[Federal Register Volume 81, Number 1 (Monday, January 4, 2016)]
[Rules and Regulations]
[Pages 13-19]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-32760]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 141
[EPA-HQ-OW-2012-0155; FRL-9940-64-OW]
Announcement of Final Regulatory Determinations for Contaminants
on the Third Drinking Water Contaminant Candidate List
AGENCY: Environmental Protection Agency (EPA).
ACTION: Final regulatory determinations.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is announcing
final regulatory determinations not to issue national primary drinking
water regulations for four of the 116 contaminants listed on the Third
Contaminant Candidate List. The Safe Drinking Water Act, as amended in
1996, requires the EPA to make regulatory determinations every five
years on at least five unregulated contaminants. A regulatory
determination is a decision about whether or not to begin the process
to propose and promulgate a national primary drinking water regulation
for an unregulated contaminant. On October 20, 2014, the agency
published its preliminary determinations not to regulate dimethoate,
1,3-dinitrobenzene, terbufos, terbufos sulfone and begin the process to
regulate strontium. The agency requested public comment on the
determinations, process, rationale and supporting technical
information. The agency received comments from 14 individuals or
organizations on the preliminary regulatory determinations. After
careful review and consideration of the public comments, the agency is
making a final determination not to regulate dimethoate, 1,3-
dinitrobenzene, terbufos and terbufos sulfone. The agency, however, is
delaying the final regulatory determination on strontium in order to
consider additional data and decide whether there is a meaningful
opportunity for health risk reduction by regulating strontium in
drinking water.
DATES: In accordance with 40 CFR 23.7 for purposes of judicial review,
the regulatory determinations in this document are issued as of January
4, 2016.
FOR FURTHER INFORMATION CONTACT: Zeno Bain, Standards and Risk
Management Division, Office of Ground Water and Drinking Water, Office
of Water (Mailcode 4607M), Environmental Protection Agency, 1200
Pennsylvania Ave. NW., Washington, DC 20460; telephone number: (202)
564-5970; email address: [email protected]. For general information,
contact the Safe Drinking Water Hotline, telephone number: (800) 426-
4791. The Safe Drinking Water Hotline is open Monday through Friday,
excluding legal holidays, from 10 a.m. to 4 p.m., eastern time.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this action apply to me?
These final regulatory determinations will not impose any
requirements on anyone. Instead, this action notifies interested
parties of the EPA's final regulatory determinations for four
contaminants and provides a summary of the major comments received on
the October 20, 2014, preliminary determinations (USEPA, 2014c).
B. How can I get copies of this document and other related information?
Docket: The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OW-2012-0155. Publicly available docket materials
are available either electronically at http://www.regulations.gov or in
hard copy at the Water Docket, EPA/DC, EPA West, Room 3334, 1301
Constitution Ave. NW., Washington, DC. The Water Docket Public Reading
Room is open from 8:30 a.m. to 4:30 p.m., Monday through Friday,
excluding legal holidays. The telephone number for the Public Reading
Room is (202) 566-1744, and the telephone number for the Water Docket
is (202) 566-2426.
Electronic Access: You may access this Federal Register document
electronically from the Government Printing Office under the ``Federal
Register'' listings at http://www.gpo.gov/fdsys/browse/collection.action?collectionCode=FR.
Abbreviations Used in This Document
CCL Contaminant Candidate List
CCL 3 Third Contaminant Candidate List
CFR Code of Federal Regulations
EPA Environmental Protection Agency
FR Federal Register
HRL Health Reference Level
MCL Maximum Contaminant Level
MCLG Maximum Contaminant Level Goal
MRL Minimum Reporting Limit
[[Page 14]]
NPDWR National Primary Drinking Water Regulation
PWS Public Water System
RD Regulatory Determination
RD 3 Third Regulatory Determination
RSC Relative Source Contribution
SDWA Safe Drinking Water Act
STORET Storage and Retrieval Data System
UCMR Unregulated Contaminant Monitoring Regulation
UCMR 1 First Unregulated Contaminant Monitoring Regulation
UCMR 2 Second Unregulated Contaminant Monitoring Regulation
UCMR 3 Third Unregulated Contaminant Monitoring Regulation
USDA United States Department of Agriculture
USGS United States Geological Survey
[mu]g/L micrograms per Liter
Table of Contents
I. General Information
A. Does this action apply to me?
B. How can I get copies of this document and other related
information?
