[Federal Register Volume 65, Number 204 (Friday, October 20, 2000)]
[Proposed Rules]
[Pages 63027-63035]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-27034]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Parts 141 and 142
[WH-FRL-6888-8]
RIN 2040-AB75
National Primary Drinking Water Regulations; Arsenic and
Clarifications to Compliance and New Source Contaminants Monitoring
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice of data availability.
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SUMMARY: The Environmental Protection Agency (EPA) proposed regulations
for arsenic in drinking water on June 22, 2000 (65 FR 38888), and
comments on that action were due on September 20, 2000. Since that
time, EPA has received new risk information which the Agency is
considering during the development of the final regulation. This
document summarizes the new risk information received and analyzed by
the Agency. In addition, this document makes available the cost curves
used to develop the costs published in the proposal. This information
does not change the overall technical approach for the proposal. EPA is
requesting comments on EPA's
[[Page 63028]]
use of the new risk analysis and development of cost estimates for the
final rule and any comments on other parts of the proposal which would
change because of the information provided today.
DATES: Your comments on this document must be submitted to EPA in
writing and should be postmarked or received November 20, 2000.
ADDRESSES: Send written comments to the W-99-16 NODA Arsenic Comments
Clerk, Water Docket (MC-4101); U.S. Environmental Protection Agency;
1200 Pennsylvania Ave., NW., Washington, DC 20460. Comments may be
hand-delivered to the Water Docket, U.S. Environmental Protection
Agency; 401 M Street, SW; East Tower Basement, room EB-57; Washington,
DC 20460; (202) 260-3027 between 9 a.m. and 3:30 p.m. Eastern Time,
Monday through Friday. Comments may be submitted electronically, marked
docket number W-99-16 NODA, to [email protected]. Please refer to the
information under the headings ``Additional Information for
Commenters'' and ``Availability of Docket'' in SUPPLEMENTARY
INFORMATION for detailed information about filing and docket review.
FOR FURTHER INFORMATION CONTACT: For technical inquiries about risk and
benefits discussed in this notice, contact Dr. John B. Bennett, (202)
260-0446, email: [email protected], and for technical inquiries
about treatment and cost discussed in this notice, contact Jeff Kempic,
(202) 260-9567, email: [email protected]. For general information
about this notice, contact Irene Dooley, (202) 260-9531, email:
[email protected].
SUPPLEMENTARY INFORMATION:
Regulated Entities
A public water system, as defined in 40 CFR 141.2, provides water
to the public for human consumption through pipes or other constructed
conveyances, if such system has ``at least fifteen service connections
or regularly serves an average of at least twenty-five individuals
daily at least 60 days out of the year.'' A public water system is
either a community water system (CWS) or a non-community water system
(NCWS). A community water system, as defined in Sec. 141.2, is ``a
public water system which serves at least fifteen service connections
used by year-round residents or regularly serves at least twenty-five
year-round residents.'' The definition in Sec. 141.2 for a non-
transient, non-community water system [NTNCWS] is ``a public water
system that is not a [CWS] and that regularly serves at least 25 of the
same persons over 6 months per year.'' EPA has an inventory totaling
over 54,000 community water systems and approximately 20,000 non-
transient, non-community water systems nationwide. Entities potentially
regulated by this action are community water systems and non-transient,
non-community water systems. The following table provides examples of
the regulated entities under this rule.
Table of Regulated Entities
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Examples of potentially regulated
Category entities
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Industry.................... Privately owned/operated community water
supply systems using ground water or
mixed ground water and surface water.
State, Tribal, and Local State, Tribal, or local government-owned/
Government. operated water supply systems using
ground water or mixed ground water and
surface water.
Federal Government.......... Federally owned/operated community water
supply systems using ground water or
mixed ground water and surface water.
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The table is not intended to be exhaustive, but rather provides a
guide for readers regarding entities likely to be regulated by this
action. This table lists the types of entities that EPA is now aware
could potentially be regulated by this action. Other types of entities
not listed in this table could also be regulated. To determine whether
your facility is regulated by this action, you should carefully examine
the applicability criteria in Secs. 141.11 and 141.62 of the rule. If
you have any questions regarding the applicability of this action to a
particular entity, consult the general information person listed in the
FOR FURTHER INFORMATION CONTACT section.
Additional Information for Commenters
Please submit an original and three copies of your comments and
enclosures (including references) and identify your submission by the
docket number W-99-16 NODA. To ensure that EPA can read, understand,
and therefore properly respond to comments, the Agency would prefer
that comments cite, where possible, the paragraph(s) or sections in the
document or supporting documents to which each comment refers.
Commenters should use a separate paragraph for each issue discussed. If
you are submitting your comments electronically and mailing hard
copies, please indicate on your electronic submission that hard copies
are being sent separately. Electronic comments must be submitted as a
WordPerfect 5.1, WP6.1 or WP8 file or as an ASCII file avoiding the use
of special characters. Comments and data will also be accepted on disks
in WP 5.1, WP6.1 or WP8, or ASCII file format. Electronic comments on
this document may be filed online at many Federal Depository Libraries.
Commenters who want EPA to acknowledge receipt of their comments should
include a self-addressed, stamped envelope. No facsimiles (faxes) will
be accepted.
Availability of Docket
The docket for this document has been established under number W-
99-16-II, and includes supporting documentation as well as printed,
paper versions of electronic comments. The docket is available for
inspection from 9 a.m. to 4 p.m., Monday through Friday, excluding
legal holidays, at the Water Docket; EB 57; in the East Tower basement
of U.S. EPA; 401 M Street, SW; Washington, DC. For access to docket
materials, please call (202) 260-3027 to schedule an appointment.
