industry study
confirms that ethylene dibromide has no significant use as a solvent.
Nonsolvent uses included use as a lead scavenger in gasoline, as an
insect and soil fumigant, and as an intermediate in the synthesis of
dyes, pharmaceuticals, and vinyl bromide.
According to industry data obtained in the RCRA 3007 Preliminary
Questionnaire, 11 facilities used a total of 127,760 kilograms of
ethylene dibromide in 1992. Only two facilities used more than 1,000 kg
per year. In response to the full RCRA 3007 Questionnaire, three
facilities reported use of 14 kg of ethylene dibromide as a solvent in
1993. The apparent sharp decline reflects the elimination of a TSD from
further study, since the use of ethylene dibromide as a solvent prior
to treatment could not be confirmed by questionnaire responses. EPA did
not find any evidence of significant solvent uses in industrial, rather
than research settings. EPA believes that the facilities that reported
using it as a solvent in the 3007 Survey probably used the chemical in
an undefined manner in a laboratory, which may or may not include minor
use as a solvent.
Of the three facilities providing data in the RCRA 3007
Questionnaire, a total of 34,197 kg of waste was generated, from a
total use of 14 kg. All this waste was classified as spent laboratory
waste. According to the Questionnaire data, all the wastes generated
were sent to a hazardous waste incineration facility, either on-site or
off-site. While no exact non-CBI waste concentrations were reported,
given that only 14 kg of ethylene dibromide was reported used, the
Agency believes that the wastes sent to incineration have very low
(part per million range or lower) concentrations of ethylene dibromide.
Ethylene dibromide (EDB) has been detected at two sites undergoing
a ROD evaluation. The ROD database indicates that EDB has contaminated
soil, soil gas, and ground water at the two sites. Records indicate
that the source of the contamination for the two sites can be linked to
the use of EDB as a grain fumigant/pesticide. At a pesticide
manufacturing facility EDB has been detected in the soil in an area
where pesticide production wastes had been dumped. EDB has also been
detected at a site that includes a grain storage facility where EDB was
used to fumigate grain. None of the information on these sites
indicates that ethylene dibromide was used as a solvent in these
situations. In water ethylene dibromide hydrolyses relatively rapidly;
the half-life of this reaction is 5-10 days.
The Agency proposes that waste from the use of ethylene dibromide
as a solvent not be listed as hazardous waste under 40 CFR 261.31. The
use of ethylene dibromide as a solvent, if it occurs, appears to be
very limited, having specialty applications in laboratories and no
known industrial solvent use. Residuals from the apparent use of
ethylene dibromide as a solvent contain negligible concentrations of
the solvent. Furthermore, all wastes were reported to be incinerated as
hazardous waste. The reactivity of the chemical severely limits any
solvent use. Thus, EPA believes that there are no residuals from
solvent use that pose a threat to human health and the environment.
O. Relationship to RCRA Regulations and Other Regulatory Programs
There are several recent regulations and ongoing rulemaking efforts
that may affect the usage, generation, and management of certain
solvents being examined under the current judicially mandated listing
determinations. Each of these rules is briefly described below.
Resource Conservation and Recovery Act Regulations
The Agency recently has published universal treatment standards for
several of the chemicals addressed in today's proposal (59 FR 47980,
September 19, 1994). These standards establish consistent concentration
limits for constituents that previously may have been subject to
inconsistent standards under various land disposal rulemakings. Under
the final rule, universal standards are established for four of the 14
currently targeted solvents when found in nonwastewaters, and for four
of the 14 solvents in wastewaters. Figure 2 presents the universal
treatment standards proposed for solvents subject to the current
listing determination.
