Chronic and Transgenerational Effects of Polystyrene Microplastics at Environmentally Relevant Concentrations in Earthworms (Eisenia fetida)

Recently, soil contamination with microplastics has emerged as a serious global environmental concern that has necessitated more research on their potential impacts on soil biota. We investigated the acute and chronic toxicity of 2 different polystyrene microplastics, pure versus commercial (0–0.5% w/w in soil; sized 65–125 µm) on earthworm mortality, reproduction, and genotoxicity. Whereas the microplastics showed no acute toxicity in terms of mortality, reproduction was adversely affected in both parents (F0) and first filial generation (F1) of earthworms, with >50% reduction in juvenile production at 0.5% microplastics concentration in soil. Also, significant genotoxicity in terms of DNA damage was observed in the F0 and F1 earthworms. Chemical analysis of microplastic-exposed soils showed the presence of several benzene derivatives that are associated with polystyrene particles. Our study, for the first time to our knowledge, demonstrated the long-term adverse effects on earthworms of polystyrene microplastics even at environmentally relevant concentrations. The results have significant implications for risk assessment of polystyrene microplastics to soil biota.