Preliminary data on the ecotoxicity effects of the novel synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV) on Danio rerio during early developmental stages

Background: The use of synthetic cathinones (SC) for recreational purposes has become increasingly common among young individuals in recent years [1]. As a result, SC have been detected in aquatic environments even at low concentrations (between ng L‒1 to µg L‒1) [2] that can negatively impact freshwater vertebrates [3]. Since SC are designed to affect the nervous system, they could potentially cause unpredictable harmful effects on nontarget organisms [1]. Several SC, including 3,4-methylenedioxypyrovalerone (MDPV) were frequently detected in wastewater and aquatic environments [2]. Given the limited research on the ecotoxicity of MDPV, it is essential to evaluate its potentially harmful effects on aquatic organisms. Objective: This work aimed to assess the adverse effects of racemic MDPV on the mortality and embryonic development of zebrafish (Danio rerio) after 96 hours of exposure. Methods:Zebrafish embryos (≈ 3-hours post-fertilization (hpf)) were exposed to different nominal concentrations of MDPV (0.18, 0.35, 0.70, 1.4, and 2.8 μg L‒1) for 4 days at 28 °C, using 50 animals per concentration and control (5 replicates). Mortality data was recorded every day until day 4. Embryonic development data, namely the first spontaneous movements were evaluated at 24-hpf in a random subsample of 10 individuals per concentration and replicate, and hatching rate at 48- and 72-hpf in all alive organisms per concentration and each replicate. Results: MDPV did not cause significant effects on either mortality or embryonic development parameters. Despite that, it should be noted that organisms exposed to MDPV showed a slight increase in the 48-hpf hatching rate (at all concentrations tested) compared to the control. Conclusions: The present study shows that MDPV exposure seems not to impair D. reriodevelopment in the early stages, however, more studies should be performed to verify and clarify the observed effects, as well as the assessment of potential teratogenic effects.