Arsenic is widely found in nature. Its inorganic form has been classified as a definite human carcinogen by the International Agency for Research on Cancer since 1980. The maximum permissible concentration of arsenic in water intended for human consumption—where arsenic is primarily in inorganic form—currently stands at 50 micrograms per liter (μg/L) and will be lowered to 10 μg/L in December 2003, in accordance with regulatory changes. The carcinogenic risk associated with ingesting arsenic from water is typically skin cancer. In recent years, epidemiological research in the general population has intensified, and other health risks have been studied in relation to exposure to waterborne arsenic: bladder and lung cancers, cardiovascular diseases, and non-insulin-dependent diabetes in particular. In 1997, more than 100,000 people in Auvergne were supplied with water whose arsenic levels exceeded the future standard of 10 micrograms per liter. In 1999, the Puy-de-Dôme Departmental Health and Social Services Office (DDASS) referred the matter to the Rhône-Alpes-Auvergne Regional Health and Safety Commission (CIRE) regarding the risks faced by populations exposed to these levels of arsenic in drinking water. This report presents 1) a review of epidemiological knowledge regarding the health effects associated with chronic exposure to arsenic in water among the general population and 2) the results of a quantitative health risk assessment conducted in Allier, Puy-de-Dôme, and Haute-Loire. Based on the results of the risk assessment, it is essential to take immediate measures to reduce arsenic concentrations in water intended for human consumption to below 10 micrograms per liter. Comprehensive and continuous monitoring of exposure is necessary to improve the management of this risk. (R.A.)