[Federal Register Volume 91, Number 53 (Thursday, March 19, 2026)]
[Rules and Regulations]
[Pages 13227-13236]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2026-05452]
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ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 141
[EPA-HQ-OW-2024-0456; FRL-10774-02-OW]
Announcement of Final Regulatory Determinations for Contaminants
on the Fifth Drinking Water Contaminant Candidate List
AGENCY: Environmental Protection Agency (EPA).
ACTION: Regulatory determinations.
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SUMMARY: The U.S. Environmental Protection Agency (EPA) is announcing
final regulatory determinations for nine contaminants listed on the
fifth Contaminant Candidate List. Specifically, the Agency is making
final determinations not to regulate 2-aminotoluene,
cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin,
profenofos, tebuconazole, and tribufos. The Safe Drinking Water Act
(SDWA) requires the EPA to make regulatory determinations every five
years on at least five unregulated contaminants. A regulatory
determination is a decision about whether or not to begin the process
to propose and promulgate- a national primary drinking water regulation
(NPDWR) for an unregulated contaminant.
DATES: For the purpose of judicial review, the determinations not to
regulate in this document are issued as of March 19, 2026.
FOR FURTHER INFORMATION CONTACT: George Gardenier, Standards and Risk
Management Division, Office of Ground Water and Drinking Water (Mail
Code 4607M), Environmental Protection Agency, 1200 Pennsylvania Avenue
NW, Washington, DC 20460; telephone number: (202) 564-3333; email
address: [email protected].
SUPPLEMENTARY INFORMATION:
Abbreviations Used in This Document
ATSDR Agency for Toxic Substances and Disease Registry
CCL Contaminant Candidate List
CCL 5 Fifth Contaminant Candidate List
CRL Cancer Risk Level
CSF Cancer Slope Factor
DWI-BW Drinking Water Intake Adjusted for Body Weight
FIFRA Federal Insecticide, Fungicide and Rodenticide Act
HABs Harmful Algal Blooms
HESD Health Effects Support Document
HHRA Human Health Risk Assessment
HRL Health Reference Level
HRRCA Health Risk Reduction Cost Analysis
MRL Minimum Reporting Level
NPDWR National Primary Drinking Water Regulation
NRDC Natural Resources Defense Council
OW Office of Water
PPRTV Provisional Peer-Reviewed Toxicity Value
PWS Public Water System
RD 5 Regulatory Determination 5
RSC Relative Source Contribution
SDWA Safe Drinking Water Act
UCMR Unregulated Contaminant Monitoring Rule
UCMR 3 Third Unregulated Contaminant Monitoring Rule
UCMR 4 Fourth Unregulated Contaminant Monitoring Rule
USEPA United States Environmental Protection Agency
USGS United States Geological Survey
Table of Contents
I. General Information
A. Does this action apply to me?
B. How can I get copies of this document and other related
information?
II. Purpose and Background
A. What is the purpose of this action?
B. What are the statutory requirements for the SDWA Contaminant
Candidate List (CCL) and regulatory determinations?
C. Which contaminants did the EPA consider for regulation?
III. Approach to Identifying and Evaluating Contaminants for
Regulatory Determinations
[[Page 13228]]
A. How the EPA Identified and Evaluated Contaminants for the
Fifth Regulatory Determination
B. Consideration of Public Comments
IV. The EPA's Findings on Specific Contaminants
A. 2-Aminotoluene
B. Cylindrospermopsin
C. Ethoprop
D. Microcystins
E. Molybdenum
F. Permethrin
G. Profenofos
H. Tebuconazole
I. Tribufos
V. The EPA's Considerations for Future Regulatory Determinations
VI. Next Steps
VII. References
I. General Information
A. Does this action apply to me?
These final regulatory determinations will not impose any
requirements on anyone. Instead, this action notifies interested
parties of the EPA's final determinations not to regulate nine
contaminants under the SDWA.
B. How can I get copies of this document and other related information?
1. Docket. The EPA has established a docket for this action under
Docket ID No. EPA-HQ-OW-2024-0456. Publicly available docket materials
are available either electronically through https://www.regulations.gov
or in hard copy at the EPA Docket Center, WJC West Building, Room 3334,
1301 Constitution Ave. NW, Washington, DC. The Docket Center's hours of
operations are 8:30 a.m.-4:30 p.m., Monday through Friday (except
Federal Holidays). For further information on the EPA Docket Center
services and the current status, see: https://www.epa.gov/dockets.
2. Electronic Access. You may access this Federal Register document
electronically from https://www.federalregister.gov/documents/current.
II. Purpose and Background
A. What is the purpose of this action?
The purpose of this action is to present a summary of the EPA's
final SDWA regulatory determinations for nine contaminants on the fifth
Contaminant Candidate List (CCL 5) (87 FR 68060; USEPA, 2022). The
Agency is making determinations not to regulate 2-aminotoluene,
cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin,
profenofos, tebuconazole, and tribufos. This action summarizes the SDWA
statutory requirements for selecting new contaminants in drinking water
to regulate, provides an overview of the contaminants that the Agency
considered for regulation, and describes the approach used to make the
final regulatory determinations. In addition, this action summarizes
the public comments received on the Agency's preliminary determinations
announcement and the Agency's responses to those comments.
B. What are the statutory requirements for the SDWA Contaminant
Candidate List (CCL) and regulatory determinations?
The SDWA provides a stepwise process for establishing drinking
water standards for unregulated contaminants. First, the SDWA section
1412(b)(1)(B)(i) requires the EPA to publish a list of unregulated
contaminants that are candidates for drinking water regulations,
referred to as the Contaminant Candidate List (CCL). The statute
requires the EPA to publish this CCL every five years after public
notice and an opportunity to comment. The SDWA defines the CCL as a
list of contaminants which are not subject to any proposed or
promulgated National Primary Drinking Water Regulations (NPDWRs) but
are known or anticipated to occur in public water systems (PWSs) and
may require regulation under the SDWA.
Second, the SDWA section 1412(b)(1)(B)(ii) directs the EPA to
determine, after public notice and an opportunity to comment, whether
to regulate at least five contaminants from the CCL every five years.
Under SDWA section 1412(b)(1)(A), the EPA makes a determination to
regulate a contaminant in drinking water if the Administrator
determines that:
(i) The contaminant may have an adverse effect on the health of
persons;
(ii) 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
(iii) 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, after considering public comment on a preliminary
determination, the Agency makes a final determination to regulate a
contaminant, section 1412(b)(1)(E) requires the EPA to propose and
promulgate an NPDWR and publish a Maximum Contaminant Level Goal for
that contaminant. In that case, the statutory time frame provides for
the Agency's proposal of a regulation within 24 months and action on a
final regulation within 18 months of proposal (which may be extended by
9 months).
