GUEST EDITORIAL Critique of the new SDWA In the Nov. 13, 1985, Federal Register EPA published RMCLs (recommended maximum contaminant levels) and proposed MCLs (maximum contaminant levels) for eight volatile organic chemicals occurring as drinking-water contaminants as required by the June amendments to the Safe Drinking Water Act (SDWA). The same issue contained a list of proposed RMCLs for additional synthetic organic, inorganic, and microbiological contaminants. EPA set RMCLs for carcinogenic organic contaminants at zero even though that is not a specific requirement of SDWA. Rather, SDWA states that RMCLs are to be set at a level at which, in the administrator’s judgment, “no known or anticipated adverse effects on the health of persons occur and which allows an adequate margin of safety.” In the Federal Register notice, however, EPA states that an RMCL of zero for carcinogenic chemicals is justified on the basis of the “legislative history of the SDWA.” The act requires that MCLs be set as close as feasible to RMCLs “with the use of the best technology, treatment techniques and other means, which the Administrator finds as generally available (taking costs into consideration).” In its attempt to meet these conditions, the agency has chosen to set MCLs by using the practical lower limit of the ability to analytically detect specific chemicals. Using this approach, EPA has chosen to disregard epidemiological data, cancer dose-response information from experimental animal studies, and other relevant health effects data. In effect, EPA has, in the case of organic carcinogenic chemicals, taken the Food and Drug Act’s Delaney amendment and applied it to MCLs for drinking water. The reasoning used in setting RMCLs for inorganic carcinogenic contaminants in drinking water is quite different from that used for organic carcinogens. Thus, finite RMCLs are recommended for inorganic carcinogens, most of which are known human carcinogens. In setting the RMCLs for inorganic carcinogens, however, EPA has again largely ignored health effects data and their relevance to human risk. A number of reasons were given, some of which had scientific validity and some of which did not. 0013936w86(o9M1067$01.50/0
@ 1986 American Chemical Satiety
The point here is that MCLs for organic and inorganic contaminants alike in drinking water should be based on a careful consideration of all relevant health effects data as well as on practical issues such as feasibility. By setting RMCLs at zero and basing MCLs on analytical detection limits, health effects information is disregarded. Moreover, setting RMCLs for organic carcinogens at zero will, in the end, have an adverse effect on the regulation of carcinogenic chemicals in drinking water. EPAs approach ignores differences in the carcinogenic potency of chemicals, abandons the use of weight-ofevidence in assessing potential human cancer risks, and disclaims cancer risk assessment procedures used by other regulatory agencies and other programs within EPA. The result may well be to discourage scientific investigation of drinking-water contaminants. At least two questions must be asked: Why test a chemical contaminant for its potential carcinogenicity if carcinogenic potency or other data pertaining to its potential to cause cancer in humans are ignored? Why attempt to develop sensitive, practical analytical methods for detecting carcinogenic chemicals in drinking water if the more sensitive analytical method rather than an evaluation of the available health effects data will decide what the MCL will be?
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