[Federal Register Volume 65, Number 240 (Wednesday, December 13, 2000)]
[Notices]
[Pages 77866-77874]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-31730]
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ENVIRONMENTAL PROTECTION AGENCY
[OPPTS-00302; FRL-6752-5]
National Advisory Committee for Acute Exposure Guideline Levels
(AEGLs) for Hazardous Substances; Proposed AEGL Values
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
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SUMMARY: The National Advisory Committee for Acute Exposure Guideline
Levels for Hazardous Substances (NAC/AEGL Committee) is developing
AEGLs on an ongoing basis to provide Federal, State, and local agencies
with information on short-term exposures to hazardous chemicals. This
notice provides AEGL values and Executive Summaries for 7 chemicals for
public review and comment. Comments are welcome on both the AEGL values
in this notice and the Technical Support Documents placed in the public
version of the official record for these 7 chemicals.
DATES: Comments, identified by the docket control number OPPTS-00302,
must be received by EPA on or before January 12, 2001.
ADDRESSES: Comments may be submitted by mail, electronically, or in
person. Please follow the detailed instructions for each method as
provided in Unit I. of the SUPPLEMENTARY INFORMATION. To ensure proper
receipt by EPA, it is imperative that you identify docket control
number OPPTS-00302 in the subject line on the first page of your
response.
FOR FURTHER INFORMATION CONTACT: For general information contact:
Barbara Cunningham, Acting Director, Environmental Assistance Division,
Office of Pollution Prevention and Toxics (7408), Environmental
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460;
telephone number: (202) 554-1404 and TDD: (202) 554-055; e-mail
address: [email protected].
For technical information contact: Paul S. Tobin, Designated
Federal Officer (DFO), Office of Prevention, Pesticides and Toxic
Substances (7406), 1200 Pennsylvania Ave., NW., Washington, DC 20460;
telephone number: (202) 260-1736; e-mail address: [email protected].
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this Action Apply to Me?
This action is directed to the general public to provide an
opportunity for review and comment on ``Proposed'' AEGL values and
their supporting scientific rationale. This action may be of particular
interest to anyone who may be affected if the AEGL values are adopted
by government agencies for emergency planning, prevention, or response
programs, such as EPA's Risk Management Program under the Clean Air Act
and Amendments Section 112r. It is possible that other Federal agencies
besides EPA, as well as State and local agencies and private
organizations, may adopt the AEGL values for their programs. As such,
the Agency has not attempted to describe all the specific entities that
may be affected by this action. If you have any questions regarding the
applicability of this action to a particular entity, consult the
technical person listed under FOR FURTHER INFORMATION CONTACT.
B. How Can I Get Additional Information, Including Copies of this
Document or Other Related Documents?
1. Electronically. You may obtain electronic copies of this
document, and certain other related documents that might be available
electronically, from the EPA Internet Home Page at http://www.epa.gov/.
To access this document, on the Home Page select ``Laws and
Regulations,'' ``Regulations and Proposed Rules,'' and then look up the
entry for this document under the ``Federal Register--Environmental
Documents.'' You can also go directly to the Federal Register listings
at http://www.epa.gov/fedrgstr/.
2. In person. The Agency has established an official record for
this action under docket control number OPPTS-00302. The official
record consists of the documents specifically referenced in this
action, any public comments received during an applicable comment
period, and other information related to this action, including any
information claimed as Confidential Business Information (CBI). This
official record includes the documents that are physically located in
the docket, as well as the documents that are referenced in those
documents. The public version of the official record does not include
any information claimed as CBI. The public version of the official
record, which includes printed, paper versions of any electronic
comments submitted during an applicable comment period, is available
for inspection in the TSCA Nonconfidential Information Center, North
East Mall Rm. B-607, Waterside Mall, 401 M St., SW., Washington, DC.
The Center is open from noon to 4 p.m., Monday through Friday,
excluding legal holidays. The telephone number of the Center is (202)
260-7099.
3. Fax-on-Demand. You may request to receive a faxed copy of the
document(s) by using a faxphone to call (202) 401-0527 and select the
item number 4800 for an index of the items available by fax-on-demand
in this category, or select the item number for the document related to
the chemical(s) identified in this document as listed in the chemical
table in Unit III. You may also follow the automated menu.
C. How and to Whom Do I Submit Comments?
You may submit comments through the mail, in person, or
electronically. To ensure proper receipt by EPA, it is imperative that
you identify docket control number OPPTS-00302 in the subject line on
the first page of your response.
1. By mail. Submit your comments to: Document Control Office
(7407), Office of Pollution Prevention and Toxics (OPPT), Environmental
Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20460.
(Note: for express delivery, please see ``In person or by courier'' in
this unit).
2. In person or by courier. Deliver your comments to: OPPT Document
Control Office (DCO) in East Tower Rm. G-099, Waterside Mall, 401 M
St., SW., Washington, DC. The DCO is open from 8 a.m. to 4 p.m., Monday
through Friday, excluding legal holidays. The telephone number for the
DCO is (202) 260-7093.
3. Electronically. You may submit your comments electronically by
e-mail
[[Page 77867]]
to: [email protected], or mail your computer disk to the address
identified above. Do not submit any information electronically that you
consider to be CBI. Electronic comments must be submitted as an ASCII
file avoiding the use of special characters and any form of encryption.
Comments and data will also be accepted on standard disks in
WordPerfect 6.1/8.1 or ASCII file format. All comments in electronic
form must be identified by docket control numbers OPPTS-00302.
Electronic comments may also be filed online at many Federal Depository
Libraries.
D. How Should I Handle CBI that I Want to Submit to the Agency?
Do not submit any information electronically that you consider to
be CBI. You may claim information that you submit to EPA in response to
this document as CBI by marking any part or all of that information as
CBI. Information so marked will not be disclosed except in accordance
with procedures set forth in 40 CFR part 2. In addition to one complete
version of the comment that includes any information claimed as CBI, a
copy of the comment that does not contain the information claimed as
CBI must be submitted for inclusion in the public version of the
official record. Information not marked confidential will be included
in the public version of the official record without official notice.
If you have any questions about CBI or the procedures for claiming CBI,
please consult the technical person listed under FOR FURTHER
INFORMATION CONTACT.
