Reproductive toxic effects of polypropylene microplastics of different particle sizes on earthworms

Using earthworms as test organisms, soil exposure experiments were conducted with polypropylene microplastics (PP-MPs) of different particle sizes to investigate the reproductive toxic effects of PP-MPs of different particle sizes on earthworms.The results indicate that earthworms can absorb and accumulate PP-MPs of different particle sizes (50, 250, 500 µm) accumulated in the soil, and the PP-MPs accumulated in earthworms significantly inhibited sperm density and activity, as well as the activity of Ca^{2 +} -ATPase, Mg^{2 +} -ATPase, and Na ⁺ -K ⁺ -ATPase in the testes, and induced a significant increase in the rate of sperm abnormalities. The reproductive toxicity of PP-MPs to earthworms increased with prolonged exposure.Compared to the 250 and 500 µm particle size treatment groups, earthworms exhibited a greater capacity to absorb and accumulate 50 µm PP-MPs, corresponding to stronger reproductive toxicity.