Micronucleus test and comet assay for the detection of genotoxicity in blood cells of Gambusia affinis exposed to produced waters

The aim of this study was to assess the potential genotoxic effect of produced water (PW) from an Italian on-shore oil platform. Produced water is a complex mixture containing residual hydrocarbons, trace elements, naturally occurring radioactive material and potentially toxic treatment chemicals, such as biocides, dispersants, detergents and scale inhibitors, used in oil production. The test organism, mosquitofish (Gambusia affinis), was divided into male and female groups and exposed in the laboratory to high concentrations (50%) of different produced water: PW before treatment and after settling. After eight days of exposure, DNA damage was evaluated in erythrocytes by single cell gel electrophoresis (Comet assay) and micronucleus test. In females, the frequencies of micronuclei and tail DNA (%) values were significantly greater in experimentally treated than in control organisms (p<0.05). This data was in line with results of PAH bile metabolites and benzo()pyrene monooxygenase (BPMO) tests. An increase, although non significant, was observed in erythrocytes of male specimens exposed to produced water. This data was compared with that of mosquitofish specimens exposed for 30 days to the produced water used in the short-term experiment.