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For access to supporting documents on final determination development, see the following:

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 fertilizers. Perchlorate may have adverse health effects because scientific research indicates that this contaminant can disrupt the thyroid’s ability to produce hormones needed for normal growth and development.

EPA is developing a proposed national primary drinking water regulation for perchlorate. EPA is committed to using the best available peer reviewed science and data to develop the perchlorate drinking water regulation. EPA is evaluating the available science on perchlorate health effects and exposure. EPA is also evaluating laboratory methods for measuring and treatment technologies for removing perchlorate in drinking water. The Agency is also evaluating costs and benefits of potential regulatory options for perchlorate. We anticipate publication of the proposed rule for public review and comment in 2013.

Consultations and Outreach

Final Regulatory Determination for Perchlorate in Drinking Water

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 Academy of Sciences. This decision reverses a 2008 preliminary determination, and considers input from almost 39,000 public commenters on multiple public notices (May 2007, October 2008, and August 2009) related to perchlorate. This action notifies interested parties of EPA’s decision to regulate perchlorate, but does not in itself impose any requirements on public water systems (PWSs). However, this action initiates a process to develop and establish a national primary drinking water regulation (NPDWR). Once the NPDWR is finalized, certain PWSs will be required to take action to comply with the regulation in accordance with the schedule specified in the regulation.

Federal Register Notice:

For more information about Perchlorate, see the Questions and Answers Tab

Key regulatory milestones for the final Perchlorate Regulatory Determination

Supplemental Request for Comment on Preliminary Regulatory Determination

On August 19, 2009, EPA published the Perchlorate Supplemental Request for Comments requesting comment on additional approaches to analyzing data related to EPA’s perchlorate regulatory determination on October 10, 2008. These additional comments were sought in an effort to ensure consideration of all potential options for evaluating whether there is a meaningful opportunity for human health risk reduction of perchlorate through a NPDWR. EPA stated that the alternative analyses presented in this notice could lead the Agency to make a determination to regulate perchlorate. EPA received over 6,000 comments on the August 2009 notice. The Comment period closed on October 8, 2009.

Federal Register Notice:

Preliminary Regulatory Determination for Perchlorate

On October 10, 2008, EPA published a preliminary regulatory determination for perchlorate. This notice requested public comment on its determination that perchlorate did not occur with a frequency and at levels of public health concern and that development of a regulation did not present a meaningful opportunity for health risk reduction for persons served by public water systems. The October 2008 notice also describes in detail EPA’s basis for its preliminary determination not to develop an NPDWR for perchlorate. The Agency received nearly 33,000 comment letters on the October 2008 notice. To ensure transparency and opportunity for public input on its decision making, the Agency developed and published a supplemental notice on August 19, 2009.

Federal Register Notice:

EPA has established a reference dose for perchlorate, which is consistent with the reference dose recommended by the National Research Council’s 2005 report.

Interim Health Advisory

In January 2009, EPA issued an Interim Health Advisory for perchlorate to assist state and local officials in addressing local contamination of perchlorate in drinking water while the Agency conducted its evaluation of the opportunity to reduce risks through a national primary drinking water standard.

Supporting Documents:

Perchlorate Questions and Answers

Additional information about perchlorate can also be found on the EPA Federal Facilities page

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How frequently is perchlorate found in drinking water?
Perchlorate has been found in just over 4 % of public water systems nationally. Perchlorate was sampled in drinking water supplies as part of the Unregulated Contaminant Monitoring Regulation 1 (UCMR 1) program. EPA collected data on perchlorate from 3,865 public water supplies between 2001 and 2005. This included all large public water systems (serving more than 10,000 people), and a statistical sample of 800 small water systems, which together serve more than 80% of the population. One hundred and sixty (4.1%) systems reported a detection of perchlorate (in at least 1 entry/sampling point) at levels greater than or equal to 4 µg/L (the minimum reporting level of the test). These 160 systems are located in 26 states and 2 territories and approximately 1.9% (or 637) of the 34,331 samples collected (by these 3,865 public water supplies) had positive detections of perchlorate at levels greater than or equal to 4 µg/L. The average concentration of perchlorate for those samples with positive detections for perchlorate was 9.85 µg/L and the median concentration was 6.40 µg/L. Results from UCMR 1 monitoring are available at the site listed below.

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How will a public water system know if it has perchlorate in its water?
Systems that were required to monitor for perchlorate as part of UCMR1 will know if they detected perchlorate and may have taken action to reduce their levels. Some public water systems have on-going monitoring programs for perchlorate in drinking water. If water systems have not monitored for perchlorate, they can review their source water assessment to determine if there are any potential sources of perchlorate contamination within their source water protection area. If an activity is taking place that could result in perchlorate contamination, they may want to test their water for the presence of perchlorate.

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How will I know if I have perchlorate in my drinking water?
EPA analyzed samples from 3,865 public water systems collected between 2001 and 2005 as part of the Unregulated Contaminant Monitoring Regulation 1 (UCMR1). EPA found that 160 Public Water Systems, located in 26 States and 2 territories, had at least 1 analytical detection of perchlorate over the minimum reporting level of 4 µg/L. The Unregulated Contaminant Monitoring Regulation is used to collect data for contaminants suspected to be present in drinking water, but do not have health-based standards set under the Safe Drinking Water Act (SDWA). Consumers interested in determining if their water system was sampled and/or had a perchlorate detection can search the “UCMR1 List 1 and List 2 chemical monitoring data PivotTable®”* located at this website. This dataset can be used to retrieve monitoring results pertaining to an area by selecting the state and contaminant of interest.

*We suggest that users unfamiliar with PivotTables® begin by reviewing the instructions provided on the website before accessing the data.

You may also call your drinking water utility or state drinking water program to learn the results of past monitoring or to find out if monitoring is required in your state. Some states have issued drinking water standards for perchlorate. If there is no requirement for monitoring in your state, you can have your water analyzed by a laboratory that is certified for the analysis of perchlorate or similar compounds. An EPA Web site provides a list of state certification officers or links to certified laboratories in your state. The contacts provided may be able to assist you in finding an appropriate laboratory. You can also call your local public health office to determine if they are aware of any problems with perchlorate in your area.

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How can perchlorate be removed if it gets in my drinking water?
There are home treatment units that are certified to remove perchlorate from drinking water. NSF International  Exit EPA Disclaimer and the Water Quality Association  Exit EPA Disclaimer provide lists of treatment devices they have certified.

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How does this decision impact clean up of perchlorate at Superfund sites?
This does not impact the Agency’s recommendation that Regions consider using the Interim Health Advisory level of 15 µg/L as a preliminary remediation goal (PRG); consistent with the National Oil and Hazardous Substances Contingency Plan. The Agency often considers health advisories as “to be considered” values for a PRG and eventually site specific cleanup levels. Also, where state regulations establish applicable or relevant and appropriate requirements (ARARs) for perchlorate, these standards should be used as the cleanup level at Superfund sites, unless the ARAR is waived at the site.

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Should I be concerned about perchlorate in food?
The Food and Drug Administration stresses that consumers should maintain a healthy diet consistent with the Dietary Guidelines for Americans, which emphasizes eating a variety of foods across all food groups each day. EPA’s exposure evaluations, which establish health based levels for perchlorate, account for the amount of perchlorate one may consume in in their diet.

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