Induction of Genotoxicity by Concurrent Exposure to Titanium Dioxide and Zinc Oxide Nanoparticles in Mice

Abstract

The recent surge in the application of nanotechnology and the specific attractive properties of nanomaterials have led to widespread applications of nanoparticles particularly in life sciences, pharmaceutical, cosmetics and textile industries. This widespread use has also led to worldwide distribution of nanoparticles and consequent increased likelihood of human exposure thereby raising concerns about their safety. Due to the rapid increase in their applications and their exponential industrial production, workers are constantly exposed to these nanoparticles in their workplace. Some previous studies have reported that nanoparticles may generate potential harm to the environment and are both genotoxic and cytotoxic to humans. Other studies argue that they are not. This study therefore aims to assess the genotoxic and cytotoxic potential of a concurrent exposure to nanoparticles using titanium dioxide nanoparticles (TiO₂.NPs) and zinc oxide nanoparticles (ZnO.NPs) in mice. Four groups 2 of mice made up of five animals each were exposed to four different concentrations (25 mg/kg body weight (bw); 50 mg/kg bw, 75 mg/kg bw and 100 mg/kg bw) of the nanoparticles. Each concentration comprised 50% titanium oxide nanoparticles and 50% zinc oxide nanoparticles given separately by oral gavaging for five consecutive days while the control group was treated with distilled water. Bone marrow was harvested for micronucleus assay and the incidence of micronuclei in polychromatic erythrocytes was scored per 1,000 cells. The results showed a concentration dependent increase in the frequency of micronuclei occurrence which was statistically significant at the concentration of 100 mg/kg bw (P < 0.05). Also the ratio of polychromatic erythrocytes to normochromatic erythrocytes was statistically significant at this concentration. This result shows that concurrent exposure to titanium oxide nanoparticles and zinc oxide nanoparticles induces both genotoxicity and cytotoxicity in mice.

Keywords: Nanoparticles, Titanium oxide, Zinc oxide, genotoxicity, micronucleus, erythrocytes