Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6323173 | Science of The Total Environment | 2016 | 10 Pages |
â¢Dietary exposure to ZnO NPs; no effect on growth or in the hepatosomatic indexâ¢Zn translocation into systemic circulation and distribution to liver and gillsâ¢Bioaccumulation of high levels of Zn in the intestine and gillsâ¢Redox imbalances associated with distribution to liver and gills
The increasing use of ZnO nanoparticles (ZnO NPs) in different fields has raised concerns about the possible environmental risks associated with these NPs entering aquatic systems. In this study, using a dietary exposure route, we have analysed the tissue distribution and depuration pattern of Zn as well as any associated redox balance disturbances in rainbow trout (Oncorhynchus mykiss) following exposure to ZnO NPs (20-30Â nm). Fish were fed a diet spiked with ZnO NPs prepared from a dispersion in sunflower oil at doses of 300 or 1000Â mg ZnO NPs/kg feed for 10Â days. This uptake phase was followed by a 28Â days depuration phase in which fish from all groups received untreated feed. While no overt signs of toxicity were observed and no important effects in fish growth (weight and length) or in the hepatosomatic index among groups were recorded, we observed high levels of Zn bioaccumulation in the gills and intestine of exposed fish following exposure to both dose levels. Zn levels were not eliminated during the depuration phase and we have evidenced oxidative stress responses in gills associated with such long term ZnO NPs bioaccumulation and lack of elimination. Furthermore, exposures to higher doses of ZnO NPs (1000Â mg/kg feed) resulted in Zn distribution to the liver of fish following 10Â days of exposure. Fish from this exposure group experienced biochemical disturbances associated with oxidative stress in the liver and ethoxy-resorufin-O-deethylase (EROD) activity which may point to the ability of ZnO NPs or its ions to interfere with cytochrome P450 metabolic processes.
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