Comparative toxicity of organic, inorganic and nanoparticulate zinc following dietary exposure to common carp (Cyprinus carpio)

Abstract

This study was carried out to compare the dietary toxicity of organic zinc (Zn-proteinate, Bioplex Zn®), mineral zinc (ZnSO4), and nanoparticulate zinc (ZnO-NPs) on the basis of some biological responses including growth performance and whole-body proximate composition, and antioxidant enzymes, as well as their accumulative affinity to target organs. These Zn sources with the nominal concentrations of 0, 30, 100, and 500 mg kg−1 diet were added to a basal diet. Juvenile common carp (n = 400; weight of 25.3 ± 2.7 g) were fed with the diets for 56 days. ZnSO4 significantly reduced condition factor (CF) at 500 mg kg−1 diet. The highest activity of superoxide dismutase (SOD) and alkaline phosphatase (ALP) was observed in the plasma of the animals received 500 mg kg−1 diet of all experimental Zn sources. However, this concentration of ZnO-NPs significantly increased the activity of SOD when compared to the respective amount of ZnSO4 and Zn-proteinate. Catalase (CAT) showed a zinc-concentration decreasing activity; the minimum activity was observed in the fish group treated with the diet containing 500 mg kg−1 ZnSO4. Digestive, muscular, and integumentary systems demonstrated the following tissue zinc burden: liver > muscle > bone > posterior intestine ≈ skin > anterior intestine, for ZnO-NPs; liver > muscle ≈ bone ≈ posterior intestine ≈ skin > anterior intestine, for Zn-proteinate; and liver > muscle ≈ bone ≈ skin > posterior intestine ≈ anterior intestine, for ZnSO4. Based on accumulative affinity, taken together, ZnO-NPs displayed the highest affinity to all of the analyzed target organs, and also intestinal Zn accumulation suggested that the gut tissue has the lowest rendering ability against ZnO-NPs in compare to ZnSO4 and Zn-proteinate.