Interaction of titanium dioxide and zinc oxide nanoparticles induced cytogenotoxicity in Allium cepa

The extensive production and utilisation of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) in consumable items may enhance significant increase in fauna and flora exposure. Studies showing the interactive effect of NPs in biological systems are limited. Herein, we showed the cytogenotoxic effects of TiO2 and ZnO NPs, and their mixture (1:1) using the Allium cepa assay. Mitotic index (MI) and chromosomal aberrations (CAs) were assessed in A. cepa L. bulbs exposed to each NP and their mixture at concentrations of 5, 10, 20, 40 and 80 mg L−1, respectively. The recovery effect of the root tip cells from the cytogenotoxic effects of the nanoparticles was also investigated. TiO2, ZnO NPs and their mixture significantly (p < 0.05) induced increase in CA and reduction in MI in A. cepa root cells, but the mixture induced the highest frequency of CA and reduction in MI. When the treated meristematic cells were placed in water for recovery, there were reduction in the number of aberrant cells in A. cepa exposed to TiO2 and the mixture. Interactive factor analysis of the effects of the mixture showed antagonism. The aberrations induced by TiO2 NPs appeared to be transient while those induced by ZnO NPs may be transmissible due to the increase in frequency of aberrations in the recovery test. This finding showed the potential of tested NPs to induce mutation in somatic cells, and is of public and environmental health significance.