United States
Environmental P
Fact Sheet: Preliminary Regulatory
Determinations for the Third
Drinking Water Contaminant
Candidate List (CCL 3)
The EPA has drinking water regulations for more than 90 contaminants. To assess and address
risks posed by unregulated contaminants, the EPA, in accordance with the Safe Drinking Water
Act (SDWA), identifies a list of contaminants which may require regulation in the future. Every
five years, the EPA determines whether we should regulate at least five contaminants in drinking
water with a national primary drinking water regulation (NPDWR).
In October 2009, the EPA published the third Drinking Water Contaminant Candidate List
(CCL3). After extensive review of health effects and occurrence data, on October 20, 2014, the
agency announced its preliminary regulatory determinations for five contaminants listed on
CCL3. The EPA is making preliminary determinations to regulate strontium in drinking water
and to not regulate four contaminants (i.e., dimethoate, 1,3-dinitrobenzene, terbufos and terbufos
sulfone). The EPA is requesting comment on these preliminary determinations in the 60-day
period following publication of the notice in the Federal Register. During the comment period,
the EPA expects to hold a stakeholder meeting to discuss and solicit input on the preliminary
determinations. The EPA will evaluate public comments prior to making the final regulatory
determinations in 2015.
Questions and Answers
What is the drinking water CCL?
The drinking water CCL is the primary source of priority contaminants for making decisions
about whether drinking water regulations are needed. The contaminants on the list are known or
anticipated to occur in public water systems. However, they are currently unregulated by existing
NPDWRs.
How often is the CCL published?
The Safe Drinking Water Act (SDWA) directs the EPA to publish a CCL every five years. The
EPA published the first CCL (CCL1) of 60 contaminants in March 1998. The agency published
the second CCL (CCL2) of 51 contaminants in February 2005. The EPA then published the third
CCL (CCL3) of 116 contaminants in October 2009. The CCL 3 includes 104 chemicals or
chemical groups and 12 microbiological contaminants. You can find a list of these 116
contaminants at the following the EPA website:
http://water.epa. gov/scitech/drinkingwater/dws/ccl/ccl3. cfm.
Office of Water (4607M) 815-F-14-001 October 2014
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What is a regulatory determination?
A regulatory determination is a formal decision on whether the EPA should initiate a rulemaking
process to develop a national primary drinking water regulation for a specific contaminant. The
law requires that we make regulatory determinations for at least five contaminants from the most
recent CCL every five years.
What criteria does the EPA consider in making regulatory determinations?
When making a determination to regulate, SDWA requires that the EPA consider three criteria:
• the potential adverse effects of the contaminant on the health of humans,
• the extent of contaminant occurrence (or likely occurrence) in public drinking water, and
• in the sole judgment of the Administrator, whether regulation of the contaminant presents
a meaningful opportunity for reducing health risks for persons served by public water
systems.
If the EPA determines that all three of these statutory criteria are met and makes a final
determination to regulate a contaminant, the agency has 24 months to publish a proposed
Maximum Contaminant Level Goal (MCLG) and NPDWR. After the proposal, the agency has
18 months to publish a final MCLG and promulgate a final NPDWR, but may extend this
deadline by up to 9 months if needed. If the answer to any of the three statutory criteria is
negative based on the available data, then the agency makes a determination that an NPDWR is
not necessary for that contaminant at that time. If the EPA has insufficient information/data to
evaluate a contaminant according to the statutory criteria, it will not make a decision until such
data become available.
What are the preliminary regulatory determinations for CCL3?
The EPA announced preliminary regulatory determinations for five contaminants listed on
CCL3: dimethoate, 1,3-dinitrobenzene, strontium, terbufos, andterbufos sulfone. Based on a
review of available health information, the agency has made the preliminary determination that
strontium may have an adverse health effect in people without enough calcium in their diet
because it replaces calcium in the bone during development. The EPA has also determined that
strontium occurs frequently in public water systems. Therefore, the EPA is making a preliminary
determination to regulate strontium so that the agency can further evaluate whether regulation of
strontium in drinking water provides an opportunity for public health protection. The EPA has
also made a preliminary determination that dimethoate, 1,3-dinitrobenzene, terbufos, and
terbufos sulfone are not occurring, or occur infrequently, in drinking water. Therefore, the EPA's
preliminary determination is that these contaminants do not require regulations for drinking
water. After considering public comments, the EPA plans to make the final regulatory
determinations in 2015.
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What about nitrosamines and chlorate?
The agency is reviewing the existing microbial and disinfection byproduct (MDBP) regulations
as part of the Six Year 3 (SYS). Because chlorate and nitrosamines are DBFs that can be
introduced or formed in public water systems partly because of disinfection practices, the agency
believes it is important to evaluate these unregulated DBFs in the context of the review of the
existing DBF regulations. DBFs need to be evaluated collectively because the potential exists
that the chemical disinfection used to control a specific DBF could affect the concentrations of
other DBFs. Therefore, the agency is not making a regulatory determination for chlorate and
nitrosamines at this time. The agency expects to complete the review of these DBFs by the end
of2015.
Does the EPA have to wait until the next regulatory determination cycle to decide whether to
develop a drinking water standard for an unregulated contaminant?
It is important to note that the agency is not precluded from making a determination prior to the
end of the next regulatory determination cycle and/or regulating a contaminant at any time when
it is necessary to address an urgent threat to public health, including any contaminant not listed
on the CCL.
Do these regulatory determinations impose any requirements on public water systems?
No. These regulatory determinations do not impose any requirements on public water systems at
this time. Instead, this action notifies interested parties of the EPA's preliminary regulatory
determinations for five unregulated contaminants and requests comment on this action.
Where can I find more information about this notice and the CCL 3 Regulatory
Determinations ?
For information on the regulatory determinations for CCL3, please visit the following website:
http://water.epa.gov/scitech/drinkingwater/dws/ccl/ccl3.cfm.
For general information on drinking water, please visit the EPA's drinking water homepage at
www.epa.gov/drink or contact the Safe Drinking Water Hotline at 1-800-426-4791. The Safe
Drinking Water Hotline is open Monday through Friday, excluding legal holidays, from 10:00
a.m. to 4:00 p.m., Eastern time.
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