Toxicity assessment of silica nanoparticles on Allium cepa

Nanotechnology is rapidly expanding, and several new nanoparticle products with improved performance have been developed. The environmental fate and toxicity of nanoparticles (NP) is poorly understood and should be studied to enable the safe use of this technology. This study aims to investigate genotoxic and phytotoxic impacts of silica nanoparticles (SiNP) using root tip cells of Allium cepa as an indicator system. A. cepa root tip cells were exposed to different concentrations (1.82 to 0.54 g L-1; dilution factor of 1.5x) of three engineered dispersions of SiNP (TM40 – 22 nm; HS30 – 12 nm; SM30 – 7 nm). The following endpoints were measured: mitotic index, different types of chromosomal aberrations, germination index and root length. A decrease in the mitotic index was observed with increasing NP concentration, and significant decreases in the MI for all tested NP were found. For all NP cytological effects including chromosomal aberrations were observed in treated cells. Phytotoxic effects were also observed as germination rate and root growth were significantly reduced (p<0.05). Plants are an essential component of ecosystems and these findings suggest that they should be included when evaluating the toxicological impact of NP on the environment.