Seneca County, New York: an area with low cancer mortality rates.

The combined mortality rates for all high-rate neoplasms and for all malignant neoplasms combined are considerably lower in Seneca County, New York, than in its surrounding counties. The possibility that these lower rates are attributable to the geochemical uniqueness of the two lakes that enclose the county, availability and concentration of selenium, high salinity of the lakes, and high concentration of potassium cations is discussed.