Drinking Water: Regulatory Determinations Regarding Contaminants on the Second Drinking Water Contaminant Candidate List, 44251-44261 [E8-17463]
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Federal Register / Vol. 73, No. 147 / Wednesday, July 30, 2008 / Notices
List of Subjects
Environmental protection, Pesticides
and pests.
Dated: July 15, 2008.
Lois Rossi,
Director, Registration Division, Office of
Pesticide Programs.
[FR Doc. E8–17236 Filed 7–29–08; 8:45 am]
BILLING CODE 6560–50–S
ENVIRONMENTAL PROTECTION
AGENCY
[EPA–HQ–OW–2007–0068; FRL–8699–1]
RIN 2040–AE60
Drinking Water: Regulatory
Determinations Regarding
Contaminants on the Second Drinking
Water Contaminant Candidate List
Environmental Protection
Agency (EPA).
ACTION: Notice.
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AGENCY:
SUMMARY: The Safe Drinking Water Act
(SDWA), as amended in 1996, requires
the United States Environmental
Protection Agency (EPA) to periodically
publish a list of unregulated
contaminants (known as the
Contaminant Candidate List or CCL) and
determine whether to regulate at least
five contaminants on each list. Today’s
action announces the Agency’s final
determinations on whether to issue
national primary drinking water
regulations (NPDWRs) for 11
contaminants listed on the second
Contaminant Candidate List (CCL 2).
On May 1, 2007, EPA published
preliminary regulatory determinations
for 11 of the 51 contaminants listed on
CCL 2 and requested public comment
on the determinations, process,
rationale, and supporting technical
information for each contaminant. The
11 regulatory determination
contaminants are boron; the dacthal
mono- and di-acid degradates; 1,1dichloro-2,2-bis(pchlorophenyl)ethylene (DDE); 1,3dichloropropene; 2,4-dinitrotoluene;
2,6-dinitrotoluene; s-ethyl
dipropylthiocarbamate (EPTC); fonofos;
terbacil; and 1,1,2,2-tetrachloroethane.
In the May 2007 notice, the Agency
made a preliminary determination that
no regulatory action was appropriate for
any of these 11 contaminants.
EPA received comments from nine
individuals or organizations on the
preliminary regulatory determinations
for the 11 contaminants and additional
comments for other contaminants on
CCL 2: perchlorate, methyl tertiary butyl
ether (MTBE), metolachlor, and
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cyanotoxins. After careful review and
consideration of these comments, the
Agency is making a final determination
that no regulatory action is appropriate
at this time for any of the 11 CCL 2
contaminants for which the Agency
made preliminary regulatory
determinations in the May 2007 notice.
DATES: For purposes of judicial review,
the regulatory determinations in this
notice are issued as of July 30, 2008, as
provided in 40 CFR 23.7.
ADDRESSES: EPA has established a
docket for this action under Docket ID
No. EPA–HQ–OW–2007–0068. All
documents in the docket are listed on
the https://www.regulations.gov Web
site. Although listed in the index, some
information is not publicly available,
e.g., Confidential Business Information
or other information whose disclosure is
restricted by statute. Certain other
material, such as copyrighted material,
is not placed on the Internet and will be
publicly available only in hard copy
form. Publicly available docket
materials are available either
electronically through https://
www.regulations.gov or in hard copy at
the Water Docket, EPA/DC, EPA West,
Room 3334, 1301 Constitution Ave.,
NW., Washington, DC. The 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 EPA Docket Center is
(202) 566–2426.
FOR FURTHER INFORMATION CONTACT:
Yvette Selby-Mohamadu, Standards and
Risk Management Division, Office of
Ground Water and Drinking Water,
4607M, Environmental Protection
Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone
number: (202) 564–5245; e-mail
address: selby-mohamadu.yvette@
epa.gov. For general information contact
the EPA Safe Drinking Water Hotline at
(800) 426–4791, or (703) 412–3330, from
10 a.m. to 4 p.m., Eastern Time, Monday
through Friday, excluding legal
holidays.
Abbreviations and Acronyms
µg/L—micrograms per liter
ATSDR—Agency for Toxic Substances and
Disease Registry
AwwaRF—American Water Works
Association Research Foundation
CCL—Contaminant Candidate List
CCL 1—EPA’s First Contaminant Candidate
List
CCL 2—EPA’s Second Contaminant
Candidate List
1,3-DCP—1,3-dichloropropene
DCPA—dimethyl tetrachloroterephthalate
(dacthal)
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44251
DDE—1,1-dichloro-2,2-bis(pchlorophenyl)ethylene
DDT—1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane
DNT—dinitrotoluene
EPA—United States Environmental
Protection Agency
EPTC—s-ethyl dipropylthiocarbamate
ESA—ethane sulfonic acid
FR—Federal Register
HRL—health reference level
IRIS—Integrated Risk Information System
kg—kilogram
L—liter
MAC—Mycobacterium avium
MCL—maximum contaminant level
MCLG—maximum contaminant level goal
MRL—minimum or method reporting limit
(depending on the study or survey cited)
MTBE—methyl tertiary butyl ether
MTP—monomethyl-2,3,5,6tetrachloroterephthalate
NDWAC—National Drinking Water Advisory
Council
NIRS—National Inorganic and Radionuclide
Survey
NRC—National Research Council
NPDWR—national primary drinking water
regulation
OA—oxanilic acid
OPP—Office of Pesticide Programs
PWS—public water system
RSC—relative source contribution
SDWA—Safe Drinking Water Act
SOT—Society of Toxicology
TPA—2,3,5,6-tetrachchloroterephthalic acid
TRI—Toxics Release Inventory
TT—treatment technique
UCM—Unregulated Contaminant Monitoring
UCMR 1—First Unregulated Contaminant
Monitoring Regulation issued after the
1996 SDWA Amendments
US—United States of America
USGS—United States Geological Survey
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Impose Any
Requirements on My Public Water
System?
II. Purpose, Background, and Summary of
This Action
A. What Is the Purpose of This Action?
B. What Is the Statutory Requirement for
the Contaminant Candidate List (CCL)
and Regulatory Determinations?
C. What Contaminants Did EPA Consider
for Regulation?
III. What Approach and Analyses Did EPA
Use To Make the Regulatory
Determinations?
A. Approach
B. Analyses
IV. Summary of Public Comments and the
Agency’s Responses on the CCL
Regulatory Determination Process
A. Regulatory Determinations for the 11
Contaminants
B. Regulatory Determinations Approach
C. Occurrence and Exposure Evaluation
D. Comments on Boron, Perchlorate,
MTBE, Metolachlor, and Cyanobacteria
and Its Toxins
V. Summary of the Agency’s Findings on the
11 CCL 2 Contaminants
A. Boron
B. Dacthal mono- and di-acid degradates
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C. 1,1-Dichloro-2,2-bis(p-chlorophenyl)
ethylene
D. 1,3-Dichloropropene
E. 2,4- and 2,6-Dinitrotoluenes
F. s-Ethyl dipropylthiocarbamate
G. Fonofos
H. Terbacil
I. 1,1,2,2-Tetrachloroethane
VI. How Will EPA Address the Data Needs
of the Remaining CCL 2 Contaminants?
VII. References
None of these regulatory
determinations will impose any
requirements on anyone. Instead, this
action notifies interested parties of
EPA’s determinations for 11 CCL 2
contaminants and provides a summary
of the major comments received on the
May 1, 2007, preliminary
determinations (72 FR 24016 (USEPA,
2007a)).
Contaminant Level Goal 1 (MCLG) and
promulgate an NPDWR 2 for a
contaminant if the Administrator
determines that:
(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 EPA 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
II. Purpose, Background and Summary
of This Action
C. What Contaminants Did EPA
Consider for Regulation?
A. What Is the Purpose of This Action?
On May 1, 2007 (72 FR 24016
(USEPA, 2007a)), EPA published
preliminary regulatory determinations
for 11 CCL 2 contaminants that have
sufficient information to support a
regulatory determination. The 11
contaminants are boron; the dacthal
mono- and di-acid degradates; 1,1dichloro-2,2-bis(pchlorophenyl)ethylene (DDE); 1,3dichloropropene; 2,4-dinitrotoluene
(DNT); 2,6-dinitrotoluene; s-ethyl
dipropylthiocarbamate (EPTC); fonofos;
terbacil; and 1,1,2,2-tetrachloroethane.
Information for the 11 contaminants is
available in the regulatory
determination support document
(USEPA, 2008a), the occurrence
technical support documents (USEPA,
2008b–c), and the Health Effects
Support Documents or Drinking Water
Advisories for each of the contaminants
(USEPA, 2008d–l). This information is
available at the Water Docket (Docket ID
No. EPA–HQ–OW–2007–0068) and is
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Impose Any
Requirements on My Public Water
System?
Today’s action briefly describes the
statutory requirements for targeting
potential drinking water contaminants
for regulatory development and the
approach EPA used to make regulatory
determinations for 11 CCL 2
contaminants. In addition, today’s
action (1) summarizes the public
comments received on EPA’s
preliminary determinations and the
Agency’s responses to those comments,
(2) presents the Agency’s findings and
final regulatory determination for 11
CCL 2 contaminants, and (3) provides
information regarding the other CCL 2
contaminants.
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B. What Is the Statutory Requirement for
the Contaminant Candidate List (CCL)
and Regulatory Determinations?
The specific statutory requirements
for the CCL and regulatory
determinations can be found in SDWA
section 1412(b)(1). The 1996 SDWA
Amendments require 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 EPA to determine whether to
regulate at least five contaminants from
the CCL every five years. SDWA
requires EPA to publish a Maximum
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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 (TT) for public water systems for a
specific contaminant or group of contaminants.
3 The statute authorizes a nine month extension
of this promulgation date.
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also available on EPA’s Safe Drinking
Water Regulatory Determination Web
site at https://www.epa.gov/safewater/
ccl/reg_determine2.html. Brief
descriptions of each of the 11
contaminants considered for regulatory
determinations are included in section
V of this notice.
III. What Approach and Analyses Did
EPA Use To Make the Regulatory
Determinations?
A. Approach
In identifying which CCL 2
contaminants are candidates for
regulatory determinations, the Agency
considered whether sufficient
information and/or data were available
to characterize the potential health
effects and the known/likely occurrence
in and exposure from drinking water.
For health effects, the Agency
considered whether an Agencyapproved health risk assessment 4 was
available to identify any potential
adverse health effect(s) and derive an
estimated level at which no adverse
health effect(s) are likely to occur. For
occurrence, the Agency considered
whether available information/data
provided a representative picture of
known and/or likely occurrence in
public water systems. If sufficient
information/data were available to
characterize adverse human health
effects and known/likely occurrence in
public water systems, the Agency
identified the contaminant as a potential
candidate for regulatory determinations.
In addition to information/data for
health and occurrence, EPA also
considered the availability and
adequacy of analytical methods (for
monitoring) and treatment.
In cases where EPA chose a
contaminant as a candidate for
regulatory determination, the Agency
considered the following in evaluating
each of the three statutory criteria.
(a) First statutory criterion—Is the
contaminant likely to cause an adverse
effect on the health of persons? The
Agency evaluated the best available,
peer-reviewed assessments and studies
to characterize the human health effects
that may result from exposure to the
contaminant when found in drinking
water. Based on this characterization,
the Agency estimated a health reference
level (HRL) for each contaminant.
4 Health information used for the regulatory
determinations process includes but is not limited
to health assessments available from the Agency’s
Integrated Risk Information System (IRIS), the
Agency’s Office of Pesticide Programs (OPP) in a
Reregistration Eligibility Decision (RED), the
National Academy of Sciences (NAS), and/or the
Agency for Toxic Substances and Disease Registry
(ATSDR).
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(b) Second statutory criterion—Is the
contaminant known or likely to occur in
public water systems at a frequency and
level of public health concern? To
evaluate known occurrence in PWSs,
the Agency compiled, screened, and
analyzed data from several occurrence
data sets to develop representative
occurrence estimates for public drinking
water systems. EPA used the HRL
estimate for each contaminant as a
benchmark against which to conduct an
initial evaluation or screening of the
occurrence data. For each contaminant,
EPA estimated the number of PWSs
(and the population served by these
PWSs) with detections greater than onehalf the HRL (> 1⁄2 HRL) and greater
than the HRL (> HRL). To further
evaluate the likelihood of a contaminant
occurring in drinking water, the Agency
considered information on the use and
release of the contaminant into the
environment and supplemental
information on occurrence in water
(e.g., ambient water quality data, State
ambient or finished water data, and/or
special studies performed by other
agencies, organizations and/or entities).
(c) Third statutory criterion—In the
sole judgment of the Administrator,
does regulation of the contaminant
present a meaningful opportunity for
health risk reduction for persons served
by public water systems? EPA evaluated
the potential health effects and the
results of the occurrence estimates, as
well as exposure estimates (i.e., the
population exposed and the sources of
exposure) at the health level of concern
to determine if regulation presents a
meaningful opportunity for health risk
reduction.
If the answers to all three statutory
criteria are affirmative for a particular
contaminant, then the Agency makes a
determination that regulation is
necessary and proceeds to develop an
MCLG and a national primary drinking
water regulation for that contaminant. It
should be noted that this regulatory
determination process is distinct from
the more detailed analyses needed to
develop a national primary drinking
water regulation. Thus, a decision to
regulate is the beginning of the Agency’s
regulatory development process, not the
end.
If the answer to any of the three
statutory criteria is negative based on
the available data, then the Agency
makes a determination that a national
primary drinking water regulation is not
necessary for that contaminant at that
time.
B. Analyses
EPA has prepared Health Effects
Support Documents or Drinking Water
Advisories (USEPA, 2008d–l) for each of
the 11 contaminants. In these
documents, EPA characterized the
human health effects that may result
from exposure to a contaminant found
in drinking water. The support
documents address exposure from
drinking water and other media,
toxicokinetics, hazard identification,
dose-response assessment, and an
overall characterization of risk from
drinking water. Based on this
characterization, EPA estimated a health
reference level (HRL) or benchmark
value for each contaminant.
To analyze occurrence and exposure,
the Agency used data from the first
Unregulated Contaminant Monitoring
Regulation (UCMR 1) for 9 of the
contaminants: The dacthal mono- and
di-acid degradates, 1,1-dichloro-2,2bis(p-chlorophenyl)ethylene (DDE), 1,3dichloropropene, 2,4-dinitrotoluene,
2,6-dinitrotoluene, s-ethyl
dipropylthiocarbamate (EPTC), fonofos,
and terbacil.5 In addition, the
Unregulated Contaminant Monitoring
44253
(UCM 6) program provided additional
data for 1,3-dichloropropene and
1,1,2,2-tetrachloroethane and the
National Inorganic and Radionuclide
Survey (NIRS 7) provided data for boron.
The Agency used the UCMR 1, UCM,
and NIRS data to estimate the number
and percentage of PWSs and the
population served by these PWSs at
concentrations above the HRL
benchmark values, and 1⁄2 the HRL
values. The Agency also used these data
to evaluate the geographic distribution
of occurrence for these 11 CCL 2
contaminants.
EPA also employed State drinking
water data, use and environmental
release information (e.g., EPA’s Toxic
Release Inventory (TRI), academic and
private sector publications), as well as
ambient water quality data (e.g., data
from the U.S. Geological Survey’s
National Water Quality Assessment
program) as secondary sources of
information to evaluate the likelihood of
contaminant occurrence.
