Background. From 1964 to 1986, the Solvay industrial complex in Tavaux (Jura) operated a landfill for chlorinated organic waste located in a clay basin. These substances gradually migrated into the groundwater. The contaminated area covers approximately 40 km² and affects five municipalities in the Jura and four in the Côte-d'Or. The public drinking water system, supplied by upstream wells, is not affected by the pollution. A detailed risk assessment nevertheless concluded that there is a long-term health risk in the event of repeated ingestion of groundwater or regular swimming in pools supplied by this water. Objective. The aim of this study is to investigate excess mortality or excess cancer incidence in the municipalities affected by the water use restriction, compared to mortality (or incidence) of these conditions in the rest of the Côte-d'Or and Jura departments. Results. The study did not reveal any excess mortality, either in the most affected municipalities or in the periphery of the groundwater use restriction zone. Cancer incidence data for the Côte-d'Or municipalities in the study area monitored by cancer registries also show no excess risk. Discussion. This epidemiological approach, applied to a small population, has limited statistical power, which does not allow for the objective assessment of the slight excesses in mortality or incidence consistent with the scenarios established by the detailed risk assessment. Since the scenarios posing the greatest health risks are based on individual behaviors that are likely infrequent, a field survey is currently underway to individually identify private wells and boreholes and assess the use made of water from the contaminated aquifer, in order to more precisely characterize the actual risk involved. (R.A.)