Abbreviations Used
%--percent
AIC--Akaike information criterion
CWS--community water system
EB--East Tower Basement
ED01--Effective dose which results in 1% excess lifetime
risk
EPA--U.S. Environmental Protection Agency
et al.--et alibi, Latin for ``and others''
FR--Federal Register
i.e.--id est, Latin for ``that is''
kg--kilograms, 2.2 pounds
L--Liter, also referred to as lower case ``l'' in older citations
LED01--a 95% lower confidence limit for ED01
MDBP--microbial/disinfection by-product
MCL--maximum contaminant level
[[Page 63029]]
mg--milligrams--one thousandth of a gram, 1 milligram = 1,000
micrograms
microgram (g)--One-millionth of gram (3.5 x
10-\8\ oz., 0.000000035 oz.)
g/L--micrograms per liter
MOE01--margin of exposure, ratio of ED01 to MCL
NAS--National Academy of Sciences
NODA--Notice of Data Availability
NRC--National Research Council, operating agency of NAS
NRC--National Research Council, the operating arm of NAS
O&M--operation and maintenance
ppb--Parts per billion. Also, g/L or micrograms per liter
RIA--Regulatory Impact Analysis
U.S.--United States
VSL--Value of a statistical life
WTP--Willingness to pay
How Does This Document Relate to the June 22, 2000 Proposal?
In the Thursday, June 22, 2000, Federal Register the U.S.
Environmental Protection Agency (EPA) proposed regulations for arsenic
and clarifications to compliance and new source contaminants monitoring
(65 FR 38888). This document applies only to the arsenic part of the
proposal. Specifically, EPA noted that ``Further work on the risk
assessment will also be done before the final rule is issued to analyze
the risks of internal cancers (65 FR 38888 at 38899).'' This document
discusses new risk information and EPA's subsequent risk analysis.
On page 39835 of the June 22, 2000, arsenic proposal, EPA noted
that the unit cost curves are in the November 1999 ``Technologies and
Costs for the Removal of Arsenic from Drinking Water.'' It has come to
EPA's attention that the cost curves used to develop the costs that are
included in the proposal and supporting Regulatory Impact Analysis
(RIA) are in an earlier version of this document dated April 1999. This
document announces the availability of the April 1999 version, with
curves that more accurately reflect the analysis in the preamble and
the RIA. The overall approach to cost estimation in the proposed rule
and the proposed Maximum Contaminant Level (MCL) remain unchanged.
What New Risk Data Has EPA Analyzed?
In the proposal we calculated bladder cancer benefits and risks
using the bladder cancer risk analysis from the 1999 National Research
Council (NRC) report, Arsenic in Drinking Water. We also estimated lung
cancer benefits in a ``What If'' analysis based on a qualitative
statement about lung cancer deaths from the 1999 NRC report. At that
time we noted that a peer-reviewed lung cancer risk study would
probably become available before the final rule came out (65 FR 38888
at 38944). This Spring, we received a copy of a peer-reviewed article
by Morales et al. (2000). This article presented additional analyses of
bladder cancer risks as well as estimates of lung and liver cancer
risks for the same Taiwanese population analyzed in the NRC report.
This document makes available for public comment the Morales et al.
(2000) information and the Agency's analysis of the bladder and lung
cancer risks from that paper.
What Is in the Article by Morales et al.?
The article ``Risk of Internal Cancer from Arsenic in Drinking
Water'' (Morales et al., 2000) presents an assessment of the magnitude
of risk for cancers of the bladder, liver and lung from exposure to
arsenic in water, based on data from 42 villages in an arseniasis
endemic region of Taiwan. The authors calculated excess lifetime risk
estimates using several Poisson regression models and a multistage-
Weibull model. (Excess lifetime risk is the additional probability of
disease or death due to the given cause over the course of a lifetime.)
Risk estimates are expressed as ED01, the concentration at
which 1% additional lifetime risk of death is incurred;
LED01, a 95% lower confidence limit for ED01; and
MOE01(50), the ``margin of exposure,'' or the ratio of
ED01 to the current MCL of 50 g/L. The authors
found that risk estimates are sensitive to the choice of model, to
whether a comparison population is used to define the unexposed disease
mortality rates, and whether the comparison population is all of Taiwan
or just an unexposed portion of the population in the study area. The
authors noted that some of the factors that may affect the magnitude of
risk could not be evaluated quantitatively: The ecological nature of
the data, the nutritional status of the study population, and the
dietary intake of arsenic. Despite all these sources of uncertainty,
however, the analysis suggests that the current standard of 50
g/L is associated with a substantial increased risk of cancer
and thus is not suffciently protective of public health. (The authors
state that ``the risk associated with a concentration of 50 g/
L is approximately 1 in 300, based on linear extrapolation from the
point of departure. * * * This is an extremely high value.'')
The Morales et al. (2000) article uses several statistical models
to estimate bladder, lung, and liver cancer risk from arsenic exposure.
It also presents the combined risk of all three cancers. The risk
assessments are based on a study from Taiwan published by Chen et al.
(1985), with the data grouped at the village level. These data are also
used for the bladder cancer risk analysis in the 1999 NRC report.
