The synthetic cannabinoid 5F-ADB induced developmental toxicity in Daphnia magna through disrupting the oxidative stress system and the nervous conduction system.

Methyl 2-{[1-(5-fluoropentyl)-1H-indazole-3-carbonyl]amino}-3,3-dimethylbutanoate (5F-ADB), which is classified as an illicit drug in China and most European countries, is susceptible to abuse. The abuse of 5F-ADB must avoid entering the water environment. However, the aquatic toxic effects of 5F-ADB remain unclear. In this study, Daphnia magna (D. magna) was used to investigate the potential toxicity of 5F-ADB at concentrations of 0, 0.01, 1, and 100 μg/L. The results showed that 5F-ADB caused significant developmental, reproductive, and neurodevelopmental toxicity in D. magna. Compared with the control group, exposure to 5F-ADB significantly reduced daphnia body length, weight, heartbeat, total number of offspring, while increased daphnia respiratory rate, and swimming behavior. Superoxide dismutase (SOD) activity increased significantly, while catalase (CAT) activity decreased, indicating that the exposed daphnia suffered obvious oxidative damage. 5F-ADB also triggered the inhibition of the serotonergic and noradrenergic systems, which ultimately stimulated the swimming behavior of D. magna. This study demonstrates that 5F-ADB has a significant toxic effect on the vital activity of D. magna upon entering aquatic environments, and that synthetic cannabinoid analogs such as 5F-ADB may pose potential ecological risks to organisms in aquatic ecosystems.