II. Purpose and Background
A. What is the purpose of this action?
B. What are the statutory requirements for the Contaminant
Candidate List (CCL) and regulatory determinations?
C. What contaminants did the EPA consider for regulations?
III. What process did the EPA use to make the regulatory
determinations?
IV. Summary of the EPA's Findings on the Four Contaminants With
Final Regulatory Determinations
A. Dimethoate
1. Description
2. Agency Findings
B. 1,3-Dinitrobenzene
1. Description
2. Agency Findings
C. Terbufos and Terbufos Sulfone
1. Description
2. Agency Findings
D. Public Comments on Four Contaminants With Final Regulatory
Determinations
V. Summary of Public Comments on Strontium and the Agency's
Responses
A. Background on Strontium and the EPA's Preliminary
Determination
B. What comments did the EPA receive on strontium?
VI. Next Steps
VII. References
II. Purpose and Background
A. What is the purpose of this action?
The purpose of this action is to present a summary of the EPA's
findings related to the final regulatory determinations for four
contaminants listed on the Third Contaminant Candidate List (CCL 3)
(USEPA, 2009). The four contaminants include: Dimethoate, 1,3-
dinitrobenzene, terbufos and terbufos sulfone. Today's action briefly
summarizes the statutory requirements for targeting drinking water
contaminants for regulatory determination, provides an overview of the
contaminants the agency considered for regulation and describes the
approach used to make the final regulatory determinations. In addition,
today's action summarizes the public comments received on the agency's
preliminary determinations and the agency's responses to those
comments, including the status of the EPA's evaluation of strontium.
B. What are the statutory requirements for the Contaminant Candidate
List (CCL) and regulatory determinations?
The specific statutory requirements for the CCL and regulatory
determinations can be found in the Safe Drinking Water Act (SDWA),
section 1412(b)(1). The 1996 SDWA Amendments require the EPA to publish
the CCL every five years. The CCL is a list of contaminants that are
not subject to any proposed or promulgated national primary drinking
water regulations (NPDWRs), are known or anticipated to occur in public
water systems (PWSs) and may require regulation under SDWA. The 1996
SDWA Amendments also direct the agency to determine whether to regulate
at least five contaminants from the CCL every five years. SDWA requires
the agency to publish a Maximum Contaminant Level Goal (MCLG) \1\ and
promulgate an NPDWR \2\ for a contaminant if the Administrator
determines that:
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\1\ The MCLG is the ``maximum level of a contaminant in drinking
water at which no known or anticipated adverse effect on the health
of persons would occur, and which allows an adequate margin of
safety. Maximum contaminant level goals are nonenforceable health
goals'' (40 CFR 141.2).
\2\ An NPDWR is a legally enforceable standard that applies to
public water systems. An NPDWR sets a legal limit (called a maximum
contaminant level or MCL) or specifies a certain treatment technique
for public water systems for a specific contaminant or group of
contaminants.
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(a) The contaminant may have an adverse effect on the health of
persons;
(b) The contaminant is known to occur or there is a substantial
likelihood that the contaminant will occur in public water systems with
a frequency and at levels of public health concern; and
(c) In the sole judgment of the Administrator, regulation of such
contaminant presents a meaningful opportunity for health risk reduction
for persons served by public water systems.
If the agency determines that all three of these statutory criteria
are met, it makes a determination that a national primary drinking
water regulation is needed. In that case, the agency has 24 months to
publish a proposed MCLG and NPDWR. After the proposal, the agency has
18 months to publish a final MCLG and promulgate a final NPDWR (SDWA
section 1412(b)(1)(E)).\3\
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\3\ The statute authorizes up to a nine-month extension of this
promulgation date.
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C. What contaminants did the EPA consider for regulation?