Morales et al. (2000) examine issues of dose-response modeling for the
generalized linear model. The authors identify several Poisson and
multistage-Weibull models which fit the data about equally well. They
prefer the Poisson models, in part because the fit of the Weibull
models is more sensitive to the omission of subsets of individual
villages. The models are based on mortality data from Taiwan, and model
results are transferred to the United States (U.S.) without adjustment
for differences in mortality-to-incidence ratios for the various
illnesses. The authors adjusted the risk analyses to reflect
differences in average population weight and in the consumption of
drinking water between the U.S. and Taiwan (assuming a representative
person in the U.S. weighs 70 kg and drinks 2 liters of water per day
vs. a Taiwanese weighing 55 kg and drinking 3.5 liters). Two comparison
populations, one from all of Taiwan and one from southwestern Taiwan,
were used in the modeling to estimate background levels of risk.
The various model results present considerable variability in
cancer risk estimates for arsenic. The authors propose several reasons
for the variability, including the large variability of exposure among
people within each village and use of a comparison population in the
analysis. The authors also suggest that a variety of factors for which
data were not available, including the dietary intake of inorganic
arsenic, could influence or even confound these models. They observe
that ``* * * this is an ecological study wherein only relatively simple
exposure and population characteristics could be measured. It will be
important to consider this and other sources of uncertainty when
interpreting the results (Morales et al., 2000).'' The authors
conclude, however, that it seems likely that arsenic is contributing to
excess cancer mortality in the U.S. based on their evaluation of
combined risks of bladder, lung, and liver cancer: ``Despite the
considerable variation in estimated ED01, the results are
sobering and indicate that current standards are not adequately
protective against cancer (Morales et al., 2000).''
What Models Did EPA Choose To Use for Additional Analysis?
Ten risk models were presented in Morales et al. (2000). Following
Dr. Louise Ryan's presentation to the SAB
[[Page 63030]]
Drinking Water Committee (SAB, 2000), and after additional consultation
with the primary authors (Morales and Ryan), EPA chose Model 1 with no
comparison population for further analysis. In Model 1 the dose effect
is assumed to follow a linear function and the age effect is assumed to
follow a quadratic function.
EPA believes, after consultation with the authors, that the models
in Morales et al. (2000) with a comparison population are less reliable
than those without a comparison population. With no comparison
population, the arsenic dose-response curve is estimated only from the
study population. Models with a comparison population include mortality
data from a similar population (in this case either all of Taiwan or
part of southwestern Taiwan), whose exposure is assumed to be zero.
Most of the models with comparison populations resulted in dose-
response curves that were supralinear (higher than a linear dose-
response) at low doses. The curves were forced down at zero dose
because the comparison population consists of a large number of people
with low risk and assumed zero exposure. EPA believes, based on
discussions with the authors, that these models are less reliable, for
two reasons. First, there is no basis in data on arsenic's carcinogenic
mode of action to consider a supralinear curve to be biologically
plausible. The conclusion of the NRC panel (NRC, 1999) was that the
mode of action data led one to expect dose responses that would be
either linear or less than linear at low dose. However, the NRC
indicated that available data are inconclusive and ``* * * do not meet
EPA's 1996 stated criteria for departure from the default assumption of
linearity.'' Second, models which include comparison populations assume
that the exposure of the comparison population is zero, and that the
study and comparison populations are the same in all important ways
except for arsenic exposure. Neither of these comparison populations
assumptions may be correct: NRC (1999) notes that ``the Taiwanese-wide
data do not clearly represent a population with zero exposure to
arsenic in drinking water''; and Morales et al. (2000) agree that
``[t]here is reason to believe that the urban Taiwanese population is
not a comparable population for the poor rural population used in this
study.'' Moreover, because of the large amount of data in the
comparison populations, the model results are relatively sensitive to
assumptions about this group. For these reasons, EPA believes that the
models without comparison populations are more reliable than those with
them.
Of the models that did not include a comparison population, EPA
believes Model 1 fits the data best, based on the Akaike information
criterion (AIC), a standard criterion of model fit, applied to the
Poisson models. EPA did not consider the multi-stage Weibull model for
additional analysis, because of its greater sensitivity to the omission
of individual villages (Morales et al., 2000) and to the grouping of
responses by village (NRC, 1999), as occurs in the Taiwanese data.
The Poisson regression model (Model 1), without a comparison
population, gave results for lifetime excess risk of bladder cancer for
males from arsenic ingestion (about 1.3 in a 1000 at an arsenic level
of 50 g/L) which were approximately the same as those risks
found by the NRC (approximately 1 in a 1000 at an arsenic level of 50
g/L). Among females, lifetime excess risk of bladder cancer is
estimated to be 2.0 in 1000 at 50 g/L. We also considered
estimates using this model for excess risks for lung and liver cancer
due to arsenic. The lung cancer risk estimates, which were comparable
to the bladder cancer risk estimates, were of special interest to the
Agency, as the NRC report did not provide a statistical analysis of
these risks.
However, EPA did not further consider the Taiwan liver cancer
estimates for U.S. liver cancer risks. Angiosarcoma liver cancer
(cancer in the liver's blood vessels) has been linked to arsenic
exposure in Germany (Roth, 1957, as reported in Smith et al., 1992),
Chile (Zaldivar et al., 1981, as reported in Smith et al., 1992), and
the U.S. (Falk et al., 1981, as reported in Smith et al., 1992).
However, most liver cancers in Taiwan were hepatocellular (i.e., liver
cell) carcinomas linked to hepatitis (Chen et al., 1985 & 1986), rather
than angiosarcoma cancer, and are extremely rare in the U.S.