E. What Should I Consider as I Prepare My Comments for EPA?
You may find the following suggestions helpful for preparing your
comments:
1. Explain your views as clearly as possible.
2. Describe any assumptions that you used.
3. Provide copies of any technical information and/or data that you
used that support your views.
4. If you estimate potential burden or costs, explain how you
arrived at the estimate that you provide.
5. Provide specific examples to illustrate your concerns.
6. Offer alternative ways to improve this notice.
7. Make sure to submit your comments by the deadline in this
document.
8. To ensure proper receipt by EPA, be sure to identify the docket
control number assigned to this action in the subject line on the first
page of your response. You may also provide the name, date, and Federal
Register citation.
II. Background
A. Introduction
EPA's Office of Prevention, Pesticides and Toxic Substances (OPPTS)
provided notice on October 31, 1995 (60 FR 55376) (FRL-4987-3) of the
establishment of the NAC/AEGL Committee with the stated charter
objective as ``the efficient and effective development of Acute
Exposure Guideline Levels (AEGLs) and the preparation of supplementary
qualitative information on the hazardous substances for federal, state,
and local agencies and organizations in the private sector concerned
with [chemical] emergency planning, prevention, and response.'' The
NAC/AEGL Committee is a discretionary Federal advisory committee formed
with the intent to develop AEGLs for chemicals through the combined
efforts of stakeholder members from both the public and private sectors
in a cost-effective approach that avoids duplication of efforts and
provides uniform values, while employing the most scientifically sound
methods available. An initial priority list of 85 chemicals for AEGL
development was published in the Federal Register of May 21, 1997 (62
FR 27734) (FRL-5718-9). This list is intended for expansion and
modification as priorities of the stakeholder member organizations are
further developed. While the development of AEGLs for chemicals are
currently not statutorily based, at lease one rulemaking references
their planned adoption. The Clean Air Act and Amendments Section 112(r)
Risk Management Program states, ``EPA recognizes potential limitations
associated with the Emergency Response Planning Guidelines and Level of
Concern and is working with other agencies to develop AEGLs. When these
values have been developed and peer-reviewed, EPA intends to adopt
them, through rulemaking, as the toxic endpoint for substances under
this rule (see 61 FR 31685).'' It is believed that other Federal and
State agencies and private organizations will also adopt AEGLs for
chemical emergency programs in the future.
B. Characterization of the AEGLs
The AEGLs represent threshold exposure limits for the general
public and are applicable to emergency exposure periods ranging from 10
minutes to 8 hours. AEGL-2 and AEGL-3 levels, and AEGL-1 levels as
appropriate, will be developed for each of five exposure periods (10
and 30 minutes, 1 hour, 4 hours, and 8 hours) and will be distinguished
by varying degrees of severity of toxic effects. It is believed that
the recommended exposure levels are applicable to the general
population including infants and children, and other individuals who
may be sensitive and susceptible. The AEGLs have been defined as
follows:
AEGL-1 is the airborne concentration (expressed as parts
per million (ppm) or milligram/meter cube (mg/m\3\) of a substance
above which it is predicted that the general population, including
susceptible individuals, could experience notable discomfort,
irritation, or certain asymptomatic, non-sensory effects. However, the
effects are not disabling and are transient and reversible upon
cessation of exposure.
AEGL-2 is the airborne concentration (expressed as ppm or
mg/m\3\) of a substance above which it is predicted that the general
population, including susceptible individuals, could experience
irreversible or other serious, long-lasting adverse health effects, or
an impaired ability to escape.
AEGL-3 is the airborne concentration (expressed as ppm or
mg/m\3\) of a substance above which it is predicted that the general
population, including susceptible individuals, could experience life-
threatening health effects or death.
Airborne concentrations below the AEGL-1 represent exposure levels
that could produce mild and progressively increasing odor, taste, and
sensory irritation, or certain non-symptomatic, non-sensory effects.
With increasing airborne concentrations above each AEGL level, there is
a progressive increase in the likelihood of occurrence and the severity
of effects described for each corresponding AEGL level. Although the
AEGL values represent threshold levels for the general public,
including sensitive subpopulations, it is recognized that certain
individuals, subject to unique or idiosyncratic responses, could
experience the effects described at concentrations below the
corresponding AEGL level.
C. Development of the AEGLs
The NAC/AEGL Committee develops the AEGL values on a chemical-by-
chemical basis. Relevant data and information are gathered from all
known sources including published scientific literature, State and
Federal agency publications, private industry, public databases, and
individual experts in both the public and private sectors. All key data
and information are summarized for the NAC/AEGL
[[Page 77868]]
Committee in draft form by Oak Ridge National Laboratories together
with ``draft'' AEGL values prepared in conjunction with NAC/AEGL
Committee members. Both the ``draft'' AEGLs and ``draft'' technical
support documents are reviewed and revised as necessary by the NAC/AEGL
Committee members prior to formal committee meetings. Following
deliberations on the AEGL values and the relevant data and information
for each chemical, the NAC/AEGL Committee attempts to reach a
consensus. Once the NAC/AEGL Committee reaches a consensus, the values
are considered ``Proposed'' AEGLs. The Proposed AEGL values and the
accompanying scientific rationale for their development are the subject
of this notice.
In this document, the NAC/AEGL Committee is publishing proposed
AEGL values and the accompanying scientific rationale for their
development for 7 hazardous substances. These values represent the
fourth set of exposure levels proposed and published by the NAC/AEGL
Committee. EPA published the first ``Proposed'' AEGLs for 12 chemicals
from the initial priority list in the Federal Register of October 30,
1997 (62 FR 58840-58851) (FRL-5737-3); for 10 chemicals in the Federal
Register of March 15, 2000 (65 FR 14186-14196) (FRL-6492-4); and for 14
chemicals in the Federal Register of June 23, 2000 (65 FR 39263-39277)
(FRL-6591-2) in order to provide an opportunity for public review and
comment. In developing the proposed AEGL values, the NAC/AEGL Committee
has followed the methodology guidance Guidelines for Developing
Community Emergency Exposure Levels for Hazardous Substances, published
by the National Research Council of the National Academy of Sciences
(NRC/NAS) in 1993. The term Community Emergency Exposure Levels (CELLS)
is synonymous with AEGLs in every way. The NAC/AEGL Committee has
adopted the term Acute Exposure Guideline Levels to better connote the
broad application of the values to the population defined by the NAS
and addressed by the NAC/AEGL Committee. The NAC/AEGL Committee invites
public comment on the proposed AEGL values and the scientific rationale
used as the basis for their development.