On October 20, 2014, the EPA published preliminary regulatory
determinations for five contaminants on the third Contaminant Candidate
List (CCL 3) that had sufficient information to support a regulatory
determination (USEPA, 2014c). The five contaminants are 1,3-
dinitrobenzene, dimethoate, terbufos, terbufos sulfone and strontium.
The agency is making final regulatory determinations not to regulate
dimethoate, 1,3-dinitrobenzene, terbufos and terbufos sulfone. The
agency is not making a final regulatory determination for strontium at
this time. The agency's decision to delay a final determination for
strontium is based on public comments received and the plan to further
evaluate scientific information that became available after publication
of the preliminary regulatory determinations. The agency is currently
conducting additional scientific analyses to determine if there is a
need to develop a national drinking water regulation for strontium. For
more information about the comments the agency received on strontium
and the analyses that are underway, see section V.A of this notice.
Information on the five contaminants can be found in the Regulatory
Determinations 3 Support Document (USEPA, 2014b). More information is
available at the Water Docket (Docket ID No. EPA-HQ-OW-2012-0155) and
also on EPA's Regulatory Determination 3 Web site at http://www2.epa.gov/ccl/regulatory-determination-3.
III. What process did the EPA use to make the regulatory
determinations?
This section gives a summary of the regulatory determination
process the agency followed to identify and evaluate contaminants for
the Third Regulatory Determination. For more detailed information on
the process and the analyses performed, please refer to the ``Protocol
for the Regulatory Determination 3'' document (USEPA, 2014a) and the
Federal Register notice for the Preliminary Regulatory Determinations
for Contaminants on CCL 3 (USEPA, 2014c).
The CCL 3 identified 116 contaminants that are currently not
subject to any proposed or promulgated national drinking water
regulation, are known or anticipated to occur in public water systems,
and may require
[[Page 15]]
regulation under SDWA (USEPA, 2009). Since some of the CCL 3
contaminants do not have adequate health and/or occurrence data to
evaluate against the three statutory criteria (see section II.B of this
notice), the agency used a three-phase process to identify which of the
contaminants are candidates for regulatory determinations. Priority was
given to identifying contaminants known to occur or with substantial
likelihood to occur at frequencies and levels of public health concern.
The three phases of the Third Regulatory Determination process are
(1) the Data Availability Phase, (2) the Data Evaluation Phase and (3)
the Regulatory Determination Assessment Phase. The overall process is
displayed in Exhibit 1.
BILLING CODE 6560-50-P
[GRAPHIC] [TIFF OMITTED] TR04JA16.000
BILLING CODE 6560-50-C
The purpose of the first phase, the Data Availability Phase, is to
determine if the agency ``may have'' sufficient data to characterize
the potential health effects and known or likely occurrence in drinking
water. Although contaminants must have sufficient data to evaluate the
statutory criteria in Phase 3, the agency does not want to rule out any
contaminants too early in the process; therefore, if sufficient health
and occurrence data are likely available, the contaminants are
considered in the Data Evaluation Phase, the second phase of the
regulatory determination process. From the 116 CCL 3 contaminants, the
agency identified 37 contaminants (35 CCL 3 contaminants and two non-
CCL 3 contaminants \4\) to further evaluate in the second phase.
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\4\ The non-CCL 3 contaminants, N-Nitroso-di-n-butylamine (NDBA)
and N-Nitrosomethylethylamine (NMEA), were included because they are
part of a larger group (nitrosamines) that also includes a number of
CCL 3 contaminants.
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During the second phase, the agency further evaluates each
contaminant on the short list to identify those that have sufficient
data (or are expected to have sufficient data within the timeframe
allotted for the second phase) for the EPA to assess the three
statutory criteria. As part of the second phase, the agency
specifically focuses its efforts on identifying those contaminants or
contaminant groups that are occurring or have substantial likelihood to
occur at levels and frequencies of public health concern, based on the
best available peer reviewed data. If the agency finds that sufficient
data are not available or not likely to be available to evaluate the
three statutory criteria during the first and second phases, then the
contaminant is not considered a candidate for making a regulatory
determination.
If sufficient data are available for a contaminant to characterize
the potential health effects and known or likely occurrence in drinking
water, the contaminant is evaluated against the three statutory
criteria in the Regulatory Determination Assessment Phase, which is the
third phase of the process. Of the 37 contaminants that were evaluated
under Phase 2, 12 were designated for further evaluation in Phase 3.
