INORGANIC ARSENIC - A NEED AND AN OPPORTUNITY TO IMPROVE RISK ASSESSMENT

This paper presents views on the current status of (inorganic) arsenic risk assessment in the United States and recommends research needed t o set standards for drinking water. The opinions are those of the Arse nic Task Force of the Society for Environmental Geochemistry and Healt h, which has met periodically since 1991 to study issues related to ar senic risk assessment and has held workshops and international confere nces on arsenic. The topic of this paper is made timely by current sci entific interest in exposure to and adverse health effects of arsenic in the United States and passage of the Safe Drinking Water Act Amendm ents of 1996, which has provisions for a research program on arsenic a nd a schedule mandating the EPA to revise the maximum contaminant leve l of arsenic in drinking water by the year 2001. Our central premise a nd recommendations are straightforward: the risk of adverse health eff ects associated with arsenic in drinking water is unknown for low arse nic concentrations found in the United States, such as at the current interim maximum contaminant level of 50 mu g/l and below. Arsenic-rela ted research should be directed at answering that question. New epidem iological studies are needed to provide data for reliable dose-respons e assessments of arsenic and for skin cancer, bladder cancer, or other endpoints to be used by the EPA for regulation. Further toxicological research, along with the observational data from epidemiology, is nee ded to determine if the dose-response relationship at low levels is mo re consistent with the current assumption of low-dose linearity or the existence of a practical threshold. Other recommendations include add ing foodborne arsenic to the calculation of total arsenic intake, calc ulation of total arsenic intake, and encouraging cooperative research within the United States and between the United States and affected co untries.