[[Page 42350]]
Figure 2.--Proposed Universal Treatment Standards for Target Solvents
----------------------------------------------------------------------------------------------------------------
Proposed wastewater standard
Solvent Proposed non-wastewater standard * **
----------------------------------------------------------------------------------------------------------------
Acetonitrile............................. ....................................... 0.17 mg/l *
p-dichlorobenzene (1,4-dichlorobenzene).. 6.0 mg/kg.............................. 0.09 mg/l *
Ethylene Dibromide (1,2-Dibromoethane)... 15.0 mg/kg............................. 0.028 mg/l *
Methyl Chloride (Chloromethane).......... 30.0 mg/kg............................. 0.19 mg/l *
Pheno.................................... l6.2 mg/kg............................. 0.039 mg/l *
----------------------------------------------------------------------------------------------------------------
* Based on grab samples.
** ased on composite samples.
Under 40 CFR 268.7(a), a waste generator must test the waste or an
extract thereof (or apply knowledge of the waste) to determine whether
the waste is hazardous and restricted from land disposal under the LDR
program. If the waste is restricted from land disposal and does not
meet the applicable treatment standards set forth in Part 268, the
generator must notify any facility receiving the waste of the
appropriate treatment standards. If a generator determines that a
restricted waste meets all applicable treatment standards, he/she must
submit a notice to facilities receiving the waste certifying that the
waste meets applicable treatment standards.
Finally, regardless of the impact of the regulations discussed
above, it is anticipated that a significant portion of the regulated
community will opt for recycling as a management technique for any
solvents that may be listed as a result of this investigation.
Recycling exemptions in the hazardous waste regulations provide
significant incentives for recycling wastes rather than managing them
through traditional means (See 40 CFR 261.2, 261.4, 261.6, and Part
266).
Occupational Safety and Health Administration Regulations
One notable regulatory initiative is the Occupational Safety and
Health Administration (OSHA) examination of the health impacts of
glycol ethers. OSHA has recently proposed amendments to its existing
regulation for occupational exposure to certain glycol ethers,
specifically 2-methoxyethanol, 2-ethoxyethanol, and their acetates (2-
methoxyethanol acetate, 2-ethoxyethanol acetate) (58 FR 15526; March
23, 1993). This proposed rule will reduce the existing 8-hour time-
weighted average (TWA) permissible exposure limit, as well as establish
guidelines to achieve generally lower exposure for employees to these
chemicals. This proposal appears to have affected facility usage of
these glycol ethers. In response to the Agency's RCRA Sec. 3007
inquiries, a number of facilities reported that use of these glycol
ethers had been discontinued at their site due to health concerns.
Others reported that the use of these glycol ethers will be phased out
in the near future.
Clean Air Act Regulations
The Clean Air Act (CAA) Amendments of 1990 require EPA to expand
the regulation of air toxics to 189 substances over a 10-year period
(such substances are presumed to warrant regulation as air toxics--the
list may be modified by the Administrator). This statutory list of air
toxics includes all but two of the 14 solvents addressed in today's
proposal. The two that are not listed as presumed air toxics are
cyclohexanol and furfural. The CAA amendments do not require that the
air toxics be regulated on a constituent-specific basis. Rather, EPA is
required to identify categories of industrial facilities that emit
substantial quantities of one or more air toxics. A list of the source
categories, as well as a schedule for promulgation of hazardous air
pollutant regulations, is published at 58 FR 63952 (December 3, 1993).
The Agency has identified 174 source categories (including 8 area
sources). The source categories include: pharmaceutical production
processes; agricultural chemicals production; polymer and resins
production; production of inorganic chemicals; production of organic
chemicals; and numerous miscellaneous processes, including
semiconductor manufacturing. Categories of area sources include, for
example, halogenated solvent cleaners. Such increased regulation of
many of the industries that use the 14 target solvents may prompt
increased recapture and reuse of the constituent, or encourage the use
of alternative compounds.
