Genotoxicity assessment in estuarine environments using oyster hemocytes: a comparative comet assay study

ABSTRACT The comet assay with sentinel organisms has been employed to determine the genotoxicity of water samples for environmental risk or hazard assessment. Methodologies with diverse sensitivities have been proposed to elucidate the sources of genetic damage, thereby enhancing environmental assessment and informing decision-making processes. The conventional method and the modified conventional method with the DNA excision enzyme formamidopyrimidine-DNA glycosylase (FPG) were used to evaluate DNA damage in oyster (Crassostrea rhizophorae) hemocytes. The oysters were exposed for seven days to water samples from three estuarine regions with different degrees of impact on the Brazilian equatorial margin: (1) Carimã Island, which is distant from the main industrial activities of Maranhão Island (reference area), (2) Itaqui Port, and (3) Bacanga Lagoon. Genetic damage tests were performed in parallel with an early-stage assay using oyster embryos. The results revealed that the degree of genetic damage varied depending on the water sampling location and genetic damage method used. Regarding sampling sites, the frequency of anomalies in embryos/larvae and genotoxic damage increased as follows: Carimã Island