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EPA Unlikely to Limit Perchlorate in Tap Water

"Perchlorate has been a serious, persistent and widespread problem which threatens the health of our families, especially our children," Boxer said. "For the Bush EPA to walk away from this problem and shrug off this danger is, in my view, unforgivable and immoral."

Federal, state and independent scientists have differed over the years as to what represents an acceptable dose of perchlorate in drinking water, though all have set the bar higher than the non-mandatory level in the EPA's new proposal. In January 2002, the EPA issued a draft risk assessment finding that 1 part per billion should be considered safe; in March 2006, the Massachusetts Department of Environmental Protection set a maximum contaminant level of 2 ppb; last year, California adopted a standard of 6 ppb.

A National Academy of Sciences panel prepared a risk analysis in 2005 that, according to the EPA's traditional models, would produce a protective standard of 1 to 6 ppb. The academy's study came under attack because two of the committee's members had financial ties to defense contractors that face legal liability because of perchlorate disposal.

In the EPA's proposed rule, the administration assumes that perchlorate contamination of 15 ppb is safe. But its regulatory document states that "between 16,000 and 28,000 pregnant women" and 900,000 to 2 million Americans could be exposed to higher levels.

The EPA document also finds that bottle-fed infants would be exposed to more than five times the level the National Academy of Sciences deemed safe -- 700 nanograms per kilogram of body weight per day -- if parents mix formula with drinking water containing perchlorate levels of 15 ppb.

OMB officials said during the drafting process that there was "no need" for detailed data to flesh out a table suggesting that infants would be exposed to perchlorate levels above the academy's recommendation.

To determine safe levels of exposure, the administration opted not to use the academy's "reference dose," a formula that includes a tenfold safety factor to protect children and vulnerable populations, and instead used a computer model developed by the Chemical Industry Institute of Toxicology. EPA officials initially inserted language in the document calling this a "novel approach," but the OMB deleted that language.

Federal officials have yet to determine the extent of perchlorate contamination nationwide, but it is known to be widespread. The GAO, which produced a 2005 report calling for a better federal tracking system for perchlorate, found that limited EPA data show the chemical compound has polluted the soil, groundwater and drinking water in 35 states and the District and has contaminated 153 public water systems in 26 states.

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