[[Page 16]]
Of the 12 contaminants that were evaluated in Phase 3, the agency
did not make preliminary regulatory determinations for seven
contaminants. The seven contaminants include chlorate and six
nitrosamines. Chlorate and the six nitrosamines are disinfection
byproducts, and the agency is further evaluating these contaminants as
part of the regulatory review of existing Microbial and Disinfection
Byproduct regulations, as announced in the Preliminary Regulatory
Determination 3 Federal Register notice published on October 20, 2014
(USEPA, 2014c).
After evaluating the five remaining CCL 3 contaminants (dimethoate,
1,3-dinitrobenzene, terbufos, terbufos sulfone and strontium) against
the three statutory criteria and considering other relevant information
(such as level and frequency of occurrence, population exposed and
information on sensitive populations and lifestages), the agency made
preliminary regulatory determinations to regulate strontium and to not
regulate the remaining four contaminants. These preliminary
determinations, with their supporting analyses and documentation, were
published in the Federal Register on October 20, 2014, for public
comment (USEPA, 2014c).
The EPA received comments from 14 organizations and individuals on
the October 20, 2014, Federal Register notice. These 14 organizations
and individuals include four environmental organizations, six industry
groups, one state association and three anonymous individuals. The
agency prepared a Response to Comments document for this action that is
available in the Public Docket at www.regulations.gov under Docket ID
No. EPA-HQ-OW-2012-0155. Comments on specific contaminants, and the
EPA's responses, are briefly summarized in the sections below.
IV. Summary of the EPA's Findings on the Four Contaminants With Final
Regulatory Determinations
After considering the public comments, the EPA is making final
regulatory determinations not to regulate dimethoate, 1,3-
dinitrobenzene, terbufos and terbufos sulfone.
This notice provides a brief description of the agency findings on
these contaminants. Details on the background, health and occurrence
information and analyses used to evaluate and make final determinations
for these contaminants can be found in the Regulatory Determinations 3
Support Document (USEPA, 2015b) and the Federal Register notice for the
Preliminary Regulatory Determination 3 (USEPA, 2014c).
For each contaminant, the agency evaluated the available human and
toxicological data, derived a health reference level (HRL),\5\
evaluated the potential and/or likely occurrence and examined the
likely exposed population for the contaminant in public water systems.
The agency also considered whether information was available on
sensitive populations. The agency used the findings from these
evaluations to determine whether the three SDWA statutory criteria are
satisfied. Table 1 gives a summary of the health and occurrence
information for the four contaminants with final determinations under
RD 3.
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\5\ HRLs are risk derived concentrations against which to
evaluate the occurrence data to determine if contaminants may occur
at levels of public health concern. They are not the level of a
contaminant in drinking water that must not be exceeded to protect
any particular population (i.e., an HRL is not an MCL).
Table 1--Summary of the Health and Occurrence Information and the Final Determinations for Four of the Contaminants Considered for RD 3
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Health Occurrence findings from primary data sources
reference ----------------------------------------------------------------------------------------------------------------------------------
RD 3 contaminants level Population served by PWSs Population served by PWSs Final
(HRL) Primary PWSs with at least 1 with at least 1 detection PWSs with at least 1 with at least 1 detection determination
([mu]g/L) database detection >=\1/2\ HRL >=\1/2\ HRL detection >=HRL >=HRL
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Dimethoate.................... 15.4 UCMR 2........ 0% (0 of 4140)........... 0% (0 of 229M).............. 0% (0 of 4140)........... 0% (0 of 229M).............. Do not regulate.
1,3-Dinitrobenzene............ 0.7 UCMR 2........ 0% (0 of 4139)........... 0% (0 of 229M).............. 0% (0 of 4139)........... 0% (0 of 229M).............. Do not regulate.