C. Which contaminants did the EPA consider for regulation?
The EPA has published five CCLs since 1996. On January 15, 2025,
the EPA published preliminary regulatory determinations not to regulate
nine contaminants on the fifth Contaminant Candidate List (CCL 5) (90
FR 3830; USEPA, 2025a). The Agency is finalizing the determinations not
to regulate 2-aminotoluene, cylindrospermopsin, ethoprop, microcystins,
molybdenum, permethrin, profenofos, tebuconazole, and tribufos.
Information further describing the Agency's analyses informing the
regulatory determinations for these nine contaminants can be found in
the Final Regulatory Determination 5 Support Document (USEPA, 2026a).
More information is available in the Public Docket at https://www.regulations.gov (Docket ID No. EPA-HQ-OW-2024-0456) and also on the
EPA's Regulatory Determination 5 website at https://www.epa.gov/ccl/regulatory-determination-5.
III. Approach to Identifying and Evaluating Contaminants for Regulatory
Determinations
A. How the EPA Identified and Evaluated Contaminants for the Fifth
Regulatory Determination
This section summarizes the Agency's approach to identifying and
evaluating contaminants for the Fifth Regulatory Determination (RD 5).
As explained in the Federal Register document for the preliminary
determinations for this fifth cycle of regulatory determinations, the
approach taken under RD 5 is similar to that used in previous rounds of
regulatory determination and formalized in a written protocol under
Regulatory Determination 3 (USEPA 2014; 81 FR 13; USEPA, 2016). For
more detailed information on the approach and the analyses performed,
please refer to the ``Protocol for the Regulatory Determination 5''
found in appendix B of the Final Regulatory Determination 5 Support
Document (USEPA, 2026a) and the Federal Register publication for the
preliminary regulatory determinations (90 FR 3830; USEPA, 2025a).
The CCL 5 identified 81 contaminants or groups of contaminants that
are not currently subject to any proposed or promulgated NPDWR, are
known or anticipated to occur in public water systems, and may require
regulation under the SDWA (87 FR 68060; USEPA, 2022). The Agency used a
three-phase process to identify which of the contaminants are
candidates for regulatory determinations and found that many of the CCL
5 contaminants do
[[Page 13229]]
not have adequate health and/or finished drinking water occurrence data
to evaluate against the three statutory criteria necessary to make a
regulatory determination (see section II.B. of this document). Priority
was given to identifying contaminants known or substantially likely to
occur at frequencies and levels of public health concern.
In accordance with the Agency's Policy on Evaluating Health Risks
to Children (USEPA, 1995), the EPA has explicitly considered children's
health and potential unique vulnerabilities in the RD 5 process by
reviewing all available scientific information on children's exposure
and health effects from the contaminants the Agency considered.
The three phases of the Fifth Regulatory Determination protocol,
like the protocol the Agency used for the Third and Fourth Regulatory
Determinations, are (1) the Data Availability Phase, (2) the Data
Evaluation Phase and (3) the Regulatory Determination Assessment Phase.
Throughout the RD 5 Evaluation process, the EPA conducted its
evaluations in a manner consistent with the U.S. Environmental
Protection Agency Implementation of Gold Standard Science (USEPA,
2025b), including through developing a standardized process for
conducting the evaluations of contaminants from RD 5, which can be
found in appendix B of the Regulatory Determination 5 Support Document
(USEPA, 2026a). The overall process is displayed in Exhibit 1.
[GRAPHIC] [TIFF OMITTED] TR19MR26.001
The purpose of the first phase, the Data Availability Phase, is to
screen out contaminants that clearly do not have sufficient data to
support a regulatory determination. The Agency applies criteria to
ensure that any contaminant that potentially has sufficient data to
characterize the health effects and known or likely occurrence in
drinking water will proceed to the Data Evaluation Phase, the second
phase of the regulatory determination process. From the 81 CCL 5
contaminants and contaminant groups, the Agency identified 35 CCL 5
contaminants to further evaluate in the second phase of the regulatory
determination process. See the Final Regulatory Determination 5 Support
Document for more details of the Data Evaluation Phase (USEPA, 2026a).
During the second phase, the Agency evaluated these 35 contaminants
in greater detail to identify those that have sufficient data (or are
expected to have sufficient data within the timeframe allotted for the
second phase) for the EPA to assess the three statutory criteria. As
part of the second phase, the Agency specifically focused its efforts
on identifying those contaminants or contaminant groups that are
occurring (or have substantial likelihood to occur) at levels and
frequencies of public health concern based on the best available peer-
reviewed data.
The EPA conducted a systematic search for human health effects
assessments from EPA and other authoritative sources for each drinking
water chemical contaminant on CCL 5 in a manner consistent with the
EPA's Scientific Integrity Policy and with the Agency's Implementation
of Gold Standard Science (USEPA, 2025b). When conducting the literature
searches for health effects assessments, the EPA prioritized
assessments that are
[[Page 13230]]
reproducible, transparent, communicative of error and uncertainty,
subject to unbiased peer review, and without conflicts of interest. The
EPA selected a health effects assessment for each contaminant and
derived a Health Reference Level (HRL). The EPA followed a structured
and transparent process to select the assessment(s) for both cancer and
noncancer HRL derivation. The process included expert evaluations
applying specific criteria. These criteria are designed to identify the
assessment relevant to drinking water that was developed using
comparable approaches to the EPA human health risk assessment methods
and based on the best available science. HRLs are health-based drinking
water concentrations, derived from qualifying health effects
assessments based on the best available science, and are not final
drinking water values. HRLs are derived using a procedure that is
inclusive of sensitive subpopulations. The EPA evaluates the HRLs
against the occurrence data to determine if contaminants occur at
levels of potential public health concern in drinking water, to inform
regulatory determinations. As with the first phase, if the Agency finds
in Phase 2 that sufficient data are not available to evaluate the three
statutory criteria, then the contaminant is not considered a candidate
for regulatory determination.
Often the primary source of nationally representative occurrence
data is from the EPA's Unregulated Contaminant Monitoring Rule (UCMR)
program. SDWA section 1412 (b)(1)(B)(ii)(II) requires that the EPA
include consideration of the data collected by the UCMR program in
making regulatory determinations. The UCMR program collects nationally
representative occurrence data that is considered by the EPA in the CCL
and regulatory determination processes. The UCMR sampling is limited by
statute to no more than 30 contaminants every five years (SDWA section
1445(a)(2)) and provides information on unregulated contaminants in
finished drinking water that is considered in this process. Under UCMR
3 and UCMR 4, the UCMRs relevant to this document, data were collected
from all PWSs serving a population of more than 10,000, and from a
nationally representative sample of 800 small PWSs serving 10,000
people or fewer.