A detailed discussion of the data
collected and analyses for each
contaminant can be found in the
regulatory determination support
document (USEPA, 2008a) and the
occurrence technical support
documents (USEPA, 2008b–c). In
addition, a summary of the occurrence
and exposure findings are included in
Table 1. Table 1 in this notice is similar
to Table 3 in the May 2007 notice (72
FR 24016 (USEPA, 2007a)); however,
note that EPA updated the occurrence
data for the UCMR 1 results to include
final results for 17 additional drinking
water systems that were not available
when the Agency was in the process of
making its preliminary regulatory
determinations. Updating these
numbers did not change the outcome of
today’s decisions.
TABLE 1—SUMMARY OF THE HEALTH AND OCCURRENCE INFORMATION AND THE FINAL DETERMINATIONS FOR THE 11
CONTAMINANTS CONSIDERED UNDER CCL REGULATORY DETERMINATIONS 2
Occurrence findings from primary data sources (UCMR 1, UCM round 1 and 2 cross sections, NIRS)
#
Contaminant and its
chemical abstract
registry number
(CASRN)
Boron (7440–42–8)
2 ...............
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1 ...............
Dacthal di acid
degradate 2
(2136–79–0).
Determination
Health
reference
level
(HRL)
Do not
1,400 µg/
reguL.
1.
late
Do not
70 µg/L 4
regulate.
5 The UCMR 1 monitoring survey began in 2001.
As discussed in the May 2007 notice, fonofos was
sampled as part of UCMR 1 Screening Monitoring
and the remaining 8 contaminants were sampled as
part of UCMR 1 Assessment Monitoring.
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Population served
by PWSs with at
least 1 detection
> 1⁄2 HRL
PWSs with at least
1 detection
> 1⁄2 HRL
NIRS .......
4.3% (43 of 989) .....
2.9% (42.7K of
1.48M).
1.7% or (17 of
989) 1.
0.4% (6.4K of
1.48M)
UCMR 1 5
0.05% (2 of 3,876) ..
0.33% (739K of
225M).
0.03% (1 of 3,876) ..
< 0.01% (500 of
225M)
6 EPA implemented the UCM program in two
phases or rounds. The first round of UCM
monitoring generally extended from 1988 to 1992
and is referred to as UCM Round 1 monitoring. The
second round of UCM monitoring generally
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PWSs with at least
1 detection
> HRL
Population served
by PWSs with at
least 1 detection
> HRL
Database
extended from 1993 to 1997 and is referred to as
UCM Round 2 monitoring.
7 The monitoring for NIRS spanned from 1984 to
1986.
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TABLE 1—SUMMARY OF THE HEALTH AND OCCURRENCE INFORMATION AND THE FINAL DETERMINATIONS FOR THE 11
CONTAMINANTS CONSIDERED UNDER CCL REGULATORY DETERMINATIONS 2—Continued
Occurrence findings from primary data sources (UCMR 1, UCM round 1 and 2 cross sections, NIRS)
#
3 ...............
4 ...............
Contaminant and its
chemical abstract
registry number
(CASRN)
Dacthal mono acid
degradate 3 (887–
54–7).
DDE 6 (72–55–9) .....
5 ...............
1,3-Dichloropropene
(Telone) (542–75–
6).
6 ...............
8 ...............
2,4-Dinitrotoluene
(121–14–2).
2,6-Dinitrotoluene
(606–20–2).
EPTC 10 (759–94–4)
9 ...............
Fonofos (944–22–9)
10 .............
Terbacil (5902–51–
2).
1,1,2,2Tetrachloroethane
(79–34–5).
7 ...............
11 .............
Determination
Health
reference
level
(HRL)
Do not
0.2 µg/L ..
regulate.
0.4 µg/L ..
Do not
regulate.
Do not
regulate.
Do not
regulate.
Do not
regulate.
Do not
regulate.
Do not
regulate.
Do not
regulate.
Database
Population served
by PWSs with at
least 1 detection
> 1⁄2 HRL
PWSs with at least
1 detection
> 1⁄2 HRL
Population served
by PWSs with at
least 1 detection
> HRL
UCMR 1
7
UCM Rd1
UCM Rd2
UCMR 1
0.86% (436K of
51M) 9.
0.42% (193K of
46M) 9.
7 ..............................
7 ..............................
0.03% 7 (1 of
3,874) 8.
0.16% (15 of
9,164) 9.
0.23% (38 of
16,787) 9.
0.00% (0 of 796) 8 ...
0.03% (1 of 3,873) 8
7
..............................
0.00% (0 of 3,873) 8
0.01% (18K of
226M) 8
0.86% (436K of
51M) 9
0.33% (152K of
46M) 9
0.00% (0 of 2.8M) 8
0.02% (38K of
226M) 8
0.00% (0 of 226M) 8
..............................
7
PWSs with at least
1 detection
> HRL
..............................
0.05 µg/L
UCMR 1
0.16% (15 of
9,164) 9.
0.30% (50 of
16,787) 9.
7 ..............................
7 ..............................
0.05 µg/L
UCMR 1
7
175 µg/L
UCMR 1
0.00% (0 of 3,873) ..
0.00% (0 of 226M) ..
0.00% (0 of 3,873) ..
0.00% (0 of 226M)
10 µg/L ...
UCMR 1
0.00% (0 of 295) .....
0.00% (0 of 41M) ....
0.00% (0 of 295) .....
0.00% (0 of 41M)
90 µg/L ...
UCMR 1
0.00% (0 of 3,873) ..
0.00% (0 of 226M) ..
0.00% (0 of 3,873) ..
0.00% (0 of 226M)
0.4 µg/L ..
UCM Rd1
UCM Rd2
0.22% (44 of
20,407) 9.
0.07% (18 of
24,800) 9.
1.69% (1.6M of
95M) 9.
0.51% (362K of
71M) 9.
0.20% (41 of
20,407) 9.
0.07% (17 of
24,800) 9.
1.63% (1.5M of
95M) 9
0.08% (56K of
71M) 9
..............................
1 EPA also considered the results of an AwwaRF study of PWSs indicating that surface water sources are unlikely to contain boron at levels > the HRL of 1,400 µg/
L (Frey et al., 2004).
2 2,3,5,6-tetrachloroterephthalic acid (TPA).
3 monomethyl-2,3,5,6-tetrachloroterephthalate (MTP).
4 Using the dacthal parent HRL since it includes the toxicity for the degradates.
5 Degradates monitored in aggregate and converted to the parent equivalent.
6 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene.
7 Not reported since MRL > 1⁄2 the HRL.
8 Shows results > MRL, rather than > HRL, since MRL is greater than the HRL. In all cases the MRL is within the 10¥4 to 10¥6 risk range.
9 The MRLs used in UCM varied from below the 1⁄2 HRL to above the HRL. However, even the highest MRLs used are within the 10¥4 to 10¥6 risk range.
10 s-ethyl dipropylthiocarbamate.
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IV. Summary of Public Comments and
the Agency’s Responses on the CCL
Regulatory Determination Process
EPA received comments from nine
organizations or individuals on the May
1, 2007, Federal Register notice. These
nine organizations/individuals include
five water-related associations, one
industry group, one State agency, one
State-related association, and one
anonymous person. A majority of the
comments focused on the following four
over-arching topic areas:
• The regulatory determinations for
the 11 contaminants;
• The regulatory determinations
approach;
• The occurrence and exposure
evaluation; and
• Comments on specific CCL 2
contaminants: boron, perchlorate,
MTBE, metolachlor, and cyanobacteria
and its toxins.
A complete copy of the public
comments and the Agency’s responses
are included in the Docket for today’s
action (USEPA, 2008m). The remainder
of this section discusses the four key
topic areas identified by commenters in
response to the May 2007 preliminary
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regulatory determination notice (72 FR
24016, (USEPA, 2007a)).
A. Regulatory Determinations for the 11
Contaminants
Comment Summary: Most of the
commenters agreed with EPA’s
decisions not to regulate the 11
contaminants. However, one State
agency recommended that EPA
reconsider its position of not regulating
2,4- and 2,6-DNT because they found
these two contaminants in ground water
in numerous locations in and around
ammunition and military sites in their
State.
Agency Response: EPA agrees with
the commenters who believe that no
regulation is warranted at this time for
the 11 contaminants. In response to
reconsidering the Agency’s decision for
2,4- and 2,6-DNT, EPA respectfully
disagrees. Monitoring data collected on
2,4- and 2,6-DNT from UCMR 1 do not
indicate that either of these chemicals
occurs nationally in public drinking
water systems at health levels of
concern. EPA found only one detection
of 2,4-DNT from among the 3,873 public
water systems evaluated and no
detections of 2,6-DNT. The information
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submitted by the commenter does not
lead the Agency to change its decision
because the occurrence appears to be
highly localized and therefore, does not
meet statutory criterion 2 (likely to
occur in PWSs with a frequency and at
a level of concern). To assist State and
local communities that may have
localized occurrence of 2,4- and/or 2,6DNT, the Agency has updated the
Health Advisory for both of these
compounds as part of the regulatory
determination process. If a State finds
that it has highly localized levels of 2,4and/or 2,6-DNT above the HRL of 0.05
µg/L, the Agency encourages States to
consider whether State-level guidance
(or some other type of action) may be
appropriate.
B. Regulatory Determinations Approach
Comment Summary: One commenter
recommended that EPA expand its
discussion of the logic underlying the
determinations for these 11
contaminants. The commenter stated
that EPA needs to raise the level of
transparency in its decision logic so that
stakeholders can understand how data
and information translate to
determinations and to ensure
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use the three criteria discussed in
section III.A. As a result, EPA will
evaluate costs and affordability in more
detail, including whether small system
variances are appropriate, as part of the
regulatory process after the Agency
makes a positive regulatory
determination.
consistency across the two parallel
regulatory efforts (regulatory
determinations and six-year reviews).
The commenter asked for a discussion
about the status of the remaining CCL 2
contaminants. In addition, the
commenter recommended that EPA’s
drinking water research agenda be
integrated with the regulatory
development process.
Another commenter agreed with the
determinations not to regulate the 11
contaminants but recommended that
EPA include affordability criteria when
evaluating whether regulation will
result in a meaningful health benefit in
future determinations. The commenter
submitted a paper in support of their
comment.8
Agency Response: In response to the
first comment, EPA developed a
consistent regulatory determination
approach for evaluating CCL 2
contaminants that followed the National
Drinking Water Advisory Council’s
(NDWAC, 2000) recommended protocol
for both health effects and occurrence
analyses. In this notice (section VI), EPA
added a narrative and tables that
summarize the data gaps for the other 40
CCL 2 contaminants, which kept the
Agency from making a regulatory
determination at this time. EPA does not
believe that it is appropriate to consider
a research agenda specifically for those
contaminants at this time because the
Agency is in the process of developing
a new CCL (CCL 3). The new process
considers the knowledge and experience
gained from evaluating unregulated
contaminants on CCL 1 and CCL 2 and
the recommendations and advice from
the National Academies of Sciences’
National Research Council (NRC, 2001)
and NDWAC (2004). The Agency
anticipates that future CCL research
needs will be directed at filling data
gaps for contaminants on the new list
(i.e., CCL 3), not CCL 2. All CCL 2
contaminants will be examined for
inclusion on CCL 3 and those that
remain a high priority will be examined
for research needs.
In response to the second comment,
the SDWA requires that EPA consider
the costs and benefits, as well as
affordability, as NPDWRs are developed.
Specifically, SDWA requires that EPA
perform a health risk reduction and cost
analysis and an affordability analysis for
proposed NPDWRs. EPA respectfully
disagrees that an affordability analysis is
necessary or required for regulatory
determinations. For regulatory
determination, SDWA requires that EPA
C. Occurrence and Exposure Evaluation
Comment Summary: One commenter
stated that ‘‘based on the first round of
regulatory determinations, a range of
0.02%–3.2% for national occurrence
could be considered as the minimum
threshold for development of a new
regulation’’ and ‘‘national occurrence
estimates for these eleven contaminants
are well below this threshold, with
boron having the highest prevalence of
occurrence, at 1.7% of systems sampled
in the National Inorganics and
Radionuclides Survey (NIRS).’’
Another commenter provided a report
by Phillips and Chambless 9 that
evaluated compliance data for seven
contaminants from five States obtained
from a cross section of State regulatory
agencies. Based on a preliminary
analysis, the authors found that the
variability in the means of quarterly
samples taken for compliance purposes
was consistently large. The commenter
expressed the opinion that the
variability (standard error of the mean
divided by the mean) is significant
enough (100 percent or more in many
cases) to question the validity of
decisions made based on the UCMR
data (for unregulated contaminants).
Based on that study, the commenter
stated that there is no reason to assume
that the quality of the occurrence data
from the UCMR effort would be any
better than the quality of the compliance
data. The second commenter urged EPA
to resolve this quality issue before trying
to make CCL 2 regulatory decisions that
are based on rather precise calculations
of occurrence levels and the number of
persons exposed.
Agency Response: In response to the
first comment, EPA considers both the
extent of national occurrence and the
severity of health effects for a
contaminant, as well as other factors
(e.g., sources of exposure), when
deciding whether regulation presents a
meaningful opportunity for health risk
reduction. As a result, the Agency does
not believe it is appropriate to set
minimum occurrence thresholds for
regulatory determinations.
In response to the second comment
regarding variability in occurrence
8 This paper can be found in the Docket for this
notice at https://www.regulations.gov under the
Docket ID No. EPA–HQ–OW–2007–0068.
9 This paper can be found in the Docket for this
notice at https://www.regulations.gov under the
Docket ID No. EPA–HQ–OW–2007–0068.
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measures based on the compliance
monitoring data for regulated
contaminants, the Agency believes the
variability issues identified by Phillips
and Chambless do not directly reflect
the dependability of the UCMR 1 data
used to support the Agency’s regulatory
determinations. Compliance monitoring
data is State data resulting from
individual public water systems efforts
to comply with regulatory monitoring
requirements. The UCMR 1 is EPA’s
program to collect data for contaminants
suspected to be present in drinking
water based upon a statistically-valid
data set for nationwide occurrence
estimates. The UCMR 1 program was
designed to address this variability issue
at the national level by defining a
vulnerable period (the season of greatest
vulnerability of contaminant
occurrence, the season of increased flux
of water movement) and requiring at
least one UCMR 1 sample during that
period. In addition, the monitoring
periods for the large and small systems
were performed over a three year
period. Approximately one-third of all
small UCMR 1 systems throughout the
country conducted monitoring in each
of the three years of UCMR 1
monitoring. Furthermore, the
monitoring schedules for these systems
were conducted to include monitoring
in every month and every season around
the country. Large systems could
conduct their one year of monitoring
anytime during the UCMR 1 period from
2001 to 2003. Like small systems, their
monitoring schedules were spread
throughout the year and were to include
one sample during what was considered
the most vulnerable season. In this way,
the UCMR 1 monitoring results reflect
multiple seasons and multiple years of
climatic conditions throughout the
country and are not directly affected (or
biased) by weather conditions of a
single season, year, or geographic
region. Whereas some variability might
still be expected, EPA believes this is
unlikely to be a source of bias for
national level occurrence estimates.