Emergency Planning and Community Right-to-Know Act Regulations (EPCRA)
Section 313 of EPCRA requires that any facility with 10 or more
employees in SIC codes 20-39 that manufactures, processes, or otherwise
uses specified chemicals in amounts exceeding established thresholds
must report, to EPA and designated state agencies, any releases of
these chemicals to the environment. The reported data comprise the
Toxics Release Inventory (TRI). The chemicals in the TRI are listed at
40 CFR 372.65, and include all but three (cyclohexanol, isophorone, and
furfural) of the 14 solvents addressed in today's proposal. Under
EPCRA, the quantity threshold for chemical use is 10,000 pounds per
calendar year. The reporting quantity threshold for manufacturing,
importing or processing is 25,000 pounds per year (1989 and-
thereafter). Although TRI release reporting does not have a direct
impact on hazardous waste generation or management capacity, it is
generally accepted that these reporting requirements create strong
incentives for facilities to reduce releases and alter operating
practices to reduce or eliminate the use of specified chemicals. Annual
TRI reporting was initiated in 1988 (addressing releases during 1987)
and is undergoing expansion. For example, a final rule published on
November 30, 1994 (59 FR 61432) added 286 chemicals and chemical
categories to the TRI reporting inventory. Among the chemicals added
are cyclohexanol and isophorone.
Clean Water Act Regulations
The Agency currently is revising the effluent guidelines and
standards for the pharmaceutical manufacturing category. This work,
which is being conducted under a Consent Decree (NRDC v. Browner,
(D.D.C. 89-2980; January 31, 1992)), involves the review and revision
of the existing effluent guidelines and will consider inclusion of
limitations on toxic and non-conventional volatile organic pollutants.
A notice of proposed rulemaking was published on May 2, 1995. The
Agency has also revised the effluent guidelines and standards
applicable to the organic chemicals, plastics, and synthetic fibers
industry (OCPSF) (58 FR 36872; July 9, 1993). These revisions add BAT
and NSPS
[[Page 42351]]
standards for 19 additional constituents (including p-dichlorobenzene,
methyl chloride, and phenol) and pretreatment standards for 11 of these
19 pollutants (including p-dichlorobenzene and methyl chloride).
The Agency also has developed effluent guidelines and standards for
the pesticide chemicals category. This work (also being conducted under
the NRDC Consent Decree) limits the discharge of pollutants into U.S.
waters and POTWs from new and existing facilities that manufacture
pesticide active ingredients. A final rule was published on September
28, 1993 (58 FR 50638), which included standards for p-dichlorobenzene
and phenol, two constituents addressed by the solvents listing
investigation. EPA is also completing effluent standards for facilities
that formulate, package, and/or repackage pesticide active ingredients
into final products. EPA expects to complete this rule by September 30,
1996.
As noted in the discussion of other rules above, these new and
revised effluent standards may result in the generation of wastes
already regulated under the CWA and/or may encourage the recycling or
reduction of CWA-regulated constituents. It is noteworthy that,
although not imposed as part of these rulemakings, the Agency routinely
evaluates zero discharge effluent standards (usually based on
recycling) as an option for new sources.
III. Waste Minimization
In the Pollution Prevention Act of 1990 (42 U.S.C. 13101 et seq.,
P.L. 101-508, November 5, 1990), Congress declared pollution prevention
to be a national policy of the United States. The act declares that
pollution should be prevented or reduced at the source whenever
feasible; pollution that cannot be prevented should be recycled or
reused; pollution that cannot be prevented/reduced or recycled should
be treated in an environmentally safe manner wherever feasible; and
disposal or release into the environment should be chosen only as a
last resort, and should be done in an environmentally safe manner. This
section provides a general discussion of some generic pollution
prevention and waste minimization techniques that facilities may wish
to explore.
Waste minimization practices fall into three general groups: change
in production practices, housekeeping practices, and practices that
employ the use of equipment that by design promote waste minimization.
Some of these practices/equipment listed below conserve water, others
reduce the amount of product in the wastestream, while others may
prevent the creation of the waste altogether. EPA acknowledges that
some of these practices/equipment may lead to media transfers or
increased energy use. This information is presented for general
information, and is not being proposed as a regulatory requirement.