Terbufos...................... 0.35 UCMR 1........ 0% (0 of 295)............ 0% (0 of 41M)............... 0% (0 of 295)............ 0% (0 of 41M)............... Do not regulate
Terbufos sulfone.............. 0.35 UCMR 2........ 0.02% (1 of 4140)........ 0.01% (44.6K of 229M)....... 0.02% (1 of 4140)........ 0.01% (44.6K of 229M)....... Do not regulate.
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A. Dimethoate
1. Description
Dimethoate is an organophosphate pesticide, commonly used as an
insecticide on field crops (e.g., wheat, alfalfa, corn and cotton),
orchard crops, vegetable crops and in forestry. Synonyms for dimethoate
include dimethogen, dimeton, dimevur and cygon (HSDB, 2010; USEPA,
2007). Dimethoate is considered highly mobile and relatively non-
persistent in the environment (USEPA, 2007).
2. Agency Findings
The agency is making a determination not to regulate dimethoate
with an NPDWR. It does not occur at levels and frequencies of public
health concern. As a result, the agency finds that an NPDWR does not
present a meaningful opportunity for health risk reduction.
The primary data for dimethoate are the 2008-2010 nationally
representative drinking water monitoring data, generated through the
EPA's Second Unregulated Contaminant Monitoring Regulation (UCMR 2).
Dimethoate was not detected in any of the 32,150 UCMR 2 samples
collected by 4,140 PWSs (serving ~230 million people) at levels greater
than the \1/2\ HRL (7.7 [mu]g/L), the HRL (15.4 [mu]g/L), or the
minimum reporting level (MRL) (0.7 [mu]g/L) (USEPA, 2015c). Based on
the results of the UCMR 2 samples, the estimated population exposed to
dimethoate at levels of public health concern is 0%.
Other supplementary sources of finished water data from the State
of California, the U.S. Department of Agriculture (USDA) and the U.S.
Geologic Survey (USGS) indicate that the occurrence of dimethoate in
PWSs is likely to be low to non-existent. Dimethoate occurrence data
for ambient water from the USGS and the Storage and Retrieval (STORET)
Data System are consistent with those for finished water. These data
sources are discussed in the October 2014 Federal Register notice of
the Preliminary Regulatory Determination 3 (USEPA, 2014c).
[[Page 17]]
B. 1,3-Dinitrobenzene
1. Description
1,3-Dinitrobenzene is a nitro aromatic compound that is used as an
industrial chemical and formed as a by-product in the manufacture of
munitions, as well as in the production of other substances (HSDB,
2009). There are no known natural sources of 1,3-dinitrobenzene. 1,3-
Dinitrobenzene appears to be moderately persistent in environmental
media and moderately mobile in soil and water, although in soils with
high clay content it will be less mobile (USEPA, 2015b).
2. Agency Findings
The agency is making a determination not to regulate 1,3-
dinitrobenzene with an NPDWR. It does not occur at levels and
frequencies of public health concern. As a result, the agency finds
that an NPDWR does not present a meaningful opportunity for health risk
reduction.
The primary data for 1,3-dinitrobenzene are the 2008-2010
nationally representative drinking water monitoring data generated
through the EPA's UCMR 2 (USEPA, 2015c). UCMR 2 is the only dataset
with finished water data for this contaminant. UCMR 2 collected 32,152
samples from 4,139 PWSs for 1,3-dinitrobenzene and it was not detected
above the MRL (0.8 [mu]g/L), which is only slightly higher than the HRL
(0.7 [mu]g/L). Based on the results of the UCMR 2 samples, the
estimated population exposed to 1,3-dinitrobenzene at or above the MRL
is 0%.
Findings from the available ambient water data for 1,3-
dinitrobenzene are consistent with the results in finished water.
Ambient water data in STORET included no measured results above 0.33
[mu]g/L in 143 samples from 70 sites (USEPA, 2012). It should be noted
that some occurrence above the HRL may have gone undetected since
reporting levels are not documented. These data sources are discussed
in the October 2014 Federal Register notice of the Preliminary
Regulatory Determination 3 (USEPA, 2014c).
C. Terbufos and Terbufos Sulfone
1. Description
Terbufos is a phosphorodithioate pesticide (i.e., an
organophosphate) used as an insecticide-nematicide to control a variety
of insect pests, primarily used on corn and sugar beets (USEPA, 2006).
