Abstract

Over the last several decades, the nanotoxicology of zinc oxide nanopaarticles (ZnO-NPs) has remained a debate topic in scientific community. Even though many researchers have attempted to elicit the mechanisms of ZnO nanotoxicity, their potential hazardous impact on humans, animals, and the environment are not yet fully understood. Prior to their safe use in biomedical, industrial, and environmental applications, it is essential to comprehensively assess their risks. This review summarizes in vivo investigations of ZnO-NPs, focusing on their interactions with different morphologies and cell types. The toxicological effects on major organs including the lung, liver, kidney, spleen, pancreas, brain, testis, skin, and reproductive organs and several mammalian cell lines was discussed using rat, mouse, domestic hens, and human cell lines. Furthermore, the impact of various exposure routes, such an acute and sub-acute inhalation, inhalation, intratracheal instillation, pharyngeal aspiration, intranasal and oral administrations, intraperitoneal injection (IP), and intravenous (IV) injection were demonstrated. Finally, the challenges of the recent assessments of ZnO nanotoxicity and future recommendations were summarized.