Following public review and comment, the NAC/AEGL Committee will
reconvene to consider relevant comments, data, and information that may
have an impact on the NAC/AEGL Committee's position and will again seek
consensus for the establishment of Interim AEGL values. Although the
Interim AEGL values will be available to Federal, State, and local
agencies and to organizations in the private sector as biological
reference values, it is intended to have them reviewed by a
subcommittee of the NAS. The NAS subcommittee will serve as a peer
review of the Interim AEGLs and as the final arbiter in the resolution
of issues regarding the AEGL values, and the data and basic methodology
used for setting AEGLs. Following concurrence, ``Final'' AEGL values
will be published under the auspices of the NAS.
III. List of Chemicals
On behalf of the NAC/AEGL Committee, EPA is providing an
opportunity for public comment on the AEGLs for the 7 chemicals
identified in Table 1. Table 1 also provides the fax-on-demand item
number for the chemical specific documents, which may be obtained as
described in Unit 1.B.
A. Fax-On-Demand Table
Table 1.--Fax-On-Demand
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Fax-On-Demand item
CAS No. Chemical name no.
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75-44-5......................... Phosgene.......... 4862
78-82-0......................... Isobutyronitrile.. 4869
107-12-0........................ Propionitrile..... 4877
126-98-7........................ Methacrylonitrile. 4888
7790- 91-2...................... Chlorine 4922
trifluoride.
151-56-4........................ Ethylenimine...... 4890
75-55-8......................... Propylenimine..... 4863
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B. Executive Summaries
The following are executive summaries from the chemical specific
Technical Support Documents (which may be obtained as described in Unit
1.B. and III.) that support the NAC/AEGL Committee's development of
AEGL values for each chemical substance. This information provides the
following information: A general description of each chemical,
including its properties and principle uses; a summary of the rationale
supporting the AEGL-1, -2, and -3 concentration levels; a summary table
of the AEGL values; and a listing of key references that were used to
develop the AEGL values. More extensive toxicological information and
additional references for each chemical may be found in the complete
Technical Support Documents. Risk managers may be interested in
reviewing the complete Technical Support Document for a chemical when
deciding issues related to use of the AEGL values within various
programs.
1. Phosgene--i. Description. Phosgene is a colorless gas at ambient
temperature and pressure. Its odor has been described as similar to
new-mown hay. Phosgene is manufactured from a reaction of carbon
monoxide and chlorine gas in the presence of activated charcoal. The
production of dyestuffs, isocyanates, carbonic acid esters
(polycarbonates), acid chlorides, insecticides, and pharmaceutical
chemicals requires phosgene.
Appropriate data were not available for deriving AEGL-1 values for
phosgene.
AEGL-2 values were based on chemical pneumonia in rats (2 ppm for
90 minutes) (Gross et al., 1965). An uncertainty factor (UF) of 3 was
applied for interspecies extrapolation since little species variability
is observed both with lethal and non lethal endpoints after exposure to
phosgene. An UF of 3 was applied to account for sensitive human
subpopulations since the mechanism of phosgene toxicity (binding to
macromolecules and irritation) is not expected to vary greatly between
individuals (total UF = 10). The 1.5 hour value was then scaled to the
30-minute, 1-hour, 4-hour, and 8-hour AEGL exposure periods, using C\n\
x t = k, where n = 1 (Haber's Law) since Haber's Law has been shown to
be valid for phosgene within certain limits. Haber's Law was originally
derived from phosgene data (USEPA, August 1986). The 30-minute value
was also adopted as the 10-minute value since extrapolation would yield
a 10-minute AEGL-2 value close to concentrations producing alveolar
edema in rats exposed for 10-minutes (Diller et al., 1985) and may not
be protective.
The 30-minute, 1-hour, 4-hour, and 8-hour AEGL-3 values were based
on a 30-minute no-effect-level for death in rats (15 ppm) (Zwart et
al., 1990). An UF of 3 was applied for interspecies extrapolation since
little species variability is observed both with lethal and non-lethal
endpoints after exposure to phosgene. An UF of 3 was applied to account
for sensitive-human subpopulations since the mechanism of phosgene
toxicity (binding to macromolecules and irritation) is not expected to
vary greatly between individuals (total UF = 10). The value was then
scaled to the 1-, 4-, and 8-hour AEGL periods, using C\n\ x t = k,
where n = 1 (Haber's Law) since Haber's Law has been shown to be valid
for phosgene within certain limits. Haber's Law was originally derived
from phosgene data (USEPA, August 1986). The 10-minute AEGL-3 value was
based on a 10-minute no-effect-level for death in rats and mice (Zwart
et al., 1990). An UF of 3 was applied for interspecies extrapolation
since little species variability is
[[Page 77869]]
observed both with lethal and non lethal endpoints after exposure to
phosgene. An UF of 3 was applied to account for sensitive human
subpopulations since the mechanism of phosgene toxicity (binding to
macromolecules and irritation) is not expected to vary greatly between
individuals (total UF = 10).
The calculated values are listed in Table 2 below:
Table 2.--Phosgene
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Summary of Proposed Aegl Values for Phosgene [ppm (mg/m\3\)]
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Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours Endpoint/Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) NA NA NA NA NA NA
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AEGL-2 (Disabling) 0.60 (2.5) 0.60 (2.5) 0.30 (1.2) 0.080 (0.33) 0.040 (0.16) Chemical pneumonia
rats (Gross et
al., 1965)
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AEGL-3 (Lethal) 3.6 (15) 1.5 (6.2) 0.75 (3.1) 0.20 (0.82 ) 0.090 (0.34 ) 30-minute r 10-
minute no-effect-
level for death
in rats (Zwart et
al., 1990)
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NA means not applicable
ii. References. a. Diller, W. F., Bruch, J., and Dehnen, W. 1985.
Pulmonary changes in rats following low phosgene exposure. Archives of
Toxicology. 57:184-190.
b. Gross, P., Rinehart, W.E., and Hatch, T. 1965. Chronic
pneumonitis caused by phosgene. Archieves of Environmental Health.
10:768-775.
c. USEPA, August 1986. Health Assessment Document for Phosgene.
