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Point source. Perchlorate seeps via ground water into the Colorado River from this Kerr-McGee facility near Las Vegas.

Hot Debate Over Rocket-Fuel Contaminant

Should tens of millions of U.S. residents worry that their children's drinking water is contaminated with tiny amounts of a rocket-fuel ingredient? The Environmental Protection Agency (EPA) says yes; the Department of Defense (DOD) and the defense and aerospace companies that manufacture or use the chemical, perchlorate, say no. Now the National Academy of Sciences (NAS) will step in to settle the issue. But some scientists worry that the new study may be more of a way to delay new standards than a quest for truth.

Both sides agree that perchlorate can decrease thyroid hormone levels, and thyroid hormone levels affect brain development. But EPA relies primarily on lab animal data that show effects at low levels of exposure, whereas the defense groups emphasize human data that show no such effects. A January 2002 EPA draft report recommended a drinking water concentration of 1 part per billion (ppb) as safe for human health, whereas DOD says the number is likely to be much higher.

The academy study will push back the final version of the EPA toxicological review, which had been expected early this year, says William Farland, EPA's acting deputy administrative director for science. Some suspect that DOD called for the review with the goal of delaying costly cleanup operations. "when they saw how the data was interpreted they didn't like it," says Kevin Mayer, EPA's regional perchlorate coordinator in San Francisco. Not so, says Jeff Cornell, adviser to the deputy assistant secretary of the Air Force. "The overriding concern of the Air Force and the Department of Defense is public health."

The Administration requested the NAS review on 17 March, 1 week after Senator Barbara Boxer (D-CA) introduced a bill that would require EPA to set a regulatory standard for perchlorate in drinking water by 1 July 2004. Three days after Boxer's action, military officials told the Senate Armed Services readiness and management support subcommittee that things were moving too fast. "We've excited the American people with little science to back it up," said H. T. Johnson, acting secretary of the Navy.

The now-delayed EPA review is the first step toward setting a regulatory standard for drinking water. The process usually takes 6 years after the review is finalized. The NAS request will slow this process; such reviews usually take about 2 years.

Related sites
Information on perchlorate from the EPA
More on perchlorate from the California Environmental Working Group