Chronic toxicity of commercial chlorpyrifos to earthworm Pheretima peguana.

A chronic toxicity study was conducted in earthworms (Pheretima peguana) exposed to soil spiked with chlorpyrifos at concentrations of 0, 0.1, 1, 10, and 100 mg/kg soil dry matter for 7, 14, and 28 days. The integrity of the coelomocyte lysosomal membrane, nervous system, and male reproductive tissue was monitored using, respectively, the neutral-red retention assay, acetylcholinesterase (AChE) enzyme assay, and histomorphology of spermatogenic cells in the seminal vesicles and cocoon production (at 28 days after 28 days' exposure).