If sufficient data are available for a contaminant to characterize
the potential health effects and known or likely occurrence in drinking
water, the contaminant is evaluated against the three SDWA statutory
criteria laid out in section 1412(b)(1)(A) in the Regulatory
Determination Assessment Phase, which is the third phase of the
process. Of the 35 contaminants that were evaluated under Phase 2, 14
were designated for evaluation against the three statutory criteria in
Phase 3.
Of the 14 CCL 5 contaminants that were evaluated in Phase 3 against
the three statutory criteria, the Agency made preliminary regulatory
determinations not to regulate nine contaminants (2-aminotoluene,
cylindrospermopsin, ethoprop, microcystins, molybdenum, permethrin,
profenofos, tebuconazole, and tribufos). These preliminary
determinations were published in the Federal Register on January 15,
2025, for public comment (90 FR 3830; USEPA, 2025a).
B. Consideration of Public Comments
The EPA received comments from eight organizations and individuals
on the preliminary regulatory determinations for CCL 5 (90 FR 3830;
USEPA, 2025a). Most of these comments were supportive of the Agency's
determinations not to regulate the nine contaminants. There were two
commenters who urged the EPA to regulate all nine contaminants because
each has the potential to cause adverse health effects. While these
contaminants may have potential adverse health effects, SDWA section
1412(b)(1)(A) requires the Agency to consider all three statutory
criteria, described in section II.B. of this document, of which the
potential to have adverse health effects is only one. In order to make
a determination to regulate a contaminant under the SDWA, all three
criteria must be met: exposure to the contaminant may result in an
adverse health effect, the contaminant is known or substantially likely
to occur in public water systems with a frequency and at levels of
public health concern, and that regulation in public water systems
would provide a meaningful opportunity to reduce the public health
risks associated with exposure to the contaminant. The potential for
adverse health effects alone, therefore, is not a sufficient basis to
determine to regulate a contaminant in drinking water under the SDWA.
See the Responses to Public Comments on Preliminary Regulatory
Determinations for Contaminants on the Fifth Drinking Water Contaminant
Candidate List for additional details about the public comments
received and the EPA's responses (USEPA, 2026b).
IV. The EPA's Findings on Specific Contaminants
After considering the public comments, the EPA is making final
determinations not to regulate the nine contaminants listed in table 1.
The next sections of this document provide a brief description of the
Agency's findings on these contaminants. Details on the background,
health and occurrence information, and analyses used to evaluate and
make final determinations for these contaminants can be found in the
Final Regulatory Determination 5 Support Document (USEPA, 2026a), the
Occurrence Data from the Fourth Unregulated Contaminant Monitoring Rule
(UCMR 4) (USEPA, 2024), and the Federal Register publication for the
preliminary regulatory determination (90 FR 3830; USEPA, 2025a).
Table 1--Summary of Health and Occurrence Information for the Nine Contaminants Receiving a Final Determination
Under RD 5
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Population
Minimum Health PWSs \2\ \2\ served
reporting reference with at by PWSs with
RD 5 contaminant level level Critical effect least 1 at least 1
(MRL), (HRL),\1\ measurement measurement
([micro]g/ ([micro]g/L) > HRL > HRL
L) (percent) (percent)
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2-Aminotoluene.................... 0.007 2 Subcutaneous fibromas 0.0 0.0
and fibrosarcomas.
Cylindrospermopsin................ 0.09 0.6 Increased relative 0.03 0.01
kidney weight.
Ethoprop.......................... 0.03 0.09 Inhibition of red 0.02 0.01
blood cell
cholinesterase.
Microcystins...................... 0.3 0.3 Liver effects........ 0.2 0.06
Molybdenum........................ 1 100 Kidney effects....... 0.1 0.06
Permethrin........................ 0.04 3,000 Decreased motor 0.0 0.0
activity.
[[Page 13231]]
Profenofos........................ 0.3 0.7 Inhibition of red 0.02 0.01
blood cell
acetylcholinesterase.
Tebuconazole...................... 0.2 200 Increased incidence 0.0 0.0
of skull/neural tube
defects.
Tribufos.......................... 0.07 1 Inhibition of red 0.0 0.0
blood cell
cholinesterase.
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\1\ An HRL is a health-based concentration against which the Agency evaluates occurrence data when making
regulatory determinations. See the Final Regulatory Determination 5 Support Document for information about how
HRLs are derived (USEPA, 2026a).
\2\ Assessment monitoring under UCMR 3 and UCMR 4 (the cycles relevant to this document) included all PWSs
servicing a population greater than 10,000. It also included a nationally representative sample of 800 small
systems, defined as those serving a population of 10,000 or fewer.
A. 2-Aminotoluene
2-Aminotoluene (also referred to as o-toluidine or 2-methylaniline)
is a synthetic aromatic amine and occurs as a colorless or light-yellow
liquid. 2-Aminotoluene is used in the manufacture of dyes, rubber
vulcanization accelerators, pharmaceuticals and pesticides (NCBI,
2024).
The EPA has found that 2-aminotoluene may have an adverse effect on
the health of persons and therefore meets SDWA's Statutory Criterion 1
for regulatory determinations. The health assessment selected to derive
an HRL for 2-aminotoluene is the 2012 EPA Provisional Peer-Reviewed
Toxicity Value (PPRTV) (USEPA, 2012), because it is a qualifying peer-
reviewed health assessment that derives an oral cancer slope factor
(CSF) based on the best available science. The 2012 EPA PPRTV health
assessment for 2-aminotoluene describes multiple adverse health
effects. The EPA selected subcutaneous fibromas and fibrosarcomas
(i.e., cancer) in male rats as the critical effect to derive the oral
toxicity value (USEPA, 2012). In this health assessment, the EPA
determined that 2-aminotoluene is ``likely to be carcinogenic to
humans'' by following the process described in the EPA's 2005
Guidelines for Carcinogen Risk Assessment (USEPA, 2005; USEPA, 2012).
The EPA derived an HRL for 2-aminotoluene of 2 [micro]g/L based on a
one-in-a-million (10-6) cancer risk level (CRL), oral CSF of
0.016 (mg/kg/day)-1 (USEPA, 2012), and a drinking water
intake adjusted for body weight (DWI-BW) for children (birth to <21
years) of 0.0343 L/kg/day (USEPA, 2019a).
