Evidence-based meta-analysis of the genotoxicity induced by microplastics in aquatic organisms at environmentally relevant concentrations.

Microplastics (MPs) attract global concern due to their ubiquitous existence in aquatic environments. However, the genotoxic effect of MPs on aquatic organisms in the natural environment remains controversial. Therefore, this meta-analysis was conducted by recompiling 44 individual studies from 12 publications to determine whether MPs could induce genotoxicity in aquatic organisms at environmentally relevant concentrations (≤1 mg/L, median = 0.5 mg/L). Multiple genotoxic endpoints were involved, including the percentage of DNA in tail (TDNA%), tail length (TL), olive tail moment (OTM), and the number of micronuclei (NM), and their increases represented the biologically adverse effects (i.e. genotoxicity). The results showed that all included endpoints tended to increase after exposure to MPs, among which TDNA%, TL and NM were significantly increased by 20%, 32% and 81% compared with the control group, respectively. The overall estimate of all endpoints in the MPs-treated groups was remarkably increased by 24%, with high statistical power and no obvious publication bias, suggesting the evident genotoxicity caused by MPs. In addition, the magnitudes of MPs-induced genotoxicity were independent of selected endpoint, MP composition, morphology, exposure concentration and duration, but closely correlated with particle size, living habitat and tested species. Overall, this work provided a reference for the health risk assessment of MPs in the natural environment, contributing to our understanding the action mode of MPs at environmentally relevant concentrations.