Terbufos sulfone is a degradate of terbufos. Total toxic residues of
terbufos and degradates are highly mobile and persistent in the
environment, with terbufos sulfone being more mobile and substantially
more persistent than terbufos (USEPA, 2006).
2. Agency Findings
The agency is making determinations not to regulate terbufos and
terbufos sulfone with NPDWRs. They do not occur at levels and
frequencies of public health concern. As a result, the agency finds
that an NPDWR does not present a meaningful opportunity for health risk
reduction.
The primary data for terbufos are from the First Unregulated
Contaminant Monitoring Regulation (UCMR 1) screening survey (2001-2003)
(USEPA, 2008). The UCMR 1 screening survey collected 2,301 finished
water samples from 295 PWSs for terbufos and it was not detected at
levels at or above the MRL (0.5 [mu]g/L), which is slightly higher than
the HRL (0.35 [mu]g/L) (USEPA, 2008). Based on the results of the UCMR
1 screening survey, the estimated population exposed to terbufos at or
above the MRL is 0%.
The primary data for terbufos sulfone are nationally representative
finished water monitoring data generated through the EPA's UCMR 2
(2008-2010) (USEPA, 2015c). UCMR 2 collected 32,149 finished water
samples from 4,140 PWSs (serving ~230 million people) for terbufos
sulfone and it was detected in only one sample, at a concentration of
0.42 [mu]g/L. The MRL is 0.4 [mu]g/L, which is slightly higher than the
HRL (0.35 [mu]g/L) (USEPA, 2015c). Based on the results of the UCMR 2
samples, the estimated population exposed to terbufos sulfone at a
level of public health concern (based on the HRL for terbufos) is
44,600 (0.02% of the population served by PWSs).
Finished water data for terbufos and terbufos sulfone from
California, Iowa, USDA and USGS are consistent with the UCMR 1 and UCMR
2 data. Terbufos and (very limited) terbufos sulfone occurrence data
for ambient water from the EPA, STORET and several USGS programs or
studies are also consistent with those for finished water. These data
sources are discussed in the October 2014 Federal Register notice of
the Preliminary Regulatory Determination 3 (USEPA, 2014c).
D. Public Comments on Four Contaminants With Final Regulatory
Determinations
The agency received comments in support of the agency's preliminary
determinations not to regulate dimethoate, 1,3-dinitrobenzene, terbufos
and terbufos sulfone. The agency did not receive any comments to the
contrary.
Agency Response: EPA agrees with the comments and, as previously
explained, is making final determinations not to regulate dimethoate,
1,3-dinitrobenzene, terbufos and terbufos sulfone.
V. Summary of Public Comments on Strontium and the Agency's Responses
A. Background on Strontium and the EPA's Preliminary Determination
Strontium is a naturally occurring element (atomic number 38) and a
member of the alkaline earth metals (ANL, 2007). There are several
radioactive strontium isotopes formed by nuclear fission of uranium or
plutonium. Since drinking water contamination by radioactive isotopes,
including beta particle emitters, is covered under the existing
Radionuclides Rule, this section describes the stable \88\Sr isotope.
In October 2014, the agency made a preliminary determination to
regulate strontium with an NPDWR after evaluating the available health,
occurrence and other related information against the three SDWA
statutory criteria. Specifically, EPA made a preliminary determination
that (a) strontium may have an adverse effect on the health of persons,
(b) it is known to occur or there is substantial likelihood that
strontium will occur in public water systems with a frequency and at
levels of public health concern and (c) regulation of strontium with an
NPDWR presents a meaningful opportunity to reduce health risks for
persons served by PWSs. EPA describes the underlying science in support
of these criteria in the Federal Register notice of the Preliminary
Regulatory Determination 3 (USEPA, 2014c).