The EPA has determined that 2-aminotoluene does not occur with a
frequency and at levels of public health concern in PWSs based on
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for 2-aminotoluene are nationally representative
drinking water monitoring data from the UCMR 4 program (2018-2020)
(USEPA, 2024). Under UCMR 4 assessment monitoring, there were no
measurements of 2-aminotoluene greater than the HRL (USEPA, 2026a).
The UCMR 4 data do not indicate that persons served by public water
systems are exposed to 2-aminotoluene at levels of public health
concern (USEPA, 2026a). The Agency, therefore, has determined that
regulating 2-aminotoluene under the SDWA does not present a meaningful
opportunity for health risk reduction for persons served by PWSs, as
required by SDWA's Statutory Criterion 3 for regulatory determinations.
The Agency has evaluated the best available information on 2-
aminotoluene against the three SDWA section 1412(b)(1)(A) statutory
criteria and found that this contaminant does not satisfy the second
and third criteria. The EPA is therefore making a final determination
not to regulate 2-aminotoluene with an NPDWR.
B. Cylindrospermopsin
Cylindrospermopsin is a toxin naturally produced and released by
cyanobacteria. Cyanobacteria, sometimes referred to as blue-green
algae, are photosynthetic bacteria that are nearly ubiquitous in
freshwater and marine environments. Harmful algal blooms (HABs) of
cyanobacteria in freshwater environments can release cyanotoxins,
including cylindrospermopsin.
The EPA has found that cylindrospermopsin may have an adverse
effect on the health of persons and therefore meets SDWA's Statutory
Criterion 1 for regulatory determinations. The health assessment
selected to derive an HRL for cylindrospermopsin is the EPA's 2015
Health Effects Support Document for the Cyanobacterial Toxin
Cylindrospermopsin (USEPA, 2015a) because it is a peer-reviewed health
assessment that derives an oral toxicity value, and it uses the best
available science in its evaluation of noncancer risk for
cylindrospermopsin. The 2015 EPA Health Effects Support Document (HESD)
health assessment describes multiple adverse health effects for
cylindrospermopsin. The EPA selected increased relative kidney weight
in mice as the critical effect to derive the oral toxicity value
(USEPA, 2015a). The EPA derived an HRL for cylindrospermopsin of 0.6
[micro]g/L based on an oral reference value of 0.0001 mg/kg/day (USEPA,
2015a), a DWI-BW for children (birth to <21 years) of 0.0343 L/kg/day
(USEPA, 2019a) and a 20% relative source contribution (RSC) (USEPA,
2000).
The EPA has determined that cylindrospermopsin does not occur with
a frequency and at levels of public health concern in PWSs based on the
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for cylindrospermopsin are nationally representative
drinking water monitoring data from the UCMR 4 program (USEPA, 2024).
Under UCMR 4 assessment monitoring, 0.03% of PWSs reported at least one
measurement of cylindrospermopsin greater than the HRL (USEPA, 2026a).
The EPA has determined that regulating cylindrospermopsin under the
SDWA does not present a meaningful opportunity for health risk
reduction for persons served by PWSs based on the exposed population
and therefore does not meet SDWA's Statutory Criterion 3 for regulatory
determinations. The PWS-served population exposed to
[[Page 13232]]
cylindrospermopsin at levels of public health concern is only 0.01%,
based on UCMR 4 finished water data (USEPA, 2026a).
Conventional water treatment (consisting of coagulation,
sedimentation, filtration and chlorination) can generally remove intact
cyanobacterial cells and low levels of cyanotoxins from source waters.
However, water systems may face challenges in providing drinking water
during a severe bloom event when there are high levels of cyanobacteria
and cyanotoxins in source waters. With proactive planning, diligent
operations and maintenance and active management, PWSs can reduce the
risks of cyanotoxins breaking through the treatment process and
occurring in finished drinking water. Because these non-regulatory
efforts to manage cyanotoxins are effective, the Agency finds that an
NPDWR for cylindrospermopsin does not present a meaningful opportunity
for health risk reduction for this reason as well.
The Agency has evaluated the best available information on
cylindrospermopsin against the three SDWA section 1412(b)(1)(A)
statutory criteria and found that this contaminant does not satisfy the
second and third criteria. The EPA is therefore making a final
determination not to regulate cylindrospermopsin with an NPDWR.
C. Ethoprop
Ethoprop is an organophosphate pesticide and is used as an
insecticide and nematicide on mostly vegetables and fruit crops. Over
the past few decades, estimated usage of ethoprop has declined, and in
2019 showed limited geographic usage to the Pacific Northwest and
California (USGS, 2023).
The EPA has found that ethoprop may have an adverse effect on the
health of persons and therefore meets SDWA's Statutory Criterion 1 for
regulatory determinations. The EPA used toxicity information from the
EPA's Office of Pesticide Programs for ethoprop as the basis for HRL
derivation (USEPA, 2015b). The health assessment selected to derive an
HRL for ethoprop is the EPA's Office of Pesticide Programs 2015 Human
Health Risk Assessment (HHRA) for ethoprop (USEPA, 2015b; USEPA,
2015c). The 2015 EPA HHRA describes multiple adverse health effects for
ethoprop. The EPA selected inhibition of red blood cell cholinesterase
in male rats as the critical effect to derive the oral toxicity value
(USEPA, 2015b). The EPA derived an HRL for ethoprop of 0.09 [micro]g/L
based on an oral reference value of 0.000065 mg/kg/day (USEPA, 2015b),
a DWI-BW for infants (birth to <1 year) of 0.143 L/kg/day (USEPA,
2019a) and a 20% RSC (USEPA, 2000).
The EPA has determined that ethoprop does not occur with a
frequency and at levels of public health concern in PWSs based on
nationally representative drinking water monitoring data from UCMR 4
(USEPA, 2024). The Agency therefore finds that ethoprop does not meet
Statutory Criterion 2 for regulatory determinations. Of the UCMR 4
systems that reported results for ethoprop, only 0.02% reported a
result above the HRL (USEPA, 2026a).
The EPA has determined that there is no meaningful opportunity for
health risk reduction through regulation of ethoprop with an NPDWR. The
PWS-served population exposed to ethoprop at levels of public health
concern is only 0.01%, based on UCMR 4 finished water data (USEPA,
2026a). Therefore, Statutory Criterion 3 for regulatory determinations
is also not met.
The Agency has evaluated the best available information on ethoprop
against the three SDWA section 1412(b)(1)(A) statutory criteria and
found that this contaminant does not satisfy the second and third
criteria. The EPA is therefore making a final determination not to
regulate ethoprop with an NPDWR.
D. Microcystins
Microcystins are toxins that are naturally produced and released by
cyanobacteria. Microcystins exist in multiple forms (congeners), based
on variations in amino acid composition; there are approximately 100
known microcystin congeners (USEPA, 2015d). Microcystins are the most
common cyanotoxins found worldwide and they have been reported in
surface waters in most of the U.S. (Funari and Testai, 2008 as cited in
USEPA, 2015d).
