Accumulation and depuration of dissolved hexavalent chromium and effects on the antioxidant response in bighead carp (Aristichthys nobilis)

The present study investigated the accumulation and depuration effects of hexavalent chromium (Cr 6+ ) in ten tissues (gills, intestines, liver, kidney, blood, heart, bladder, spleen, skin and muscle) of the bighead carp ( Aristichthys nobilis ). Fish were exposed to graded levels of waterborne Cr 6+ (0.01, 0.1, 1 and 5 mg/L) for 4, 7 and 14 days, and subsequently transferred to Cr 6+ -free water for 14 days. After 14-day exposure, a dose-dependent increase of Cr 6+ has been observed in most tissues. While after 14-day depuration, Cr 6+ contents were significantly decreased in various tissues except in kidney and spleen where Cr 6+ contents significantly increased at the group of 5 mg/L. Considering that Cr 6+ highly accumulated in gills, intestines, liver and kidney, the oxidative damage of Cr 6+ on the four tissues were further investigated and found that the antioxidant response to Cr 6+ were organ-specific. The results in this study indicated that a 14-day period is effective for accumulation and depuration of Cr 6+ in bighead carp and there was no health risk of fish muscle consumption. Additionally, the delayed efflux of Cr 6+ in the fish kidney and spleen indicates that high importance should be attached to them when evaluating the toxic effects and risk assessments of Cr 6+ .