Production practices include:
Triple-rinsing raw material shipping containers and
returning the rinsate directly to the reactor;
Scheduling production to minimize changeover cleanouts;
Segregating equipment by individual product or product
``families;''
Packaging products directly out of reactors;
Steam stripping wastewaters to recovery reactants or
solvents for reuse;
Using raw material drums for packaging final products; and
Dedicating equipment for hard to clean products.
Housekeeping practices include:
Performing preventive maintenance on all valves, fittings,
and pumps;
Promptly correcting any leaky valves and fittings;
Placing drip pans under valves and fitting to contain
leaks; and
Cleaning up spills or leaks in bulk containment areas to
prevent contamination of storm or wash wasters.
Equipment promoting waste minimization by reducing or eliminating
waste generation include:
Low-volume/high-pressure hoses for cleaning;
Drum triple-rinsing stations;
Reactor scrubber systems designed to return captured
reactants to the next batch rather than to disposal;
Material storage tanks with inert liners to prevent
contamination of water blankets with contaminants which would prohibit
its use in the process; and
Enclosed automated product handling equipment to eliminate
manual product packaging.
Waste minimization measures can be tailored to the needs of
individual industries, processes, and firms. This approach may make it
possible to achieve greater pollution reduction with less cost and
disruption to the firm.
Defined process control and good housekeeping practices often can
result in significant waste volume or toxicity reduction. Evaluations
of existing processes also may point out the need for more complex
engineering approaches (e.g., waste reuse, secondary processing of
distillation bottoms, and use of vacuum pumps instead of steam jets) to
achieve waste minimization objectives. Simple physical audits of
current waste generation and in-plant management practices for the
wastes also can yield positive results. These audits often turn up
simple nonengineering practices that can be implemented successfully.
VI. State Authority
A. Applicability of Rule in Authorized States
Because this proposal would not change the Federal program, it
would not affect authorized State programs. However, the relevant State
authorization provisions are as follows.
Under section 3006 of RCRA, EPA may authorize qualified States to
administer and enforce the RCRA program within the State. (See 40 CFR
Part 271 for the standards and requirements for authorization.)
Following authorization, EPA retains enforcement authority under
sections 3007, 3008, 3013, and 7003 of RCRA, although authorized States
have primary enforcement responsibility.
Before the Hazardous and Solid Waste Amendments of 1984 (HSWA)
amended RCRA, a State with final authorization administered its
hazardous waste program entirely in lieu of the Federal program in that
State. The Federal requirements no longer applied in the authorized
State, and EPA could not issue permits for any facilities located in
the State with permitting authorization. When new, more stringent
Federal requirements were promulgated or enacted, the State was
obligated to enact equivalent authority within specified time-frames.
New Federal requirements did not take effect in an authorized State
until the State adopted the requirements as State law.
By contrast, under section 3006(g) of RCRA, 42 U.S.C. 6926(g), new
requirements and prohibitions imposed by the HSWA (including the
hazardous waste listings proposed in this notice) take effect in
authorized States at the same time that they take effect in non-
authorized States. EPA is directed to implement those requirements and
prohibitions in authorized States, including the issuance of permits,
until the State is granted authorization to do so. While States must
still adopt HSWA-related provisions as State law to retain final
authorization, the Federal HSWA requirements apply in authorized States
in the interim.
B. Effect on State Authorizations
Because any regulations that EPA might propose (with the exception
of the actions proposed under CERCLA authority) would be promulgated
[[Page 42352]]
pursuant to the HSWA, a State submitting a program modification is able
to apply to receive either interim or final authorization under section
3006(g)(2) or 3006(b), respectively, on the basis of requirements that
are substantially equivalent or equivalent to EPA's requirements. The
procedures and schedule for State program modifications under 3006(b)
are described in 40 CFR 271.21. It should be noted that all HSWA
interim authorizations are currently scheduled to expire on January 1,
2003 (see 57 FR 60129, February 18, 1992).