The EPA has found that microcystins may have an adverse effect on
the health of persons and therefore meet SDWA's Statutory Criterion 1
for regulatory determinations. The health assessment selected for RD 5
is the EPA's 2015 Health Effects Support Document for the
Cyanobacterial Toxin Microcystins (USEPA, 2015d) because it is a peer-
reviewed health assessment that derives an oral toxicity value and uses
the best available science in its evaluation of noncancer risk. The
2015 EPA HESD describes multiple adverse health effects for
microcystins. The EPA selected liver effects in rats as the critical
effect to derive the oral toxicity value (USEPA, 2015d). The EPA
derived an HRL for microcystins of 0.3 [micro]g/L based on an oral
reference value of 0.00005 mg/kg/day (USEPA, 2015d), a DWI-BW for
adults (21 years and older) of 0.0336 L/kg/day (USEPA, 2019a) and a 20%
RSC (USEPA, 2000).
The EPA has determined that microcystins do not occur in PWSs with
a frequency and at levels of public health concern based upon
nationally representative drinking water monitoring data from the UCMR
4 program (USEPA, 2024). Only 0.2% of systems reported at least one
result above the HRL for total microcystins (USEPA, 2026a). As a
result, the EPA finds that SDWA's Statutory Criterion 2 for regulatory
determinations is not met.
Regulating microcystins under the SDWA does not present a
meaningful opportunity for health risk reduction for persons served by
PWSs based on the exposed population, including sensitive populations.
The population exposed to microcystins at levels of public health
concern is only 0.06% based on UCMR 4 finished drinking water data
(USEPA, 2026a). Therefore, the EPA finds that SDWA's Statutory
Criterion 3 for regulatory determinations is not met.
Conventional water treatment (consisting of coagulation,
sedimentation, filtration and chlorination) can generally remove intact
cyanobacterial cells and low levels of cyanotoxins from source waters.
However, water systems may face challenges in providing drinking water
during a severe bloom event when there are high levels of cyanobacteria
and cyanotoxins in source waters. With proactive planning, diligent
operations and maintenance and active management, PWSs can reduce the
risks of cyanotoxins breaking through the treatment process and
occurring in finished drinking water. Because these non-regulatory
efforts are effective, the Agency finds that an NPDWR for microcystins
does not present a meaningful opportunity for health risk reduction for
this reason as well.
The Agency has evaluated the best available information on
microcystins against the three SDWA section 1412(b)(1)(A) statutory
criteria and found that this contaminant does not satisfy the second
and third criteria. The Agency is therefore making a final
determination not to regulate microcystins with an NPDWR.
E. Molybdenum
Molybdenum is a naturally occurring element present in soils.
Anthropogenic sources of molybdenum in water include effluents from
molybdenum, uranium and copper mining and milling operations, oil
production and oil refining operations, and coal-fired power plants.
Molybdenum is commonly used in metallurgy,
[[Page 13233]]
including in alloys with cast iron, steel and superalloys. Molybdenum
compounds are also used in catalysts, lubricants and pigments (ATSDR,
2020).
The EPA has found that exposure to molybdenum may have an adverse
effect on the health of persons and therefore meets SDWA's Statutory
Criterion 1 for regulatory determinations. The health assessment
selected for RD 5 is the 2020 Agency for Toxic Substances and Disease
Registry's (ATSDR) 2020 Toxicological Profile for Molybdenum (ATSDR,
2020) because it is the most recent peer-reviewed health assessment
identified for molybdenum that derives an oral toxicity value, it uses
the best available science in its evaluation of noncancer risk, and its
toxicity value is based on a more recent critical study (Murray et al.,
2014) than those of previous health assessments (USEPA, 1992; WHO,
2011). The 2020 ATSDR health assessment describes multiple adverse
health effects for molybdenum, and ATSDR selected kidney effects in
female rats as the critical effect to derive the oral toxicity value
(ATSDR, 2020). The EPA derived an HRL for molybdenum of 100 [micro]g/L
based on an oral reference value of 0.06 mg/kg/day (ATSDR, 2020), with
an additional uncertainty factor of 3, a DWI-BW for children of 0.0343
L/kg/day (USEPA, 2019a) and a 20% RSC (USEPA, 2000).
Based on the Agency's evaluation of the available occurrence
information, the EPA has determined that molybdenum does not occur with
a frequency and at levels of public health concern in PWSs and
therefore does not meet Statutory Criterion 2 for regulatory
determinations. The primary occurrence data for molybdenum are
nationally representative drinking water monitoring data from the UCMR
3 program (2013-2015) (USEPA, 2019b). Under UCMR 3 assessment
monitoring, 0.1% of systems reported results above the HRL (USEPA,
2026a).
The UCMR 3 data indicate that the population exposed to molybdenum
above the HRL is only 0.06% (USEPA, 2026a). The Agency, therefore, has
determined that regulating molybdenum under the SDWA does not present a
meaningful opportunity for health risk reduction for persons served by
PWSs, and as required by SDWA's Statutory Criterion 3 for regulatory
determinations.
The Agency has evaluated the best available information on
molybdenum against the three SDWA section 1412(b)(1)(A) statutory
criteria and found that this contaminant does not satisfy the second
and third criteria. The EPA is therefore making a final determination
not to regulate molybdenum with an NPDWR.
F. Permethrin
Permethrin is a pyrethroid pesticide primarily used as an
insecticide. Sources of permethrin include agricultural usage and
industrial activities. Permethrin usage in agriculture has been
estimated by USGS to have peaked in 1995 with 1.4 million pounds, with
a gradual decrease to steady usage between around 600,000 and 800,000
pounds annually throughout 2001-2019 (USGS, 2023).
The EPA has found that exposure to permethrin may have an adverse
effect on the health of persons and therefore meets SDWA's Statutory
Criterion 1 for regulatory determinations. The health assessment
selected to derive an HRL for permethrin is the EPA's Office of
Pesticide Programs 2020 HHRA for permethrin (USEPA, 2020a; USEPA,
2020b). The EPA's 2020 HHRA describes multiple adverse health effects
for permethrin. The EPA selected decreased motor activity in male rats
as the critical effect to derive the oral toxicity value (USEPA, 2020a;
USEPA 2020b). The EPA derived an HRL for permethrin of 3,000 [micro]g/L
based on an oral reference value of 0.44 mg/kg/day (USEPA, 2020a;
USEPA, 2020b), a DWI-BW for children of 0.0343 L/kg/day (USEPA, 2019a)
and a 20% RSC (USEPA, 2000).
