Cytotoxicity and genotoxicity of cerium oxide micro and nanoparticles by Allium and Comet tests

Cerium oxide (CeO2) is extensively used in a range of applications like in television tubes, glass/ceramic polishing agent, fuel cells, solar cells, gas sensor andultraviolet absorbents. In current study, Allium ana-telophase and comet assays were employed to evaluate the cytotoxic and genotoxic effects of CeO2 microparticles (CMPs, < 5 mu m, bulk) and CeO2 nanoparticles (CNPs, < 25 nm) on the root meristem cells of Allium cepa by using mitotic phases, mitotic index (MI), chromosomal aberrations (CAs), and DNA damage. A cepa roots were treated with the CMPs and CNPs at four different concentrations (12.5, 25, 50, and 100 ppm) for 4 h. Methyl methane sulphonate (MMS,10 ppm) and distilled water were used as positive and negative control groups, respectively. All the applied doses statistically decreased MIs. MI values of CMPs were found higher than CNPs. CMPs and CNPs significantly increased CAS such as chromosome laggards, disturbed anaphase-telophase, stickiness and bridges and also DNA damage. Characterization of CMPs and CNPs showed the particle size as 4.24 +/- 0.7 mu m and 20.28 +/- 2.33 nm, respectively. The average diameter of CMPs and CNPs in solution were in the range of 372.75 +/- 70.23 nm and 167.74 +/- 38.7 nm, respectively. These results demonstrated that CMPs and CNPs had cytotoxic and genotoxic effects in A. cepa root meristematic cells.