Chlorophenols have contaminated the drinking water system and the local lake in the village of Järvelä in southern Finland. Local geology, ground water streams, and chemical analyses incriminated a local sawmill as the only plausible source of exposure. Cancer incidence in the municipality of Kärkölä (half of the population lives in Järvelä), compared with the rest of the local health-care district and with the greater cancer control region, indicated an excess of soft-tissue sarcomas and non-Hodgkin's lymphomas. A case-control study, which focused on cancers of the colon, bladder and soft tissues, lymphomas, and leukemia, demonstrated a significantly elevated risk ratio for non-Hodgkin's lymphomas among persons who consumed fish from the local lake, which was contaminated with chlorophenols. Probable exposure to chlorophenol-contaminated drinking water played a role in the increased incidence of non-Hodgkin's lymphomas and possibly was a factor in the development of soft-tissue sarcoma.