The EPA has determined that permethrin does not occur with a
frequency and at levels of public health concern in PWSs based on
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for permethrin are nationally representative drinking
water monitoring data from the UCMR 4 program (2018-2020) (USEPA,
2024). Under UCMR 4 assessment monitoring, there were no measurements
of permethrin greater than the HRL (USEPA, 2026a).
The UCMR 4 data indicate persons served by the public water systems
are not exposed to permethrin at levels of public health concern
(USEPA, 2026a). The Agency has thus determined that regulating
permethrin under the SDWA does not present a meaningful opportunity for
health risk reduction for persons served by PWSs, as required by SDWA's
Statutory Criterion 3 for regulatory determinations.
The Agency has evaluated the best available information on
permethrin against the three SDWA section 1412(b)(1)(A) statutory
criteria and found that this contaminant does not satisfy the second
and third criteria. The EPA is therefore making a final determination
not to regulate permethrin with an NPDWR.
G. Profenofos
Profenofos is an organophosphate pesticide that is applied as an
insecticide. Profenofos registration was canceled in 2018, and it
currently has no active labels in the EPA's Pesticide Product and Label
System database (USEPA, 2023). USGS Pesticide Use Maps show cotton is
the sole crop to which profenofos was applied in the years before
cancellation; usage diminished since the mid-1990s and ceased around
2011 according to these records (USGS, 2023).
The EPA has found exposure to profenofos may have an adverse effect
on the health of persons, meeting SDWA's Statutory Criterion 1 for
regulatory determinations. The health assessment selected to derive an
HRL for profenofos is the EPA's Office of Pesticide Programs 2015 HHRA
for profenofos (USEPA, 2015c; USEPA, 2015e). The EPA's 2015 HHRA
describes multiple adverse health effects for profenofos, and the EPA
selected inhibition of red blood cell acetylcholinesterase in rats as
the critical effect to derive the oral toxicity value (USEPA, 2015c;
USEPA, 2015e). The EPA derived an HRL for profenofos of 0.7 [micro]g/L
based on an oral reference value of 0.00012 mg/kg/day (USEPA, 2015c;
USEPA, 2015e), a DWI-BW for children of 0.0343 L/kg/day (USEPA, 2019a)
and a 20% RSC (USEPA, 2000).
The EPA has determined that profenofos does not occur with a
frequency and at levels of public health concern in PWSs based on
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for profenofos are nationally representative drinking
water monitoring data from the UCMR 4 program (USEPA, 2024), during
which 0.02% of systems reported a result above the HRL (USEPA, 2026a).
The population exposed to profenofos at levels of public health
concern in drinking water is less than 0.01%, based on UCMR 4 finished
water data (USEPA, 2026a). Therefore, the EPA has determined that
regulating profenofos under the SDWA does not present a meaningful
opportunity for health risk reduction for persons served by PWSs, as
required by SDWA's Statutory Criterion 3 for regulatory determinations.
The Agency has evaluated the best available information on
profenofos
[[Page 13234]]
against the three SDWA section 1412(b)(1)(A) statutory criteria and
found that this contaminant does not satisfy the second and third
criteria. The EPA is therefore making a final determination not to
regulate profenofos with an NPDWR.
H. Tebuconazole
Tebuconazole is a triazole that is used as a fungicide. The USGS
estimated pesticide use data show that there has been an increase in
tebuconazole use over the past few decades, peaking in 2015 at over 2.5
million pounds and then remaining steady at around 2.0 million pounds
per year from 2016 to 2019 (USGS, 2023).
The EPA has found that exposure to tebuconazole may have an adverse
effect on the health of persons and therefore meets SDWA's Statutory
Criterion 1 for regulatory determinations. The health assessment
selected to derive an HRL for tebuconazole is the EPA's Office of
Pesticide Programs 2021 HHRA for tebuconazole (USEPA, 2021a; USEPA,
2021b). The EPA's 2021 HHRA describes multiple adverse health effects
for tebuconazole. The EPA selected increased incidence of skull/neural
tube defects in mice as the critical effect to derive the oral toxicity
value (USEPA, 2021a; USEPA, 2021b). The EPA derived an HRL for
tebuconazole of 200 [micro]g/L based on an oral reference value of 0.03
mg/kg/day (USEPA, 2021a; USEPA, 2021b), a DWI-BW for females of
reproductive age (13 to < 50 years) of 0.0354 L/kg/day (USEPA, 2019a)
and a 20% RSC (USEPA, 2000).
The EPA has determined that tebuconazole does not occur with a
frequency and at levels of public health concern in PWSs based on
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for tebuconazole are nationally representative drinking
water monitoring data from the UCMR 4 program (USEPA, 2024). Under UCMR
4 assessment monitoring there were no measurements of tebuconazole
greater than the HRL (USEPA, 2026a).
The UCMR 4 finished water data indicate that there are no persons
served by public water systems exposed to tebuconazole at levels of
public health concern in drinking water (USEPA, 2026a). Therefore, the
EPA has determined that regulating tebuconazole under the SDWA does not
present a meaningful opportunity for health risk reduction for persons
served by PWSs, as required by SDWA's Statutory Criterion 3 for
regulatory determinations.
The Agency has evaluated the best available information on
tebuconazole against the three SDWA section 1412(b)(1)(A) statutory
criteria and found that this contaminant does not satisfy the second
and third criteria. The EPA is therefore making a final determination
not to regulate tebuconazole with an NPDWR.
I. Tribufos
Tribufos is a thiophosphate pesticide that is used as an
insecticide and cotton defoliant (NCBI, 2023). From 1992 to 2018,
tribufos usage has fluctuated between about 1.5 million pounds and 4.5
million pounds. Tribufos has been used almost exclusively on cotton.
The maps indicate that tribufos is most intensively used in the South,
in particular in the Atlantic coastal states, along the lower
Mississippi River, and in Texas (USGS, 2023).
The EPA has found that exposure to tribufos may have an adverse
effect on the health of persons and therefore meets SDWA's Statutory
Criterion 1 for regulatory determinations. The health assessment
selected to derive an HRL for tribufos is the EPA's 2015 HHRA for
tribufos (USEPA, 2015f; USEPA, 2015g). The EPA's 2015 HHRA describes
multiple adverse health effects for tribufos, and the EPA selected red
blood cell cholinesterase inhibition in rats as the critical effect to
derive the oral toxicity value (USEPA, 2015h; USEPA, 2015i). The EPA
derived an HRL for tribufos of 1 [micro]g/L based on an oral reference
value of 0.0002 mg/kg/day (USEPA, 2015f; USEPA, 2015g), a DWI-BW for
children of 0.0343 L/kg/day (USEPA, 2019a) and a 20% RSC (USEPA, 2000).
