Perchlorate Information Bureau
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About Regulation of Perchlorate

Credible Science Should Lead The Way

Q: What are California's proposed "safe" exposure levels and how were they derived?

A: In 2007, The State of California - accounting for perchlorate exposure from water, farm products and cow's milk - enacted a Maximum Contaminant Level (MCL) for perchlorate in drinking water of 6 ppb. This is an exceptionally conservative approach considering:

  • Studies that show perchlorate begins to affect the thyroid at approximately 245 ppb, and below this level there is no measurable effect. (Studies show levels below 14,000 ppb do inhibit the body's ability to absorb iodine, but even this is not an adverse health effect.)
  • Cal/EPA requested a peer review by a panel of scientists convened by the University of California (UC) to review its own risk assessment on perchlorate;
  • Three UC researchers conducted the review and each disagreed with Cal/ EPA's Office of Environmental Health Hazard Assessment, and one another, on how the state should proceed.

 

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Q: Are the federal 24.5 ppb Drinking Water Equivalent Level (DWEL) and California's PHG "final" standards?

A: California's MCL is "Final" but may be revived again in 2009. At the federal level, U.S. EPA now will need to determine whether to proceed with a national drinking water standard for perchlorate.

 

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Q: What are the next steps in U.S. EPA's regulatory process for perchlorate?

A: EPA's 24.5 ppb RFD may be used by officials throughout the agency to make site-specific cleanup or interim drinking water standard decisions involving perchlorate. States and private parties also may look to EPA's RfD and DWEL as they make similar decisions.

At this juncture, EPA must decide whether to promulgate a Federal drinking water standard (MCL) for perchlorate. EPA will only proceed with a standard if it determines that perchlorate adversely affects human health, is known or likely to substantially occur in public water systems at frequencies and levels that would cause adverse health effects, and that setting a Federal standard for perchlorate presents a meaningful opportunity to reduce the risk from perchlorate exposure.

 

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Q: What are the impacts of unnecessarily restrictive standards?

A: The costs of an overly restrictive (i.e., more restrictive than what credible science says is necessary to protect public health) drinking water standard for perchlorate are potentially staggering. California, Nevada and Arizona could be the states most impacted. Overly strict standards would in effect create a "problem" where one does not really exist, - forcing citizens, industry and government to incur significant expenses for new treatment plants, retrofitting existing treatment plants, purchasing additional water supplies, lowering reservoir levels and pumping more groundwater from existing sources. This could not only be a substantial expense of resources that could lead to no public health benefit, it could also contribute to a significant water shortage crisis as water supplies are closed because they do not meet the new standards.

 

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Q: What is being done now to address perchlorate in drinking water supplies?

A: Perchlorate is being contained, removed and treated at sites where it has been used in the past for manufacturing. New state-of-the-art technologies for removing perchlorate from water have been developed and put into use. Others are being developed or refined. In addition, key members of the aerospace and defense industries, along with the U.S. EPA, the U.S. Department of Defense, and the U.S. Air Force, formed the Perchlorate Information Bureau in 1993 to fund scientific research so policies could be established to protect public health based on credible science.

 

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