EPA/600/8-86/022A. p. 1-4 to 1-5.
d. Zwart, A., Arts, J.H.E., Klokman-Houweling, J.M., and Schoen,
E.D. 1990. Determination of concentration-time-mortality relationships
to replace LC50 values. Inhalation Toxicology. 2:105-117.
November 1977.
2. Isobutyronitrile--i. Description. Isobutyronitrile is a
colorless liquid at ambient temperature and pressure. It has an almond-
like odor and may cause irritation or burning of the eyes and skin. It
is metabolized to cyanide in the body and signs of exposure may include
weakness, headache, confusion, nausea, vomiting, convulsion, dilated
pupils, weak pulse, shallow and gasping breathing, and cyanosis (EPA,
1985).
Data were insufficient for derivation of AEGL-1 values for
isobutyronitrile.
The AEGL-2 was based on a no-effect-level from a developmental
toxicity study in rats (100 ppm, 6 hour/day, days 6-20 of gestation)
(Saillenfait et al., 1993). Although no interspecies information
concerning isobutyronitrile toxicity was available, data from another
nitrile (methacrylonitrile) suggest that the rat is not the most
sensitive species. Therefore, an interspecies UF of 10 will be applied.
In the absence of chemical-specific data and since much of the acute
toxicity of nitriles is due to cyanide, the intraspecies UF will be the
same as that used in the derivation of hydrogen cyanide AEGL-2 values
(NAC/AEGL Committee, 1997). Thus, an UF of 3 will be applied to account
for sensitive individuals since human accidental and occupational
exposures suggest little intraindividual variability of hydrogen
cyanide toxicity (NAC/AEGL Committee, 1997). Therefore, the total UF is
30. The concentration-time relationship for many irritant and
systemically acting vapors and gases may be described by C\n\ x t = k
(ten Berge et al., 1986). Since much of the acute toxicity of
isobutyronitrile is thought to be due to cyanide, the empirically
derived chemical-specific value of n = 2.6 derived from cyanide rat
lethality data) (NAC/AEGL Committee, 1997) will be used for scaling the
AEGL values for isobutyronitrile across time.
The AEGL-3 was based on a estimated no-effect-level for death in
rats (1/3 of the 1-hour LC50: 1,800 ppm 3 = 600
ppm) (Eastman Kodak Co., 1986a). Although no interspecies information
concerning isobutyronitrile toxicity was available, data from another
nitrile (methacrylonitrile) suggest that the rat is not the most
sensitive species. Therefore, an interspecies UF of 10 will be applied.
In the absence of chemical-specific data and since much of the acute
toxicity of nitriles is due to cyanide, the intraspecies UF will be the
same as that used in the derivation of hydrogen cyanide AEGL-3 values
(NAC/AEGL Committee, 1997). Thus, an UF of 3 will be applied to account
for sensitive individuals since human accidental and occupational
exposures suggest little intraindividual variability of hydrogen
cyanide toxicity (NAC/AEGL Committee, 1997). Therefore, the total UF is
30. The concentration-time relationship for many irritant and
systemically acting vapors and gases may be described by C\n\ x t = k
(ten Berge et al., 1986). Since much of the acute toxicity of
isobutyronitrile is thought to be due to cyanide, the empirically
derived chemical-specific value of n = 2.6 (derived from cyanide rat
lethality data, (NAC/AEGL Committee, 1997) will be used for scaling the
AEGL values for isobutyronitrile across time.
The calculated values are listed in Table 3 below:
Table 3.--Isobutyronitrile
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Summary of Proposed AEGL Values for Isobutyronitrile [ppm (mg/m\3\)]
---------------------------------------------------------------------------------------------------------------------------------------------------------
Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours Endpoint/Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) ID ID ID ID ID Insufficient data
to derive AEGL-1
values
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2 (Disabling) 13 (36) 8.7 (24) 6.6 (18) 3.9 (11) 3.0 (8.4) No-effect-level in
rats (Saillenfait
et al., 1993)
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[[Page 77870]]
AEGL-3 (Lethal) 40 (112) 26 (73) 20 (56) 12 (34) 9.0 (23) Estimated no-
observed-effect
level (NOEL) for
death in rats
(Eastman Kodak,
1986a)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ID Insufficient data.
ii. References. a. Eastman Kodak Company. 1986a. Acute inhalation
toxicity and one-hour LC10 value of isobutyronitrile in the
rat. (Study No. TX-86-193) Eastman Kodak Company, Rochester, NY 14650.
b. NAC/AEGL Committee. 1997. Acute Exposure Guideline Levels for
Hydrogen Cyanide. NAC Pro Draft 3:11/97.
c. Saillenfait, A. M., Bonnet, P., Gurnier, J. P., and de Ceaurriz,
J. 1993. Relative developmental toxicities of inhaled aliphatic
mononitriles in rats. Fundamental Applied Toxicology. 20:365-375.
d. ten Berge, W.F., Zwart, A. and Appelman, L.M. 1986.
Concentration-time mortality response relationship of irritant and
systemically acting vapours and gases. Journal Hazardous Materials.
13:301-309.
e. USEPA. 1985. Chemical Profile. Isobutyronitrile. Washington, DC.
December, 1985.
3. Propionitrile--i. Description. Propionitrile is a colorless
liquid at ambient temperature and pressure. It has a pleasant,
ethereal, sweetish odor and may cause irritation or burning of the eyes
and skin. It is metabolized to cyanide in the body and signs of
exposure may include weakness, headache, confusion, nausea, vomiting,
convulsion, dilated pupils, weak pulse, shallow and gasping breathing,
and cyanosis (Hazardous Substances Data Bank (HSDB), 1998).
Data were insufficient for derivation of AEGL-1 values for
propionitrile.