Section 271.21(e)(2) of EPA's State authorization regulations (40
CFR Part 271) requires that states with final authorization modify
their programs to reflect federal program changes and submit the
modifications to EPA for approval. The deadline by which the States
must modify their programs to adopt a final rule will be determined by
the date of promulgation of a final rule in accordance with section
271.21(e)(2). If any HSWA regulations are adopted in the final rule,
Table 1 at 40 CFR 271.1 would be amended accordingly. Once EPA approves
the modification, the State requirements become RCRA Subtitle C
requirements.
States with authorized RCRA programs already may have regulations
similar to those EPA may issue. These State regulations have not been
assessed against the Federal regulations being proposed to determine
whether they meet the tests for authorization. Thus, a State would not
be authorized to implement any such regulations as RCRA requirements
until State program modifications are submitted to EPA and approved,
pursuant to 40 CFR 271.21. Of course, States with existing regulations
that are more stringent than or broader in scope than current Federal
regulations may continue to administer and enforce their regulations as
a matter of State law.
It should be noted that authorized States are required to modify
their programs only when EPA promulgates Federal standards that are
more stringent or broader in scope than existing Federal standards.
Section 3009 of RCRA allows States to impose standards more stringent
than those in the Federal program. For those Federal program changes
that are less stringent or reduce the scope of the Federal program,
States are not required to modify their programs. See 40 CFR 271.1(i).
V. CERCLA Designation and Reportable Quantities
All RCRA hazardous wastes listed in 40 CFR 261.31 through 261.33,
as well as any solid waste that exhibits one or more of the hazardous
waste characteristics, are also hazardous substances under Section
101(14) of the Comprehensive Environmental Response, Compensation, and
Liability Act (CERCLA) of 1980, as amended. Hazardous substances are
listed in Table 302.4 at 40 CFR 302.4, along with their respective
reportable quantities (RQs). Because EPA is not proposing to list any
wastes, the Agency is not proposing changes to Table 302.4.
Under CERCLA 103(a), the person in charge of a vessel or facility
from which a hazardous substance has been released in a quantity that
equals or exceeds its RQ must immediately notify the National Response
Center of the release as soon as that person has knowledge of the
release. In addition to this reporting requirement under CERCLA,
Section 304 of the Emergency Planning and Community Right-To-Know Act
(EPCRA) requires owners or operators of certain facilities to report
the release of a hazardous substance to State and local authorities.
EPCRA Section 304 notification must be given to the community emergency
coordinator of the local emergency planning committee (LEPC) for each
area likely to be affected by the release, and to the State emergency
response commission (SERC) of any State likely to be affected by the
release.
Under Section 102(b) of CERCLA, all hazardous wastes are assigned a
statutory RQ of one pound unless and until adjusted by regulation. The
Agency's methodology for adjusting RQs of individual hazardous
substances begins with an evaluation of the intrinsic physical,
chemical, and toxicological properties of each hazardous substance. The
intrinsic properties examined, called ``primary criteria,'' are aquatic
toxicity, mammalian toxicity (oral, dermal, and inhalation),
ignitability, reactivity, chronic toxicity, and potential
carcinogenicity. Generally, for each intrinsic property, the Agency
ranks hazardous substances on a scale, associating a specific range of
values on each scale with an RQ of 1, 10, 100, 1,000, or 5,000 pounds.
The data for each hazardous substance are evaluated using various
primary criteria; each hazardous substance may receive several
tentative RQ values based on its particular intrinsic properties. The
lowest of the tentative RQs becomes the ``primary criteria RQ'' for
that substance.
