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Fall/Winter 2001 Vol. 1 No. 2

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Glass of water ©PhotoDisc Arsenic Reconsidered

EPA Asks for Advice on Risk

While the nation grapples with securing its drinking water supplies from possible terrorist attacks, it still must contend with a concern being debated well before Sept. 11 -- how to keep levels of arsenic down. Drinking water can become contaminated when arsenic seeps in from natural sources or is discharged into water supplies by agricultural and industrial processes. The Safe Drinking Water Act requires the U.S. Environmental Protection Agency to limit the level of arsenic in drinking water. What that limit should be, how-ever, has been the subject of intense public discussion, and the National Research Council has been called upon twice in recent years to make sure that any resulting regulations are based on the best available science.

In its 1999 report, a Research Council committee concluded that EPA's maximum allowable level for arsenic in drinking water at the time -- 50 parts per billion -- was too high given the chance of developing cancer from consuming that much on a daily basis.

EPA lowered the standard to 10 parts per billion in January 2001, but when the Bush administration entered office, it determined that new research conducted since 1999 warranted a look by the Research Council before the standard was implemented. In particular, EPA wanted to know what the risks were of drinking water with arsenic concentrations between 3 and 20 parts per billion.

The committee assigned to the new study found that a link could be found between bladder and lung cancer and exposure to arsenic in drinking water, and that the evidence for this association is stronger than it was only two years earlier. For example, men and women who daily consume water with 3 parts per billion of arsenic in it have a 1 in 1,000 increased risk of cancer. The risk jumps to greater than 3 in 1,000 at 10 parts per billion, and is close to 7 in 1,000 at 20 parts per billion.

The committee was not asked to recommend a new standard to EPA, nor was it asked to conduct the cost-benefit analyses that are needed to make such a decision. It did recommend that new research be carried out to determine the extent to which chronic arsenic exposure causes diseases other than cancer, since some foreign studies have linked arsenic exposure to diabetes, heart and respiratory ailments, and birth defects.

Following public release of the report, the Bush administration announced in early November its intent to adopt the earlier proposed level of 10 parts per billion.   -- Bill Kearney

Arsenic in Drinking Water: 2001 Update. Subcommittee to Update the 1999 Arsenic in Drinking Water Report, Committee on Toxicology, Board on Environmental Studies and Toxicology, Division on Earth and Life Studies (2001, 244 pp.; ISBN 0-309-07629-3; available from National Academy Press, tel. 1-800-624-6242; $39.00 plus $4.50 shipping for single copies).

The study was chaired by Robert A. Goyer, professor emeritus of pathology, University of Western Ontario (retired), Chapel Hill, N.C. The study was funded by EPA.

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Copyright 2001 by the National Academy of Sciences