The AEGL-2 was based on headache, nausea, dizziness, vomiting,
confusion, and disorientation in a 34-year-old male worker exposed to
approximately 33.8 ppm propionitrile for 2 hours (Scolnick et al.,
1993). In the absence of chemical-specific data and since much of the
acute toxicity of propionitrile appears to be due to cyanide, an UF of
3 was applied to account for sensitive individuals since human
accidental and occupational exposures suggest little intraindividual
variability of hydrogen cyanide toxicity (NAC/AEGL Committee, 1997). A
modifying factor of 2 was also applied to account for the poor
database. Thus, the total uncertainty/modifying factor is 6. The
concentration-time relationship for many irritant and systemically
acting vapors and gases may be described by C\n\ x t = k (ten Berge et
al., 1986). Since much of the acute toxicity of proprionitrile is
thought to be due to cyanide, the empirically derived chemical-specific
value of n = 2.6 (derived from cyanide rat lethality data, (NAC/AEGL
Committee, 1997) was used for scaling the AEGL-2 values for 30-minutes,
1-, 4-, and 8-hours. The 30-minute AEGL-2 value was also adopted as the
10-minute value due to the fact that reliable data are limited to
durations 2 hours, and it is considered inappropriate to
extrapolate back to 10-minutes.
The AEGL-3 was based on a 4-hour no-effect-level for death in rats
of 690 ppm (Younger Labs, 1978). An interspecies UF of 10 was applied
since toxicity information suggests that the rat is not the most
sensitive species. In the absence of chemical-specific data and since
much of the acute toxicity of proprionitrile appears to be due to
cyanide, an UF of 3 was applied to account for sensitive individuals
since human accidental and occupational exposures suggest little
intraindividual variability of hydrogen cyanide toxicity (NAC/AEGL
Committee, 1997). Thus, the total UF is 30. The concentration-time
relationship for many irritant and systemically acting vapors and gases
may be described by C\n\ x t = k (ten Berge et al., 1986). Since much
of the acute toxicity of propionitrile is thought to be due to cyanide,
the empirically derived chemical-specific value of n = 2.6 (derived
from cyanide rat lethality data, (NAC/AEGL Committee, 1997) was used
for scaling the AEGL values for values for 30-minutes, 1-hour, and 8-
hours. The 30-minute AEGL-3 value was also adopted as the 10-minute
value due to the fact that the values are derived from a 4 hour
exposure, and it is considered inappropriate to extrapolate back to 10-
minutes.
The calculated values are listed in the Table 4 below:
Table 4.--Propionitrile
--------------------------------------------------------------------------------------------------------------------------------------------------------
Summary of Proposed AEGL Values for Propionitrile [ppm (mg/m\3\)]
------------------------------------------------------------------------------------------------------------------------------------- Endpoint/Reference
Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) ID ID ID ID ID Insufficient data
to derive AEGL-1
values
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2 (Disabling) 9.6 (22) 9.6 (22) 7.4 (17) 4.3 (9.8) 3.3 (7.6) Headache, nausea,
vomiting,
dizziness,
confusion in a
human subject
(Scolnick et al.,
1993)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-3 (Lethal) 51 (120) 51 (120) 39 (89) 23 (53) 18 (41) No-effect-level
for death in rats
(Younger Labs,
1978)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ID Insufficient data.
[[Page 77871]]
ii. References. a. HSDB. 1998. Propionitrile. Reviewed 9/24/92.
Updated 6/2/98. Retrieved 6/16/98.
b. NAC/AEGL Committee. 1997. Acute Exposure Guideline Levels for
Hydrogen Cyanide. NAC Pro Draft 3:11/97.
c. Scolnick, B., Hamel, D., and Woolf, A.D. 1993. Successful
treatment of life threatening propionitrile exposure with sodium
thiosulfate followed by hyperbaric oxygen. Journal of Occupational
Medicine. 35:577-580.
d. ten Berge, W.F., Zwart, A. and Appelman, L.M. 1986.
Concentration-time mortality response relationship of irritant and
systemically acting vapours and gases. Journal of Hazardous Materials.
13:301-309.
e. Younger Labs. 1978. Initial Submission: Toxicological
Investigation of Propionitrile with Cover Letter Dated 081992.
OTS0546148.
4. Methacrylonitrile--i. Description. Methacrylonitrile is a
colorless liquid at ambient temperature and pressure. It has an odor
similar to bitter almonds and may cause irritation or burning of the
eyes and skin. It is metabolized to cyanide in the body and signs of
exposure may include weakness, headache, confusion, nausea, vomiting,
convulsion, dilated pupils, weak pulse, shallow and gasping breathing,
and cyanosis (HSDB, 1998).
Data were insufficient for derivation of AEGL-1 values for
methacrylonitrile.
The AEGL-2 values were set as 1/3 of the AEGL-3 values. The values
obtained from this approach are supported by a repeated-exposure study
in which dogs were exposed to 13.5 ppm methacrylonitrile, 7 hours/day,
5 days/week for 90 days (Pozzani et al., 1968). Convulsions and loss of
motor control of the hindlimbs were observed starting at day 39 of
exposure.
The AEGL-3 was based on a no-effect-level for death in mice (19 ppm
for 4 hours) (Pozzani et al., 1968). An interspecies UF of 3 will be
applied since the mouse is the most sensitive species. In the absence
of chemical-specific information on intraspecies variability and since
much of the acute toxicity of nitriles is due to cyanide, the
intraspecies UF will be the same as that used in the derivation of
hydrogen cyanide AEGL-3 values (NAC/AEGL Committee, 1997). Thus, an UF
of 3 will be applied to account for sensitive individuals since human
accidental and occupational exposures suggest little intraindividual
variability of hydrogen cyanide toxicity (NAC/AEGL Committee, 1997).
Thus, the total UF is 10. The concentration-time relationship for many
irritant and systemically acting vapors and gases may be described by
C\n\ x t = k (ten Berge et al., 1986). In the absence of chemical-
specific information and since much of the acute toxicity of
methacryonitrile is thought to be due to cyanide, the empirically
derived chemical-specific value of n = 2.6 (derived from cyanide rat
lethality data, (NAC/AEGL Committee, 1997) will be used for scaling the
30-minute, 1-, and 8-hour AEGL values for propionitrile across time.
The 30-minute AEGL-3 value was also adopted as the 10-minute value due
to the fact that reliable data are limited to durations 4
hours, and it is considered inappropriate to extrapolate back to 10-
minutes.
