Toxicity assessment of manganese oxide micro and nanoparticles in Wistar rats after 28days of repeated oral exposure

In the near future, nanotechnology is envisaged for large-scale use. Hence health and safety issues of nanoparticles (NPs) should be promptly addressed. Twenty-eight-day oral toxicity, genotoxicity, biochemical alterations, histopathological changes and tissue distribution of nano and microparticles (MPs) of manganese oxide (MnO sub(2)) in Wistar rats was studied. Genotoxicity was assessed using comet, micronucleus and chromosomal aberration assays. The results demonstrated a significant increase in DNA damage in leukocytes, micronuclei and chromosomal aberrations in bone marrow cells after exposure of MnO sub(2)-NPs at 1000, 300mgkg super(-1) bw per day and MnO sub(2)-MPs at the dose of 1000mgkg super(-1) bw per day. Our findings showed acetylcholinestrase inhibition at 1000 as well as at 300mgkg super(-1) bw per day in blood and with all the doses in the brain indicating the toxicity of MnO sub(2)-NPs. Further, the doses significantly inhibited different ATPases in the brain P sub(2) fraction. Significant changes were observed in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in the liver, kidney and serum in a dose-dependent manner. MnO sub(2)-MPs at 1000mgkg super(-1) bw per day were found to induce significant alterations in biochemical enzymes. A significant distribution was found in all the tissues in a dose-dependent manner. MnO sub(2)-NPs showed a much higher absorptivity and tissue distribution as compared with MnO sub(2)-MPs. A large fraction of MnO sub(2)-NPs and MnO sub(2)-MPs was cleared by urine and feces. Histopathological analysis revealed that MnO sub(2)-NPs caused alterations in liver, spleen, kidney and brain. The MnO sub(2)-NPs induced toxicity at lower doses compared with MnO sub(2)-MPs. Further, this study did not display gender differences after exposure to MnO sub(2)-NPs and MnO sub(2)-MPs. Therefore, the results suggested that prolonged exposure to MnO sub(2) has the potential to cause genetic damage, biochemical alterations and histological changes. Copyright [copy 2013 John Wiley & Sons, Ltd. Repeated oral doses of manganese oxide NPs and MPs were administered for 28 days to rats. The genotoxicity results demonstrated significant increase in DNA damage in leukocytes, micronuclei and chromosomal aberrations in bone marrow cells after exposure of MnO sub(2)-NPs at 1000, 300mg/kg/bw/day and MnO sub(2)-MPs at the dose of 1000mg/kgbw/day. Our findings showed significant biochemical an