In the Federal Register notice of the Preliminary Regulatory
Determination 3, EPA calculated a non-cancer HRL of 1500 [micro]g/L for
strontium using the reference dose of 0.3 mg/kg/day, a default Relative
Source Contribution (RSC) of 20% and age-specific exposure factors
(i.e., drinking water intake expressed as liters per kg of body weight)
for the sensitive population of birth through 18 years to reflect the
most active period of bone growth and development. The RSC is the level
of exposure believed to result from drinking water when compared to
other sources (e.g., food, ambient air). In the Preliminary Regulatory
Determination 3 EPA used the default 20% RSC to calculate the HRL. For
more detailed information see the October 20, 2014, Federal Register
notice of the
[[Page 18]]
Preliminary Regulatory Determination 3 (USEPA, 2014c).
After consideration of public comments on the preliminary
regulatory determination for strontium (see Section V.B.), the agency
is delaying the final determination for strontium in order to consider
additional scientific data and decide whether there is a meaningful
opportunity for health risk reduction by regulating strontium in
drinking water.
B. What comments did the EPA receive on strontium?
Some commenters supported the preliminary determination to regulate
strontium. These commenters supported a regulation due to the adverse
effect on bone growth and/or the potential for elevated levels of
strontium in the environment as a result of spills and disposal of
waste products related to gas production.
Many comments called upon the agency to delay the final
determination, collect more data and perform additional analyses before
making a final determination for strontium. Specifically, the comments
were focused on the following areas: The relationship between
occurrence and health risk, the RSC of strontium, the costs and
benefits of a potential strontium regulation and the feasibility of
treating strontium.
Three commenters questioned whether enough water systems show
strontium at levels and frequency of concern that a meaningful
reduction in health risk can be achieved through a national regulation.
Two of these commenters suggested conducting an epidemiology study that
evaluates whether adverse human health effects are occurring and at
what drinking water concentrations (and frequency of occurrence) to
determine whether there is a meaningful opportunity for health risk
reduction of a regulation.
Two commenters indicated the agency should quantify the RSC or
provide stronger justification for using an RSC of 20%. One commenter
stated the RSC has a significant impact on the reference dose. One
commenter stated that defaults of 20% and 80% have utility in
relatively simple circumstances where it is accepted that the drinking
water component is either very small or large. The commenter indicated
that it is essential to analyze and quantify the RSC when it is
intermediate and there are data to perform a meaningful estimate. The
commenter asserted that it is essential because the impact on the MCLG
and ultimately the MCL and compliance costs can become significant.
Several commenters indicated concerns with the costs and benefits
of a potential strontium regulation. One commenter urged the agency to
update the current affordability standard under SDWA before
promulgating any new NPDWRs in order to allow rural and small
communities to utilize the most economical and safe treatment options.
One commenter stated that the agency failed to estimate the social
benefits and social costs in its analysis for the strontium
determination, specifically the additional energy usage and its
externalities. Several commenters compared the cost of a potential
strontium regulation to that of the arsenic regulation, based on the
percentage and type of systems with strontium occurrence at levels of
concern.
Several commenters supported the agency's commitment to conducting
more extensive treatment research prior to promulgating a regulation
for strontium. Two commenters indicated that the treatment technology
to remove strontium may remove beneficial alkaline earth metals, such
as calcium, that partially counter the uptake of strontium.
Agency Response: The agency is delaying the final determination for
strontium in order to consider additional scientific data and decide
whether there is a meaningful opportunity for health risk reduction by
regulating strontium in drinking water.
Strontium is known to occur in food, ambient air and soil. While
data on levels in those media and estimates of intake from those
sources were limited when EPA made the preliminary determination to
regulate strontium, the EPA is evaluating recent additions to the
exposure database to determine if the agency can develop a data-derived
RSC rather than using a default 20% RSC in the calculation of the HRL.
In the absence of this type of relevant exposure information, the
agency supports the use of the default RSC and may ultimately use the
default 20% RSC in the final regulatory determination for strontium and
for other compounds in the future. The agency selects the default RSCs
for regulatory determinations based on the Methodology for Deriving
Ambient Water Quality Criteria for the Protection of Human Health
(USEPA, 2000).
If the agency makes a final determination to regulate strontium,
the EPA will conduct tests on treatment technologies for strontium
prior to developing a regulation. The agency understands that strontium
may co-occur with beneficial calcium in some drinking water systems and
treatment technologies that remove strontium may also remove calcium.