In addition, it should be noted that
EPA used peak occurrence estimates
(the number and percent of systems
with at least one observed detection
greater than 1⁄2 the HRL and the HRL)
as opposed to mean values in making its
final decisions not to regulate the 11
CCL 2 contaminants. Hence, taking
variability around the mean into
account would not have influenced the
outcome of the final determinations for
these 11 contaminants. The
characterization of national occurrence
provided by the UCMR 1 monitoring
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D. Comments on Boron, Perchlorate,
MTBE, Metolachlor, and Cyanobacteria
and Its Toxins
1. Boron. One anonymous commenter
agreed with our determination for boron
but commented on the fact that the
health reference level does not
incorporate the results of the
preliminary chemical-specific Health
Advisory Level (HAL) derived recently
by EPA and presented at the 2007
Society of Toxicology (SOT) meeting.
Agency Response: The HRL used in
making regulatory determinations is not
equivalent to a lifetime health advisory
value. As stated in the Health Effects
Support Document for Boron (USEPA,
2008d) and the May 1, 2007, notice (72
FR 24016 (USEPA, 2007a)), an HRL is a
benchmark against which to measure
the occurrence data; it is not a Health
Advisory guideline. For noncarcinogens
such as boron, the HRL is calculated by
multiplying the Agency Reference Dose
by a 70 kg body weight and a 20 percent
default Relative Source Contribution
(RSC) and dividing the product by a
drinking water intake of 2 L/day.
As described in the May 2007 notice
(72 FR 24016 (USEPA, 2007a)) and in
evaluating contaminants for regulatory
determinations, the Agency initially
uses a default 20 percent RSC to
estimate the HRLs for non-carcinogens
because this approach derives the
lowest and most conservative HRL value
to use in screening the occurrence data.
EPA used this approach to calculate the
HRL benchmark for boron and to
determine if boron might be occurring
nationally at a level of potential health
concern. In developing the health
advisory for boron, the Agency
performed a more refined assessment of
the risk for those PWSs that
occasionally find levels of boron that
exceed the lifetime or shorter term
health advisory values. While the
Agency derived a more refined RSC for
the determination of the lifetime Health
Advisory for boron, this value is still
limited by the RSC ceiling of 80 percent
as a matter of policy. The derivation of
health advisory values also incorporates
the use of appropriate body weights for
the target population. The 2007 SOT
poster presentation used a body weight
of 67 kg for a pregnant woman,
consistent with the Human Health
Methodology (USEPA, 2000) guidelines.
There may be changes to that policy
based on more recent data on pregnancy
weights, and if so, the draft Health
Advisory will be revised to reflect the
new policy.
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2. Perchlorate. EPA received comment
letters on perchlorate from eight
commenters. The major areas of concern
raised in the comments related to (1) the
Agency’s decision not to make a
regulatory determination for perchlorate
at the same time as for the 11
contaminants for which a regulatory
determination is being finalized today,
and (2) the Agency’s discussion of
potential analyses to more fully
characterize total perchlorate exposure
in order to assess the opportunity for
public health protection through a
drinking water regulation.
Agency Response: EPA will soon
publish a preliminary determination for
perchlorate. EPA will request public
comment as part of that notice. EPA will
consider the comments received on the
May 2007 notice (72 FR 24016 (USEPA,
2007a)) with respect to perchlorate as a
part of that regulatory determination
and will respond to such public
comments at the time the Agency issues
a regulatory determination for
perchlorate. EPA intends to finalize a
regulatory determination for perchlorate
by December 2008.
3. MTBE. Most commenters supported
EPA’s decision not to make a regulatory
determination for methyl tertiary-butyl
ether (MTBE) at this time because the
IRIS assessment is currently being
revised. Also, one commenter felt that
UCMR 1 would provide valuable
occurrence data for MTBE when the risk
assessment becomes available.
Agency Response: EPA agrees that
UCMR 1 data provides important
occurrence information on MTBE and
will be useful in making a regulatory
determination once the final risk
assessment is available.
4. Metolachlor. Some commenters
noted that additional research for the
health effects and occurrence of
metolachlor and its degradates is
needed. One commenter felt that UCMR
2 would provide valuable occurrence
information for metolachlor and its
degradates. One commenter did not
have additional data but believes more
information is needed on the occurrence
and health effects of many herbicides
and pesticides and their degradates. The
results of this research should be
appropriately included in regulatory
decisions by the Office of Pesticide
Programs (OPP) and the Office of
Ground Water and Drinking Water. The
commenter stated that EPA should
promote further research to definitively
determine whether metolachlor, a very
widely used pesticide, is carcinogenic,
as acetochlor, alachlor and metolachlor
have very similar chemical structures.
Agency Response: The Agency agrees
that more information on the occurrence
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of metolachlor and its degradates is
needed in order to determine if the
combined parent compound and its
degradates are occurring at levels of
health concern. The available
metolachlor data from earlier
unregulated contaminant monitoring
surveys indicate that metolachlor is
found in finished water in many
locations but at levels below the HRL.
The occurrence data on the parent
metolachlor, combined with the
knowledge that it decomposes to several
degradates that are more persistent than
the parent, supported the inclusion of
both metolachlor and its degradates in
UCMR 2. Once available, the UCMR 2
data will be useful in evaluating the
occurrence of metolachlor and its
degradates in public water systems and
will assist the Agency in deciding
whether to regulate these compounds.
5. Cyanobacteria and its toxins. In the
May 2007 notice (72 FR 24016 (USEPA,
2007a)), EPA asked for comment on the
usefulness of providing an information
summary about cyanobacteria and its
toxins. One commenter responded and
recommended that EPA provide an
information summary describing the
state of the knowledge on the
prevention, treatment, and health effects
of cyanobacteria and its toxins. The
commenter felt that a document would
be useful for utilities and State agencies.
The commenter recommended that the
summary include information on
occurrence, conditions that might favor
growth of algae and production of
toxins, and a strategy for
communicating this information to
utility customers. In addition, the
commenter suggested that the summary
include information on research funded
by other organizations, particularly the
AWWA Research Foundation
(AwwaRF).
Agency Response: EPA is developing
an information sheet that will include
the information suggested by the
commenter and links to organizations
performing research on the
cyanobacteria and its toxins. The
Agency anticipates making this
information sheet available on its
Safewater Web site (https://
www.epa.gov/safewater) shortly after
the publication of this notice.
V. Summary of the Agency’s Findings
on the 11 CCL 2 Contaminants
A. Boron
1. Description. Boron, a metalloid,
tends to occur in nature in the form of
borates (e.g., boric acid, borax, boron
oxide). Man-made releases are typically
in the form of borates or boron halides
(e.g., boron trichloride, boron
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trifluoride). Boron compounds are used
in the production of glass, ceramics,
cleaning agents, fire retardants,
pesticides, cosmetics, photographic
materials, and high energy fuels (USGS,
2004; ATSDR, 1992).
2. Agency Findings. The Agency is
making a determination not to regulate
boron with a national primary drinking
water regulation. As noted in the May
2007 notice (72 FR 24016 (USEPA,
2007a)), EPA used data from NIRS and
an AwwaRF study (Frey et al., 2004) to
evaluate occurrence and exposure at the
HRL of 1,400 µg/L (as well as 1⁄2 the
HRL). The NIRS data indicate that
approximately 4.3 percent (or 43) of the
989 ground water PWSs sampled had at
least one detection of boron at levels
greater than 700 µg/L, affecting
approximately 2.9 percent of the
population served (or 42,700 people
from 1.48 million). Approximately 1.7
percent (or 17) of 989 ground water
PWSs sampled had at least one
detection of boron at levels greater than
1,400 µg/L, affecting approximately 0.4
percent of the population served (6,400
people from 1.48 million) (USEPA,
2008c and 2008d).
Because NIRS did not contain data for
surface water systems, the Agency
evaluated the results of the AwwaRF
study (Frey et al., 2004) to gain a better
understanding of the potential
occurrence of boron in surface water
systems. The AwwaRF study recruited
189 PWSs representing 407 source
waters that covered 41 States. Of these
407 PWS source water samples, 342
were returned and 341 were analyzed
for boron. Of these 341 samples,
approximately 67 percent (or 228)
represented ground water sources and
33 percent (or 113) represented surface
water sources. None of the 113 surface
water sources exceeded the boron HRL
of 1,400 µg/L and the maximum
concentration observed in surface water
was 345 µg/L. Extrapolation of the data
indicates that 95 percent of the ground
water detections had boron levels less
than 1,054 µg/L; the maximum observed
concentration in ground water was
approximately 3,300 µg/L. Seven of the
228 ground water sources (from 5
systems) had at least one sample with a
boron concentration greater than 1,400
µg/L (Seidel, 2006).
While boron was found at levels
greater than the HRL of 1,400 µg/L (and
1⁄2 the HRL) in several of the ground
water systems surveyed by NIRS, it was
not found at levels greater than the HRL
(or 1⁄2 the HRL) in the surface water
sources evaluated in the AwwaRF
study. Taking this surface water
information into account, the Agency
believes the overall occurrence and
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exposure from both surface and ground
water systems together is likely to be
lower than the values observed for the
NIRS ground water data. Because boron
is not likely to occur at health levels of
concern when considering both surface
and ground water systems, the Agency
believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
boron in the May 2007 notice (72 FR
24016 (USEPA, 2007a)), the final
regulatory support document (USEPA,
2008a), and the health effects support
document for boron (USEPA, 2008d).
The Agency also plans to update the
Health Advisory for boron to provide
more recent health information. The
updated Health Advisory will provide
information to any States with public
water systems that may have boron
above the HRL. If a State finds highly
localized occurrence of boron at
concentrations above the HRL, the
Agency encourages States to consider
whether State-level guidance (or some
other type of action) may be
appropriate.
regulation does not present a
meaningful opportunity for health risk
reduction. While the Agency recognizes
that these degradates have been detected
in the PWSs monitored under the
UCMR 1, only one PWS detected these
degradates at a concentration above the
HRL of 70 µg/L.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
dacthal mono- and di-acid degradates in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), the final regulatory
support document (USEPA, 2008a), and
the health effects support document
(USEPA, 2008e). The Agency also plans
to update the Health Advisory for the
DCPA parent to include the mono- and
di-acid degradates, as well as any recent
health information related to these
compounds. The updated Health
Advisory will provide information to
any States with public water systems
that may have DCPA degradates at
levels above the HRL. If a State finds
highly localized occurrence of DCPA
degradates at concentrations above the
HRL, the Agency encourages States to
consider whether State-level guidance
(or some other type of action) may be
appropriate.
B. Dacthal Mono- and Di-Acid
Degradates
1. Description. Dimethyl
tetrachloroterephthalate (DCPA), a
synthetic organic compound (SOC)
marketed under the trade name
’’Dacthal,’’ is a pre-emergent herbicide
historically used to control weeds in
ornamental turf and plants,
strawberries, seeded and transplanted
vegetables, cotton, and field beans.
DCPA is not especially mobile or
persistent in the environment.
Biodegradation and volatilization are
the primary dissipation routes.
Degradation of DCPA forms two
breakdown products, the mono-acid
degradate (monomethyl
tetrachloroterephthalate or MTP) and
the di-acid degradate
(tetrachloroterephthalic acid or TPA).
The di-acid, which is the major
degradate, is unusually mobile and
persistent in the field, with a potential
to leach into water (USEPA, 1998a).
2. Agency Findings. The Agency is
making a determination not to regulate
the DCPA mono-acid degradate and/or
the DCPA di-acid degradate with a
national primary drinking water
regulation. As noted in the May 2007
notice (72 FR 24016 (USEPA, 2007a)),
these degradates appear to occur
infrequently at health levels of concern
in PWSs, and the Agency believes that
a national primary drinking water
C. 1,1-Dichloro-2,2-bis(pchlorophenyl)ethylene
1. Description. DDE is a primary
metabolite of 1,1,1-trichloro-2,2-bis(pchlorophenyl)ethane (DDT), a pesticide
used to protect crops and eliminate
disease-carrying insects in the U.S. until
it was banned in 1973. DDE itself has no
commercial use and is only found in the
environment as a result of prior
contamination with DDT. While DDE
tends to adsorb strongly to surface soil
and is fairly insoluble in water, it may
enter surface waters from runoff that
contains DDE bound to soil particles. In
both soil and water, DDE is subject to
photodegradation, biodegradation, and
volatilization (ATSDR, 2002).
2. Agency Findings. The Agency is
making a determination not to regulate
DDE with a national primary drinking
water regulation. As noted in the May
2007 notice (72 FR 24016 (USEPA,
2007a)), DDE appears to occur
infrequently at health levels of concern
in PWSs, and the Agency believes that
a national primary drinking water
regulation does not present a
meaningful opportunity for health risk
reduction. DDE was detected in only
one of the PWSs monitored under the
UCMR 1 at a level greater than the MRL
(0.8 µg/L). The MRL is greater than the
HRL of 0.2 µg/L but represents a
concentration that is within the 10¥4 to
the 10¥6 cancer risk range targeted by
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the Agency. In addition, ambient water
data from the USGS (Martin et al., 2003;
Kolpin and Martin, 2003) indicate that
the maximum concentrations detected
in surface and ground water were less
than the HRL.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
DDE in the May 2007 notice (72 FR
24016 (USEPA, 2007a)), the final
regulatory support document (USEPA,
2008a), and the health effects support
document (USEPA, 2008f). If a State
finds highly localized occurrence of
DDE at concentrations above the HRL,
the Agency encourages States to
consider whether State-level guidance
(or some other type of action) may be
appropriate.
D. 1,3-Dichloropropene
1. Description. 1,3-Dichloropropene
(1,3-DCP), a synthetic volatile organic
compound, is used as a pre-plant soil
fumigant to control nematodes and
other pests in soils planted with all
types of food and feed crops. 1,3-DCP is
typically injected 12 inches to 18 inches
beneath the soil surface and can only be
used by certified handlers (USEPA,
1998b).
2. Agency Findings. The Agency is
making a determination not to regulate
1,3-DCP with a national primary
drinking water regulation. As noted in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), 1,3-DCP appears to
occur infrequently at health levels of
concern in PWSs, and the Agency
believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction. While 1,3-DCP
was detected in the UCM Round 1 (late
1980s) and the UCM Round 2 (mid
1990s) surveys, it was not detected in a
subsequent evaluation of 796 small
systems from the UCMR 1 survey. In
addition, the USGS did not detect 1,3DCP in two occurrence studies
performed between 1999 and 2001 using
monitoring levels that were lower than
the HRL. EPA believes the 1999
pesticide application requirements,
which are intended to mitigate risks to
drinking water, may be one reason for
the lack of occurrence of 1,3-DCP at
health levels of concern in subsequent
monitoring surveys.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
1,3-DCP in the May 2007 notice (72 FR
24016 (USEPA, 2007a)) and in the
health effects support document
(USEPA, 2008j). The Agency also plans
to update the Health Advisory
document for 1,3-DCP with more recent
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health information. The updated Health
Advisory will provide information to
any States with public water systems
that may have 1,3-DCP above the HRL.
If a State finds a highly localized
occurrence of 1,3-DCP at concentrations
above the HRL, the Agency encourages
States to consider whether State-level
guidance (or some other type of action)
may be appropriate.
E. 2,4-Dinitrotoluene and 2,6Dinitrotoluene
1. Description. 2,4- and 2,6dinitrotoluene (DNT), semi-volatile
organic compounds, are two of the six
isomers of dinitrotoluene.
Dinitrotoluenes are used in the
production of polyurethane foams,
automobile air bags, dyes, ammunition,
and explosives, including
trinitrotoluene or TNT (HSDB, 2004a
and 2004b; ATSDR, 1998). Neither 2,4DNT nor 2,6-DNT occurs naturally.
