Toxicological studies of zinc oxide nanomaterials in rats

Abstract

In this study, we have evaluated the ability of zinc oxide (ZnO) nanoparticles to induce pulmonary and extrapulmonary toxicities was examined in rats following intratracheal (IT) instillation. Lungs of rats were instilled IT with either phosphate-buffered saline (PBS) + 1% Tween 80, ZnO nanoparticles, carbonyl iron or quartz particles at a dose of 1 or 5 mg kg⁻¹ body weight. Following exposure, bronchoalveolar lavage (BAL) fluid, blood samples and organs including lung, liver, kidneys, heart, pancreas, and brain were collected at 24 h, 1 week, or 1 month of post instillation of nanoparticles and different parameters estimated to assess toxicity. BAL fluid was analyzed for lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) to assess pulmonary toxicity. Exposures to ZnO or quartz particles produced transient dose-dependant increase in BAL fluid LDH and ALP activities at all post exposure periods. Blood samples were analyzed for the tissue damage biomarkers to assess extrapulmonary toxicity. Histopathological examination of lung, liver and kidneys revealed dose-dependent degeneration and necrosis which worsened at 1 week post-instillation periods but recovered at 1 month post instillation. Histopathological examination of rat pancreas, heart, and brain exposed to quartz or ZnO particles showed no marked changes. Data suggest the instillation of ZnO nanoparticles produced a greater pulmonary toxicity in rats comparable with quartz; and extrapulmonary toxicities of these ZnO nanoparticles might be due to translocation into liver and kidney.

Keywords:

• nanomaterials
• ZnO
• pulmonary toxicity
• BAL fluid
• LDH
• ALP

Acknowledgments

The authors are thankful to Dr I. Ravinder, Vamshi Krishna Diagnostics, Karimnagar and Dr Md. Anwar, Crystal Diagnostics, Hanmakonda for their help in the interpretation of histological studies. The authors are grateful to G. Kiranmai for her help during this study.