GUEST EDITORIAL Control of organic contaminants in drinking water On February 9, 1977, the Environmental Protection Agency proposed regulations to limit organic contaminants in drinking water. This action was taken to call public attention to the health problems posed by such contaminants and to the specific details of our suggested regulatory approach. We look forward to valuable public debate of the issues involved. EPA believes there are two dimensions of the organic problem in drinking water. The first is a family of compounds call trihalomethanes (including chlorine), formed as a by-product of disinfection and caused primarily by the inter-reaction of chlorine and naturally occurring humic substances. These contaminants are all but universally present wherever chlorination is practiced. The second area of concern is man-made organic chemicals that find their way into our drinking-water sources from pollution and are largely uncontrolled by current treatment practices. Here our prime focus is on the list of 21 carcinogens identified by the National Academy of Science. The list of such compounds will doubtlessly grow in the future as research progresses. Even with projected tighter discharge controls for toxic and hazardous pollutants, EPA believes there is a need for modification at the water treatment plant wherever raw-water sources are vulnerable to such contaminations. Treatment technologies are available to reduce human exposure to both parts of the problem. Trihalomethane levels can be reduced without reducing bacteriological quality, and reduction in the broad spectrum of organic contaminants can be achieved by the addition of granular-activated carbon. The proposed regulation addresses both aspects of the problem establishing a Maximum Contaminant Level for total trihalomethanes and requiring granular-activated carbon for systems vulnerable to contamination with synthetic organic chemicals. Both parts of the regulation propose a phased-implementation process initially covering systems serving pop-
ulations greater than 75 000, which includes about one hundred million people. For the treatment techniques the regulations prescribe a three- to five-year development schedule including monitoring, pilot studies, design and construction. EPA’s rational for making this proposal may be described in four sentences. First, there is sufficient reason to believe organic contaminants may pose a serious risk to health, and the main stream of scientific thought supports the reduction of human exposure to carcinogens whenever it is feasible to do so. Second, outside of an unexpected breakthrough, health-effects scientists foresee little improvement in our ability to discern the magnitude of health risks with significantly greater precision within the next few years. Third, the anticipated costs are in our judgment reasonable, at least for larger systems, and the requisite technology is available. Fourth, regulatory action is necessary to precipitate the use of the appropriate technology. Since these regulations will constitute a major step in water treatment, the active participation of the professional community is critical at this time. The quality of the ultimate regulation will be directly related to the extent and clarity of current communication. These and other issue are addressed in the proposed regulation and available supporting documentation. EPA wishes to invite as many people as possible to obtain these materials by writing to me at U.S. EPA, (WHSSO), 401 M Street, S.W., Washington, D.C. 20460.
Victor J. Kimm is Deputy Assistant Administrator f o r Water Supply, US.Enuironmental Protection Agency, and is responsible for the administration of the Safe Drinking Water Act.
Volume 12, Number 4, April 1978
363