The calculated values are listed in Table 5 below:
Table 5.--Methacrylonitrile
--------------------------------------------------------------------------------------------------------------------------------------------------------
Summary of Proposed AEGL Values for Methacrylonitrile [ppm (mg/m\3\)]
---------------------------------------------------------------------------------------------------------------------------------------------------------
Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours Endpoint/Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) ID ID ID ID ID Insufficient data
to derive AEGL-1
values
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2 (Disabling) 1.5 (4.1) 1.5 (4.1) 1.1 (3.0) 0.70 (1.9) 0.50 (1.4) 1/3 of the AEGL-3
values
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-3 (Lethal) 4.5 (12) 4.5 (12) 3.4 (9.3) 2.0 (5.5) 1.5 (4.1) 4-hr. no-effect-
level for death
in mice (Pozzani
et al., 1968)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ID Insufficient data.
ii. References. a. HSDB. 1998. Methacrylonitrile. Reviewed 9/24/92.
Updated 6/3/98. Retrieved 6/16/98.
b. NAC/AEGL Committee. 1997. Acute Exposure Guideline Levels for
Hydrogen Cyanide. NAC Pro Draft 3: 11/97.
c. Pozzani, U.C., Kinkead, E.R., and King, J.M. 1968. The mammalian
toxicity of methacrylonitrile. American Industrial Hygiene Association
Journal. 29:202-210.
d. ten Berge, W.F., Zwart, A. and Appelman, L.M. 1986.
Concentration-time mortality response relationship of irritant and
systemically acting vapours and gases. Journal of Hazardous Materials.
13:301-309.
5. Chlorine trifluoride--i. Description. Chlorine trifluoride is an
extremely reactive and corrosive oxidizing agent used in nuclear
reactor fuel processing, as a fluorinating agent, as an incendiary,
igniter and propellant for rockets, and as a pyrolysis inhibitor for
fluorocarbon polymers. It is unstable in air and rapidly hydrolyses to
hydrogen fluoride (HF) and a number of chlorine-containing compounds
including chlorine dioxide (ClO2). The toxic effects of
ClF3 are likely due to HF and ClO2.
Chlorine trifluoride is a mucous membrane irritant. Contact with
the skin and eyes produces burns and inhalation causes pulmonary
irritation and edema. Inhalation studies with the monkey, dog, rat, and
mouse for several endpoints and exposure durations were located. Data
on irritant effects were available for the dog and rat; data on
sublethal and lethal concentrations were available for the monkey, rat,
and mouse. Although human exposures have occurred, no data on exposure
concentrations were located.
The AEGL-1 was based on the threshold for notable discomfort
(lacrimation) that was observed in dogs after 3 hours during a 6-hour
exposure to an average concentration of 1.17 ppm (Horn and Weir, 1956).
The only other sign of exposure was mild sensory irritation (nasal
discharge) that usually occurred within 45 minutes. Nasal discharge in
the sensitive nose of the dog was considered below the definition of
the AEGL-1. No effects were observed in rats exposed to this
concentration for 6 hours. The 1.17 ppm concentration for an exposure
duration of 3 hours was divided by a combined interspecies and
intraspecies UF of 10 (3 for interspecies differences [the dog was more
sensitive than the rat] and 3 for intraspecies differences in
sensitivity [the mechanism of toxicity is irritation; response to such
a basic chemical effect on tissue is not expected to vary
[[Page 77872]]
significantly among individuals]). Scaling across time was based on
C\n\ x t = k where n = 1 (Haber's Law); this concentration-exposure
duration relationship was determined from several lethality studies.
Because of the long exposure duration of the key study, the 10-minute
AEGL-1 was set equal to the 30-minute AEGL-1.
The AEGL-2 was based on signs of strong irritation (salivation,
lacrimation, rhinorrhea, and blinking of the eyes) in dogs exposed to a
concentration of 5.15 ppm for 6 hours (Horn and Weir, 1955). Although
these effects appeared reversible by the end of the day, they may
impair the ability to escape. Rats exposed to this concentration for 6
hours appeared unaffected. The 6-hour concentration of 5.15 ppm was
divided by a combined interspecies and intraspecies UF of 10 and scaled
across time using the same reasons and relationships as for the AEGL-1
in this unit. Because of the long exposure duration of the key study,
the 10-minute AEGL-2 was set equal to the 30-minute AEGL-2.
Lethality data (1-hour LC50 values) were available for
the monkey, rat, and mouse. The AEGL-3 was based on the calculated 1-
hour LC01 for the mouse, the most sensitive species based on
LC50 values (MacEwen and Vernot, 1970). This concentration,
135 ppm, was divided by a combined interspecies and intraspecies UF of
10 and scaled across time using the same reasons and relationships as
for the AEGL-1 in this unit. Death was due to extreme irritation
resulting in massive lung hemorrhaging. Data from another study in
which dogs exposed to a concentration of 21 ppm for 6 hours showed
extreme signs of irritation but no deaths resulted in essentially the
same AEGL-3 values when adjusted by an UF of 10 and scaled across time
using Haber's Law.
The calculated values are listed in Table 6 below:
Table 6.--Chlorine Trifluoride
--------------------------------------------------------------------------------------------------------------------------------------------------------
Summary of Proposed AEGL Values for Chlorine Trifluoride [ppm (mg/m\3\)]
---------------------------------------------------------------------------------------------------------------------------------------------------------
Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours Endpoint/Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) 0.70 (2.7) 0.70 (2.7) 0.35 (1.3) 0.090 (0.34) 0.040 (0.15) Threshold, notable
discomfort--dog
(Horn and Weir,
1956)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2 (Disabling) 6.2 (24) 6.2 (24) 3.1 (12) 0.77 (2.9) 0.39 (1.5) Strong irritation--
dog (Horn and
Weir, 1955)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-3 (Lethal) 81 (308) 27 (103) 14 (53) 3.4 (13) 1.7 (6.5) Lethality (LC01)--
mouse (MacEwen
and Vernot, 1970)
--------------------------------------------------------------------------------------------------------------------------------------------------------
ii. References. a. Horn, H.J. and R.J. Weir. 1955. Inhalation
toxicology of chlorine trifluoride. I. Acute and subacute toxicity.
