Zinc oxide nanoparticles induce oxidative stress and histopathological toxicity in the thyroid gland and liver of rats

Zinc oxide nanoparticles are incorporated into cosmetics and sunscreens and are widely used in biomedical applications and the food industry. The increasing use of zinc oxide nanoparticles raises concerns about their safety. The aim of the study was to assess the effects of zinc oxide nanoparticles on oxidative and genotoxic parameters in the thyroid gland and liver of adult albino rats. Rats were divided into three groups; control, vehicle, and zinc oxide nanoparticles (200 mg/kg) and were subjected to treatment for 30 days. Oxidative stress parameters and genotoxicity were determined. Histopathological examination of both organs was undertaken. A significant reduction in triiodothyronine, thyroxine and thyroid-stimulating hormone was noted, whereas aspartate aminotransferase and alanine aminotransferase levels were significantly elevated. Increased malondialdehyde and decreased reduced glutathione levels were indicative of oxidative stress response in both organs. Additionally, elevated serum 8-hydroxydeoxyguanosine was noted which was supported by the results of the comet assay. Histopathological examination revealed alterations in the thyroid gland and liver. Sub-chronic exposure resulted in oxidative stress-mediated toxicity and genetic perturbations in both organs. Caution is warranted with repeated usage of products containing zinc oxide nanoparticles.