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Perchlorate

On August 19, 2009, EPA published a Supplemental Request for Comments Federal Register notice seeking input on additional ways to analyze 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. A key focus is the re-evaluation of perchlorate exposure to sensitive life stages including infants and developing children, in addition to pregnant women and their developing fetuses. EPA will make a final regulatory determination for perchlorate after considering comments provided on this and previous notices related to the perchlorate regulatory determination. EPA’s final decision may be a determination to regulate.

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 evaluates the opportunity to reduce risks through a national primary drinking water standard.

In October 2008, EPA made a preliminary regulatory determination for perchlorate in drinking water.

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

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

Questions and Answers

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What is Perchlorate?
Perchlorate is both a naturally occurring and man-made chemical. Perchlorate is used to manufacture fireworks, explosives, flares and rocket propellant.

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Why isn’t EPA making a final regulatory determination?
EPA received a significant number of comments on its October 2008 preliminary regulatory determination and the supporting analysis that raised technical and other issues. As a result, EPA has re-evaluated and identified alternative approaches of analyzing data related to the perchlorate regulatory determination. To ensure transparency and opportunity for public input on its decision making, the Agency is seeking comments on these alternative approaches for interpreting data before making its final regulatory determination.

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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 detection 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?

You may want to 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. While EPA does not regulate perchlorate in drinking water, some public drinking water systems monitored for this contaminant in the past to meet EPA requirements. In addition, California and Massachusetts have issued drinking water standards for perchlorate of 6 µg/L and 2 µg/L, respectively. 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?

Reverse osmosis technology has been certified by NSF International to remove perchlorate from levels as high as 130 µg/L to 4 µg/L or less in drinking water. However, before installing a home treatment unit, we recommend that you contact the manufacturer to determine if the unit can remove perchlorate from your water supply.

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Is EPA seeking further review from the National Academies of Science \ National Research Council (NRC)?

EPA is not, at present, planning to request additional NRC review of issues related to perchlorate. The Agency believes that further review by the NRC would unnecessarily delay regulatory decision making for perchlorate. Instead, EPA sought comment through its August 5, 2009, Federal Register notice on a broad range of alternative approaches to the interpretation of the scientific data relevant to a regulatory determination for perchlorate in drinking water.

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What is the status of EPA’s Interim Health Advisory?

EPA published an Interim Health Advisory for perchlorate in January 2009. The Interim Health Advisory is established based on the most sensitive population identified by the NAS, the fetus of the iodide-deficient pregnant woman. The August 5, 2009, Federal Register notice does not change the Interim Health Advisory; however, in this notice, EPA requested comment on alternative analyses that result in lower health based levels for other sensitive life stages such as infants and children. EPA will consider the comments on these alternative approaches as it makes a final regulatory determination and as it decides what modifications are needed to the Interim Health Advisory for perchlorate.

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What comments did EPA get on its peer review of the Interim Health Advisory?

EPA had a draft of its Interim Health Advisory for perchlorate reviewed by four external peer reviewers. The recommendations from the four reviewers ranged from generally supportive with some suggested minor improvements to concerns over gaps in the underlying analysis. The analytical issues identified by the peer reviewers include questions over the adequacy of the analysis to address all of the potentially sensitive sub populations (e.g., iodide deficient pregnant women) and life stages (pre-term and full term infants).

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How does this decision impact clean up of perchlorate at Superfund sites?

At the time of publication of the Interim Health Advisory for perchlorate, the Agency withdrew the January 26, 2006, guidance it issued regarding perchlorate and sites addressed under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substances Contingency Plan (National Contingency Plan or NCP). The January 2006 guidance recommended that Regions consider using a preliminary remediation goal (PRG) of 24.5 ppb (or µg/L). In its place, the Agency recommends that Regions consider using the Interim Health Advisory level of 15 µg/L as a PRG; consistent with the NCP, the Agency often considers health advisories as “to be considered” (TBC) values for setting 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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How do alternative approaches described in the August 2009 Federal Register notice differ from the approach in EPA’s October 2008 Federal Register notice?

A key area of difference is the development of alternative perchlorate health reference levels (HRL) based on body weight and exposure data for infants and children. The HRL is a comparison value that the Agency uses to determine if perchlorate is in water systems at levels of health concern. EPA’s previous analysis focused its HRL derivation on exposure to the pregnant woman because the National Research Council (NRC) identified “the fetuses of pregnant women who might have hypothyroidism or iodide deficiency” as “the most sensitive population.” However, the NRC also identified infants and developing children as additional “sensitive populations.” Infants and young children have greater exposure to contaminants in food and water because of greater consumption of food and water on a per unit body weight basis. Therefore, these life stages may be the most vulnerable populations when their relative exposure is considered. The alternatives under consideration could result in HRLs that are much lower than the level identified in the October 2008 notice. A second difference is how to evaluate the levels of perchlorate occurrence in public water supplies if levels are below the reporting limit of 4 µg/L. This would be necessary if the Agency selected an HRL less than 4 µg/L. Finally the Agency is requesting comment on other ways to use Physiologically Based Pharmacokinetic (PBPK) modeling to inform regulatory decision making for perchlorate.

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What kind of comments did the Agency receive on the October 2008 Federal Register notice?

EPA received more than 32,000 comments on the preliminary regulatory determination. The majority of comments were submitted by individuals opposed to the decision using similar language linked to organized write-in campaigns. There were also unique comments that provided additional scientific evaluation of the information EPA used in making the preliminary determination. All of the comments received on the notice can be reviewed on www.regulations.gov. Refer to docket number EPA-HQ-OW-2008-0692

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