The behavioral, physiological, and biochemical responses of Lumbriculus variegatus exposed to cannabidiol and its metabolites.

Cannabidiol (CBD) is a major non-psychoactive cannabinoid that has been detected in environmental samples, but the ecotoxicological effects remain unknown. In this study, Lumbriculus variegatus were exposed to CBD and its metabolites 7-hydroxy-cannabidiol (7-OH-CBD) and 7-carboxy-cannabidiol (7-COOH-CBD). In this study, toxicity, tactile stimulation to elicit stereotypical behaviors, and locomotor activity were measured after 24-hr exposure of L. variegatus to CBD and its metabolites. We describe the impacts on dorsal blood vessel pulsation and oxygen consumption after 24-hr exposure to CBD and 7-OH-CBD and the effects on regenerative capacity and total energy reserves after 72 hr of exposure to CBD and 7-OH-CBD. We observed that CBD, 7-OH-CBD, and 7-COOH-CBD displayed toxicity in 50% of test populations at 14.12 µM, 11.29 µM, and 15.36 µM, respectively. A 24-hr exposure to CBD decreased tactile stimulation response to elicit body reversal at ≥ 2.5 µM and helical swimming at ≥ 0.5 µM and reduced locomotor activity. Lumbriculus variegatus oxygen consumption was not affected by CBD, but ≥ 2.5 µM significantly reduced dorsal blood vessel pulse rate. We observed that exposure to 7-OH-CBD did not affect the regenerative capacity of L. variegatus whereas CBD was shown to reduce regeneration. Exposure to CBD also resulted in a significant decrease in carbohydrates, increased lipids, and no effect on protein levels in L. variegatus. We determined that CBD can reduce L. variegatus behaviors, decrease pulse rates and regenerative capacity, and disrupt energy reserves. Our findings show that CBD is toxic to this common aquatic organism and the increased availability and use of CBD and related substances warrants further study of their environmental impact.