How Will the New Data Affect EPA's Risk Analysis?
This section describes EPA's risk analysis in the June 22, 2000,
proposed arsenic rulemaking, then extends the analysis to incorporate
new information from Morales et al. (2000).
The June 22, 2000, proposed arsenic rulemaking contained an
analysis of the excess exposed population risks associated with arsenic
consumption for bladder cancer. This analysis was based on the 1999
National Research Council (NRC) report, in which the NRC examined risk
distributions for male bladder cancer in 42 villages in Taiwan. This
population was exposed to drinking water with arsenic ranging from 10
to 934 g/L; arsenic exposure estimates were grouped by
village. To monetize bladder cancer benefits, EPA calculated the number
of cases potentially avoided, based on the NRC bladder cancer risk
analyses, for populations exposed to MCL options of 3 g/L, 5
g/L, 10 g/L, and 20 g/L. The proposal's
analytic approach included five components. First, EPA used data from
the recent EPA water consumption study (US EPA, 2000a). Second, we used
Monte Carlo simulations to develop a distribution of ``relative
exposure factors,'' which account for individual variations in risk due
to water consumption and body weight. Third, arsenic occurrence
estimates (US EPA, 2000c) were used to identify the population exposed
to levels above 3 g/L. We assumed drinking water exposure
reflected treatment to 80% of the MCL level, because water systems tend
to treat below the MCL level in order to provide a margin of safety.
Fourth, EPA chose four NRC risk distributions (NRC, 1999, from Tables
10-11 and 10-12) for the analysis, that used Poisson-model derived risk
estimates, with and without baseline comparison data. Fifth, EPA used
Monte Carlo simulations to develop estimates of the risks faced by the
exposed population, using the relative exposure factors, occurrence,
and the NRC risk distributions. These components of the analysis are
described in the proposed rulemaking (US EPA, 2000d, section X.A). EPA
also monetized the potential benefits of avoided lung cancer, using a
``What If'' analysis based on statements in the NRC report.
Table 1 shows the mean and 90th percentile bladder cancer incidence
risks summarized from Tables X-4A, X-4B, X-2A, and X-2B in the June 22,
2000, arsenic proposed rulemaking (65 FR 38888), after treatment, for
the U.S. population currently exposed at or above 3 g/L, 5
g/L, 10 g/L, and 20 g/L. These risk
distributions are based on bladder cancer mortality data in Taiwan, in
a section of Taiwan where arsenic concentrations in the water are very
high by comparison to those in the U.S. It is also an area of low
incomes (NRC, 1999, pg. 292) and poor diet (NRC, 1999, pg. 295), and
the availability and quality of medical care is not of high quality, by
U.S. standards. In its estimate of bladder cancer risk, the Agency
assumed that within the Taiwanese study area at the time of the study,
the risk of contracting bladder cancer was relatively close to the risk
of dying from bladder cancer (that is, that
[[Page 63031]]
the bladder cancer incidence rate was equal to the bladder cancer
mortality rate). Survival rates for bladder cancer in the U.S. have
been improving from 1973 to 1996 (i.e., U.S. bladder cancer mortality
rates decreased overall 24% to 26%). Recent bladder cancer survival
rates in developing countries range from 23.5% to 66.1%, and are
currently 45% for bladder cancer in Taiwan, as discussed in the
proposed rulemaking (65 FR 38888 at 38942). At most, the Agency
concluded that bladder cancer incidence could be no more than 2 times
bladder cancer mortality; and that an 80% mortality rate would be
plausible. The benefits analysis included estimates using an assumed
mortality rate ranging from 80% to 100%.
Table 1.--Bladder Cancer Risks From the June 22, 2000 Proposal: Mean (From Tables X-4A and X-4B) and 90th
Percentile (From Tables X-2A and X-2B) Lifetime Incidence Risks,\1\ for U.S. Populations Exposed at or Above MCL
Options, After Treatment \2\ (Lower Bounds: Low NRC Risk, CWS Water Consumption; Upper Bounds: High NRC Risk,
Total Water Consumption)
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90th percentile exposed population
MCL g/L Mean exposed population risk risk
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3................................... 2.1-4.5 x 10-\5\ 4-7 x 10-\5\
5................................... 3.6-7.5 x 10-\5\ 6-12 x 10-\5\
10.................................. 5.5-11.4 x 10-\5\ 1-2 x 10-\4\
20.................................. 6.9-13.9 x 10-\5\ 1.4-2.8 x 10-\4\
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\1\ Actual risks could be lower, given the various uncertainties discussed, or higher, as these estimates assume
a 100% mortality rate.
\2\ The risk analysis assumed exposure at 80% of the MCL level, because water systems tend to treat below the
MCL level in order to provide a margin of safety.
The Morales et al. (2000) article provided a new analysis of
bladder cancer risk. Although the data used were the same as used by
the NRC to analyze bladder cancer risk in their 1999 publication,
Morales et al. (2000) consider more dose-response models and evaluate
how well they fit the Taiwanese data. Therefore the Agency decided to
examine the implications of the new bladder cancer risk assessment from
Morales et al. (2000), as well as the lung cancer risk assessment.
Using the same analytical approach as in the arsenic proposed rule
(with Monte Carlo simulations combining relative exposure factors,
occurrence estimates, and risk distributions), the Agency recalculated
the mean bladder cancer risks for U.S. populations, based on the risk
estimates from Morales et al. (2000), derived from Model 1 with no
comparison population. The results are shown in Table 2, along with the
bladder cancer risks remaining, after treatment, for the 90th
percentile U.S. population.
