| Summary: | Canada is the world's leading uranium (U) producer; mining and milling operations in northern Saskatchewan generate about one third of total global production. These activities discharge U directly into aquatic ecosystems, where it accumulates in sediments. In turn, fish accumulate U via ingestion of sediments and contaminated diet items. However, there is a paucity of data regarding accumulation and deleterious effects of U in freshwater fish. To address these issues, a benthic feeding fish, lake whitefish (Coregonus clupeaformis), was fed a commercial diet containing U at concentrations of 100 $\mu$g/g, 1000 $\mu$g/g, and 10 000 $\mu$g/g for 10, 30, and 100 days. The exposure concentrations represent the reported range of U concentrations in sediments of impacted systems in Canada. The results indicate that diets containing concentrations of U at least as low as 100 $\mu$g/g exert sub-lethal toxicity in lake whitefish. The most sensitive and reliable indicators of U exposure and toxicity are: U residues in intestines, liver, kidney, bone, and scales, LPO in serum, and histopathologies in liver and posterior kidney. (Abstract shortened by UMI.)
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