The agency is evaluating the effectiveness of treatment technologies
under different water conditions, including calcium concentrations. The
agency will continue to work with stakeholders in evaluating treatment
technologies for strontium.
At this time, the agency does not plan to initiate any longer term
health effect studies, including human epidemiological studies on the
relationship of skeletal effects and strontium exposure levels through
consumption of drinking water and foods. The agency will continue to
evaluate new health studies related to strontium exposure, including
any epidemiology studies. It should be noted that while the agency is
not precluded from conducting epidemiological studies, the agency is
not required to do so to support the decision to regulate a
contaminant.
An evaluation of the costs and benefits of a potential strontium
regulation is outside the scope of the regulatory determination
process. If the agency decides to regulate strontium, as part of the
regulation development process, the agency will conduct a health risk
reduction and cost analysis, including an evaluation of the costs and
benefits of regulating strontium.
VI. Next Steps
Prior to making a final regulatory determination for strontium, the
agency will consider additional data gathered and analyses completed
after publication of the preliminary determination (for further
information, see discussion in section V.B. of this notice). The agency
published the Draft Contaminant Candidate List 4 (CCL 4) on February 4,
2015 (USEPA, 2015a) and will issue a Final CCL 4 after consideration of
public comments received. The agency will evaluate and consider
contaminants on the Final CCL 4 for the Fourth Regulatory
Determination.
VII. References
Argonne National Laboratory (ANL). 2007. Radiological and Chemical
Fact Sheets to Support Health Risk Analyses for Contaminated Areas.
Environmental Science Division. Available on the Internet at: http://www.gfxtechnology.com/ArgonneRadFacts.pdf.
HSDB. 2010. Available on the Internet at: http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?HSDB. Accessed September 2010.
USEPA. 2000. Methodology for Deriving Ambient Water Quality Criteria
for the
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Protection of Human Health (2000). EPA 822-B-00-004.
USEPA. 2006. Reregistration Eligibility Decision for Terbufos.
Office of Pesticide Programs. Available on the Internet at: http://archive.epa.gov/pesticides/reregistration/web/pdf/terbufos_red.pdf.
Accessed Oct 2015.
USEPA. 2007. Revised Interim Reregistration Decision for Dimethoate.
Available on the Internet at: http://archive.epa.gov/pesticides/reregistration/web/pdf/dimethoate_ired_revised.pdf. Accessed October
2015.
USEPA. 2008. The Analysis of Occurrence Data from the First
Unregulated Contaminant Monitoring Regulation (UCMR 1) in Support of
Regulatory Determinations for the Second Drinking Water Contaminant
Candidate List. EPA 815-R-08-012. June 2008.
USEPA. 2009. Drinking Water Contaminant Candidate List 3--Final.
Federal Register. Vol. 74, No. 194, p. 51850. October 8, 2009.
USEPA. 2012. Storage and Retrieval (STORET) Data Warehouse.
Available on the Internet at: http://www.epa.gov/storet/index.html.
Data Warehouse. Accessed March 2012.
USEPA. 2014a. Protocol for the Regulatory Determinations 3.
Including Appendices A-F. EPA 815-R14-005. April 2014.
USEPA. 2014b. Regulatory Determinations 3 Support Document. EPA 815-
R14-003. April 2014.
USEPA. 2014c. Announcement of the Preliminary Regulatory
Determinations for Contaminants on the Third Drinking Water
Contaminant Candidate List; Proposed Rule. Federal Register. Vol.
79, No. 202, p. 62716. October 20, 2014.
USEPA. 2015a. Drinking Water Contaminant Candidate List 4--Draft.
Federal Register. Vol. 80, No. 23, p. 6076. February 4, 2015.
USEPA. 2015b. Regulatory Determinations 3 Support Document (Final).
EPA 815-R15-014. December 2015.
USEPA. 2015c. Occurrence Data from the Second Unregulated
Contaminant Monitoring Regulation (UCMR 2). EPA 815-R15-013.
December 2015.
Dated: December 22, 2015.
Gina McCarthy,
Administrator.
[FR Doc. 2015-32760 Filed 12-31-15; 8:45 am]
BILLING CODE 6560-50-P