Table 2.--Bladder Cancer: Mean and 90th Percentile Lifetime Incidence Risks,\1\ for U.S. Populations Exposed At
or Above MCL Options, after Treatment \2\ (Morales Risk, Low Water Consumption for Lower Bound, High Water
Consumption for Upper Bound)
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MCL g/L Mean exposed population risk 90th percentile population risk
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3........................................... 4.9-6.0 x 10-5 1-1.2 x 10-4
5........................................... 8.4-10.2 x 10-5 1.8-2.0 x 10-4
10.......................................... 1.2-1.47 x 10-4 2.6-3.1 x 10-4
20.......................................... 1.55-1.89 x 10-4 3.5-4.1 x 10-4
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\1\ Actual risks could be lower, given the various uncertainties discussed, or higher, as these estimates assume
a 100% mortality rate.
\2\ The risk analysis assumed exposure at 80% of the MCL level, because water systems tend to treat below the
MCL level in order to provide a margin of safety.
The Agency also estimated the mean and 90th percentile lung cancer
risks for U.S. populations, using the same analytical approach and the
risk estimates from Morales et al. (2000), derived from Model 1 with no
comparison population. The results are shown in Table 3.
[[Page 63032]]
Table 3.--Lung Cancer: Mean Lifetime Incidence Risks,\1\ for U.S. Populations Exposed at or Above MCL Options,
After Treatment \2\ (Morales Risk, Low Water Consumption for Lower Bound, High Water Consumption for Upper
Bound)
----------------------------------------------------------------------------------------------------------------
MCL g/L Mean exposed population risk 90th percentile population risk
----------------------------------------------------------------------------------------------------------------
3.................................. 4.9-6.1 x 10-5 1.0-1.2 x 10-4
5.................................. 8.2-10.5 x 10-5 1.7-2.1 x 10-4
10................................. 1.21-1.46 x 10-4 2.7-3.1 x 10-4
20................................. 1.52-1.87 x 10-4 3.4-4.3 x 10-4
----------------------------------------------------------------------------------------------------------------
\1\ Actual risks could be lower, given the various uncertainties discussed, or higher, as these estimates assume
a 100% mortality rate.
\2\ The risk analysis assumed exposure at 80% of the MCL level, because water systems tend to treat below the
MCL level in order to provide a margin of safety.
EPA believes, based upon this most recent risk information, that
the combined risk of excess cases of lung and bladder cancer
attributable to arsenic in drinking water could be at least twice that
of bladder cancer alone. However, EPA will need to conduct additional
analyses of this risk information, together with additional analyses of
the various uncertainties associated with the underlying data, and of
comments submitted in response to the proposed rule, to develop its
best estimate of the overall risk in support of a final rulemaking.
How Did EPA Analyze the Lower Bound of its Risk Estimates?
The Agency performed a sensitivity analysis of the lower bound risk
estimates, considering the effect on risk estimates of exposure to
arsenic through water used in preparing food in Taiwan. The 1988 EPA
``Special Report on Ingested Inorganic Arsenic'' contained the
following discussion:
For the studied population, rice and sweet potatoes were the
main staple and might account for as much as 80% of food intake per
meal. For the purpose of discussion we will assume that a man in the
study population ate one cup of dry rice and two pounds of potatoes
per day and that the amount of water required to cook the rice and
potatoes was about 1 L. Under this assumption, the risk calculated
before is overestimated by about 30% (1 L/ 3.5 L). This calculation
considers only the water used for cooking; the arsenic content in
the rice and potatoes that might have been absorbed from soil
arsenic is not considered because of the lack of information.
The Taiwanese staple foods were dried sweet potatoes and rice (Wu et
al., 1989). Both the 1988 EPA report and the 1999 NRC report assumed
that an average Taiwanese male weighed 55 kg and drank 3.5 liters of
water daily, and that an average Taiwanese female weighed 50 kg and
drank 2 L of water daily. Using these assumptions, along with an
assumption that Taiwanese men and women ate one cup of dry rice and two
pounds of sweet potatoes a day, the Agency re-estimated risks for
bladder and lung cancer, using one additional liter water consumption
for food preparation (i.e., the water absorbed by hydration during
cooking). The food consumed in Taiwan contains more arsenic than in the
U.S.: on average, about 50 g/day in Taiwan, versus about 10
g/day in the U.S. (NRC, 1999, pp. 50-51). Thus our analysis
may still overstate the risk to the U.S. population, when the total
consumption of inorganic arsenic (from food preparation and drinking
water) is considered. Results of the EPA analysis considering water
used in cooking are shown in Table 4, using the NRC bladder cancer
risk, the Morales et al. (2000) bladder cancer risk, and the Morales et
al. (2000) lung cancer risk estimates utilized earlier in this
Document. Table 5 shows the cancer risks remaining, after treatment to
80% MCL options, for high percentile U.S. populations, providing a
sensitivity analysis for the lower bound risk taking into account the
arsenic intake from water used in cooking dried foods.
