RESUMO
Monocrotophos (MCP) is a highly toxic and broad-spectrum pesticide extensively used for agricultural and household purposes. The present study was aimed to evaluate the genotoxicity and alterations in the biochemical and physiological conditions induced by monocrotophos in a non-target organism, an estuarine bivalve, Donax incarnatus. The bivalves were exposed to three sub-lethal concentrations (6.8, 13.7, and 27.45 ppm) of MCP for a period of 72 h. DNA damage was assessed using the comet assay. Oxidative stress was analyzed using catalase, glutathione peroxidase, and superoxide dismutase. Neurotoxicity was evaluated using the acetylcholinesterase assay (AChE) and the physiological condition was assessed using the condition index (CI). A significant concentration-dependent increase of DNA damage was observed as well as a decline in the activities of the antioxidant enzymes. However, a decrease in DNA damage was observed with advancing time. A significant decrease of AChE activity and CI was observed in the bivalves exposed to MCP. Positive correlations were also observed between DNA damage and the antioxidant enzymes whereas negative correlations were observed between AChE and the antioxidant enzymes indicating MCP toxicity mediated by oxidative stress.