They are generally produced as
individual isomers or as a mixture
called technical grade DNT. Technical
grade DNT primarily contains a mixture
of 2,4-DNT and 2,6-DNT, with the
remainder consisting of the other
isomers and minor contaminants such
as TNT and mononitrotoluenes (HSDB,
2004c).
2. Agency Findings. The Agency is
making a determination not to regulate
2,4-or 2,6-DNT with a national primary
drinking water regulation. As noted in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), 2,4- and 2,6-DNT
appear to occur infrequently at health
levels of concern in PWSs, and the
Agency believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction. 2,4-DNT was
detected only once at a minimum
reporting level (MRL) of 2 µg/L and 2,6DNT was not detected at this same level
in any of the PWSs monitored under the
UCMR 1. While the MRL is slightly
greater than the HRL of 0.05 µg/L, this
concentration is within the acceptable
10¥4 to the 10¥6 cancer risk range
targeted by the Agency.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
2,4- and 2,6-DNT in the May 2007
notice (72 FR 24016 (USEPA, 2007a))
and in the health effects support
document (USEPA, 2008l). The
Agency’s original Health Advisories for
2,4- and 2,6-DNT were developed for
military installations. Because the
Agency recognizes that 2,4 and 2,6-DNT
may still be found at some military sites,
the Agency has updated the Health
Advisories to reflect recent health
effects publications. EPA published a
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draft of the updated Health Advisory
document for both 2,4 and 2,6-DNT as
part of the regulatory determinations for
these two isomers. The updated
document is available on the Web at:
https://www.epa.gov/safewater/ccl/
reg_determine2.html. The final Health
Advisory document will be published in
2008 and will provide information to
States with public water systems that
may have either 2,4- or 2,6-DNT at
concentrations above health levels of
concern. If a State finds highly localized
occurrence of 2,4- and/or 2,6-DNT at
concentrations above the HRL, the
Agency encourages States to consider
whether State-level guidance (or some
other type of action) may be
appropriate.
F. s-Ethyl dipropylthiocarbamate
1. Description. EPTC, a synthetic
organic compound, is a thiocarbamate
herbicide used to control weed growth
during the pre-emergence and early
post-emergence stages of weed
germination. First registered for use in
1958, EPTC is used across the U.S. in
the agricultural production of a number
of crops, most notably corn, potatoes,
dried beans, alfalfa, and snap beans.
EPTC is also used residentially on shade
trees, annual and perennial
ornamentals, and evergreens (USEPA,
1999c).
2. Agency Findings. The Agency is
making a determination not to regulate
EPTC with a national primary drinking
water regulation. As noted in the May
2007 notice (72 FR 24016 (USEPA,
2007a)), EPTC does not appear to occur
at health levels of concern in PWSs, and
the Agency believes that a national
primary drinking water regulation does
not present a meaningful opportunity
for health risk reduction. While EPTC
has been found in ambient waters at
levels less than the HRL of 175 µg/L (as
well as 1⁄2 the HRL), it was not found
in the UCMR 1 survey of public water
supplies. The Agency presented a
complete review of our analysis of the
health effects, occurrence, and exposure
for EPTC in the May 2007 notice (72 FR
24016 (USEPA, 2007a)), the final
regulatory support document (USEPA,
2008a), and in the health effects support
document (USEPA, 2008g).
G. Fonofos
1. Description. Fonofos, an
organophosphate, is a soil insecticide
used to control pests such as corn
rootworms, cutworms, symphylans (i.e.,
garden centipedes), and wireworms.
Primarily used on corn crops, fonofos
was also used on other crops such as
asparagus, beans, beets, onions,
peppers, tomatoes, cole crops, sweet
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potatoes, peanuts, peas, peppermint,
plantains, sorghum, soybeans,
spearmint, strawberries, sugarcane,
sugar beets, white (Irish) potatoes, and
tobacco (USEPA, 1999d).
Fonofos was scheduled for a
reregistration decision in 1999.
However, before the review was
completed, the registrant requested
voluntary cancellation. The cancellation
was announced in the Federal Register
on May 6, 1998 (63 FR 25033 (USEPA,
1998d)), with an effective date of
November 2, 1998, plus a one-year grace
period to permit the exhaustion of
existing stocks (USEPA, 1999d).
2. Agency Findings. The Agency is
making a determination not to regulate
fonofos with a national primary
drinking water regulation. As noted in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), fonofos does not
appear to occur at health levels of
concern in PWSs and the Agency
believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction. While fonofos has
been found in ambient waters at levels
less than the HRL of 10 µg/L (as well as
1⁄2 the HRL), it was not found in the
UCMR 1 Screening Survey of public
water supplies. Fonofos was voluntarily
cancelled in 1998 and the Agency
expects any remaining stocks and
releases into the environment to
decline. In addition, since fonofos tends
to bind strongly to soil, any releases to
the environment are not likely to
contaminate source waters. The Agency
presented a complete review of our
analysis of the health effects,
occurrence, and exposure for fonofos in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), the final regulatory
support document (USEPA, 2008a), and
in the health effects support document
(USEPA, 2008h).
H. Terbacil
1. Description. Terbacil, a synthetic
organic compound, is a selective
herbicide used to control broadleaf
weeds and grasses on terrestrial food/
feed crops (e.g., apples, mint,
peppermint, spearmint, and sugarcane),
terrestrial food (e.g., asparagus,
blackberry, boysenberry, dewberry,
loganberry, peach, raspberry,
youngberry, and strawberry), terrestrial
feed (e.g., alfalfa, forage, and hay) and
forest trees (e.g., cottonwood) (USEPA,
1998c).
2. Agency Findings. The Agency is
making a determination not to regulate
terbacil with a national primary
drinking water regulation. As noted in
the May 2007 notice (72 FR 24016
(USEPA, 2007a)), terbacil does not
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23:06 Jul 29, 2008
Jkt 214001
appear to occur at health levels of
concern in PWSs. Accordingly, the
Agency believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction. While terbacil has
been found in ambient waters at the
levels less than the HRL of 90 µg/L (as
well as 1⁄2 the HRL), it was not found
in the UCMR 1 survey of public water
supplies. The Agency presented a
complete review of our analysis of the
health effects, occurrence, and exposure
for terbacil in the May 2007 notice (72
FR 24016 (USEPA, 2007a)), the final
regulatory support document (USEPA,
2008a), and in the health effects support
document (USEPA, 2008i).
I. 1,1,2,2-Tetrachloroethane
1. Description. 1,1,2,2Tetrachloroethane, a volatile organic
compound, is not known to occur
naturally in the environment (IARC,
1979). Prior to the 1980s, 1,1,2,2tetrachloroethane was synthesized for
use in the production of other
chemicals, primarily chlorinated
ethylenes. 1,1,2,2-Tetrachloroethane
was also once used as a solvent to clean
and degrease metals, in paint removers,
varnishes, lacquers, and photographic
films, and for oil/fat extraction (Hawley,
1981). Commercial production of
1,1,2,2-tetrachloroethane in the U.S.
ceased in the 1980s, when other
processes to generate chlorinated
ethylenes were discovered (ATSDR,
1996).
2. Agency Findings. The Agency is
making a determination not to regulate
1,1,2,2-tetrachloroethane with a national
primary drinking water regulation. As
noted in the May 2007 notice (72 FR
24016 (USEPA, 2007a)), 1,1,2,2tetrachloroethane appears to occur
infrequently at health levels of concern
in PWSs. Accordingly, the Agency
believes that a national primary
drinking water regulation does not
present a meaningful opportunity for
health risk reduction. While 1,1,2,2tetrachloroethane was detected in both
the UCM Round 1 and the UCM Round
2 surveys, the percentage of detections
had decreased by the time the UCM
Round 2 survey was performed in the
mid-1990’s.10 In addition, the USGS did
not detect 1,1,2,2-tetrachloroethane in
two subsequent monitoring surveys of
source waters that supply community
water systems, using a reporting limit
that is less than the 1,1,2,2tetrachloroethane HRL of 0.4 µg/L. The
10 The UCM Round 1 and 2 surveys were
performed in the late 1980’s and the mid 1990’s.
These surveys should not be confused with the
UCMR 1 Screening and Assessment Monitoring that
began in 2001.
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44259
Agency believes that this decrease in
detections occurred because commercial
production of 1,1,2,2-tetrachloroethane
ceased in the mid-1980’s. Hence, the
Agency does not expect 1,1,2,2tetrachloroethane to occur in many
public water systems today.
The Agency presented a complete
review of our analysis of the health
effects, occurrence, and exposure for
1,1,2,2-tetrachloroethane in the May
2007 notice (72 FR 24016 (USEPA,
2007a)), the final regulatory support
document (USEPA, 2008a), and in the
health effects support document
(USEPA, 2008k). The Agency also plans
to update the Health Advisory
document for 1,1,2,2-tetrachloroethane
to provide more recent health
information. The updated Health
Advisory will provide information to
any States with public water systems
that may have 1,1,2,2-tetrachloroethane
at levels above the HRL. If a State finds
highly localized occurrence of 1,1,2,2tetrachloroethane at concentrations
above the HRL, the Agency encourages
States to consider whether State-level
guidance (or some other type of action)
may be appropriate.
VI. How Will EPA Address the Data
Needs of the Remaining CCL 2
Contaminants?
To support decisions on CCL
contaminants, the Agency evaluates
when and where these contaminants
occur, the extent of exposure, and their
risk to public health. EPA must also
determine if regulating the contaminant
presents a meaningful opportunity for
reducing public health risk.
Contaminants deemed ready for
regulatory determination are those that
have sufficient health and occurrence
data to evaluate both exposure and risk
to public health and support a decision
as to whether a regulation is
appropriate. The remaining CCL 2
contaminants for which decisions are
not being made today do not have
sufficient data to support regulatory
decisions at this time, except for
perchlorate, which is the subject of a
separate regulatory determination effort
(see section IV.D.2 in this notice).
Tables 2 and 3 list each contaminant
and the type of data lacking for each
contaminant.
In addition, the Agency is evaluating
the contaminants on CCL 2 as part of the
new CCL 3 classification process. The
new process is an expanded
comprehensive system that evaluates a
wider range of existing information,
including data published after the CCL
2 preliminary regulatory
determinations. The new process also
applies revised screening criteria to
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Federal Register / Vol. 73, No. 147 / Wednesday, July 30, 2008 / Notices
generate the CCL 3 based upon
recommendations from NRC (2001) and
NDWAC (2004). EPA anticipates
determining future research needs once
the CCL 3 is finalized.
TABLE 2—INFORMATION GAPS FOR THE CCL 2 CHEMICAL CONTAMINANTS (AS OF MAY 2007)*
Health effects
Occurrence
Health effects and occurrence
Acetochlor 3 .........................................................
Aluminum 4 5 .......................................................
Bromobenzene 3 .................................................
1,1-Dichloroethane 4 ...........................................
1,3-Dichloropropane 4 .........................................
2,2-Dichloropropane 4 .........................................
1,1-Dichloropropene 4 .........................................
p-Isopropyltoluane 4 ............................................
Methyl Bromide 4 ................................................
Methyl Tertiary-Butyl Ether (MTBE) 3 .................
Molinate 3 ............................................................
Nitrobenzene 3
1,2,4-Trimethylbenzene 4
Vanadium 4
Diazinon 6 .........................................................
2,4-Dichloropheno 6 ..........................................
2,4-Dinitrophenol 6 ............................................
1,2-Diphenylhydrazine 6 ...................................
Disulfoton 6 .......................................................
Diuron 6.
Linuron 6.
2-Methylphenol 6.
Terbufos 6.
Triazines 2 5 7.
2,4,6-Trichlorophenol 6.
Alachlor ESA 4 7
Metolachlor 7 8
Organotins 1 3 5 7
Prometon 3 6
RDX 3 7
* Perchlorate is not included in this table (see section IV.D.2).
1 Organotins include dimethyl tin, dibutyl tin, monomethyl tin, monobutyl tin from PVC stabilizers and triphenyl tin pesticide.
2 Triazines include the chlorodegradates (DEA, DIA, and DACT) of regulated contaminants—atrazine and simazine.
3 IRIS or OPP assessment in progress or needs an updated risk assessment.
4 Insufficient data to do a quantitative risk assessment, health assessment incomplete, or no risk assessment available.
5 These chemicals also have analytical methods (i.e., organotins) and/or treatment (i.e. triazines, aluminum) gaps.
6 Insufficient occurrence (sampling) data for a national estimate.
7 Lack of finished water occurrence (monitoring) data.
8 Lack of occurrence data for metolachlor’s degradates (ESA & OA). Metolachlor and its degradates are on UCMR 2.
TABLE 3—INFORMATION GAPS FOR THE MICROBIAL CONTAMINANTS (AS OF MAY 2007)
Health effects
Occurrence
Treatment
Microsporidia ..................................
Some Cyanotoxins .........................
Microsporidia ................................
Some Cyanotoxins .......................
Aeromonas ...................................
Helicobacter ..................................
MAC ..............................................
Adenoviruses ................................
Caliciviruses ..................................
Coxsackieviruses ..........................
Echoviruses ..................................
Microsporidia ................................
Some Cyanotoxins .......................
Aeromonas ...................................
Helicobacter ..................................
MAC ..............................................
Adenoviruses ................................
Caliciviruses ..................................
Coxsackieviruses ..........................
Echoviruses ..................................
mstockstill on PROD1PC66 with NOTICES
VII. References
Agency for Toxic Substances and Disease
Registry (ATSDR). 1992. Toxicological
Profile for Boron. Atlanta, GA: Agency
for Toxic Substances and Disease
Registry, Public Health Service, U.S.
Department of Health and Human
Services. Available on the Internet at:
https://www.atsdr.cdc.gov/toxprofiles/
tp26.html.
ATSDR. 1996. Toxicological Profile for
1,1,2,2-Tetrachloroethane. Available on
the Internet at: https://www.atsdr.cdc.gov/
toxprofiles/tp93.html.
ATSDR. 1998. Toxicological Profile for 2,4and 2,6-Dinitrotoluene. Available on the
Internet at: https://www.atsdr.cdc.gov/
toxprofiles/tp109.html.
ATSDR. 2002. Toxicological Profile DDT,
DDE, and DDD. Available on the Internet
at: https://www.atsdr.cdc.gov/toxprofiles/
tp35.html.
Frey, M.M., C. Seidel, M. Edwards, J. Parks,
and L. McNeill. 2004. Occurrence Survey
for Boron and Hexavalent Chromium.
AwwaRF Report 91044F.
Hawley, G.G. 1981. Condensed Chemical
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Dictionary. 10th ed. New York, NY: Van
Nostrand Reinhold Co. (As cited in
ATSDR, 1996)
Hazardous Substances Database (HSDB).
2004a. ‘‘TOXNET: Toxicology Data
Network—2,4-Dinitrotoluene.’’ Available
on the Internet at: https://
toxnet.nlm.nih.gov. [Search for 2,4dinitrotoluene.] Accessed November 1,
2004.
HSDB. 2004b. ‘‘TOXNET: Toxicology Data
Network—2,6-Dinitrotoluene.’’ Available
on the Internet at: https://
toxnet.nlm.nih.gov. [Search for 2,6dinitrotoluene.] Accessed November 1,
2004.
International Agency for Research on Cancer
(IARC). 1979. 1,1,2,2-Tetrachloroethane.
