Perchlorate: EPA’s Office of the Inspector General calls for cumulative risk assessment

Perchlorate is a toxic chemical that blocks the uptake of iodine by the thyroid gland, which leads to many types of metabolic disorders and problems with children whose mothers were exposed while pregnant. It is a chemical used in rockets and fertilizer. In the U.S. 90% of perchlorate contamination comes from the military and aerospace industries.

Perchlorate has been identified in the water in Nohili and in fish samples in Makua. It was also identified in Pohakuloa. The military has resisted attempts to set stricter standards for perchlorate, and the EPA has been weak in exercising its regulatory power in the face of the Pentagon’s opposition. Because the levels of perchlorate found in Hawai’i fall below the current lax standards, the military has declined to remediate the contamination.

This email from Lenny Siegel of the Center for Public Environmental Oversight provides a link to an EPA Office of Inspector General report that is somewhat critical of the EPA’s approach to perchlorate.  Hopefully, it will lead the EPA to consider cumulative risk assessment with regard to perchlorate and other factors that affect the thyroid.

Date: Wed, 31 Dec 2008 09:36:30 -0800
From: Lenny Siegel <>
Subject: [CPEO-MEF] PERCHLORATE: EPA’s Office of the Inspector General calls for cumulative risk assessment
To: Military Environmental Forum <>
On December 30, 2008 U. S. EPA’s Office of the Inspector General (OIG)released its External Review Draft of its “Scientific Analysis of Perchlorate” report. The 213-page 2.5 MB PDF file may be downloaded from OIG is taking comments through March 10, 2009.

Thus far I have only read the cover letter, but the letter makes it clear that the Analysis’ authors find fault in the single-chemical risk assessment approach that EPA, as well as the National Academy of Sciences, have taken to develop acceptable risk levels for perchlorate exposure. OIG calls for a cumulative risk assessment that would consider other compounds that stress the thyroid’s ability to uptake iodide, such as thiocyanate, nitrate, and the lack of iodide.

This appears to be an appropriate response to the critique I wrote about what I call EPA’s “O.J.” draft decision not to develop a drinking water standard for perchlorate. I excerpt my November 24, 2008 letter below:

“… EPA states that Blount did not establish a causal relationship. That is, other factors – such as exposure to nitrates or thiocyanate, might be influencing thyroid function. It wrote, ‘It is also not known whether the association between perchlorate and thyroid hormone levels is causal or mediated by some other correlate of both.’

“That is, EPA recognizes that there is a major threat to public health, but it refuses to take action because there is a chance that the association between perchlorate and decreased thyroid function might be caused by another. unknown chemical compound. Yet EPA promises no action to track down and investigate that mysterious cause. This is unconscionable!

“This reminds me of O.J. Simpson’s criminal defense. He insisted that some third party or parties killed his wife and Ronald Goldman, but he showed little interest in finding the unknown perpetrators.

“If EPA were serious about protecting the health of America’s children, it would move forward with plans to develop a legal standard for perchlorate in drinking water. In the course of that effort, it should consider how other contaminants might contribute to the problem.”


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