United State
       Environmental Protection
                         Fact Sheet:  Final Regulatory
                         Determination for Perchlorate
EPA has decided to regulate perchlorate under the Safe Drinking Water Act (SDWA). The
science that has lead to this decision has been peer reviewed by independent scientists and
public health experts including the National Academies of Science.

This decision is the first time EPA has decided to regulate a substance from the Contaminant
Candidate List required by the 1996 Amendments to the Safe Drinking Water Act. This decision
reverses a 2008 preliminary determination and considers input from almost 39,000 public

Questions and Answers

What is perchlorate?

Perchlorate is both a naturally occurring and man-made chemical that is used to produce rocket
fuel, fireworks, flares and explosives. Perchlorate can also be present in bleach and in some

Why did EPA decide to regulate perchlorate?

EPA has determined that perchlorate meets SDWA's thee criteria for regulating a contaminant.
1) Perchlorate may have adverse health effects because scientific research indicates that
perchlorate can disrupt the thyroid's ability to produce hormones needed for normal growth and
development. 2)There is a substantial likelihood that perchlorate occurs with frequency at
levels of health concern in public water systems because monitoring data show over four
percent of public water  systems have detected perchlorate, and 3.) There is a meaningful
opportunity for health risk reduction for the between 5.2 and 16.6 million people who may be
served drinking water containing perchlorate.

Is EPA requiring public water systems to take action now to address perchlorate?

No, this action notifies interested parties of EPA's determination to regulate perchlorate, but
imposes no requirements on public water systems at this time. However, this action initiates the
process to develop a national primary drinking water regulation (NPDWR) for perchlorate.

What happens next?

EPA will continue to evaluate the science on perchlorate health effects and occurrence in
developing a proposed  NPDWR for perchlorate.   EPA will also now begin to evaluate the
feasibility and affordability of treatment technologies to remove perchlorate and will examine the
costs and benefits of potential standards. EPA will consult with our Science Advisory Board and
with the National Drinking Water Advisory Council. EPA intends to publish the proposed
regulation and analyses for public review and comment within 24 months. EPA will consider the
public comments and expects to promulgate a final regulation within 18 months of the proposal.
Office of Water (4607M)     EPA 815-F-11-003    February 2011    water.epa.gov/drink

What is a regulatory determination?

A regulatory determination is a formal decision on whether EPA should initiate a rulemaking
process to develop a national primary drinking water regulation (NPDWR) for a specific

EPA identifies contaminants for decisions on whether drinking water regulations are needed and
for research prioritization with the drinking water Contaminant Candidate List (CCL). The
contaminants on the list are known or anticipated to occur in public water systems. However,
they are currently not regulated 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. EPA included perchlorate on the first, second, and
third CCLs that were published in the Federal Register on March 2, 1998, February 24, 2005,
and October 8, 2009, respectively.
Where can I find more information about this notice and the Perchlorate Regulatory

For information on the regulatory determinations for the second CCL, 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 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.

For information on perchlorate, please visit
Office of Water (4607M)      EPA 815-F-11-003    February 2011    water.epa.gov/drink