Table 4.--Sensitivity Analysis of Mean Lower Bound Incidence Risk Estimates,1, 2 Risks Adjusted for Water Used
in Cooking (CWS Water Consumption Data)
----------------------------------------------------------------------------------------------------------------
MCL (g/L) Bladder (NRC) Bladder (Morales) Lung (Morales)
----------------------------------------------------------------------------------------------------------------
3................................ 1.7 x 10-5 3.5 x 10-5 3.6 x 10-5
5................................ 2.9 x 10-5 5.7 x 10-5 5.7 x 10-5
10............................... 4.1 x 10-5 8.4 x 10-5 8.4 x 10-5
20............................... 5.1 x 10-5 1.01 x 10-5 1.06 x 10-5
----------------------------------------------------------------------------------------------------------------
\1\ Risks are adjusted under assumption that Taiwanese males and females consume one additional liter of water
in rehydrating dried rice and sweet potatoes.
\2\ The bladder cancer risks presented in this table provide ``best'' estimates. Actual risks could be lower,
given the various uncertainties discussed, or higher, as these estimates assume a 100% mortality rate.
[[Page 63033]]
Table 5.--Sensitivity Analysis of 90th Percentile Lower Bound Incidence Risk Estimates,1, 2 Risks Adjusted for
Water Used in Cooking (CWS Water Consumption Data)
----------------------------------------------------------------------------------------------------------------
MCL (g/L) Bladder (NRC) Bladder (Morales) Lung (Morales)
----------------------------------------------------------------------------------------------------------------
3................................ 3.5 x 10-5 7.5 x 10-5 7.2 x 10-5
5................................ 5.9 x 10-5 1.2 x 10-4 1.2 x 10-4
10............................... 9.0 x 10-5 1.8 x 10-4 1.8 x 10-4
20............................... 1.1 x 10-4 2.3 x 10-4 2.4 x 10-4
----------------------------------------------------------------------------------------------------------------
\1\ Risks are adjusted under assumption that Taiwanese males and females consume one additional liter of water
in rehydrating dried rice and sweet potatoes.
\2\ The bladder cancer risks presented in this table provide ``best'' estimates. Actual risks could be lower,
given the various uncertainties discussed, or higher, as these estimates assume a 100% mortality rate.
How Will EPA Evaluate Benefits in the Final Rule?
The benefits of a regulatory option depend primarily on the number
of cases of an illness avoided due to the reduction in risk resulting
from the implementation of the option. For the arsenic proposed rule
and following established Agency practices, EPA estimated the number of
cases of bladder cancer avoided using mean exposed population incidence
risk estimates at various MCL levels (these mean exposed population
incidence risks are shown in Table 1). We converted lifetime risk
estimates to annual risk factors, and applied these to the exposed
population to determine the number of cases avoided (both fatal and
non-fatal). We adjusted the upper bound bladder cancer number of cases
estimates by assuming an 80% mortality rate in Taiwan, which is a
plausible mortality rate for the area of Taiwan during the Chen study.
The lower bound estimates assumed a 100% mortality rate from bladder
cancer in Taiwan. For the benefits assessment, EPA used U.S. mortality
information to divide the number of cases into fatal and non-fatal
cases avoided. Benefits are assumed to begin to accrue on the effective
date of the arsenic rule (65 FR 38888 at 38946).
The avoided cases of fatal bladder cancer are valued by what is
known as the ``value of a statistical life'' (VSL), currently estimated
at $6.1 million (in 1999 dollars).\1\ VSL does not refer to the value
of an identifiable life, but instead to the value of small reductions
in mortality risks in a population. We used the central tendency
estimate of $604,000 (1999 dollars) \2\ of the willingness to pay (WTP)
to avoid a case of chronic bronchitis to monetize the benefits of
avoiding non-fatal bladder cancers (Viscusi et al., 1991). WTP data for
avoiding chronic bronchitis has been used before by EPA (the microbial/
disinfection by-product (MDBP) rulemaking) as a surrogate for the WTP
to avoid non-fatal bladder cancer. EPA summed the monetized benefits
for fatal and non-fatal bladder cancer cases avoided to obtain total
monetized benefits for avoided bladder cancer cases (shown in Tables X-
7 and XI-1 of the proposed rule preamble, in 1999 dollars).
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\1\ The June 20, 2000, proposal (65 FR 38888) cited the central
tendency estimate of the VSL as $5.8 million in 1997 $ in the
preamble text. However, the analyses presented in the proposal's
tables reflect 1999 $ values, as noted.
\2\ The June 20, 2000, proposal (65 FR 38888) cited the central
tendency estimate of the WTP as $536,000 in 1997 $ in the preamble
text. However, the analyses presented in the proposal's tables
reflect 1999 $ values, as noted.
---------------------------------------------------------------------------
In the arsenic proposed rule, EPA also estimated the number of lung
cancer cases avoided, for the various options considered, using a
``What If'' analysis, and monetized these cases using the same process
that was used to monetize the benefits of avoided bladder cancer cases.
The ``What If'' analysis examined possible benefits from avoided lung
cancer cases if the number of those cases in the U.S. which were fatal
in outcome was 2-5 times the number of fatal bladder cancer cases (the
implicit risk for lung cancer ranged from about half to about twice
that of the risk for bladder cancer).
EPA plans to use the benefits evaluation process described in this
section for the final rule, using the data and analysis of the bladder
and lung cancer risks described in this document instead of the ``What
If'' lung cancer analysis included in the proposal. These more
definitive benefits estimates will be derived from the new risk
calculations that will accompany the final rule (based upon further
consideration of additive risk analyses) and other pertinent
information. Background information on the economic concepts that
provide the foundation for benefits valuation, and the methods that are
typically used by economists to monetize the value of risk reductions,
such as wage-risk, cost of illness, and contingent valuation studies
are provided in the arsenic RIA.
