2,3,7,8 Tetrachlorodibenzodioxin in fish from the Pigeon River of eastern Tennessee, USA: its toxicity and mutagenicity as revealed by the Ames Salmonella assay.

Levels of 2,3,7,8 tetrachlorodibenzodioxin (TCDD) were determined in both striated muscle (fillets) and whole body extracts of fish specimens harvested during a two-year period (1987-1989) from the Pigeon River (between Hartford and Newport) of Eastern Tennessee (USA). Whole body (wet weight) fish extract levels as high as 117 micrograms/kg body weight and composite fish fillet (wet weight) extract levels as high as 87 micrograms/kg fillet weight were observed. Pure TCDD was found to be highly toxic to the Salmonella typhimurium strains TA97, TA98, and TA100 at dosages which exceeded 825 ng TCDD/ml in the top agar of the Ames Salmonella assay. An 825 ng/ml TCDD dosage was not mutagenic to any of the tested Salmonella strains, either with or without metabolic activation (S9 mix). However, when acidic fish extracts from the Pigeon River were tested for mutagenicity, most of the fish extracts were mutagenic to Salmonella strains TA97, TA98, and TA100. These mutagenic extracts also demonstrated mutagenic dose-response curves. Other chemicals within the extracts as well as synergistic effects may account for the mutagenicity.