After the primary criteria RQs are assigned, substances are further
evaluated for their susceptibility to certain degradative processes,
which are used as secondary adjustment criteria. These natural
degradative processes are biodegradation, hydrolysis, and photolysis
(BHP). If a hazardous substance, when released into the environment,
degrades relatively rapidly to a less hazardous form by one or more of
the BHP processes, its RQ, as determined by the primary RQ adjustment
criteria, is generally raised one level. This adjustment is made
because the relative potential for harm to public health or welfare or
the environment posed by the release of such a substance is reduced by
these degradative processes. Conversely, if a hazardous substance
degrades to a more hazardous form after its release, the original
substance is assigned an RQ equal to the RQ for the reaction product.
The downward adjustment is appropriate because the hazard posed by the
release of the original substance is increased if it degrades to a more
hazardous form.
The methodology summarized above is applied to adjust the RQs of
individual hazardous substances. An additional process applies to RCRA
waste streams that contain individual hazardous substances as
constituents. In the August 14, 1989 Federal Register (54 FR 33440),
the Agency stated that, in assigning an RQ to a waste stream, the
Agency determines the RQ for each waste stream constituent and then
assigns the lowest of these constituent RQs to the waste stream itself.
VI. Regulatory Impacts
A. Executive Order 12866
Under Executive Order 12866 (58 FR 51735; October 4, 1993), the
Agency must determine whether a new regulation is a ``significant
regulatory action'' and, therefore, subject to the requirements of the
Executive Order and to review by the Office of Management and Budget.
The E.O. defines ``significant regulatory action'' as one that is
likely to result in a rule that may:
(1) Have an annual effect on the economy of $100 million or more or
adversely affect, in a material way, the economy, a sector of the
economy, productivity, competition, jobs, the environment, public
health or safety, or State, local, or tribal governments or
communities;
(2) Create a serious inconsistency or otherwise interfere with an
action taken or planned by another agency;
(3) Materially alter the budgetary impact of entitlements, grants,
user fees, or loan programs, or the rights and obligations of
recipients thereof; or
(4) Raise novel legal or policy issues arising out of legal
mandates, the
[[Page 42353]]
President's priorities, or the principles set forth in the Executive
Order.
The Agency has analyzed the costs associated with this proposal,
which are discussed in the following section, and has determined that
this proposed rule is not a significant regulatory action. Because the
Agency is not proposing to change any regulatory requirements for these
chemicals, there are no costs to industry associated with this
proposal, nor any economic impacts.
VII. Environmental Justice
Executive Order 12898 (59 FR 7629; February 16, 1994) requires
Federal agencies to identify and address, as appropriate,
disproportionately high and adverse human health and environmental
effects of their programs, policies, rulemakings, and other activities,
on minority populations and low-income populations. The Order directs
each Federal agency to develop an agency-wide environmental justice
strategy that will list agency programs, policies, public participation
processes, enforcement activities, and rulemakings related to human
health and environment that should be revised to, at a minimum: (1)
promote enforcement of all human health and environmental statutes in
areas with minority and low-income populations; (2) ensure greater
public participation; (3) improve research and data collection relating
to the health and environment of minority and low-income populations;
and (4) identify differential patterns of natural resource consumption
among minority and low-income populations.
Specifically, E.O. 12898 directs Federal agencies, in connection
with the development and implementation of Agency strategies on
environmental justice, to collect, maintain, and analyze information on
the race, national origin, income level, and other appropriate
information for areas surrounding facilities or sites expected to have
a substantial environmental, human health, or economic impact on the
surrounding populations, when such facilities or sites are the subject
of a substantial Federal environmental administrative or judicial
action.
Today's proposal not to list any of the target solvents as
hazardous waste is expected to have no impact on any minority or low-
income populations. EPA has evaluated risks to hypothetical receptors
that might live close to facilities using these chemicals as solvents,
and in all cases the Agency found no significant risks are likely to
any nearby population. Therefore, EPA does not believe that any further
analysis is required under Executive Order 12898.