A.M.A. Archives of Industrial Health. 12:515-521.
b. Horn, H.J. and R.J. Weir. 1956. Inhalation toxicology of
chlorine trifluoride. II. Chronic toxicity. A.M.A. Archives of
Industrial Health. 13:340-345.
c. MacEwen, J.D. and E.H. Vernot. 1970. Toxic Hazards Research Unit
Annual Technical Report: 1970. AMRL-TR-70-77, Aerospace Medical
Research Laboratory, Wright-Patterson Air Force Base, OH; National
Technical Information Service, Springfield,VA
6. Ethyleneimine--i. Description. Ethylenimine is a volatile,
clear, colorless, flammable explosive liquid that has an odor similar
to that of ammonia and an odor detection level of 2 ppm. It is a very
reactive direct-acting alkylating agent, the activity of which is
similar to that of nitrogen mustards. It is also very caustic,
attacking numerous substances including plastics, metals, and glass
that does not contain carbonate or borax. Estimates of domestic
production of ethylenimine range between 3.3 and 4.85 million pounds.
Ethylenimine is used in the manufacture of products, such as
triethylenemelamine, paper, textile chemicals, adhesive binders, and
petroleum refining chemicals. Ethylenimine is stored in 320-pound
cylinders, but shipping quantities are unknown.
Relevant data on ethylenimine consisted of only a few case studies
in humans and acute inhalation lethality studies in laboratory animals.
One individual died after a brief exposure to an unknown concentration
of ethylenimine. Death was preceded by eye irritation, salivation,
vomiting, respiratory tract irritation, breathlessness, and pulmonary
edema; death may have been due to medical treatment. Individuals
exposed to ethylenimine at estimated concentrations of 235-353 ppm and
N-ethylethylenimine at 722 to 1,084 ppm for 11/2 to 2 hours suffered
severe eye and respiratory tract irritation and vomiting that were
delayed for 1 to 5 hours after exposure, followed by hemoglobinemia,
eosinophilia, and albuminuria. Effects reported for occupational
exposure to ethylenimine included skin sensitization, slow-healing
dermatitis, rapidly reversible irritation to the eyes and respiratory
tract, and blistering, reddening, and edema of the scrotum. Direct
contact of liquid ethylenimine to the tongue caused delayed
inflammation and edematous swelling of the oral cavity and inflammation
of eyes, and direct contact of liquid with the skin causes necrotizing
painless burns. Ethylenimine was genotoxic in all test systems
investigated including bacteria, fungi, plants, insects, and mammalian
cells in vitro. It is clastogenic in cultured human cells. Subcutaneous
injection of rats with ethylenimine produced sarcomas at the injection
site.
Acute inhalation LC50 values were 2,558, 1,407, 545,
268, 259, 58, and 35 ppm for rats exposed to ethylenimine for 5, 10,
15, 60, 120, 240, or 480 minutes, respectively; 2,906, 2,824, 1,283,
364, 235, 158, 45, and 27 ppm for guinea pigs exposed for 5, 10, 15,
30, 60, 120, 240, or 480 minutes, respectively; and 2,236 ppm for mice
exposed for 10 minutes. In all studies, death and other signs of
toxicity were delayed depending on exposure concentration. Signs of
toxicity included eye irritation, respiratory tract irritation,
respiratory difficulty, prostration, complete loss of muscular
coordination (mouse only), and convulsions (mouse only). Systemic
effects included lung damage, congestion in lungs and all internal
organs, damage to the kidney tubules, and albuminuria in rats and
guinea pigs.
AEGL-1 values were not derived, because ethylenimine is an
insidious agent (effects are delayed) that has an odor similar to that
of ammonia, and an odor detection limit at 2 ppm; consequently,
ethylenimine has no specific warning properties (sensory irritation or
odor). The odor detection level is similar to or higher than the
[[Page 77873]]
AEGL-2 values for 4-hour and 8-hour exposures; therefore, it is not
valid nor would it be a benefit to the public to propose AEGL-1 values.
No animal studies designed specifically to examine nonlethal
effects of ethylenimine were located in the literature, and the human
study involved exposure to another substance that could have
contributed to the observed toxic effects. Therefore, the AEGL-2 values
were based on a NOEL for extreme respiratory difficulty in guinea pigs
(10 ppm for 240 minutes) in the study by Carpenter et al. (1948). An UF
of 3 was applied for intraspecies variability because of the insidious
nature of ethylenimine, and effects of exposure may not become apparent
before exposure is terminated. Under these conditions; individuals with
respiratory or heart diseases are not expected to respond differently
from the general population. The very reactive alkylating activity of
ethylenimine also suggests that it would be similarly effective in all
individuals. A UF of 3 was also applied for interspecies sensitivity
because of the reactive alkylating activity of ethylenimine and the
similarity of the mode of action in different species. Further, the
available evidence suggests that humans may be less sensitive than
rodents. The total UF is 10. Scaling across the pertinent time frames
was based on the equation C\0.91\ x t = k, where n was derived from the
LC50 data for guinea pigs. The AEGL-2 values do not take
into account the potential carcinogenicity of ethylenimine.
AEGL-3 values were based on the acute inhalation study in rats
(Carpenter et al. , 1948). The LC01 (lethality threshold) of
15 ppm for the 8-hour exposure duration was estimated by probit
analysis. The 8-hour LC01 was selected because it had the
smallest standard error. A total UF of 10 (3 for intraspecies
variability and 3 for interspecies sensitivity) was applied to the
LC01 value. Scaling across the pertinent time frames was
based on the equation C\1.1\ x t = k, where n was derived from
LC50 data for rats.
The calculated values are listed in Table 7 below:
Table 7.--Ethylenimine
--------------------------------------------------------------------------------------------------------------------------------------------------------
Summary of Proposed AEGL Values for Ethylenimine\a,b\ [ppm (mg/m\3\)]
---------------------------------------------------------------------------------------------------------------------------------------------------------
Classification 10-minutes 30-minutes 1-hour 4-hours 8-hours Endpoint/Reference
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 (Nondisabling) No values derived for AEGL-1
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2 (Disabling) 33 (59) 9.8 (185) 4.6 (8.2) 1.0 (1.8) 0.47 (0.84 ) NOEL for extreme
respiratory
difficulty
(Carpenter et
al., 1948)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-3 (Lethal) 51 (91) 19 (34) 9.9 (18) 2.8 (5.0) 1.5 (2.7) Threshold for
lethality
(Carpenter et
al., 1948)
--------------------------------------------------------------------------------------------------------------------------------------------------------
a AEGL-2 and -3 values do not take into consideration the potential cancer risk due to exposure to ethylenimine.
b Effects at these concentrations may be delayed until sometime after exposure; toxic levels may be absorbed through the skin.
ii. Reference. Carpenter, C. P.; Smyth, H. F., Jr.; Shaffer, C. B.
