Concern over long-term, latent hazards in drinking water has grown enormously over the past several years, but the extent of the risks remains uncertain and precautionary steps to reduce identified risks have been rare. On the positive side, several things happened in 1977.
EPA used the Safe Drinking Water Act of 1974 for the first time to shut down a plant that had been dumping massive quantities of carbon tetrachloride, a known carcinogen, into the Ohio River.
Also for the first time, EPA implemented the hazardous substances section of the Federal Water Pollution Control Act (section 307) to set standards for toxic chemicals.
After working nearly the whole year on the legislation, Congress enacted amendments to the Water Pollution Control Act, with a principal focus on toxic substances.
The National Academy of Sciences issued a 1,100 page report, "Drinking Water and Health," which dealt primarily with the problem of long-term latent hazards.
Finally, the National Cancer Institute began its consideration of a series of case-controlled epidemiological studies of the association between cancer and drinking water.
While each of these events has its positive side, each raises questions about the safety of drinking water.
Federal action. The carbon tetrachloride episode and the EPA response prompted the House Subcommittee on Oversight and Investigations to study efforts to ensure safe drinking water. Why was this the first enforcement action for an act passed three years earlier and specifically designed to deal with toxic hazards? The House report found that there were no standards for maximum levels of drinking water contaminants, only "interim standards," which "may afford the public less protection" than regulations in effect from 1962 to 1971, which were designed to prevent communicable diseases.
Implementation of the hazardous substances section of the FWPCA was not initiated voluntarily by EPA. On the contrary, the Natural Resources Defense Council sued EPA for failing to administer this section of the 1972 law; in a court consent decree EPA agreed to set standards for 129 chemicals which had been identified in the court proceeding as potentially toxic. The standards promulgated in 1977 for five chemicals—benzidine, aldrindieldrin, DDT, endrin, and toxaphene—were the first resulting from the decree.
The Federal Water Pollution Control Act Amendments of 1977 require EPA to publish a list of toxic chemicals, which will contain the 129 chemicals cited in the consent decree, among others. These chemicals are to be singled out for especially stringent control. EPA is to establish regulations requiring best available treatment by July 1, 1980, and industry is to comply by July 1, 1984. These deadlines mean that there will be little limitation of exposure to toxic chemicals for a long time.
The National Academy's assessment. How risky is present and future exposure to toxic chemicals in water? This is the question the National Academy of Sciences was charged to answer, as part of the mandate of the 1974 Safe Drinking Water Act. The Academy found too much uncertainty to make a sound evaluation of the risk of cancer. Extrapolations from animal data applied to the concentrations at which nineteen carcinogens and three suspected carcinogens are found in drinking water suggested that the risks are low. However, questions remain because these extrapolations treated each chemical singly, ignoring possible interactions. Synergisms can be extraordinarily powerful; for example, the potency of benzo[a]pyrene as a carcinogen is enhanced a thousandfold by the presence of n-dodecane, which by itself is not a carcinogen.
Moreover, further questions remain because the report did not discuss recent epidemiological studies of cancer and drinking water. About nine of these studies have been carried out. None of them is strongly conclusive, but each suggests an observable link between drinking water that has been used by industry and cancer. (It was epidemiological research that identified the problem of carcinogens in drinking water.)
The Academy report mentioned several teratogens, but only to say that the uncertainty with them is even greater than with carcinogens. As for heavy metals, the report considered chronic lead poisoning to be an especially important problem.
Finally, the report pointed to a new area of concern. It accepted the hypothesis of the association of soft water and cardiovascular diseases as "plausible," and estimated that by treating drinking water for hardness by different methods than now used, the death rate from cardiovascular disease could be cut by 15 percent. If true, soft water is an enormous health problem, since cardiovascular disease is the leading cause of death, with cancer second.
The NCI studies. In the past few years EPA has supported several epidemiological studies of cancer and drinking water. These studies, which all follow the basic methodology of the original Louisiana study, in which an RFF staff member participated, are aggregative in nature and for this reason have distinct limitations. While they are suggestive, they are not entirely independent, as they overlap somewhat in their data sets. In a sense they are hypothesis-forming studies, indicating, for example, that cancers of the gastrointestinal tract and urinary organs appear to be most closely related to carcinogens in drinking water. By the end of 1977 this series of studies appeared to have fulfilled its purpose in the sense that it led to another stage of epidemiological research—the National Cancer Institute's more precise (and costly) case-controlled studies. How these later studies will come out is anybody's guess.
The question at the beginning of 1978 —despite research and regulation progress—remains essentially just as it was posed in 1974 before the enactment of the Safe Drinking Water Act: How much do we need to know before we take precautionary action, and how long can we reasonably wait?
A version of this article appeared in print in the January 1978 issue of Resources magazine.
