The Environmental Protection Agency (EPA) proposed new regulations last year that may make it prohibitively expensive to disinfect public water supplies with chlorine. And a provision of a Senate bill would exempt these regulations from cost-benefit analysis.

Chlorine and chlorinated compounds have been used to disinfect water in the United States for nearly 100 years, resulting in the virtual elimination of such water-borne diseases as cholera and typhoid fever. By contrast, an estimated 25,000 people die from water-borne diseases every day in developing countries where public water supplies are not disinfected.

However, when chlorine combines with other organic compounds (such as decomposing leaves) that are in raw water, it creates "disinfection by-products" such as chloroform. The health effects of these by-products are largely unknown, but the EPA says they might cause cancer and has proposed requiring water systems to eliminate the process known as pre-disinfection. Public health officials have protested, saying:

• The regulations would add $4 billion a year to the cost of chlorination.

• Small water systems might be forced to abandon chlorination altogether, adopting alternative treatment methods that produce by-products and health risks of their own.

The Congressional Budget Office points out that the EPA is so unsure of the cancer risk that its estimates of the average cost per cancer case avoided range from $867,000 to as much as $19 billion.

Sources: "Controversial Disinfectants/ Disinfection By-Products Rule Clouds Future of SDWA in House," EPA Watch, Vol. 5, No.1, January 15, 1996; and "The Safe Drinking Water Act: A Case Study of an Unfunded Federal Mandate," Congressional Budget Office, September 1995, Washington, DC.

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