Risk assessment methodologies form the basis for deriving guidelines for environmental contaminants in drinking water. A state may have to set, on an emergency basis, an interim guideline for a drinking water contaminant for which only limited data are available. Additional national drinking water standards will be useful for state regulatory agencies, because maximum contaminant levels (MCLs) are legally enforceable, but the risk assessment formulations of the regulatory agencies can be challenged. A state has to issue advisories and set interim guidelines for use of water for non-drinking purposes such as washing hands, cleaning dishes, taking baths, and showers, etc. The exposure to volatile organic compounds via inhalation and through dermal absorption during showering and bathing may be equal to the exposure from ingesting 2 L/day of the same water. Further research in this area is indicated. The implementation of drinking water regulations is costly for some local water supply programs and state regulatory agencies. There is a need to find solutions to this problem. This paper was presented at the symposium on Drinking Water Issues at the 12th Annual Meeting of the American College of Toxicology held at Savannah, GA on October 21–23, 1991. The opinions presented here are solely those of the author. They do not necessarily reflect the official policy of the author's organizational affiliation (Michigan Department of Public Health or FSTRAC) or of any state or other government agency.
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