The EPA has determined that tribufos does not occur with a
frequency and at levels of public health concern in PWSs based on
available occurrence information and therefore does not meet SDWA's
Statutory Criterion 2 for regulatory determinations. The primary
occurrence data for tribufos are nationally representative drinking
water monitoring data from the UCMR 4 program (USEPA, 2024). Under UCMR
4 assessment monitoring there were no measurements of tribufos greater
than the HRL (USEPA, 2026a).
The UCMR 4 finished water data indicate that there are no persons
served by public water systems exposed to tribufos at levels of public
health concern in drinking water (USEPA, 2026a). Therefore, the EPA has
determined that regulating tribufos under the SDWA does not present a
meaningful opportunity for health risk reduction for persons served by
PWSs, as required by SDWA's Statutory Criterion 3 for regulatory
determinations.
The Agency has evaluated the best available information on tribufos
against the three SDWA section 1412(b)(1)(A) statutory criteria and
found that this contaminant does not satisfy the second and third
criteria. The Agency is therefore making a final determination not to
regulate tribufos with an NPDWR.
V. The EPA's Considerations for Future Regulatory Determinations
In a 2023 decision, the D.C. Circuit Court of Appeals in NRDC v.
Regan, 67 F.4th 397 (D.C. Cir. 2023), held that the EPA must proceed to
regulate a contaminant after finalizing a determination to regulate
even when the Agency later determines that the contaminant no longer
satisfies the statutory criteria for regulation. This ruling presented
a change to the EPA's understanding of the flexibilities afforded to
the Agency under the SDWA. Prior to this ruling, the EPA had understood
that the Agency could withdraw a positive determination if, during the
more-detailed analyses conducted during the development of the proposed
rule, the EPA determined that the potential for health-risk reduction
was less beneficial than initially predicted.
In light of this ruling, the EPA continues to consider changes to
its approach to making future determinations to regulate contaminants
as explained in the preliminary regulatory determination for RD 5 (90
FR 3830; USEPA, 2025a). The EPA is evaluating conducting preliminary
benefits analyses and treatment feasibility analysis for some future
regulatory determinations. The EPA is considering performing these
analyses for future regulatory determinations such as certain of those
contaminants that are determined to meet the first two regulatory
determination criteria under SDWA section 1412(b)(1)(A)(i) and (ii).
The results of these analyses would add to information for the Agency's
evaluation under the third regulatory determination criterion (SDWA
section 1412(b)(1)(A)(iii)) on whether regulation of the contaminant
presents a meaningful opportunity for health risk reduction for persons
served by PWSs.
[[Page 13235]]
Several commenters expressed support for the EPA's intention to
conduct preliminary benefits or treatment feasibility analyses prior to
making positive regulatory determinations (USEPA, 2026b). The
commenters noted that these analyses will be especially important in
light of the 2023 D.C. Circuit Court ruling in NRDC v. Regan (USEPA,
2026b).
In the preliminary regulatory determination FRN for RD 5 (90 FR
3830; USEPA, 2025a) the EPA stated that the Agency was working
collaboratively across programs to address the unreasonable risk from
1,4 -dioxane identified under TSCA. Since that time, the EPA is
administratively reconsidering the 2024 supplemental risk evaluation
and revised risk determination, as well as the underlying 2020 risk
evaluation, focusing on the cancer risk analysis in the hazard
assessment and its consistency with the best available science and
EPA's 2005 Cancer Guidelines (https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/final-risk-evaluation-14-dioxane).
Results of the reconsideration of the cancer risk analysis may be taken
into consideration for future Agency actions, as appropriate, to
protect public health based on the best available science.
VI. Next Steps
The Agency will not be taking regulatory action under the SDWA for
the nine contaminants receiving negative determinations at this time.
However, if new information about any of these contaminants becomes
available (e.g., new studies on adverse health effects or new
occurrence data), the EPA will evaluate whether to include them on a
future CCL.
VII. References
Agency for Toxic Substances and Disease Registry (ATSDR). 2020.
Toxicological Profile for Molybdenum. U.S. Department of Health and
Human Services, Public Health Service. https://www.atsdr.cdc.gov/ToxProfiles/tp212.pdf.
D.C. Circuit Court (D.C. Cir.). 2023. National Resources Defense
Council v. Michael S. Regan, Administrator, U.S. Environmental
Protection Agency and Environmental Protection Agency, 67 F.4th 397.
https://casetext.com/case/nat-res-def-council-v-regan-1.
Murray F.J., F.M. Sullivan, A.K. Tiwary, and S. Carey. 2014. 90-Day
Subchronic Toxicity Study of Sodium Molybdate Dihydrate in Rats.
Regulatory Toxicology and Pharmacology, 70(3): 579-88. https://doi.org/10.1016/j.yrtph.2013.09.003.
National Center for Biotechnology Information (NCBI). 2023. PubChem
Compound Summary for CID 5125, Tribufos. Accessed December 11, 2023.
https://pubchem.ncbi.nlm.nih.gov/compound/Tribufos.
NCBI. 2024. PubChem Compound Summary for CID 7242, o-Toluidine.
https://pubchem.ncbi.nlm.nih.gov/compound/o-Toluidine. Accessed
January 5, 2024.
United States Environmental Protection Agency (USEPA). 1992.
Molybdenum; CASRN 7439-98-7. National Center for Environmental
Assessment, Integrated Risk Information System, Chemical Assessment
Summary. https://iris.epa.gov/static/pdfs/0425_summary.pdf.
USEPA. 1995. Policy on Evaluating Health Risks to Children. October
20, 1995. Science Policy Council, Washington, DC. Available on the
internet at: https://www.epa.gov/sites/production/files/2014-05/documents/1995_childrens_health_policy_statement.pdf; Cover memo
at:https://www.epa.gov/sites/production/files/2014-05/documents/health_policy_cover_memo.pdf.
USEPA. 2000. Methodology for Deriving Ambient Water Quality Criteria
for the Protection of Human Health (2000). Office of Water, Office
of Science and Technology. EPA/822/B-00/004. October. https://www.epa.gov/sites/default/files/2018-10/documents/methodology-wqc-protection-hh-2000.pdf.
USEPA. 2005. Guidelines for Carcinogen Risk Assessment. Risk
Assessment Forum. EPA/630/P-03/001F. March. https://www.epa.gov/sites/default/files/2013-09/documents/cancer_guidelines_final_3-25-05.pdf.
