Toxicological response and its reversibility in rats fed Lake Ontario or pacific coho salmon for 13 weeks

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Abstract
Lake Ontario [USA, Canada] coho salmon were known to contain a mixture of chemical contaminants. A previous study demonstrated that rats fed the Lake Ontario fish-supplemented diet for 28 days exhibited mild biochemical and histological changes. The purpose of the present study was to determine the effects due to a longer term of exposure and the reversibility of these effects. Growth rate and food consumption were not affected by feeding the animals with Lake Ontario or Pacific fish-supplemented diets for 13 wk. No deaths were observed. Decreased spleen weights were observed in groups of males fed 1.45 and 5.8% Lake Ontario and 2.9% Pacific diet. After a 13 wk recovery the spleen weights returned to normal. Decreased serum K was observed in male rats fed 2.9% Lake Ontario diet, and all levels of Pacific diet for 13 wk, and was not evident following maintenance on normal diet. Serum glucose was not affected by the 13 wk period of treatment; a reduction in this parameter occurred in male rats fed the 2 highest doses of Lake Ontario diet and all doses of Pacific diet following the 13 wk recovery period. Minor hematological changes occurred only in the male rats fed Lake Ontario or Pacific diet following a 13 wk recovery period and included reduced marrow myeloid cells and myeloid/erythroid ratio. Hepatic microsomal ethoxyresorufin deethylase activity was significantly increased in rats ingesting Lake Ontario diet. Mild histological changes occurred in the liver and thyroid of the treated males, and in the liver and kidney of the treated females. These changes were attributed to the chemical residues and/or the fish diet. The Lake Ontario fish-supplemented diet caused mild biochemical, hematological and histological changes but most of these were reversible when exposure was terminated.