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Drinking Water: Regulatory Determinations Regarding Contaminants on the Second Drinking Water Contaminant Candidate List

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[Federal Register: July 30, 2008 (Volume 73, Number 147)]
[Notices]
[Page 44251-44261]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr30jy08-72]

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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.

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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
http://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 http://www.regulations.gov or in hard copy at
the Water Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave.,
NW., Washington, DC. The 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)
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 http://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
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                                                                       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
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1..........  Boron (7440-42-   Do not regulate   1,400 μg/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
http://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.
---------------------------------------------------------------------------

    \9\ This paper can be found in the Docket for this notice at
http://www.regulations.gov under the Docket ID No. EPA-HQ-OW-2007-
0068.
---------------------------------------------------------------------------

    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 (http://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: http://
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 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 1,1,2,2-tetrachloroethane to occur in many public water
systems today.
---------------------------------------------------------------------------

    \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.
---------------------------------------------------------------------------

    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 1,1,2,2-tetrachloroethane 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

[[Page 44260]]

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 and
       Health effects              Occurrence            occurrence
------------------------------------------------------------------------
 Acetochlor \3\.............   Diazinon \6\.......   Alachlor ESA \4\
                                                     \7\
 Aluminum \4\ \5\...........   2,4-Dichloropheno     Metolachlor \7\ \8\
                               \6\.
 Bromobenzene \3\...........   2,4-Dinitrophenol     Organotins \1\ \3\
                               \6\.                  \5\ \7\
 1,1-Dichloroethane \4\.....   1,2-                  Prometon \3\ \6\
                               Diphenylhydrazine
                               \6\.
 1,3-Dichloropropane \4\....   Disulfoton \6\.....   RDX \3\ \7\
 2,2-Dichloropropane \4\....   Diuron \6\.........
 1,1-Dichloropropene \4\....   Linuron \6\........
 p-Isopropyltoluane \4\.....   2-Methylphenol \6\.
 Methyl Bromide \4\.........   Terbufos \6\.......
 Methyl Tertiary-Butyl Ether   Triazines \2\ \5\
 (MTBE) \3\.                   \7\.
 Molinate \3\...............   2,4,6-
                               Trichlorophenol \6\.
 Nitrobenzene \3\
 1,2,4-Trimethylbenzene \4\
 Vanadium \4\
------------------------------------------------------------------------
* 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            Analytical methods
----------------------------------------------------------------------------------------------------------------
 Microsporidia.......................   Microsporidia.........   Microsporidia.........   Microsporidia
Some Cyanotoxins.....................  Some Cyanotoxins.......  Some Cyanotoxins.......  Some Cyanotoxins
                                       Aeromonas..............  Aeromonas..............  Aeromonas
                                       Helicobacter...........  Helicobacter...........  Helicobacter
                                       MAC....................  MAC....................  MAC
                                       Adenoviruses...........  Adenoviruses...........
                                       Caliciviruses..........  Caliciviruses..........
                                       Coxsackieviruses.......  Coxsackieviruses.......
                                       Echoviruses............  Echoviruses............
----------------------------------------------------------------------------------------------------------------

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: http://www.atsdr.cdc.gov/toxprofiles/tp26.html.
ATSDR. 1996. Toxicological Profile for 1,1,2,2-Tetrachloroethane.
Available on the Internet at: http://www.atsdr.cdc.gov/toxprofiles/
tp93.html.
ATSDR. 1998. Toxicological Profile for 2,4- and 2,6-Dinitrotoluene.
Available on the Internet at: http://www.atsdr.cdc.gov/toxprofiles/
tp109.html.
ATSDR. 2002. Toxicological Profile DDT, DDE, and DDD. Available on
the Internet at: http://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 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:
http://toxnet.nlm.nih.gov. [Search for 2,4-dinitrotoluene.] Accessed
November 1, 2004.
HSDB. 2004b. ``TOXNET: Toxicology Data Network--2,6-
Dinitrotoluene.'' Available on the Internet at: 
http://toxnet.nlm.nih.gov. [Search for 2,6-dinitrotoluene.] 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), 1992-2001.'' Available on
the Internet at: http://water.usgs.gov/nawqa/pnsp/. 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: http://water.usgs.gov/nawqa/pnsp/
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 6-Year 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.

[[Page 44261]]

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: http://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: http://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: http://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: http://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: 
http://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: 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.
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(p-chlorophenyl)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: http://
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

 
 


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