IARC Monographs on the Evaluation of
the Carcinogenic Risk of Chemicals to
Humans: Some Halogenated
Hydrocarbons. Vol. 20. pp. 477–489. (As
cited in ATSDR, 1996)
Kolpin, D.W. and J.D. Martin. 2003.
‘‘Pesticides in Ground Water: Summary
Statistics; Preliminary Results from
Cycle I of the National Water Quality
Assessment Program (NAWQA), 1992–
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Analytical methods
Microsporidia
Some Cyanotoxins
Aeromonas
Helicobacter
MAC
2001.’’ Available on the Internet at:
https://ca.water.usgs.gov/pnsp/pestgw/
Pest-GW_2001_Text.html. Accessed
August 24, 2004. A copy of this report
is available in the docket.
Martin, J.D., C.G. Crawford, and S.J. Larson.
2003. ‘‘Pesticides in Streams: Summary
Statistics; Preliminary Results from
Cycle I of the National Water Quality
Assessment Program (NAWQA), 1992–
2001.’’ Available on the Internet at:
https://ca.water.usgs.gov/pnsp/pestsw/
Pest-SW_2001_Text.html. Accessed
August 24, 2004. A copy of this report
is available in the docket.
National Drinking Water Advisory Council
(NDWAC). 2004. Report on the CCL
Classification Process to the U.S.
Environmental Protection Agency; May
19, 2004.
NDWAC. 2000. Proposed Recommendation
from the Working Group on CCL and 6Year Review to the U.S. Environmental
Protection Agency; May 23, 2000.
National Research Council. 2001. Classifying
Drinking Water Contaminants for
Regulatory Consideration. National
Academy Press, Washington DC.
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Federal Register / Vol. 73, No. 147 / Wednesday, July 30, 2008 / Notices
Seidel, C. 2006. Email Communication from
C. Seidel to Brent Ranalli at The Cadmus
Group, Inc. [concerning boron data from
an AwwaRF-sponsored study, with data
in an attached spreadsheet]. Denver, CO:
McGuire Malcolm Pirnie; May 19, 2006.
USEPA. 1998a. Reregistration Eligibility
Decision (RED)—DCPA. EPA Report
738–R–98–005. Washington, DC: Office
of Prevention, Pesticides and Toxic
Substances. November 1998. Available
on the Internet at: https://www.epa.gov/
oppsrrd1/REDs/0270red.pdf.
USEPA. 1998b. Reregistration Eligibility
Decision (RED)—1,3-Dichloropropene.
EPA Report 738–R–98–016. Washington,
DC: Office of Prevention, Pesticides and
Toxic Substances. December 1998.
Available on the Internet at: https://
www.epa.gov/oppsrrd1/REDs/
0328red.pdf.
USEPA. 1998c. Reregistration Eligibility
Decision (RED)—Terbacil. EPA Report
738–R–97–011. Washington, DC: Office
of Prevention, Pesticides and Toxic
Substances. January 1998. Available on
the Internet at: https://www.epa.gov/
oppsrrd1/REDs/0039red.pdf.
USEPA. 1998d. Notice of Receipt of Requests
to Voluntarily Cancel Certain Pesticide
Registrations. Federal Register. Vol. 63,
No. 87. p. 25033, May 6, 1998.
USEPA. 1999c. Reregistration Eligibility
Decision (RED)—EPTC. EPA Report 738–
R–99–006. Washington, DC: Office of
Prevention, Pesticides and Toxic
Substances. December 1999. Available
on the Internet at: https://www.epa.gov/
oppsrrd1/REDs/0064red.pdf.
USEPA. 1999d. Reregistration Eligibility
Decision (RED) Facts—O-Ethyl S-phenyl
ethylphosphonodithiolate (Fonofos).
EPA Report 738–F–99–019. Washington,
DC: Office of Prevention, Pesticides and
Toxic Substances. November 1999.
Available on the Internet at: https://
www.epa.gov/oppsrrd1/REDs/factsheets/
0105fact.pdf.
USEPA. 2000. Methodology for Deriving
Ambient Water Quality Criteria for the
Protection of Human Health (2000). EPA
Report EPA–822–B–00–004. Washington,
DC: Office of Water. October 2000.
Available on the Internet at: https://
www.epa.gov/waterscience/criteria/
humanhealth/method/method.html
USEPA. 2007a. Drinking Water: Regulatory
Determinations Regarding Contaminants
on the Second Drinking Water
Contaminant Candidate List—
Preliminary Determinations. Notice.
Federal Register. Vol. 72, No. 83, p.
24016, May 1, 2007.
USEPA. 2008a. Regulatory Determinations
Support Document for Selected
Contaminants from the Second Drinking
Water Contaminant Candidate List (CCL
2). EPA Report 815–R–08–012. June
2008.
USEPA. 2008b. 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
Report 815–R–08–013. June 2008.
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USEPA. 2008c. The Analysis of Occurrence
Data from the Unregulated Contaminant
Monitoring (UCM) Program and National
Inorganics and Radionuclides Survey
(NIRS) in Support of Regulatory
Determinations for the Second Drinking
Water Contaminant Candidate List. EPA
Report 815–R–08–014. June 2008.
USEPA. 2008d. Health Effects Support
Document for Boron. EPA Report 822–R–
08–002. June 2008.
USEPA. 2008e. Health Effects Support
Document for Dacthal Degradates:
Tetrachloroterephthalic Acid (TPA) and
Monomethyl Tetrachloroterephthalic
Acid (MTP). EPA Report 822–R–08–005.
June 2008.
USEPA. 2008f. Health Effects Support
Document for 1,1-Dichloro-2,2-bis(pchlorophenyl)ethylene (DDE). EPA
Report 822–R–08–003. June 2008.
USEPA. 2008g. Health Effects Support
Document for S-Ethyl
dipropylthiocarbamate (EPTC). EPA
Report 822–R–08–006. June 2008.
USEPA. 2008h. Health Effects Support
Document for Fonofos. EPA Report 822–
R–08–009. June 2008.
USEPA. 2008i. Health Effects Support
Document for Terbacil. EPA Report 822–
R–08–004. June 2008.
USEPA. 2008j. Health Effects Support
Document for 1,3-Dichloropropene. EPA
Report 822–R–08–008. June 2008.
USEPA. 2008k. Health Effects Support
Document for 1,1,2,2-Tetrachloroethane.
EPA Report 822–R–08–007. June 2008.
USEPA. 2008l. Health Advisory for 2,4- and
2,6-Dinitrotoluene. EPA Report 822–R–
08–010. June 2008.
USEPA. 2008m. Comment Response
Document for the Regulatory
Determinations on the Second Drinking
Water Contaminant Candidate List 2
(Categorized Public Comments). June
2008.
USGS. 2004. ‘‘Mineral Commodity
Summaries, January 2004—Boron.’’
January 2004. Available on the Internet
at: https://minerals.usgs.gov/minerals/
pubs/commodity/boron/boronmcs04.pdf.
Dated: July 24, 2008.
Stephen L. Johnson,
Administrator.
[FR Doc. E8–17463 Filed 7–29–08; 8:45 am]
BILLING CODE 6560–50–P
ENVIRONMENTAL PROTECTION
AGENCY
[EPA–HQ–OPP–2003–0397; FRL–8374–6]
Molinate; Product Cancellation Order
and Amendment to Terminate Uses
Environmental Protection
Agency (EPA).
ACTION: Notice.
AGENCY:
SUMMARY: This notice announces EPA’s
amendment to the order for the
termination of uses, voluntarily
requested by the registrant and accepted
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44261
by the Agency, of products containing
the pesticide molinate, pursuant to
section 6(f)(1) of the Federal Insecticide,
Fungicide, and Rodenticide Act
(FIFRA), as amended. This amendment
follows an April 7, 2004 Federal
Register Notice of Order to Amend
Registrations to Terminate Uses of
molinate to control water grass in rice
grown in California and the south
central/south eastern states of Arkansas,
Louisiana, Missouri, Tennessee, and
Texas. Nothing in today’s action
changes the previous stop production
date of June 30, 2008, nor does it change
the stop use date of August 31, 2009.
Today’s action only clarifies the
deadline for persons other than the
registrant to sell and distribute molinate
until July 1, 2009.
DATES: The cancellation amendment is
effective July 30, 2008.
FOR FURTHER INFORMATION CONTACT:
Wilhelmena Livingston, Special Review
and Reregistration Division (7508P),
Office of Pesticide Programs,
Environmental Protection Agency, 1200
Pennsylvania Ave., NW., Washington,
DC 20460–0001; telephone number:
(703) 308–8025; fax number: (703) 308–
8005; e-mail address:
livingston.wilhelmena@epa.gov.
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does this Action Apply to Me?
This action is directed to the public
in general, and may be of interest to a
wide range of stakeholders including
environmental, human health, and
agricultural advocates; the chemical
industry; pesticide users; and members
of the public interested in the sale,
distribution, or use of pesticides. Since
others also may be interested, 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 person
listed under FOR FURTHER INFORMATION
CONTACT.
B. How Can I Get Copies of this
Document and Other Related
Information?
1. Docket. EPA has established a
docket for this action under docket
identification (ID) number EPA–HQ–
OPP–2003–0397. Publicly available
docket materials are available either in
the electronic docket at https://
www.regulations.gov, or, if only
available in hard copy, at the Office of
Pesticide Programs (OPP) Regulatory
Public Docket in Rm. S–4400, One
Potomac Yard (South Bldg.), 2777 S.
Crystal Dr., Arlington, VA. The hours of
E:\FR\FM\30JYN1.SGM
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]]>Agencies
[Federal Register Volume 73, Number 147 (Wednesday, July 30, 2008)]
[Notices]
[Pages 44251-44261]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-17463]
-----------------------------------------------------------------------
ENVIRONMENTAL PROTECTION AGENCY
[EPA-HQ-OW-2007-0068; FRL-8699-1]
RIN 2040-AE60
Drinking Water: Regulatory Determinations Regarding Contaminants
on the Second Drinking Water Contaminant Candidate List
AGENCY: Environmental Protection Agency (EPA).
ACTION: Notice.
-----------------------------------------------------------------------
SUMMARY: The Safe Drinking Water Act (SDWA), as amended in 1996,
requires the United States Environmental Protection Agency (EPA) to
periodically publish a list of unregulated contaminants (known as the
Contaminant Candidate List or CCL) and determine whether to regulate at
least five contaminants on each list. Today's action announces the
Agency's final determinations on whether to issue national primary
drinking water regulations (NPDWRs) for 11 contaminants listed on the
second Contaminant Candidate List (CCL 2).
On May 1, 2007, EPA published preliminary regulatory determinations
for 11 of the 51 contaminants listed on CCL 2 and requested public
comment on the determinations, process, rationale, and supporting
technical information for each contaminant. The 11 regulatory
determination contaminants are boron; the dacthal mono- and di-acid
degradates; 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,3-
dichloropropene; 2,4-dinitrotoluene; 2,6-dinitrotoluene; s-ethyl
dipropylthiocarbamate (EPTC); fonofos; terbacil; and 1,1,2,2-
tetrachloroethane. In the May 2007 notice, the Agency made a
preliminary determination that no regulatory action was appropriate for
any of these 11 contaminants.
EPA received comments from nine individuals or organizations on the
preliminary regulatory determinations for the 11 contaminants and
additional comments for other contaminants on CCL 2: perchlorate,
methyl tertiary butyl ether (MTBE), metolachlor, and cyanotoxins. After
careful review and consideration of these comments, the Agency is
making a final determination that no regulatory action is appropriate
at this time for any of the 11 CCL 2 contaminants for which the Agency
made preliminary regulatory determinations in the May 2007 notice.
DATES: For purposes of judicial review, the regulatory determinations
in this notice are issued as of July 30, 2008, as provided in 40 CFR
23.7.
ADDRESSES: EPA has established a docket for this action under Docket ID
No. EPA-HQ-OW-2007-0068. All documents in the docket are listed on the
https://www.regulations.gov Web site. Although listed in the index, some
information is not publicly available, e.g., Confidential Business
Information or other information whose disclosure is restricted by
statute. Certain other material, such as copyrighted material, is not
placed on the Internet and will be publicly available only in hard copy
form. Publicly available docket materials are available either
electronically through https://www.regulations.gov or in hard copy at
the Water Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave.,
NW., Washington, DC. The 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 EPA Docket Center is (202) 566-2426.
FOR FURTHER INFORMATION CONTACT: Yvette Selby-Mohamadu, Standards and
Risk Management Division, Office of Ground Water and Drinking Water,
4607M, Environmental Protection Agency, 1200 Pennsylvania Ave., NW.,
Washington, DC 20460; telephone number: (202) 564-5245; e-mail address:
selby-mohamadu.yvette@epa.gov. For general information contact the EPA
Safe Drinking Water Hotline at (800) 426-4791, or (703) 412-3330, from
10 a.m. to 4 p.m., Eastern Time, Monday through Friday, excluding legal
holidays.
Abbreviations and Acronyms
[mu]g/L--micrograms per liter
ATSDR--Agency for Toxic Substances and Disease Registry
AwwaRF--American Water Works Association Research Foundation
CCL--Contaminant Candidate List
CCL 1--EPA's First Contaminant Candidate List
CCL 2--EPA's Second Contaminant Candidate List
1,3-DCP--1,3-dichloropropene
DCPA--dimethyl tetrachloroterephthalate (dacthal)
DDE--1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene
DDT--1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane
DNT--dinitrotoluene
EPA--United States Environmental Protection Agency
EPTC--s-ethyl dipropylthiocarbamate
ESA--ethane sulfonic acid
FR--Federal Register
HRL--health reference level
IRIS--Integrated Risk Information System
kg--kilogram
L--liter
MAC--Mycobacterium avium
MCL--maximum contaminant level
MCLG--maximum contaminant level goal
MRL--minimum or method reporting limit (depending on the study or
survey cited)
MTBE--methyl tertiary butyl ether
MTP--monomethyl-2,3,5,6-tetrachloroterephthalate
NDWAC--National Drinking Water Advisory Council
NIRS--National Inorganic and Radionuclide Survey
NRC--National Research Council
NPDWR--national primary drinking water regulation
OA--oxanilic acid
OPP--Office of Pesticide Programs
PWS--public water system
RSC--relative source contribution
SDWA--Safe Drinking Water Act
SOT--Society of Toxicology
TPA--2,3,5,6-tetrachchloroterephthalic acid
TRI--Toxics Release Inventory
TT--treatment technique
UCM--Unregulated Contaminant Monitoring
UCMR 1--First Unregulated Contaminant Monitoring Regulation issued
after the 1996 SDWA Amendments
US--United States of America
USGS--United States Geological Survey
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Impose Any Requirements on My Public Water
System?
II. Purpose, Background, and Summary of This Action
A. What Is the Purpose of This Action?
B. What Is the Statutory Requirement for the Contaminant
Candidate List (CCL) and Regulatory Determinations?
C. What Contaminants Did EPA Consider for Regulation?
III. What Approach and Analyses Did EPA Use To Make the Regulatory
Determinations?