VIII. Regulatory Flexibility Act
Pursuant to the Regulatory Flexibility Act of 1980, 5 U.S.C. 601 et
seq., whenever an agency publishes a notice of rulemaking, it must
prepare and make available for public comment a Regulatory Flexibility
Analysis (RFA) that describes the effect of the rule on small entities
(i.e., small businesses, small organizations, and small governmental
jurisdictions). This analysis is unnecessary, however, if the rule is
estimated not to have a significant economic impact on a substantial
number of small entities.
According to EPA's guidelines for conducting an RFA, if over 20
percent of the population of small entities is likely to experience
financial distress based on the costs of the rule, then the Agency
considers that the rule will have a significant impact on a substantial
number of small entities, and must perform an RFA. Because today's
proposal would not change any regulatory requirements, the Agency
estimates that this action will not significantly impact 20 percent of
the population of small entities. Therefore, the Agency has not
conducted an RFA for today's proposed rule.
IX. Paperwork Reduction Act
Today's proposed rule does not contain any new information
collection requirements subject to OMB review under the Paperwork
Reduction Act of 1980, 44 U.S.C. 3501 et seq. Because there are no new
information collection requirements proposed in today's rule, an
Information Collection Request has not been prepared.
X. Unfunded Mandates Reform Act
Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), P.L.
104-4, establishes requirements for Federal agencies to assess the
effects of their regulatory actions on State, local, and tribal
governments and the private sector. Under section 202 of the UMRA, EPA
generally must prepare a written statement, including a cost-benefit
analysis, for proposed and final rules with ``Federal mandates'' that
may result in expenditures to State, local, and tribal governments, in
the aggregate, or to the private sector, of $100 million or more in any
one year. Before promulgating an EPA rule for which a written statement
is needed, section 205 of the UMRA generally requires EPA to identify
and consider a reasonable number of regulatory alternatives and adopt
the least costly, most cost-effective or least burdensome alternative
that achieves the objectives of the rule. The provisions of section 205
do not apply when they are inconsistent with applicable law. Moreover,
section 205 allows EPA to adopt an alternative other than the least
costly, most cost-effective or least burdensome alternative if the
Administrator publishes with the final rule an explanation why that
alternative was not adopted. Before EPA establishes any regulatory
requirements that may significantly or uniquely affect small
governments, including tribal governments, it must have developed under
section 203 of the UMRA a small government agency plan. The plan must
provide for notifying potentially affected small governments, enabling
officials of affected small governments to have meaningful and timely
input in the development of EPA regulatory proposals with significant
Federal intergovernmental mandates, and informing, educating, and
advising small governments on compliance with the regulatory
requirements.
Today's rule contains no Federal mandates (under the regulatory
provisions of Title II of the UMRA) for State, local, or tribal
governments or the private sector.
XI. Compliance and Implementation
Because no regulatory action is being proposed today, the Agency
expects no change in regulatory status for authorized and nonauthorized
states.
List of Subjects
40 CFR Part 261
Environmental Protection, Hazardous Materials, Waste treatment and
disposal, Recycling.
40 CFR Part 271
Environmental protection, Administrative practice and procedure,
Confidential business information, Hazardous material transportation,
Hazardous waste, Indians--lands, Intergovernmental relations,
Penalties, Reporting and record keeping requirements, Water pollution
control, Water supply.
40 CFR Part 302
Environmental Protection, Air pollution control, Chemicals,
Emergency Planning and Community Right-to-Know Act, Extremely hazardous
substances, Hazardous chemicals, Hazardous materials transportation,
Hazardous substances, Hazardous wastes, Intergovernmental relations,
Natural resources, Pesticides and pests, Reporting and record keeping
requirements, Superfund, Waste treatment and disposal, Water pollution
control, Water supply.
[[Page 42354]]
Dated: August 2, 1996.
Carol M. Browner,
Administrator.
[FR Doc. 96-20592 Filed 8-13-96; 8:45 am]
BILLING CODE 6560-50-P