Silver toxicity to the earthworm Eisenia fetida is inconsistent in natural and artificial soils amended with wastewater biosolids

Silver nanoparticles (AgNPs) are present in biosolids from wastewater treatment facilities, a common soil amendment. Exposing earthworms ( Eisenia fetida) to AgNP and AgNO 3 in soil with 0 and 7.5 g biosolids kg −1 for 28 days showed AgNO 3 was more lethal to earthworms in artificial soil (LC20 ≤ 325 mg Ag kg −1 ) than natural soil (LC20 ≥ 573 mg Ag kg −1 ). In contrast, AgNPs were more lethal in natural soil (LC20 ≤ 425 mg Ag kg −1 ) than artificial soil (LC20 ≥ 653 mg Ag kg −1 ). Earthworm response to silver in artificial soil may not reflect toxicity in biosolids-amended natural soils.