Table 4.
Toxicity reports of nano zinc supplementation.
| Species | Dose | Organs affected | Toxicity | References |
|---|---|---|---|---|
| Mice | 5 g/kg body weight | Liver, kidney | Inflammation in stomach, intestines, elevated ALT, ALP, and LDH in the nano Zn (nZn) group. Nano Zn supplementation is having less hepatotoxicity than micro Zn. Severe lesions in kidney on histopathological examination in the nZn group. Anaemia, hepatotoxic, renal toxic and also slight stomach and intestinal inflammation. | Wang et al. (2006) |
| Mice | 20-nm and 120-nm ZnO powder at doses of 1-, 2-, 3-, 4-, 5-g/kg body weight | Stomach, liver heart and spleen | Zn was mainly retained in the bone, kidney and pancreas; increase in blood viscosity; 120-nm ZnO treated mice had dose dependant pathological damages in stomach, liver, heart and spleen; 20-nm ZnO displayed inverse dose dependant damages in liver, spleen and pancreas; liver, spleen, heart, pancreas and bone are the target organs of zinc oxide nanoparticles (ZnO NP) on oral exposure. | Wang et al. (2008) |
| Algae, crustaceans and fishes | – | Gene expression of metallothionin, heat shock protein, SOD | More toxic towards algae than crustaceans and fish. The toxicity is due to dissolved Zn2+ ions. Exposure to ZnO NP caused a significant up-regulation of superoxide dismutase (SOD), metallothionein (MT). Heat shock protein 70 was increased 2- to 4-fold indication substantial oxidative stress. | Wong et al. (2010) |
| Zebrafish | 5 mg/L | Stomach, liver | The malondialdehyde levels in the liver was elevated and gut tissues exhibited oxidative effects after exposure. | Xiong et al. (2011) |
| Human | – | Gene expression of keratinocytes | Zinc oxide nanoparticles can produce ROS inducing oxidative stress. Antioxidant enzymes and SOD levels were significantly higher and glutathione levels were decreased in ZnO NP exposed cells; up-regulation of SOD genes by ZnO NP could increase the production of ROS and oxidative stress. | Lee et al. (2014) |
| Sheep | 20 mg/kg body weight orally for 25 d | Liver and kidney | Alkaline phosphatase significantly decreased and creatinine level was significantly increased by ZnO NP. Cell swelling, eosinophilic necrosis of hepatocytes, and multifocal interstitial nephritis were also observed. | Najafzadeh et al. (2013) |
| Eisenia veneta (earthworm) | 250 and 750 mg Zn/kg for 21 d. | Immune activity body Zn concentrations | Zinc oxide nanoparticles are less toxic than ZnCl2. At 750 mg Zn/kg, reproduction declined by 50% when exposed to ZnO NP; but was almost completely inhibited by ZnCl2. Immune activity was unaffected by ZnO NP but was suppressed by 20% when exposed to ZnCl2. Nanoparticles can be taken up in particulate form. | Hooper et al. (2011) |
| Saccharomyces cerevisiae | – | Growth, recombinant microbial sensors | Nano and macro ZnO were of comparable toxicity. The toxicity was explained by soluble Zn ions. | Kasemets et al. (2009) |
| Daphnia magna | – | Reproduction | Toxicity is independent of particle size, coating of particles, aggregation of particles, the type of medium or the applied pre-treatment of the test dispersions. | Wiench et al. (2009) |
| D. magna | 28 and 61 μg/L | Reproduction | Drop in number of juveniles per adult. Drop in reproductive performance from generation to generation. Elevated zinc accumulation in the 61 μg/L. | De Schamphelaere et al. (2004) |
| Folsomia candida | – | Reproduction | Toxicity of the Zn supplementation depends on the Zn ions released, not on the particle size of the Zn sources. Survival of F. Candida was not affected by particle size of ZnO. Reproduction was dose-dependently reduced with the Zn source. | Kool et al. (2011) |
ALT = alanine aminotransferase; ALP = alkaline phosphatase; LDH = lactate dehydrogenase.