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Impact of toxicity effects of zinc oxide nanoparticles in rats within acute and subacute experiments

Introduction. Occupational air is contaminated with zinc oxide nanoparticles in the copper smelting industry, especially in the smelting of brass and copper. A wide range of toxic effects with varied clinical symptomatology is observed in zinc and its compounds. Competitive relations with many other metals, including calcium, copper, and iron, are the foundation of most cases of zinc intoxication. Long-term administration of zinc or its compounds to laboratory rodents affects enzymes, carbohydrates and mineral metabolism. Materials and methods. Subchronic intoxication with repeated intraperitoneal injections and acute low respiratory tract reaction to a single intratracheal injection of zinc nanoparticles were simulated in outbred white rats. Water suspensions of zinc oxide nanoparticles with a 30-80 nm diameter were applied in both experimental models. Upon completion of the exposure, the condition of the rats in all groups was evaluated in many generally accepted criteria for toxicity. The student’s t-test was applied for statistical analysis of the obtained data. Results. Moderate intoxication development in a subchronic experiment is demonstrated. Homogeneous ultrastructural changes in the spleen tissue were revealed. Mitochondrial damage with partial or complete loss of crista is the most common. The fragmentation ratio of DNA was found by a statistically significant increase. A single intratracheal injection of zinc oxide nanoparticles revealed the increase in the attraction of cells capable of their phagocytosis (mainly neutrophils) into the low respiratory tract. This shows their cytotoxicity. Conclusion. Moderate general toxic and cytotoxic effects of zinc oxide nanoparticles on the rat body were identified.