United States
Environmental Protection
Agency
Fact Sheet: Perchlorate Supplemental
Request for Comments
EPA is seeking comments on additional approaches to analyzing data related to EPA's
perchlorate regulatory determination. On October 10, 2008, EPA published a preliminary
determination not to regulate perchlorate. After reviewing comments received related to this
notice and conducting further analyses, the Agency is requesting comment on alternative
approaches for evaluating whether perchlorate occurs at a frequency and level of health concern
and whether there is a meaningful opportunity for health risk reduction through a national
primary drinking water regulation (NPDWR) for perchlorate. A key focus of the re-evaluation
has been consideration of exposure of infants and young children to perchlorate, which can
affect the thyroid gland. EPA will consider the comments received in response to this
supplemental request as well as the earlier notices that include perchlorate (May 1, 2007 and
October 10, 2008) before deciding whether to issue a NPDWR for perchlorate. EPA's final
decision may be to regulate perchlorate in drinking water .
Questions and Answers
Why is EPA requesting additional comment on perchlorate?
EPA is seeking comments on additional approaches to analyzing data related to the regulatory
determination of perchlorate. EPA is considering a broader range of alternatives for interpreting
the available data on: the level of health concern, the frequency of occurrence of perchlorate in
drinking water, and the opportunity for health risk reduction through a national primary drinking
water standard. The Agency is re-evaluating the scientific data on perchlorate exposure at
different life stages, which included the fetus of the iodide deficient pregnant mother, infants and
developing children. EPA will consider the comments before completing its regulatory
determination for perchlorate.
What happens next?
EPA will accept public comment on its Supplemental Request for Comments for 30 days
following publication in the Federal Register. After considering comments, EPA will decide
whether to regulate perchlorate under the Safe Drinking Water Act.
What is a regulatory determination?
A regulatory determination is not a regulation, it is a formal decision on whether EPA should
initiate a rulemaking process to develop a national primary drinking water regulation for a
specific contaminant. EPA identifies contaminants from the drinking water Contaminant
Candidate List (CCL) for decisions on whether drinking water regulations are needed. The
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Office of Water (4607M) EPA 815-F-09-004 August 2009 www.epa.gov/safewater
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contaminants on the list are known or anticipated to occur in public water systems. However,
they are currently unregulated with a national primary drinking water regulation. Under the Safe
Drinking Water Act, EPA publishes a CCL every five years. EPA then makes regulatory
determinations from the list of contaminants. The first CCL was published in March 1998, and
the second CCL (CCL 2) was published in February 2005.
What criteria does EPA consider in making regulatory determinations?
When making a determination to regulate, the law requires consideration of three areas:
• the potential adverse effects of the contaminant on the health of humans,
• the frequency and level of contaminant occurrence in public drinking water, and
• whether regulation of the contaminant presents a meaningful opportunity for reducing
public health risks.
Do regulatory determinations impose any requirements on public water systems?
No. The notice seeks public comment on supplementary information on perchlorate and thus
imposes no requirements on public water systems. After review and consideration of public
comment, EPA will issue a final regulatory determination. If a decision is made to regulate a
contaminant, the rulemaking process begins.
Where can I find more information about this notice and the perchlorate regulatory
determination ?
For information on the regulatory determinations for contaminants from the second CCL
including perchlorate, please visit http://www.epa.gov/safewater/ccl/reg_determine2.html.
For general information on drinking water, please visit the EPA Safewater Web site at
http://www.epa.gov/safewater 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.
Office of Water (4607M) EPA 815-F-09-004 August 2009 www.epa.gov/safewater
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