EPA Benefits Summary and Conclusions
Morales et al. (2000) assess the risks of lung and bladder cancer
associated with arsenic consumption in water, based on data from
Taiwan, using several statistical models. Although the data used were
the same as used by the NRC (1999). Morales et al. consider more dose-
response models, providing a more exhaustive treatment of model fit.
They also discuss additional factors, for which data were not
available, which might influence or confound the analysis. Dose-
response risk estimate for both bladder and lung cancer, derived from
the best-fitting model, were analyzed further by the Agency. The Agency
calculated new risk estimates for the U.S. exposed population, for the
various MICL options under consideration. The resulting risk estimates
for bladder cancer are higher than those examined in detail in the
proposal, and the new lung cancer risks are approximately equal to the
new bladder cancer risks. As noted earlier, EPA believes that the
combined risk of excess cases from lung and bladder cancer could be at
least twice that of bladder cancer alone and will be refining its
overall risk estimate in support of the final rule based on a number of
factors, with a particular focus on the additive risks of lung and
bladder cancer. Monetized benefits from avoided cases overall are
expected to fall within the ranges presented in the June 22 Proposed
Rule, because of the implicit assumptions of lung cancer risk in the
``What If'' analysis. However, the lung cancer monetized benefits would
be more certain, and removed from the ``What If'' categorization. In
addition, the Agency performed a lower bound sensitivity analysis of
risk estimates given a variation in the assumption about water used for
cooking in Taiwan.
What Technologies and Costs Document Is Being Made Available?
In the June 22, 2000, Federal Register, the EPA presented national
cost
[[Page 63034]]
estimates of the proposed arsenic rule (65 FR 38888). In several tables
\3\ in the preamble EPA presented annualized national cost estimates
for four MCL options (3, 5, 10 and 20 L). The methodology and
data used to develop these estimates are described in the Regulatory
Impact Analysis (RIA) (EPA 2000b). This document is making available
for public comment additional information on the costs of treatment
technologies EPA: ``Technologies and Costs for the Removal of Arsenic
From Drinking Water,'' April 1999, which has been placed in the docket,
and will be made available on EPA's website. EPA used this April 1999
document to develop the national estimates presented in the proposed
rule.
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\3\ Table VIII-3. Annual Costs of Treatment Trains (Per
Household); Table IX-11. National Annual Treatment Costs; Table IX-
12. Total Annual Costs Per Household; Table IX-13. Incremental
National Annual Costs; Table IX-14. Incremental Annual Costs Per
Household; Table X-7. Estimated Costs and Benefits From Reducing
Arsenic in Drinking Water; Table XI-1. Estimated Costs and Benefits
From Reducing Arsenic in Drinking Water; Table XIII-3. Estimated
Costs and Benefits From Reducing Arsenic in Drinking Water; Table
XIII-4. Estimated Annualized National Costs of Reducing Arsenic
Exposures; Table XIII-5. Estimated Annual Costs Per Household and
(Number of Households Affected); Table XIII-6. Summary of the Total
Annual National Costs of Compliance with the Proposed Arsenic Rule
Across MCL Options; Table XIII-7. Estimates of the Annual
Incremental Risk Reduction, Benefits, and Costs of Reducing Arsenic
in Drinking Water; Table XIV-2. Average Annual Cost per CWS by
Ownership; Table XIV-3. Average Compliance Costs per Household for
CWSs Exceeding MCLs; and Table XIV-4. Average Compliance Costs per
Household for CWSs Exceeding MCLs as a Percent of Median Household
Income.
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The RIA describes the model (SafeWaterXL) that was used by EPA to
estimate national costs. The model uses data on arsenic occurrence,
compliance decision trees, unit treatment technology train costs and
other relevant data to generate national cost estimates. All of these
inputs are described in the RIA. The treatment trains that were used in
the national cost estimation are given in Exhibit 6-1 of the RIA. The
RIA provides information on treatment technology costs by system size
in Exhibit 6-2. The exhibit has cost estimates on treatment capital,
treatment operation and maintenance (O&M), waste disposal capital, and
waste disposal O&M costs for each treatment train.
Today's document is advising the public about the availability in
the docket of ``Technologies and Costs for the Removal of Arsenic from
Drinking Water,'' April 1999, which provides the unit cost curves
(regressions) that were used to generate Exhibit 6-1 of the RIA. The
April 1999 technology and cost document contains curves for several
removal efficiencies, including the ones corresponding to the removal
efficiencies identified in Exhibit 6-1 of the RIA.
The unit cost treatment curves for each technology can be found in
the April 1999 technology and cost document. The unit cost waste
disposal curves can be derived from Table 4-1, ``Summary of Residuals
Characteristics,'' in the technology and cost document. Those
interested in reproducing the waste disposal curves should consult the
``Small Water System Byproducts Treatment and Disposal Cost'' (EPA
1993a) document and the ``Water System Byproducts Treatment and
Disposal Cost'' (EPA 1993b) document. The former is for small water
systems, and the latter is for larger ones. An electronic copy of the
treatment technology and waste disposal equations used in the
development of the RIA can also be found in the docket.
Why Does the Docket Have a Copy of a Newer Version of the
Technologies & Costs for Comment?
The EPA has continued to refine and update cost estimates of the
treatment technologies discussed in the proposed rule. In addition, EPA
is following the development of emerging technologies that would be
relevant for arsenic removal. An update of the April 1999 document was
inadvertently included in the docket: EPA, ``Technologies and Costs for
Removal of Arsenic from Drinking Water,'' November 1999. This was not,
however, the version used to develop the RIA. The RIA costs were
developed using the earlier April 1999 version, which is being provided
with this document. This data and information is being made available
to those interested in reproducing our national cost estimates.
