Adam Bluestein

On January 1, Felicity Barringer reported in the New York Times that the EPA’s own inspector general has concluded that the agency failed to follow its own guidelines and made a basic error in evaluating how perchlorate, a rocket-fuel ingredient that has contaminated surface and groundwater supplies throughout the U.S., harms human health. Good studies show that perchlorate can impact thyroid function, and in pregnant women, the resulting iodide insufficiencies are “associated with permanent mental deficits in the children,” according to the EPA.

Map of perchlorate manufacturing in U.S.

The inspector general stated that rather than looking at the effect of perchlorate in isolation, the EPA “should have followed its own guidance and examined the cumulative impact of perchlorate, other substances in the environment that inhibit the uptake of iodide by the thyroid, and potentially inadequate supplies of iodide in American diets,” Barringer writes.

The EPA also has chosen to ignore the most comprehensive human exposure study on perchlorate, which was completed by the Centers for Disease Control ( a summary of that study is here). That study found both that perchlorate exposure was widespread and that there existed a correlation between exposure and reduced thyroid hormone levels. Instead, the EPA has relied largely on hypothetical exposure data derived from a computer model created by the Chemical Industry Institute of Toxicology, which was not fully vetted by other scientists.

This past October, the EPA issued a proposed ruling that would have rejected any regulation of perchlorate in drinking water on the national level. However, the EPA’s own Science Advisory Board called for an extension of the public comment period, which was formally extended to the end of November. While many feared that the final announcement would come sometime in December, it is now looking more likely that the Obama administration may actually have a crack at doing the right thing and at least looking at the correct studies and looking at the studies correctly. The states of Massachusetts and California have independently set strict drinking water standards.

While the perchlorate issue has been well covered for a variety of reasons — “rocket fuel” in water is dramatic and scary, for one thing, and the big bad defense industry is a major villain in all this — I urge you to go and take a look at all the OTHER possibly very dangerous contaminants that the EPA has been mulling over regulating for YEARS now. These get put into a document called the Contaminant Candidate List, or CCL, which is published every few years. The Safe Drinking Water Act requires that the EPA make a determination on at least five contaminants from this list (it isn’t clear whether thay have any timeframe for doing so, though). The second CCL, published in 2005, listed roughly 50 chemical and microbial candidates that the agency was considering evaluating for possible regulation. Some three years later, in July 2008, the EPA published its (not surprising) final determination that no regulatory action was “appropriate or necessary” for eleven contaminants. The EPA chose to regulate none. The third CCL is a staggeringly long list — with somewhere around 100 potentially dangerous contaminants. Let’s hope that under the new administration it doesn’t take another few years to decide that we’re not going to do anything about them.