1948. The acute toxicity ethyleneimine to small animals. Journal of
Industrial Hygiene and Toxicology. 30:2-6.
7. Propyleneimine--i. Description. Propylenimine is an aziridine
compound used to modify latex surface coating resins to improve
adhesion and to modify bonding properties of textiles, paper, and dyes;
it is also used in photography, in the pharmaceutical industry, in
gelatins, and in organic syntheses. Propylenimine is a colorless oily
liquid that has an odor similar to that of ammonia. It is flammable and
is an explosion hazard. Propylenimine is similar in structure and
toxicity to ethylenimine.
No data were found in the literature concerning toxicity or the
odor detection threshold for exposure to propylenimine in humans. A
time-response study conducted in rats and guinea pigs showed that 1/6
guinea pigs died after exposure to 500 ppm for 60 minutes and 0/6 died
after exposure to the same concentration for 30 minutes (Carpenter et
al., 1948). In rats, 5/6 died after exposure to 500 ppm for 240 minutes
and 0/6 died after exposure to the same concentration for 120 minutes.
No concentration-response data were available for deriving AEGL values
from animal studies. Therefore, a relative potency approach was used to
derive AEGL-2 values, because the toxicity of propylenimine is
considered to be qualitatively similar to that of ethylenimine. The
study of Carpenter et al. (1948) showed that propylenimine is 4 to 8
times less toxic than ethylenimine depending on the species: 4 or 5
times less toxic to the guinea pig and 8 times less toxic to the rat.
Tumors developed at multiple sites in rats treated orally with
propylenimine for 28 or 60 weeks; therefore, International Agency for
Research on Cancer (IARC) has classified propylenimine as Group 2B
(possibly carcinogenic to human). Propylenimine is mutagenic in
salmonella and drosophila.
No AEGL-1 values were proposed for ethylenimine, and no values are
proposed for propylenimine. Propylenimine has an odor similar to that
of ammonia, the odor detection and irritation thresholds are not known,
and propylenimine is probably an insidious agent similar to
ethylenimine. It would not be valid nor beneficial to propose AEGL-1
values for propylenimine.
The derivation of AEGL-2 values is based on the relative toxicity
approach. The AEGL values proposed for ethylenimine based on a no-
effect-level for extreme respiratory difficulty were as follows: 33,
9.8, 4.6, 1.0, and 0.47 ppm for 10 minutes, 30 minutes, 1 hour, 4
hours, and 8 hours, respectively. The NAC/AEGL Committee selected 5 as
the appropriate relative toxicity value for deriving AEGL-2 values for
propylenimine. The NAC/AEGL Committee also proposed that a modifying
factor of 2 should be applied to account for a deficient database.
Therefore, the resulting values for propylenimine based on a relative
toxicity value of 5 and a modifying factor of 2 are 83, 25, 12, 2.5,
and 1.2 ppm for exposure durations of 10 minutes, 30 minutes, 1 hour, 4
hours, and 8 hours, respectively.
It was the consensus of the NAC/AEGL Committee to consider a 500
ppm exposure for 30 minutes as the no-effect-level for lethality and to
use this concentration to derive AEGL-3 values. An UF of 10 (3 for
intraspecies sensitivity and 3 for interspecies sensitivity) was
applied to the no-effect-levels for lethality. Propylenimine is an
insidious agent and signs of toxicity may not become apparent until
after exposure. Propylenimine a very reactive direct-acting alkylating
agent, and its mode of action is not expected to vary
[[Page 77874]]
considerably across species or within the population. Time
extrapolation was based on the equation, C\n\ x t = k, where n = 0.91
derived by probit analysis of LC50 data for guinea pigs
exposed to ethylenimine.
The calculated values are listed in Table 8 below:
Table 8.--Propylenimine
--------------------------------------------------------------------------------------------------------------------------------------------------------
Summary of Proposed AEGL Values for Propylenimine\a,b\ [ppm (mg/m\3\)]
---------------------------------------------------------------------------------------------------------------------------------------------------------
ppm (mg/m\3\)
Classification ---------------------------------------------------------------------------------------------------- Endpoint/Reference
10-minutes 30-minutes 1-hour 4-hours 8-hours
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-1 No values derived for AEGL-1
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-2\c\ 83 (200) 25 (58) 12 (28) 2.5 (5.8) 1.2 (2.8) NOEL for extreme
respiratory
difficulty
(Carpenter et
al., 1948)
--------------------------------------------------------------------------------------------------------------------------------------------------------
AEGL-3 167 (390) 50 (120 ) 23 (54 ) 5.1 (12) 2.4 (5.6 ) Lethality
threshold
(Carpenter et
al., 1948)
--------------------------------------------------------------------------------------------------------------------------------------------------------
a AEGL-2 and -3 values do not take into consideration the potential cancer risk due to inhalation exposure to propylenimine.
b Effects including lethality, irritation to eyes, and irritation to the respiratory tract may be delayed until after exposure; toxic levels of
propylenimine may be absorbed through the skin.
c AEGL values for propylenimine = AEGL for ethylenimine x 5 (relative potency factor) 2 (modifying factor).
ii. Reference. Carpenter, C.P., Smyth, H.F., Jr., Shaffer, C.B.
1948. The acute toxicity of ethylenimine to small animals. Journal of
Industrial Hygiene and Toxicology. 30:2-6.
IV. Next Steps
The NAC/AEGL Committee plans to publish ``Proposed'' AEGL values
for five-exposure periods for other chemicals on the priority list in
groups of approximately 10 to 20 chemicals in future Federal Register
notices during the calendar year 2001.
The NAC/AEGL Committee will review and consider all public comments
received on this notice, with revisions to the ``Proposed'' AEGL values
as appropriate. The resulting AEGL values will be established as
``Interim'' AEGLs and will be forwarded to the NRC/NAS, for review and
comment. The ``Final'' AEGLs will be published under the auspices of
the NRC/NAS following concurrence on the values and the scientific
rationale used in their development.
List of Subjects
Environmental protection, Hazardous substances.
Dated: December 6, 2000.
Stephen L. Johnson,
Acting Assistant Administrator for Prevention, Pesticides and Toxic
Substances.
[FR Doc. 00-31730 Filed 12-12-00; 8:45 am]
BILLING CODE 6560-50-S