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Transcriptomic and metabolic responses of earthworms to contaminated soil with polypropylene and polyethylene microplastics at environmentally relevant concentrations

Journal of Hazardous Materials 2021 126 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Keyi Chen, Keyi Chen, Ronggui Tang, Yongming Luo, Youchao Chen, Youchao Chen, Ali El‐Naggar, Jianhang Du, Aiai Bu, Yan Yan, Xinghang Lu, Yanjiang Cai, Scott X. Chang

Summary

Researchers studied how environmentally realistic concentrations of polypropylene and polyethylene microplastics affect earthworms at the molecular level. They found that both plastic types triggered oxidative stress, damaged digestive and immune systems, disrupted lipid metabolism, and altered the earthworms' ability to regulate water balance. The study suggests that even at concentrations commonly found in the environment, microplastic-contaminated soil poses measurable health risks to earthworms.

Examining transcriptomic and metabolic responses of earthworms to microplastic-contaminated soil is critical for understanding molecular-level toxicity of microplastics; yet very little research on this topic exists. We investigated influences of environmentally relevant concentrations (ERC) of polypropylene (PP) and polyethylene (PE) microplastic-contaminated soil on earthworms at the transcriptomic, metabolic, tissue and whole-body levels to study their molecular toxicity. The addition of PP and PE at ERC induced oxidative stress on earthworms, as indicated by the high enrichment of glutathione metabolism and increased glutamine at the transcriptomic and metabolic levels. Digestive and immune systems of earthworms were damaged according to the injuries of the intestinal epithelium, partial shedding of chloragogenous tissues and unclear structure of coelom tissues, which were confirmed by pathway analysis at the transcriptomic level. Significant enrichment of arachidonic acid and glycerolipid metabolisms indicated that PP and PE disturbed the lipid metabolism in earthworms. Significantly increased betaine and myo-inositol, and decreased 2-hexyl-5-ethyl-3-furansulfonate suggested that PP and PE caused differences in osmoregulation extent. In conclusion, most similar responses of earthworm might result from special size rather than type effects of PP and PE microplastics. Contamination of soils with microplastics even at ERC has health risks to earthworms; therefore, proper management of microplastics to reduce their input to the environment is key to reducing the health risks to soil fauna.

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