Oxidative and genetic responses induced by Δ-9-tetrahydrocannabinol (Δ-9-THC) to Dreissena polymorpha

Cannabis is the most used illicit substance worldwide and its main psychoactive compound, the Δ-9-tetrahydrocannabinol (Δ-9-THC), is detected in aquatic environments at measurable concentrations. Even though its occurrence is well documented, no information is available on its hazard to aquatic organisms. The aim of this study was to assess the adverse effects induced to zebra mussel (Dreissena polymorpha) specimens by 14 day exposures to environmentally relevant Δ-9-THC concentrations (0.05 μg/L and 0.5 μg/L) by means of the application of a biomarker suite. Catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione S-transferase (GST) activities, as well as the lipid peroxidation (LPO) and protein carbonyl content (PCC), were measured as oxidative stress indices. The single cell gel electrophoresis (SCGE) assay, the DNA diffusion assay and the micronucleus test (MN test) were applied to investigate DNA injuries, while the neutral red retention assay (NRRA) was used to assess Δ-9-THC cytotoxicity. The lowest treatment induced negligible adverse effects to bivalves, while 0.5 μg/L Δ-9-THC exposure caused remarkable alterations in D. polymorpha oxidative status, which lead to significant increase of lipid peroxidation, protein carbonylation and DNA damage.