Toxicity Assessment of Ketamine, Metaphedrone and Methylenedioxypyrovalerone to the Red Earthworm (Eisenia fetida)

Background: The consumption of psychoactive substances (PASs), including ketamine (KET), metaphedrone (3-MMC) and methylenedioxypyrovalerone (MDPV), has increased globally. Their presence in sewage sludge, biosolids and other soil amendments raises concerns about potential impacts on soil organisms and ecosystem functioning. However, their effects on terrestrial ecosystems remain poorly understood. Methods: This study assessed the acute and chronic toxicity of KET, 3-MMC and MDPV in the earthworm Eisenia fetida by evaluating avoidance behaviour, biomass, mortality, genotoxicity and reproduction. Results: Significant avoidance responses were observed only for 3-MMC (25 µg/kg) and MDPV (2500 µg/kg). No significant effects on adult mortality were detected, although MDPV (250 µg/kg) reduced biomass. All three compounds induced genotoxicity in coelomocytes at 250 and 2500 µg/kg. While DNA damage occurred at concentrations above those reported in environmental studies, MDPV significantly reduced reproduction at 25 µg/kg, a concentration detected under real environmental conditions. Conclusions: These findings demonstrate that PASs, particularly MDPV, may pose risks to soil invertebrates, highlighting the need for further ecotoxicological studies across different terrestrial species, trophic levels and environmental compartments to better understand their ecological impacts.