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GUEST EDITORIAL
Drinking water and risk Today, we are a nation on worry overload. Contamination of our drinking water adds to the worries. Congress just passed the Safe Drinking Water Act Amendments of 1986 in response to these concerns. The amendments require EPA to set standards for more than 80 specific contaminants by 1989 and for 25 more every three. years thereafter. They also mandate filtration and disinfection of certain supplies. This ambitious agenda prompts me to reflect on drinking-water risks and the reason we need standards for all these contaminants, which pose risks large and small. Over the past decade, we have been able to measure many drinking-water contaminants previously unrecognized. Many are measurable by available analytical methods, can be removed from water, and may have adverse effects on human health, but do they all warrant regulation? Bruce Ames, professor of biochemistry at the University of California, Berkeley, has suggested that the public may be inordinately concerned about risks from drinking-water contaminants compared with other risks. His calculations suggest that 1 L of drinking water containing 250 ppb trichloroethylene is 300 times less dangerous than a peanut butter sandwich, 550 times less dangerous than a plate of pasta al pesto, and 3000 times less dangerous than a bottle of beer. First, I submit that not all drinking-water contaminants present such small risks. There are about 20,000 non-smoking-related deaths due to lung cancer each year. Radon in homes could account for about half of these cancers, and drinking-water standards could prevent 30 to 600 of them. Radon in drinking water is readily controllable. Contrary to popular belief, biological contamination of drinking water is still a serious problem. Disinfection and filtration of surface waters would probably have prevented the 23,000 cases of drinking-water-related giardiasis recorded over the past decade. Cholera outbreaks have occurred in recent years in the U.S. island territories. Existing controls on trihalomethanes have resulted in significant reductions of the most common organic contaminants at low cost, preventing as many as 600 cancer cases per year.
We h o w that exposure to lead in drinking water is more serious than we had thought. In addition to its well-known neurotoxic effects in children, it also appears to have cardiovascular effects in adults. A recent cross-media study suggests that drinkingwater risks constitute a substantial part of the health risks subject to EPAs control; and drinking-water quality is more readily controllable than most other sources of exposure. Therefore, we need to maintain and extend the protection of public health that is achievable by setting and meeting drinking-water standards. A reasonable person might nonetheless ask why we should set standards for other contaminants, which may indeed present only the slightest of risks. First, it's the law of the land. In addition, it provides a comprehensive and systematic basis for control of pollution sources that may contaminate drinking water. It also provides authoritative conclusions on the safety of a large number of substances that are sometimes found in drinking water, thus eliminating the uncertainty and speculation that often follow their detection. And finally, it will help to restore the public's confidence in the quality and safety of its drinking water. It might also be a way to divert attention away from slight risks and focus it on important threats. America's drinking-water supplies are among the best in the world, but we can improve upon them. EPA wants to work with the states and utilities to ensure that improvements are made when they are warranted by risks and avoided when risks are low enough to be safely ignored.
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This article no1 Subject lo U.S. Copyrighl. Published 1986 American Chemical Society
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B.A. in hisroryfrorn the Universiry of Utoh in 1973 ond an U.B. from Brik'horn Young Universiry in 1976 Environ. Sci. Technol., Vol. 20. No. 8. 1986 747