The differences between the cost curves in the April and November
drafts are attributable to the different design criteria assumptions
made when running the unit cost models. Three unit cost models were
used: ``Very Small Systems'' (for systems between 0.015 to 0.100 mgd),
``Water model'' (for systems between 0.27 and 1.00 mgd), and ``W/W
Cost'' (for systems between 10 to 200 mgd). The design criteria
assumptions are described prior to the presentation of the cost curves
in each document. For example, the design criteria assumptions for
coagulation assisted microfiltration are listed on page 3-47 of the
November 1999 document and on page 3-60 of the April 1999 document. EPA
will continue to refine the cost curves and other cost of compliance
information and data based on comments submitted on the proposal.
How Will EPA Use the November 1999 Cost Document?
EPA will carefully consider all comments on the proposed rule and
will develop new national cost estimates for the final rule, along with
a new supporting treatment technology and cost document, which would
update both the April 1999 and November 1999 versions of the treatment
technology and cost document. The new version that will be developed
will include cost estimates for emerging technologies, and where
necessary, updates to the treatment technology cost curves already
developed. EPA may also develop an updated decision tree to refine and
improve the cost estimates, based on comments received on the proposal.
Changes in these inputs to EPA's models for determining the cost of
compliance and any changes to the national cost estimates generated by
the model will be presented in the final rule.
References
Chen, C. J., Y. C. Chuang, T. M. Lin and H. Y. Wu. 1985. Malignant
neoplasms among residents of a Blackfoot disease endemic area in
Taiwan: High arsenic well water and cancers. ``Cancer Research''
45:5895-5899.
Chen, C. J., Y. C. Chuang, T. M. Lin and H. Y. Wu. 1986. A
retrospective study on malignant neoplasms of bladder, lung and
liver in Blackfoot disease endemic area in Taiwan. ``British Journal
of Cancer'' 53:399-405.
Morales, K.H., L. Ryan, K.G. Brown, T-L Kuo, M-M Wu, and C.J. Chen.
2000. Risk of Internal Cancers from Arsenic in Drinking Water.
``Environmental Health Perspectives'' 108:655-661.
National Research Council. 1999. ``Arsenic in Drinking Water.''
Washington, DC. National Academy Press.
Smith, A.H., C. Hopenhayn-Rich, M.N. Bates, H.M. Goeden, I. Hertz-
Picciotto, H.M. Duggan, R. Wood, M.J. Kosnett, and M.T. Smith. 1992.
Cancer risks from arsenic in drinking water. ``Environmental Health
Perspectives'' 97:259-267.
US EPA. 1988. ``Special Report on Ingested Inorganic Arsenic: Skin
Cancer; Nutritional Essentiality.'' Risk Assessment Forum. EPA/625/
3-87/013. 124 pp. July 1988.
US EPA. 1993a. Small Water System Byproducts Treatment and Disposal
Cost Document. April 1993.
US EPA. 1993b. Water System Byproducts Treatment and Disposal Cost
Document. April 1993.
US EPA. 1999a. Technologies and Costs for Removal of Arsenic From
Drinking Water. EPA-815-R-00-012. Prepared by International
Consultants, Inc. and Malcolm Pirnie, Inc. under contract to EPA
OGWDW. November 1999.
US EPA. 1999b. Technologies and Costs for the Removal of Arsenic
From Drinking Water. Prepared by International
[[Page 63035]]
Consultants, Inc. and Malcolm Pirnie, Inc. under contract 68-C-C6-
0039 with EPA OGWDW. April 1999.
US EPA. 2000a. ``Estimated Per Capita Water Ingestion in the United
States: Based on Data Collected by the United States Department of
Agriculture's (USDA) 1994-1996 Continuing Survey of Food Intakes by
Individuals.'' Office of Water, Office of Standards and Technology.
EPA-822-00-008. April 2000.
US EPA. 2000b. Proposed Arsenic in Drinking Water Rule: Regulatory
Impact Analysis (RIA). Prepared by Abt Associates, Inc. under
contract to EPA OGWDW. EPA 815-R-013. June 2000.
US EPA. 2000c. ``Arsenic Occurrence in Public Drinking Water
Supplies.'' Public Comment Draft. Office of Water, Washington DC.
EPA 815-D-00-001. May 2000.
US EPA. 2000d. National Primary Drinking Water Regulations; Arsenic
and Clarifications to Compliance and New Source Contaminants
Monitoring; Proposed Rule. Federal Register. Vol. 65, No. 121, p.
38888. June 22, 2000.
Viscusi, W.K., W.A. Magat, and J. Huber. 1991. Pricing Environmental
Health Risks: Survey Assessments of Risk-Risk and Risk-Dollar Trade-
Offs for Chronic Bronchitis. ``Journal of Environmental Economics
and Management.'' 21:32-51.
Wu, M.M., T.L. Kuo, Y.H. Hwant, and C.J. Chen. 1989. Dose-response
relation between arsenic concentration in well water and mortality
from cancers and vascular diseases. American Journal of
Epidemiology. 130:1123-1132.
Authority: 42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-
5, 300g-6, 300j-4, 300j-9, and 300j-11.
Dated: October 13, 2000.
J. Charles Fox,
Assistant Administrator for Water.
[FR Doc. 00-27034 Filed 10-19-00; 8:45 am]
BILLING CODE 6560-50-P