Multi-biomarker assessment of chronic toxicity induced by the chemical warfare agent adamsite in Danio rerio

Several hundred thousand tons of chemical warfare agents (CWAs) were disposed of at sea, leading to environmental contamination. Among the most toxic and persistent CWAs is adamsite; however, the ecotoxicological data on this compound is limited. Presented research focuses on the long-term effects of adamsite on fish. A 28-day exposure study was conducted, evaluating the impact of adamsite on life history parameters (body length, body mass, growth rate), tissue accumulation, and the expression/activity of detoxification-related enzymes in the model fish species, Danio rerio. Results indicate that chronic adamsite exposure significantly reduces body length, weight, and growth rate of fish at trace concentrations (0.20 and 0.25 μg × L^-1). Adamsite-related compounds accumulate in fish muscle tissues, increasing by approximately 4 μg per gram (dry weight) for every microgram of adamsite per litre of water during chronic exposure. The mRNA expression and activity of detoxification-related enzymes were elevated in the gills of fish, indicating oxidative stress. This study highlights the severe chronic toxicity of adamsite, which could not be anticipated based on acute toxicity. It underscores the need for comprehensive long-term toxicity assays for CWAs and emphasizes the potential ecological and health risks posed by adamsite, necessitating more stringent risk assessments.