A. Approach
B. Analyses
IV. Summary of Public Comments and the Agency's Responses on the CCL
Regulatory Determination Process
A. Regulatory Determinations for the 11 Contaminants
B. Regulatory Determinations Approach
C. Occurrence and Exposure Evaluation
D. Comments on Boron, Perchlorate, MTBE, Metolachlor, and
Cyanobacteria and Its Toxins
V. Summary of the Agency's Findings on the 11 CCL 2 Contaminants
A. Boron
B. Dacthal mono- and di-acid degradates
[[Page 44252]]
C. 1,1-Dichloro-2,2-bis(p-chlorophenyl) ethylene
D. 1,3-Dichloropropene
E. 2,4- and 2,6-Dinitrotoluenes
F. s-Ethyl dipropylthiocarbamate
G. Fonofos
H. Terbacil
I. 1,1,2,2-Tetrachloroethane
VI. How Will EPA Address the Data Needs of the Remaining CCL 2
Contaminants?
VII. References
SUPPLEMENTARY INFORMATION:
I. General Information
A. Does This Action Impose Any Requirements on My Public Water System?
None of these regulatory determinations will impose any
requirements on anyone. Instead, this action notifies interested
parties of EPA's determinations for 11 CCL 2 contaminants and provides
a summary of the major comments received on the May 1, 2007,
preliminary determinations (72 FR 24016 (USEPA, 2007a)).
II. Purpose, Background and Summary of This Action
A. What Is the Purpose of This Action?
Today's action briefly describes the statutory requirements for
targeting potential drinking water contaminants for regulatory
development and the approach EPA used to make regulatory determinations
for 11 CCL 2 contaminants. In addition, today's action (1) summarizes
the public comments received on EPA's preliminary determinations and
the Agency's responses to those comments, (2) presents the Agency's
findings and final regulatory determination for 11 CCL 2 contaminants,
and (3) provides information regarding the other CCL 2 contaminants.
B. What Is the Statutory Requirement for the Contaminant Candidate List
(CCL) and Regulatory Determinations?
The specific statutory requirements for the CCL and regulatory
determinations can be found in SDWA section 1412(b)(1). The 1996 SDWA
Amendments require 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 EPA
to determine whether to regulate at least five contaminants from the
CCL every five years. SDWA requires EPA to publish a Maximum
Contaminant Level Goal \1\ (MCLG) 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
(TT) 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 EPA 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 a nine month extension of this
promulgation date.
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C. What Contaminants Did EPA Consider for Regulation?
On May 1, 2007 (72 FR 24016 (USEPA, 2007a)), EPA published
preliminary regulatory determinations for 11 CCL 2 contaminants that
have sufficient information to support a regulatory determination. The
11 contaminants are boron; the dacthal mono- and di-acid degradates;
1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE); 1,3-
dichloropropene; 2,4-dinitrotoluene (DNT); 2,6-dinitrotoluene; s-ethyl
dipropylthiocarbamate (EPTC); fonofos; terbacil; and 1,1,2,2-
tetrachloroethane.
Information for the 11 contaminants is available in the regulatory
determination support document (USEPA, 2008a), the occurrence technical
support documents (USEPA, 2008b-c), and the Health Effects Support
Documents or Drinking Water Advisories for each of the contaminants
(USEPA, 2008d-l). This information is available at the Water Docket
(Docket ID No. EPA-HQ-OW-2007-0068) and is also available on EPA's Safe
Drinking Water Regulatory Determination Web site at https://www.epa.gov/
safewater/ccl/reg_determine2.html. Brief descriptions of each of the
11 contaminants considered for regulatory determinations are included
in section V of this notice.
III. What Approach and Analyses Did EPA Use To Make the Regulatory
Determinations?
A. Approach
In identifying which CCL 2 contaminants are candidates for
regulatory determinations, the Agency considered whether sufficient
information and/or data were available to characterize the potential
health effects and the known/likely occurrence in and exposure from
drinking water. For health effects, the Agency considered whether an
Agency-approved health risk assessment \4\ was available to identify
any potential adverse health effect(s) and derive an estimated level at
which no adverse health effect(s) are likely to occur. For occurrence,
the Agency considered whether available information/data provided a
representative picture of known and/or likely occurrence in public
water systems. If sufficient information/data were available to
characterize adverse human health effects and known/likely occurrence
in public water systems, the Agency identified the contaminant as a
potential candidate for regulatory determinations. In addition to
information/data for health and occurrence, EPA also considered the
availability and adequacy of analytical methods (for monitoring) and
treatment.
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\4\ Health information used for the regulatory determinations
process includes but is not limited to health assessments available
from the Agency's Integrated Risk Information System (IRIS), the
Agency's Office of Pesticide Programs (OPP) in a Reregistration
Eligibility Decision (RED), the National Academy of Sciences (NAS),
and/or the Agency for Toxic Substances and Disease Registry (ATSDR).
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In cases where EPA chose a contaminant as a candidate for
regulatory determination, the Agency considered the following in
evaluating each of the three statutory criteria.
(a) First statutory criterion--Is the contaminant likely to cause
an adverse effect on the health of persons? The Agency evaluated the
best available, peer-reviewed assessments and studies to characterize
the human health effects that may result from exposure to the
contaminant when found in drinking water. Based on this
characterization, the Agency estimated a health reference level (HRL)
for each contaminant.
[[Page 44253]]
(b) Second statutory criterion--Is the contaminant known or likely
to occur in public water systems at a frequency and level of public
health concern? To evaluate known occurrence in PWSs, the Agency
compiled, screened, and analyzed data from several occurrence data sets
to develop representative occurrence estimates for public drinking
water systems. EPA used the HRL estimate for each contaminant as a
benchmark against which to conduct an initial evaluation or screening
of the occurrence data. For each contaminant, EPA estimated the number
of PWSs (and the population served by these PWSs) with detections
greater than one-half the HRL (> \1/2\ HRL) and greater than the HRL (>
HRL). To further evaluate the likelihood of a contaminant occurring in
drinking water, the Agency considered information on the use and
release of the contaminant into the environment and supplemental
information on occurrence in water (e.g., ambient water quality data,
State ambient or finished water data, and/or special studies performed
by other agencies, organizations and/or entities).
(c) Third statutory criterion--In the sole judgment of the
Administrator, does regulation of the contaminant present a meaningful
opportunity for health risk reduction for persons served by public
water systems? EPA evaluated the potential health effects and the
results of the occurrence estimates, as well as exposure estimates
(i.e., the population exposed and the sources of exposure) at the
health level of concern to determine if regulation presents a
meaningful opportunity for health risk reduction.
If the answers to all three statutory criteria are affirmative for
a particular contaminant, then the Agency makes a determination that
regulation is necessary and proceeds to develop an MCLG and a national
primary drinking water regulation for that contaminant. It should be
noted that this regulatory determination process is distinct from the
more detailed analyses needed to develop a national primary drinking
water regulation. Thus, a decision to regulate is the beginning of the
Agency's regulatory development process, not the end.
If the answer to any of the three statutory criteria is negative
based on the available data, then the Agency makes a determination that
a national primary drinking water regulation is not necessary for that
contaminant at that time.
B. Analyses
EPA has prepared Health Effects Support Documents or Drinking Water
Advisories (USEPA, 2008d-l) for each of the 11 contaminants. In these
documents, EPA characterized the human health effects that may result
from exposure to a contaminant found in drinking water. The support
documents address exposure from drinking water and other media,
toxicokinetics, hazard identification, dose-response assessment, and an
overall characterization of risk from drinking water. Based on this
characterization, EPA estimated a health reference level (HRL) or
benchmark value for each contaminant.
To analyze occurrence and exposure, the Agency used data from the
first Unregulated Contaminant Monitoring Regulation (UCMR 1) for 9 of
the contaminants: The dacthal mono- and di-acid degradates, 1,1-
dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), 1,3-dichloropropene,
2,4-dinitrotoluene, 2,6-dinitrotoluene, s-ethyl dipropylthiocarbamate
(EPTC), fonofos, and terbacil.\5\ In addition, the Unregulated
Contaminant Monitoring (UCM \6\) program provided additional data for
1,3-dichloropropene and 1,1,2,2-tetrachloroethane and the National
Inorganic and Radionuclide Survey (NIRS \7\) provided data for boron.
The Agency used the UCMR 1, UCM, and NIRS data to estimate the number
and percentage of PWSs and the population served by these PWSs at
concentrations above the HRL benchmark values, and \1/2\ the HRL
values. The Agency also used these data to evaluate the geographic
distribution of occurrence for these 11 CCL 2 contaminants.
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\5\ The UCMR 1 monitoring survey began in 2001. As discussed in
the May 2007 notice, fonofos was sampled as part of UCMR 1 Screening
Monitoring and the remaining 8 contaminants were sampled as part of
UCMR 1 Assessment Monitoring.
\6\ EPA implemented the UCM program in two phases or rounds. The
first round of UCM monitoring generally extended from 1988 to 1992
and is referred to as UCM Round 1 monitoring. The second round of
UCM monitoring generally extended from 1993 to 1997 and is referred
to as UCM Round 2 monitoring.
\7\ The monitoring for NIRS spanned from 1984 to 1986.
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EPA also employed State drinking water data, use and environmental
release information (e.g., EPA's Toxic Release Inventory (TRI),
academic and private sector publications), as well as ambient water
quality data (e.g., data from the U.S. Geological Survey's National
Water Quality Assessment program) as secondary sources of information
to evaluate the likelihood of contaminant occurrence.
A detailed discussion of the data collected and analyses for each
contaminant can be found in the regulatory determination support
document (USEPA, 2008a) and the occurrence technical support documents
(USEPA, 2008b-c). In addition, a summary of the occurrence and exposure
findings are included in Table 1. Table 1 in this notice is similar to
Table 3 in the May 2007 notice (72 FR 24016 (USEPA, 2007a)); however,
note that EPA updated the occurrence data for the UCMR 1 results to
include final results for 17 additional drinking water systems that
were not available when the Agency was in the process of making its
preliminary regulatory determinations. Updating these numbers did not
change the outcome of today's decisions.
Table 1--Summary of the Health and Occurrence Information and the Final Determinations for the 11 Contaminants Considered Under CCL Regulatory
Determinations 2
--------------------------------------------------------------------------------------------------------------------------------------------------------
Occurrence findings from primary data sources (UCMR 1, UCM round 1 and 2 cross
sections, NIRS)
Contaminant and --------------------------------------------------------------------------------------
its chemical Health reference Population Population
abstract Determination level (HRL) PWSs with at served by PWSs PWSs with at served by PWSs
registry number Database least 1 with at least 1 least 1 with at least 1
(CASRN) detection > \1/ detection > \1/ detection > detection >
2\ HRL 2\ HRL HRL HRL
--------------------------------------------------------------------------------------------------------------------------------------------------------
1.......... Boron (7440-42- Do not regulate 1,400 [mu]g/L... NIRS............ 4.3% (43 of 989) 2.9% (42.7K of 1.7% or (17 of 0.4% (6.4K of
8). \1\. 1.48M). 989) \1\. 1.48M)
2.......... Dacthal di acid Do not regulate. 70 [mu]g/L \4\.. UCMR 1 \5\...... 0.05% (2 of 0.33% (739K of 0.03% (1 of < 0.01% (500 of
degradate \2\ 3,876). 225M). 3,876). 225M)
(2136-79-0).
[[Page 44254]]
3.......... Dacthal mono
acid degradate
\3\ (887-54-7).
4.......... DDE \6\ (72-55- Do not regulate. 0.2 [mu]g/L..... UCMR 1.......... \7\............. \7\............ 0.03% \7\ (1 of 0.01% (18K of
9). 3,874) \8\. 226M) \8\
5.......... 1,3- Do not regulate. 0.4 [mu]g/L..... UCM Rd1......... 0.16% (15 of 0.86% (436K of 0.16% (15 of 0.86% (436K of
Dichloropropene UCM Rd2......... 9,164) \9\. 51M) \9\. 9,164) \9\. 51M) \9\
(Telone) (542- UCMR 1.......... 0.30% (50 of 0.42% (193K of 0.23% (38 of 0.33% (152K of
75-6). 16,787) \9\. 46M) \9\. 16,787) \9\. 46M) \9\
\7\............. \7\............ 0.00% (0 of 0.00% (0 of
796) \8\. 2.8M) \8\
6.......... 2,4- Do not regulate. 0.05 [mu]g/L.... UCMR 1.......... \7\............. \7\............ 0.03% (1 of 0.02% (38K of
Dinitrotoluene 3,873) \8\. 226M) \8\
(121-14-2).
7.......... 2,6- Do not regulate. 0.05 [mu]g/L.... UCMR 1.......... \7\............. \7\............ 0.00% (0 of 0.00% (0 of
Dinitrotoluene 3,873) \8\. 226M) \8\
(606-20-2).
8.......... EPTC \10\ (759- Do not regulate. 175 [mu]g/L..... UCMR 1.......... 0.00% (0 of 0.00% (0 of 0.00% (0 of 0.00% (0 of
94-4). 3,873). 226M). 3,873). 226M)
9.......... Fonofos (944-22- Do not regulate. 10 [mu]g/L...... UCMR 1.......... 0.00% (0 of 295) 0.00% (0 of 0.00% (0 of 0.00% (0 of
9). 41M). 295). 41M)
10......... Terbacil (5902- Do not regulate. 90 [mu]g/L...... UCMR 1.......... 0.00% (0 of 0.00% (0 of 0.00% (0 of 0.00% (0 of
51-2). 3,873). 226M). 3,873). 226M)
11......... 1,1,2,2- Do not regulate. 0.4 [mu]g/L..... UCM Rd1......... 0.22% (44 of 1.69% (1.6M of 0.20% (41 of 1.63% (1.5M of
Tetrachloroetha UCM Rd2......... 20,407) \9\. 95M) \9\. 20,407) \9\. 95M) \9\
ne (79-34-5). 0.07% (18 of 0.51% (362K of 0.07% (17 of 0.08% (56K of
24,800) \9\. 71M) \9\. 24,800) \9\. 71M) \9\
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\1\ EPA also considered the results of an AwwaRF study of PWSs indicating that surface water sources are unlikely to contain boron at levels > the HRL
of 1,400 [mu]g/L (Frey et al., 2004).
\2\ 2,3,5,6-tetrachloroterephthalic acid (TPA).
\3\ monomethyl-2,3,5,6-tetrachloroterephthalate (MTP).
\4\ Using the dacthal parent HRL since it includes the toxicity for the degradates.
\5\ Degradates monitored in aggregate and converted to the parent equivalent.
\6\ 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene.
\7\ Not reported since MRL > \1/2\ the HRL.
\8\ Shows results > MRL, rather than > HRL, since MRL is greater than the HRL. In all cases the MRL is within the 10-4 to 10-6 risk range.
\9\ The MRLs used in UCM varied from below the \1/2\ HRL to above the HRL. However, even the highest MRLs used are within the 10-4 to 10-6 risk range.
\10\ s-ethyl dipropylthiocarbamate.
IV. Summary of Public Comments and the Agency's Responses on the CCL
Regulatory Determination Process
EPA received comments from nine organizations or individuals on the
May 1, 2007, Federal Register notice. These nine organizations/
individuals include five water-related associations, one industry
group, one State agency, one State-related association, and one
anonymous person. A majority of the comments focused on the following
four over-arching topic areas:
The regulatory determinations for the 11 contaminants;
The regulatory determinations approach;
The occurrence and exposure evaluation; and
Comments on specific CCL 2 contaminants: boron,
perchlorate, MTBE, metolachlor, and cyanobacteria and its toxins.
A complete copy of the public comments and the Agency's responses
are included in the Docket for today's action (USEPA, 2008m). The
remainder of this section discusses the four key topic areas identified
by commenters in response to the May 2007 preliminary regulatory
determination notice (72 FR 24016, (USEPA, 2007a)).