USEPA. 2012. Provisional Peer-Reviewed Toxicity Values for o-
Toluidine (CASRN 95-53-4). Office of Research and Development's
National Center for Environmental Assessment, Superfund Health Risk
Technical Support Center. EPA/690/R-12/032F. December. https://cfpub.epa.gov/ncea/pprtv/documents/ToluidineoMethylaniline2.pdf.
USEPA. 2014. Protocol for the Regulatory Determinations 3. Including
appendices A-F. EPA 815-R14-005. April 2014.
USEPA. 2015a. Health Effects Support Document for the Cyanobacterial
Toxin Cylindrospermopsin. Office of Water, Health and Ecological
Criteria Division. EPA-820R15103. June. https://www.epa.gov/sites/default/files/2017-06/documents/cylindrospermopsin-support-report-2015.pdf.
USEPA. 2015b. Ethoprop: Draft Human Health Risk Assessment for
Registration Review. September 15, 2015, memo from Office of
Chemical Safety and Pollution Prevention, Office of Pesticide
Programs, Health Effects Division. DP D410028. https://www.regulations.gov/document/EPA-HQ-OPP-2008-0560-0028.
USEPA. 2015c. Pesticide Registration: Draft Human Health and
Ecological Risk Assessments for Sulfonylureas and Certain Other
Pesticides. Federal Register, 80(186): 57812-57816, Sept 25, 2015.
https://www.federalregister.gov/documents/2015/09/25/2015-24452/pesticide-registration-review-draft-human-health-and-ecological-risk-assessments-for-sulfonylureas.
USEPA. 2015d. Health Effects Support Document for the Cyanobacterial
Toxin Microcystins. EPA-820-R-15-102. June. https://www.epa.gov/sites/default/files/2017-06/documents/microcystins-support-report-2015.pdf.
USEPA. 2015e. Profenofos: Human Health Draft Risk Assessment (DRA)
for Registration Review. September 15, 2015 memo from Office of
Chemical Safety and Pollution Prevention. DP D414150. https://www.regulations.gov/document/EPA-HQ-OPP-2008-0345-0024.
USEPA. 2015f. Tribufos: Human Health Draft Risk Assessment for
Registration Review. September 15, 2015, memo from Office of
Chemical Safety and Pollution Prevention. DP D357537. https://www.regulations.gov/document/EPA-HQ-OPP-2008-0883-0011.
USEPA. 2015g. Pesticide Registration Review; Draft Human Health and
Ecological Risk Assessments for Certain Organophosphates; Extension
of Comment Period. Federal Register, 80(246): 79888-79889, December
23, 2015. https://www.govinfo.gov/content/pkg/FR-2015-12-23/pdf/2015-32326.pdf.
USEPA. 2016. Announcement of Final Regulatory Determinations for
Contaminants on the Third Drinking Water Contaminant Candidate List.
Federal Register 81(1): 13, January 4, 2016.
USEPA. 2019a. Exposure Factors Handbook Chapter 3 (Update):
Ingestion of Water and Other Select Liquids. Office of Research and
Development. EPA/600/R-8/259F. https://cfpub.epa.gov/ncea/efp/recordisplay.cfm?deid=343661.
USEPA. 2019b. Occurrence Data from the Third Unregulated Contaminant
Monitoring Rule (UCMR 3). EPA 815-R-19-007.
USEPA. 2020a. Pesticide Registration Review: Interim Decisions for
Several Pesticides. Federal Register, 85(206): 67538-67540, Oct 23,
2020. https://www.federalregister.gov/documents/2020/10/23/2020-23504/pesticide-registration-review-interim-decisions-for-several-pesticides-notice-of-availability.
USEPA. 2020b. Permethrin: Human Health Risk Assessment for New Use
on ``Fruit, Small, Vine Climbing, Except Fuzzy Kiwifruit, Subgroup
13-07F''; Multiple Crop Group Conversions/Expansions; and the
Establishment of a Tolerance without a U.S. Registration for Tea,
and the Revised Draft Risk Assessment (DRA) for Registration Review.
March 17, 2020, memo from Office of Chemical Safety and Pollution
Prevention, Office of Pesticide Programs, Health Effects Division.
DPs D449288, D455545. https://www.regulations.gov/document/EPA-HQ-OPP-2011-0039-0130.
USEPA. 2021a. Registration Review Draft Risk Assessment for the
Antimicrobial Uses of Tebuconazole. March 24, 2021, memo from Office
of Chemical Safety and Pollution Prevention. DP 455145. https://downloads.regulations.gov/EPA-HQ-OPP-2015-0378-0020/content.pdf.
[[Page 13236]]
USEPA. 2021b. Pesticide Registration Review; Draft Human Health and/
or Ecological Risk Assessments for Several Pesticides; Notice of
Availability. Federal Register, 86(97): 27593-27594, May 21, 2021.
https://www.govinfo.gov/content/pkg/FR-2021-05-21/pdf/2021-10715.pdf.
USEPA. 2022. Drinking Water Contaminant Candidate List 5-Final.
Federal Register. Vol. 87, No. 218. P. 68060, November 14, 2022.
USEPA. 2023. Pesticide Product and Label System Database. https://ordspub.epa.gov/ords/pesticides/f?p=PPLS:1.
USEPA. 2024. Occurrence Data from the Fourth Unregulated Contaminant
Monitoring Rule (UCMR 4). EPA 815-B-24-016.
USEPA. 2025a. Announcement of Preliminary Regulatory Determinations
for Contaminants on the Fifth Drinking Water Contaminant Candidate
List. Federal Register Vol 90 Number 9 Page 3830. January 15, 2025.
USEPA. 2025b. U.S. Environmental Protection Agency Implementation of
Gold Standard Science. https://www.epa.gov/scientific-leadership/gold-standard-science.
USEPA. 2026a. Final Regulatory Determination 5 Support Document. EPA
815-R-26-002.
USEPA. 2026b. Responses to Public Comments on Preliminary Regulatory
Determinations for Contaminants on the Fifth Drinking Water
Contaminant Candidate List. EPA-815-R-26-003.
United States Geological Survey (USGS). 2023. Estimated Annual
Agricultural Pesticide Use. https://water.usgs.gov/nawqa/pnsp/usage/maps/index.php. Last updated June 14, 2023.
World Health Organization (WHO). 2011. Molybdenum in Drinking-Water.
Background Document for Development of WHO Guidelines for Drinking-
Water Quality. WHO/SDE/WSH/03.04/11/Rev/1. https://cdn.who.int/media/docs/default-source/wash-documents/wash-chemicals/molybdenum.pdf?sfvrsn=d01920eb_4.
Lee Zeldin,
Administrator.
[FR Doc. 2026-05452 Filed 3-18-26; 8:45 am]
BILLING CODE 6560-50-P