THE RIDDLE OF HEPATIC NEOPLASIA IN BROWN BULLHEADS FROM RELATIVELY UNPOLLUTED WATERS IN NEW-YORK-STATE

Since 1985, pathologists at Cornell University have investigated the c auses of lesions in freshwater fish throughout New York waters in orde r to clarify possible impairment of fish health by environmental conta minants. Fishermen and biologists alerted us to several relatively pro tected reservoirs and ponds in which we have found no evidence of elev ated levels of anthropogenic environmental contaminants but in which u p to 100% of brown bullheads exhibited skin neoplasia. Complete necrop sies and histologic study revealed that over 30% of mature brown bullh eads from some of these sites had benign or malignant hepatocellular o r biliary liver neoplasia. Up to 50% of brown bullheads had benign or malignant liver neoplasia in other relatively unpolluted waters with n o evidence of skin neoplasia in bullheads. Multiple samplings of brown bullheads from several of these sites have revealed puzzling variabil ity in the prevalence of skin, liver, and other neoplasia in these fis h populations. The cause of these striking epizootics of neoplasia in brown bullheads in unpolluted waters in New York State remains unclear . We hypothesize that natural carcinogens such as N-nitroso compounds formed in aquatic sediments or radon from geologic formations may cont ribute to epizootic fish neoplasia in New York waters.