A. Regulatory Determinations for the 11 Contaminants
Comment Summary: Most of the commenters agreed with EPA's decisions
not to regulate the 11 contaminants. However, one State agency
recommended that EPA reconsider its position of not regulating 2,4- and
2,6-DNT because they found these two contaminants in ground water in
numerous locations in and around ammunition and military sites in their
State.
Agency Response: EPA agrees with the commenters who believe that no
regulation is warranted at this time for the 11 contaminants. In
response to reconsidering the Agency's decision for 2,4- and 2,6-DNT,
EPA respectfully disagrees. Monitoring data collected on 2,4- and 2,6-
DNT from UCMR 1 do not indicate that either of these chemicals occurs
nationally in public drinking water systems at health levels of
concern. EPA found only one detection of 2,4-DNT from among the 3,873
public water systems evaluated and no detections of 2,6-DNT. The
information submitted by the commenter does not lead the Agency to
change its decision because the occurrence appears to be highly
localized and therefore, does not meet statutory criterion 2 (likely to
occur in PWSs with a frequency and at a level of concern). To assist
State and local communities that may have localized occurrence of 2,4-
and/or 2,6-DNT, the Agency has updated the Health Advisory for both of
these compounds as part of the regulatory determination process. If a
State finds that it has highly localized levels of 2,4- and/or 2,6-DNT
above the HRL of 0.05 [mu]g/L, the Agency encourages States to consider
whether State-level guidance (or some other type of action) may be
appropriate.
B. Regulatory Determinations Approach
Comment Summary: One commenter recommended that EPA expand its
discussion of the logic underlying the determinations for these 11
contaminants. The commenter stated that EPA needs to raise the level of
transparency in its decision logic so that stakeholders can understand
how data and information translate to determinations and to ensure
[[Page 44255]]
consistency across the two parallel regulatory efforts (regulatory
determinations and six-year reviews). The commenter asked for a
discussion about the status of the remaining CCL 2 contaminants. In
addition, the commenter recommended that EPA's drinking water research
agenda be integrated with the regulatory development process.
Another commenter agreed with the determinations not to regulate
the 11 contaminants but recommended that EPA include affordability
criteria when evaluating whether regulation will result in a meaningful
health benefit in future determinations. The commenter submitted a
paper in support of their comment.\8\
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\8\ This paper can be found in the Docket for this notice at
https://www.regulations.gov under the Docket ID No. EPA-HQ-OW-2007-
0068.
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Agency Response: In response to the first comment, EPA developed a
consistent regulatory determination approach for evaluating CCL 2
contaminants that followed the National Drinking Water Advisory
Council's (NDWAC, 2000) recommended protocol for both health effects
and occurrence analyses. In this notice (section VI), EPA added a
narrative and tables that summarize the data gaps for the other 40 CCL
2 contaminants, which kept the Agency from making a regulatory
determination at this time. EPA does not believe that it is appropriate
to consider a research agenda specifically for those contaminants at
this time because the Agency is in the process of developing a new CCL
(CCL 3). The new process considers the knowledge and experience gained
from evaluating unregulated contaminants on CCL 1 and CCL 2 and the
recommendations and advice from the National Academies of Sciences'
National Research Council (NRC, 2001) and NDWAC (2004). The Agency
anticipates that future CCL research needs will be directed at filling
data gaps for contaminants on the new list (i.e., CCL 3), not CCL 2.
All CCL 2 contaminants will be examined for inclusion on CCL 3 and
those that remain a high priority will be examined for research needs.
In response to the second comment, the SDWA requires that EPA
consider the costs and benefits, as well as affordability, as NPDWRs
are developed. Specifically, SDWA requires that EPA perform a health
risk reduction and cost analysis and an affordability analysis for
proposed NPDWRs. EPA respectfully disagrees that an affordability
analysis is necessary or required for regulatory determinations. For
regulatory determination, SDWA requires that EPA use the three criteria
discussed in section III.A. As a result, EPA will evaluate costs and
affordability in more detail, including whether small system variances
are appropriate, as part of the regulatory process after the Agency
makes a positive regulatory determination.
C. Occurrence and Exposure Evaluation
Comment Summary: One commenter stated that ``based on the first
round of regulatory determinations, a range of 0.02%-3.2% for national
occurrence could be considered as the minimum threshold for development
of a new regulation'' and ``national occurrence estimates for these
eleven contaminants are well below this threshold, with boron having
the highest prevalence of occurrence, at 1.7% of systems sampled in the
National Inorganics and Radionuclides Survey (NIRS).''
Another commenter provided a report by Phillips and Chambless \9\
that evaluated compliance data for seven contaminants from five States
obtained from a cross section of State regulatory agencies. Based on a
preliminary analysis, the authors found that the variability in the
means of quarterly samples taken for compliance purposes was
consistently large. The commenter expressed the opinion that the
variability (standard error of the mean divided by the mean) is
significant enough (100 percent or more in many cases) to question the
validity of decisions made based on the UCMR data (for unregulated
contaminants). Based on that study, the commenter stated that there is
no reason to assume that the quality of the occurrence data from the
UCMR effort would be any better than the quality of the compliance
data. The second commenter urged EPA to resolve this quality issue
before trying to make CCL 2 regulatory decisions that are based on
rather precise calculations of occurrence levels and the number of
persons exposed.
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\9\ This paper can be found in the Docket for this notice at
https://www.regulations.gov under the Docket ID No. EPA-HQ-OW-2007-
0068.
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Agency Response: In response to the first comment, EPA considers
both the extent of national occurrence and the severity of health
effects for a contaminant, as well as other factors (e.g., sources of
exposure), when deciding whether regulation presents a meaningful
opportunity for health risk reduction. As a result, the Agency does not
believe it is appropriate to set minimum occurrence thresholds for
regulatory determinations.
In response to the second comment regarding variability in
occurrence measures based on the compliance monitoring data for
regulated contaminants, the Agency believes the variability issues
identified by Phillips and Chambless do not directly reflect the
dependability of the UCMR 1 data used to support the Agency's
regulatory determinations. Compliance monitoring data is State data
resulting from individual public water systems efforts to comply with
regulatory monitoring requirements. The UCMR 1 is EPA's program to
collect data for contaminants suspected to be present in drinking water
based upon a statistically-valid data set for nationwide occurrence
estimates. The UCMR 1 program was designed to address this variability
issue at the national level by defining a vulnerable period (the season
of greatest vulnerability of contaminant occurrence, the season of
increased flux of water movement) and requiring at least one UCMR 1
sample during that period. In addition, the monitoring periods for the
large and small systems were performed over a three year period.
Approximately one-third of all small UCMR 1 systems throughout the
country conducted monitoring in each of the three years of UCMR 1
monitoring. Furthermore, the monitoring schedules for these systems
were conducted to include monitoring in every month and every season
around the country. Large systems could conduct their one year of
monitoring anytime during the UCMR 1 period from 2001 to 2003. Like
small systems, their monitoring schedules were spread throughout the
year and were to include one sample during what was considered the most
vulnerable season. In this way, the UCMR 1 monitoring results reflect
multiple seasons and multiple years of climatic conditions throughout
the country and are not directly affected (or biased) by weather
conditions of a single season, year, or geographic region. Whereas some
variability might still be expected, EPA believes this is unlikely to
be a source of bias for national level occurrence estimates.
In addition, it should be noted that EPA used peak occurrence
estimates (the number and percent of systems with at least one observed
detection greater than \1/2\ the HRL and the HRL) as opposed to mean
values in making its final decisions not to regulate the 11 CCL 2
contaminants. Hence, taking variability around the mean into account
would not have influenced the outcome of the final determinations for
these 11 contaminants. The characterization of national occurrence
provided by the UCMR 1 monitoring
[[Page 44256]]
data is adequate and the best available data to support today's
decisions.
D. Comments on Boron, Perchlorate, MTBE, Metolachlor, and Cyanobacteria
and Its Toxins
1. Boron. One anonymous commenter agreed with our determination for
boron but commented on the fact that the health reference level does
not incorporate the results of the preliminary chemical-specific Health
Advisory Level (HAL) derived recently by EPA and presented at the 2007
Society of Toxicology (SOT) meeting.
Agency Response: The HRL used in making regulatory determinations
is not equivalent to a lifetime health advisory value. As stated in the
Health Effects Support Document for Boron (USEPA, 2008d) and the May 1,
2007, notice (72 FR 24016 (USEPA, 2007a)), an HRL is a benchmark
against which to measure the occurrence data; it is not a Health
Advisory guideline. For noncarcinogens such as boron, the HRL is
calculated by multiplying the Agency Reference Dose by a 70 kg body
weight and a 20 percent default Relative Source Contribution (RSC) and
dividing the product by a drinking water intake of 2 L/day.
As described in the May 2007 notice (72 FR 24016 (USEPA, 2007a))
and in evaluating contaminants for regulatory determinations, the
Agency initially uses a default 20 percent RSC to estimate the HRLs for
non-carcinogens because this approach derives the lowest and most
conservative HRL value to use in screening the occurrence data. EPA
used this approach to calculate the HRL benchmark for boron and to
determine if boron might be occurring nationally at a level of
potential health concern. In developing the health advisory for boron,
the Agency performed a more refined assessment of the risk for those
PWSs that occasionally find levels of boron that exceed the lifetime or
shorter term health advisory values. While the Agency derived a more
refined RSC for the determination of the lifetime Health Advisory for
boron, this value is still limited by the RSC ceiling of 80 percent as
a matter of policy. The derivation of health advisory values also
incorporates the use of appropriate body weights for the target
population. The 2007 SOT poster presentation used a body weight of 67
kg for a pregnant woman, consistent with the Human Health Methodology
(USEPA, 2000) guidelines. There may be changes to that policy based on
more recent data on pregnancy weights, and if so, the draft Health
Advisory will be revised to reflect the new policy.
2. Perchlorate. EPA received comment letters on perchlorate from
eight commenters. The major areas of concern raised in the comments
related to (1) the Agency's decision not to make a regulatory
determination for perchlorate at the same time as for the 11
contaminants for which a regulatory determination is being finalized
today, and (2) the Agency's discussion of potential analyses to more
fully characterize total perchlorate exposure in order to assess the
opportunity for public health protection through a drinking water
regulation.
Agency Response: EPA will soon publish a preliminary determination
for perchlorate. EPA will request public comment as part of that
notice. EPA will consider the comments received on the May 2007 notice
(72 FR 24016 (USEPA, 2007a)) with respect to perchlorate as a part of
that regulatory determination and will respond to such public comments
at the time the Agency issues a regulatory determination for
perchlorate. EPA intends to finalize a regulatory determination for
perchlorate by December 2008.
3. MTBE. Most commenters supported EPA's decision not to make a
regulatory determination for methyl tertiary-butyl ether (MTBE) at this
time because the IRIS assessment is currently being revised. Also, one
commenter felt that UCMR 1 would provide valuable occurrence data for
MTBE when the risk assessment becomes available.
Agency Response: EPA agrees that UCMR 1 data provides important
occurrence information on MTBE and will be useful in making a
regulatory determination once the final risk assessment is available.
4. Metolachlor. Some commenters noted that additional research for
the health effects and occurrence of metolachlor and its degradates is
needed. One commenter felt that UCMR 2 would provide valuable
occurrence information for metolachlor and its degradates. One
commenter did not have additional data but believes more information is
needed on the occurrence and health effects of many herbicides and
pesticides and their degradates. The results of this research should be
appropriately included in regulatory decisions by the Office of
Pesticide Programs (OPP) and the Office of Ground Water and Drinking
Water. The commenter stated that EPA should promote further research to
definitively determine whether metolachlor, a very widely used
pesticide, is carcinogenic, as acetochlor, alachlor and metolachlor
have very similar chemical structures.
Agency Response: The Agency agrees that more information on the
occurrence of metolachlor and its degradates is needed in order to
determine if the combined parent compound and its degradates are
occurring at levels of health concern. The available metolachlor data
from earlier unregulated contaminant monitoring surveys indicate that
metolachlor is found in finished water in many locations but at levels
below the HRL. The occurrence data on the parent metolachlor, combined
with the knowledge that it decomposes to several degradates that are
more persistent than the parent, supported the inclusion of both
metolachlor and its degradates in UCMR 2. Once available, the UCMR 2
data will be useful in evaluating the occurrence of metolachlor and its
degradates in public water systems and will assist the Agency in
deciding whether to regulate these compounds.
5. Cyanobacteria and its toxins. In the May 2007 notice (72 FR
24016 (USEPA, 2007a)), EPA asked for comment on the usefulness of
providing an information summary about cyanobacteria and its toxins.
One commenter responded and recommended that EPA provide an information
summary describing the state of the knowledge on the prevention,
treatment, and health effects of cyanobacteria and its toxins. The
commenter felt that a document would be useful for utilities and State
agencies. The commenter recommended that the summary include
information on occurrence, conditions that might favor growth of algae
and production of toxins, and a strategy for communicating this
information to utility customers. In addition, the commenter suggested
that the summary include information on research funded by other
organizations, particularly the AWWA Research Foundation (AwwaRF).
Agency Response: EPA is developing an information sheet that will
include the information suggested by the commenter and links to
organizations performing research on the cyanobacteria and its toxins.
The Agency anticipates making this information sheet available on its
Safewater Web site (https://www.epa.gov/safewater) shortly after the
publication of this notice.
V. Summary of the Agency's Findings on the 11 CCL 2 Contaminants
A. Boron
1. Description. Boron, a metalloid, tends to occur in nature in the
form of borates (e.g., boric acid, borax, boron oxide). Man-made
releases are typically in the form of borates or boron halides (e.g.,
boron trichloride, boron
[[Page 44257]]
trifluoride). Boron compounds are used in the production of glass,
ceramics, cleaning agents, fire retardants, pesticides, cosmetics,
photographic materials, and high energy fuels (USGS, 2004; ATSDR,
1992).
2. Agency Findings. The Agency is making a determination not to
regulate boron with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), EPA used
data from NIRS and an AwwaRF study (Frey et al., 2004) to evaluate
occurrence and exposure at the HRL of 1,400 [mu]g/L (as well as \1/2\
the HRL). The NIRS data indicate that approximately 4.3 percent (or 43)
of the 989 ground water PWSs sampled had at least one detection of
boron at levels greater than 700 [mu]g/L, affecting approximately 2.9
percent of the population served (or 42,700 people from 1.48 million).
Approximately 1.7 percent (or 17) of 989 ground water PWSs sampled had
at least one detection of boron at levels greater than 1,400 [mu]g/L,
affecting approximately 0.4 percent of the population served (6,400
people from 1.48 million) (USEPA, 2008c and 2008d).
Because NIRS did not contain data for surface water systems, the
Agency evaluated the results of the AwwaRF study (Frey et al., 2004) to
gain a better understanding of the potential occurrence of boron in
surface water systems. The AwwaRF study recruited 189 PWSs representing
407 source waters that covered 41 States. Of these 407 PWS source water
samples, 342 were returned and 341 were analyzed for boron. Of these
341 samples, approximately 67 percent (or 228) represented ground water
sources and 33 percent (or 113) represented surface water sources. None
of the 113 surface water sources exceeded the boron HRL of 1,400 [mu]g/
L and the maximum concentration observed in surface water was 345
[mu]g/L. Extrapolation of the data indicates that 95 percent of the
ground water detections had boron levels less than 1,054 [mu]g/L; the
maximum observed concentration in ground water was approximately 3,300
[mu]g/L. Seven of the 228 ground water sources (from 5 systems) had at
least one sample with a boron concentration greater than 1,400 [mu]g/L
(Seidel, 2006).
