Selenium toxicosis in wild aquatic birds.

Severe gross and microscopic lesions and other changes were found in adult aquatic birds and in embryos from Kesterson Reservoir (a portion of Kesterson National Wildlife Refuge), Merced County, Calif., during 1984. Adult birds from that area were emaciated, had subacute to extensive chronic hepatic lesions, and had excess fluid and fibrin in the peritoneal cavity. Biochemical changes in their livers included elevated glycogen and non-protein-bound sulfhydryl concentrations and glutathione peroxidase activity but lowered protein, total sulfhydryl, and protein-bound sulfhydryl concentrations. Congenital malformations observed grossly in embryos were often multiple and included anophthalmia, microphthalmia, abnormal beaks, amelia, micromelia, ectrodactyly, and hydrocephaly. Mean concentrations of selenium in livers (94.4 ppm, dry weight) and kidneys (96.6 ppm) of birds collected at the Kesterson ponds were about 10 times those found at a nearby control area (8.3 and 12.2 ppm). We conclude that selenium present in the agricultural drainage water supplied to the Kesterson ponds accumulated in the food chain of aquatic birds to toxic concentrations and caused the lesion and other changes observed.

Amyotrophic lateral sclerosis in a high selenium environment.

During a ten-year period, four cases of amyotrophic lateral sclerosis have been found in a sparsely populated county (population 4,000) in west-central South Dakota. The patients were unrelated male farmer-ranchers between 57 and 66 years of age, living within a 15-km radius of each other. The cases occurred in a region where naturally occurring selenium toxication is endemic in farm animals.