EPA botched perchlorate analysis, report says

The Environmental Protection Agency apparently erred in its analysis of the potential human health impacts of perchlorate, according to a draft report by the agency's inspector general. Perchlorate is a major element of rocket fuel that has contaminated drinking water in dozens of states. The chemical acts in concert with a handful of other chemicals common in foods to inhibit the uptake of the nutrient iodide. That's particularly harmful for pregnant or nursing women because it can result in "subtle mental deficiencies" in their children. But instead of analyzing the cumulative effects of those chemicals,  the EPA analyzed perchlorate in isolation, the report says, thereby painting an inaccurate picture of a complex public health problem.

But, as the New York Times reports, the 200-page document

. . . did not quarrel with (the EPA's) two controversial regulatory actions involving perchlorate: one decision to set a safe dosage level four times greater than California’s, and a second not to require cleanup of perchlorate contamination.

In October, the E.P.A. announced that after “extensive review of scientific data related to the health effects of exposure to perchlorate from drinking water and other sources,” a rule setting nationwide maximum limits for the chemical in drinking water was unnecessary as it would do little to reduce risks to human health.

In fact, the report seems to agree with the EPA's conclusions, despite the apparent analytical error:

Potentially lowering the perchlorate drinking water limit from 24.5 ppb to 6 ppb does not provide a meaningful opportunity to lower the public’s risk. By contrast, addressing moderate and mild iodide deficiency that occurs in about 29% of the U.S. pregnant and nursing population appears to be a more effective approach of increasing TIU (total iodide uptake) to healthy levels during pregnancy and nursing, thereby reducing the frequency and severity of permanent mental deficits in children. 

. . . The most effective and efficient approach for reducing the health risk of permanent mental
deficits in children from low maternal TIU during pregnancy and nursing is to add iodide to all
prenatal vitamins and use them before and during pregnancy and nursing.

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In 2002, EPA scientists determined that a safe exposure dose of perchlorate is 1 part per billion -- roughly the equivalent of a drop of water in a home swimming pool. This was expected to propel a stringent cleanup policy, one that would have cost the Department of Defense -- which is responsible for hundreds of spills -- an estimated $40 billion. But after six years of political infighting between the EPA and the Office of Management and Budget, the EPA was expected to announce in December that it would not regulate perchlorate in drinking water. . . The OMB -- which controls the White House purse strings and quietly wields a great deal of power -- had heavily edited the proposal, eliminating key passages. It had also urged the EPA to rely on computer modeling to calculate the chemical's risks, rather than use the broad scientific data already available, according to EPA staff scientists. The assessment fails entirely to consider how perchlorate impacts infants, the most sensitive population.