Toxicity induction by nano polystyrene in Allium cepa L. seedlings

In recent years there has been a great emphasis on the problems related to worldwide plastic pollution that affects all environmental matrices such as marine and fresh water, soil and atmosphere. Plastics persist in the environment undergoing fragmentation into smaller pieces to generate macroplastics (˃ 2 cm), mesoplastics (5 mm - 2 cm), microplastics (<5 mm), and nanoplastics (≤100 nm). Especially the smaller fractions are of specific concern as they have been found in agroecosystems where they can interact with animals and plants, entering the food chain up to humans. Our research considers the effects of plastic nanoparticles (P-NPs) (Red Dyed Polystyrene, 50 nm, 0.01, 0.05, 0.1 and 1g/L concentrations) on Allium cepa L., well known model plant for ecotoxicological studies. Acute phytotoxicity effects were observed during seed germination after 3 days exposure, while genotoxic effects were revealed by cytogenetic analysis of primary root meristems, in a dose dependent manner. Oxidative stress markers analysis (content of H2O2 and of thiobarbituric acid reactive substances) and histochemical localization of H2O2 in root tissues, indicated toxic effects especially at the highest doses. TEM analysis of root cells displayed NPs internalization and damages in different cell compartments. Our data indicate that P-NPs can enter plant cells inducing phytotoxicity, genotoxicity and oxidative stress; moreover, their entry into plants induces food plants contamination and entry into food chain.