While boron was found at levels greater than the HRL of 1,400
[mu]g/L (and \1/2\ the HRL) in several of the ground water systems
surveyed by NIRS, it was not found at levels greater than the HRL (or
\1/2\ the HRL) in the surface water sources evaluated in the AwwaRF
study. Taking this surface water information into account, the Agency
believes the overall occurrence and exposure from both surface and
ground water systems together is likely to be lower than the values
observed for the NIRS ground water data. Because boron is not likely to
occur at health levels of concern when considering both surface and
ground water systems, the Agency believes that a national primary
drinking water regulation does not present a meaningful opportunity for
health risk reduction.
The Agency presented a complete review of our analysis of the
health effects, occurrence, and exposure for boron in the May 2007
notice (72 FR 24016 (USEPA, 2007a)), the final regulatory support
document (USEPA, 2008a), and the health effects support document for
boron (USEPA, 2008d). The Agency also plans to update the Health
Advisory for boron to provide more recent health information. The
updated Health Advisory will provide information to any States with
public water systems that may have boron above the HRL. If a State
finds highly localized occurrence of boron at concentrations above the
HRL, the Agency encourages States to consider whether State-level
guidance (or some other type of action) may be appropriate.
B. Dacthal Mono- and Di-Acid Degradates
1. Description. Dimethyl tetrachloroterephthalate (DCPA), a
synthetic organic compound (SOC) marketed under the trade name
''Dacthal,'' is a pre-emergent herbicide historically used to control
weeds in ornamental turf and plants, strawberries, seeded and
transplanted vegetables, cotton, and field beans. DCPA is not
especially mobile or persistent in the environment. Biodegradation and
volatilization are the primary dissipation routes. Degradation of DCPA
forms two breakdown products, the mono-acid degradate (monomethyl
tetrachloroterephthalate or MTP) and the di-acid degradate
(tetrachloroterephthalic acid or TPA). The di-acid, which is the major
degradate, is unusually mobile and persistent in the field, with a
potential to leach into water (USEPA, 1998a).
2. Agency Findings. The Agency is making a determination not to
regulate the DCPA mono-acid degradate and/or the DCPA di-acid degradate
with a national primary drinking water regulation. As noted in the May
2007 notice (72 FR 24016 (USEPA, 2007a)), these degradates appear to
occur infrequently at health levels of concern in PWSs, and the Agency
believes that a national primary drinking water regulation does not
present a meaningful opportunity for health risk reduction. While the
Agency recognizes that these degradates have been detected in the PWSs
monitored under the UCMR 1, only one PWS detected these degradates at a
concentration above the HRL of 70 [mu]g/L.
The Agency presented a complete review of our analysis of the
health effects, occurrence, and exposure for dacthal mono- and di-acid
degradates in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), the
final regulatory support document (USEPA, 2008a), and the health
effects support document (USEPA, 2008e). The Agency also plans to
update the Health Advisory for the DCPA parent to include the mono- and
di-acid degradates, as well as any recent health information related to
these compounds. The updated Health Advisory will provide information
to any States with public water systems that may have DCPA degradates
at levels above the HRL. If a State finds highly localized occurrence
of DCPA degradates at concentrations above the HRL, the Agency
encourages States to consider whether State-level guidance (or some
other type of action) may be appropriate.
C. 1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene
1. Description. DDE is a primary metabolite of 1,1,1-trichloro-2,2-
bis(p-chlorophenyl)ethane (DDT), a pesticide used to protect crops and
eliminate disease-carrying insects in the U.S. until it was banned in
1973. DDE itself has no commercial use and is only found in the
environment as a result of prior contamination with DDT. While DDE
tends to adsorb strongly to surface soil and is fairly insoluble in
water, it may enter surface waters from runoff that contains DDE bound
to soil particles. In both soil and water, DDE is subject to
photodegradation, biodegradation, and volatilization (ATSDR, 2002).
2. Agency Findings. The Agency is making a determination not to
regulate DDE with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), DDE appears
to occur infrequently at health levels of concern in PWSs, and the
Agency believes that a national primary drinking water regulation does
not present a meaningful opportunity for health risk reduction. DDE was
detected in only one of the PWSs monitored under the UCMR 1 at a level
greater than the MRL (0.8 [mu]g/L). The MRL is greater than the HRL of
0.2 [mu]g/L but represents a concentration that is within the
10-4 to the 10-6 cancer risk range targeted by
[[Page 44258]]
the Agency. In addition, ambient water data from the USGS (Martin et
al., 2003; Kolpin and Martin, 2003) indicate that the maximum
concentrations detected in surface and ground water were less than the
HRL.
The Agency presented a complete review of our analysis of the
health effects, occurrence, and exposure for DDE in the May 2007 notice
(72 FR 24016 (USEPA, 2007a)), the final regulatory support document
(USEPA, 2008a), and the health effects support document (USEPA, 2008f).
If a State finds highly localized occurrence of DDE at concentrations
above the HRL, the Agency encourages States to consider whether State-
level guidance (or some other type of action) may be appropriate.
D. 1,3-Dichloropropene
1. Description. 1,3-Dichloropropene (1,3-DCP), a synthetic volatile
organic compound, is used as a pre-plant soil fumigant to control
nematodes and other pests in soils planted with all types of food and
feed crops. 1,3-DCP is typically injected 12 inches to 18 inches
beneath the soil surface and can only be used by certified handlers
(USEPA, 1998b).
2. Agency Findings. The Agency is making a determination not to
regulate 1,3-DCP with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), 1,3-DCP
appears to occur infrequently at health levels of concern in PWSs, and
the Agency believes that a national primary drinking water regulation
does not present a meaningful opportunity for health risk reduction.
While 1,3-DCP was detected in the UCM Round 1 (late 1980s) and the UCM
Round 2 (mid 1990s) surveys, it was not detected in a subsequent
evaluation of 796 small systems from the UCMR 1 survey. In addition,
the USGS did not detect 1,3-DCP in two occurrence studies performed
between 1999 and 2001 using monitoring levels that were lower than the
HRL. EPA believes the 1999 pesticide application requirements, which
are intended to mitigate risks to drinking water, may be one reason for
the lack of occurrence of 1,3-DCP at health levels of concern in
subsequent monitoring surveys.
The Agency presented a complete review of our analysis of the
health effects, occurrence, and exposure for 1,3-DCP in the May 2007
notice (72 FR 24016 (USEPA, 2007a)) and in the health effects support
document (USEPA, 2008j). The Agency also plans to update the Health
Advisory document for 1,3-DCP with more recent health information. The
updated Health Advisory will provide information to any States with
public water systems that may have 1,3-DCP above the HRL. If a State
finds a highly localized occurrence of 1,3-DCP at concentrations above
the HRL, the Agency encourages States to consider whether State-level
guidance (or some other type of action) may be appropriate.
E. 2,4-Dinitrotoluene and 2,6-Dinitrotoluene
1. Description. 2,4- and 2,6-dinitrotoluene (DNT), semi-volatile
organic compounds, are two of the six isomers of dinitrotoluene.
Dinitrotoluenes are used in the production of polyurethane foams,
automobile air bags, dyes, ammunition, and explosives, including
trinitrotoluene or TNT (HSDB, 2004a and 2004b; ATSDR, 1998). Neither
2,4-DNT nor 2,6-DNT occurs naturally. They are generally produced as
individual isomers or as a mixture called technical grade DNT.
Technical grade DNT primarily contains a mixture of 2,4-DNT and 2,6-
DNT, with the remainder consisting of the other isomers and minor
contaminants such as TNT and mononitrotoluenes (HSDB, 2004c).
2. Agency Findings. The Agency is making a determination not to
regulate 2,4-or 2,6-DNT with a national primary drinking water
regulation. As noted in the May 2007 notice (72 FR 24016 (USEPA,
2007a)), 2,4- and 2,6-DNT appear to occur infrequently at health levels
of concern in PWSs, and the Agency believes that a national primary
drinking water regulation does not present a meaningful opportunity for
health risk reduction. 2,4-DNT was detected only once at a minimum
reporting level (MRL) of 2 [mu]g/L and 2,6-DNT was not detected at this
same level in any of the PWSs monitored under the UCMR 1. While the MRL
is slightly greater than the HRL of 0.05 [mu]g/L, this concentration is
within the acceptable 10-4 to the 10-6 cancer
risk range targeted by the Agency.
The Agency presented a complete review of our analysis of the
health effects, occurrence, and exposure for 2,4- and 2,6-DNT in the
May 2007 notice (72 FR 24016 (USEPA, 2007a)) and in the health effects
support document (USEPA, 2008l). The Agency's original Health
Advisories for 2,4- and 2,6-DNT were developed for military
installations. Because the Agency recognizes that 2,4 and 2,6-DNT may
still be found at some military sites, the Agency has updated the
Health Advisories to reflect recent health effects publications. EPA
published a draft of the updated Health Advisory document for both 2,4
and 2,6-DNT as part of the regulatory determinations for these two
isomers. The updated document is available on the Web at: https://
www.epa.gov/safewater/ccl/reg_determine2.html. The final Health
Advisory document will be published in 2008 and will provide
information to States with public water systems that may have either
2,4- or 2,6-DNT at concentrations above health levels of concern. If a
State finds highly localized occurrence of 2,4- and/or 2,6-DNT at
concentrations above the HRL, the Agency encourages States to consider
whether State-level guidance (or some other type of action) may be
appropriate.
F. s-Ethyl dipropylthiocarbamate
1. Description. EPTC, a synthetic organic compound, is a
thiocarbamate herbicide used to control weed growth during the pre-
emergence and early post-emergence stages of weed germination. First
registered for use in 1958, EPTC is used across the U.S. in the
agricultural production of a number of crops, most notably corn,
potatoes, dried beans, alfalfa, and snap beans. EPTC is also used
residentially on shade trees, annual and perennial ornamentals, and
evergreens (USEPA, 1999c).
2. Agency Findings. The Agency is making a determination not to
regulate EPTC with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), EPTC does
not appear to occur at health levels of concern in PWSs, and the Agency
believes that a national primary drinking water regulation does not
present a meaningful opportunity for health risk reduction. While EPTC
has been found in ambient waters at levels less than the HRL of 175
[mu]g/L (as well as \1/2\ the HRL), it was not found in the UCMR 1
survey of public water supplies. The Agency presented a complete review
of our analysis of the health effects, occurrence, and exposure for
EPTC in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), the final
regulatory support document (USEPA, 2008a), and in the health effects
support document (USEPA, 2008g).
G. Fonofos
1. Description. Fonofos, an organophosphate, is a soil insecticide
used to control pests such as corn rootworms, cutworms, symphylans
(i.e., garden centipedes), and wireworms. Primarily used on corn crops,
fonofos was also used on other crops such as asparagus, beans, beets,
onions, peppers, tomatoes, cole crops, sweet
[[Page 44259]]
potatoes, peanuts, peas, peppermint, plantains, sorghum, soybeans,
spearmint, strawberries, sugarcane, sugar beets, white (Irish)
potatoes, and tobacco (USEPA, 1999d).
Fonofos was scheduled for a reregistration decision in 1999.
However, before the review was completed, the registrant requested
voluntary cancellation. The cancellation was announced in the Federal
Register on May 6, 1998 (63 FR 25033 (USEPA, 1998d)), with an effective
date of November 2, 1998, plus a one-year grace period to permit the
exhaustion of existing stocks (USEPA, 1999d).
2. Agency Findings. The Agency is making a determination not to
regulate fonofos with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), fonofos does
not appear to occur at health levels of concern in PWSs and the Agency
believes that a national primary drinking water regulation does not
present a meaningful opportunity for health risk reduction. While
fonofos has been found in ambient waters at levels less than the HRL of
10 [mu]g/L (as well as \1/2\ the HRL), it was not found in the UCMR 1
Screening Survey of public water supplies. Fonofos was voluntarily
cancelled in 1998 and the Agency expects any remaining stocks and
releases into the environment to decline. In addition, since fonofos
tends to bind strongly to soil, any releases to the environment are not
likely to contaminate source waters. The Agency presented a complete
review of our analysis of the health effects, occurrence, and exposure
for fonofos in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), the
final regulatory support document (USEPA, 2008a), and in the health
effects support document (USEPA, 2008h).
H. Terbacil
1. Description. Terbacil, a synthetic organic compound, is a
selective herbicide used to control broadleaf weeds and grasses on
terrestrial food/feed crops (e.g., apples, mint, peppermint, spearmint,
and sugarcane), terrestrial food (e.g., asparagus, blackberry,
boysenberry, dewberry, loganberry, peach, raspberry, youngberry, and
strawberry), terrestrial feed (e.g., alfalfa, forage, and hay) and
forest trees (e.g., cottonwood) (USEPA, 1998c).
2. Agency Findings. The Agency is making a determination not to
regulate terbacil with a national primary drinking water regulation. As
noted in the May 2007 notice (72 FR 24016 (USEPA, 2007a)), terbacil
does not appear to occur at health levels of concern in PWSs.
Accordingly, the Agency believes that a national primary drinking water
regulation does not present a meaningful opportunity for health risk
reduction. While terbacil has been found in ambient waters at the
levels less than the HRL of 90 [mu]g/L (as well as \1/2\ the HRL), it
was not found in the UCMR 1 survey of public water supplies. The Agency
presented a complete review of our analysis of the health effects,
occurrence, and exposure for terbacil in the May 2007 notice (72 FR
24016 (USEPA, 2007a)), the final regulatory support document (USEPA,
2008a), and in the health effects support document (USEPA, 2008i).
I. 1,1,2,2-Tetrachloroethane
1. Description. 1,1,2,2-Tetrachloroethane, a volatile organic
compound, is not known to occur naturally in the environment (IARC,
1979). Prior to the 1980s, 1,1,2,2-tetrachloroethane was synthesized
for use in the production of other chemicals, primarily chlorinated
ethylenes. 1,1,2,2-Tetrachloroethane was also once used as a solvent to
clean and degrease metals, in paint removers, varnishes, lacquers, and
photographic films, and for oil/fat extraction (Hawley, 1981).
Commercial production of 1,1,2,2-tetrachloroethane in the U.S. ceased
in the 1980s, when other processes to generate chlorinated ethylenes
were discovered (ATSDR, 1996).
2. Agency Findings. The Agency is making a determination not to
regulate 1,1,2,2-tetrachloroethane with a national primary drinking
water regulation. As noted in the May 2007 notice (72 FR 24016 (USEPA,
2007a)), 1,1,2,2-tetrachloroethane appears to occur infrequently at
health levels of concern in PWSs. Accordingly, the Agency believes that
a national primary drinking water regulation does not present a
meaningful opportunity for health risk reduction. While 1,1,2,2-
tetrachloroethane was detected in both the UCM Round 1 and the UCM
Round 2 surveys, the percentage of detections had decreased by the time
the UCM Round 2 survey was performed in the mid-1990's.\10\ In
addition, the USGS did not detect 1,1,2,2-tetrachloroethane in two
subsequent monitoring surveys of source waters that supply community
water systems, using a reporting limit that is less than the 1,1,2,2-
tetrachloroethane HRL of 0.4 [mu]g/L. The Agency belie
