Diclofenac eco-geno-toxicity in freshwater algae, rotifers and crustaceans

Abstract

This study assessed the eco-genotoxic impact of diclofenac (DCF) in sentinel species of the freshwater ecosystem. DCF residues are found in freshwater from few ng/L to tens of μg/L due to the inability of conventional wastewater treatment plants to ensure removal efficiency of the drug. An ample body of literature reports on the acute toxicity of DCF in non-target organisms without addressing potential chronic long-term effects on organisms at actual, environmental concentrations. Herein, assessment for acute and chronic toxicity was performed on organisms in vivo exposed to DCF, specifically on the green alga Raphidocelis subcapitata, the rotifer Brachionus calyciflorus and the crustacean Ceriodaphnia dubia. Furthermore, potential DNA damage and expression of antioxidant genes (MnSOD, Cu/ZnSOD and CAT) were evaluated in crustacean neonates. The toxicological risk of DCF was assessed as well as its. GENOTOXIC RISK: The acute toxicity was observed at concentrations far from those of environmental concern. Rotifers and crustaceans were much more chronically sensitive than the algae to DCF, observing besides, the median effect concentrations at tens of μg/L. In crustaceans, DNA damage was noted at units of μg/L, revealing concentrations of environmental concern. The dysregulated activity of SOD and CAT also showed the ability of DCF to provoke oxidative stress. On assessment of environmental risk, the chronic Risk Quotient (RQ) was above the threshold value of 1. Nevertheless, the genotoxic RQ was significantly greater than the chronic RQ, thus, the need of regulatory bodies to acknowledge the genotoxic impact as an environmental risk factor. To our knowledge, this study is the first investigation to perform environmental genotoxic risk assessment of DCF.

Keywords: Algae/rotifers/crustaceans; CAT/MnSOD/CuSOD level expression; Chronic risk assessment; Comet assay; Genotoxic risk assessment; Real-time qPCR.