Cytotoxic and genotoxic effect in RTG-2 cell line exposed to selected biocides used in the disinfection of cooling towers

The cytotoxic and genotoxic effects induced by trichloroisocyanuric acid, Oxone, and sodium bromide, active principles included in formulations for cleaning and disinfection of cooling towers, were studied on RTG-2 cell line. Neutral red assay was used to determine the cellular viability. Toxicity ranking based on IC(50) values found that trichloroisocyanuric acid was the most cytotoxic biocide tested followed by Oxone, whereas sodium bromide resulted in a very low cytotoxicity. DNA damage has been evaluated on RTG-2 cultures by means of an in vitro assay based on the ability of PicoGreen fluorochrome to interact preferentially with dsDNA, and the results indicated that trichloroisocyanuric acid induced DNA strand breaks at concentrations above 1.2 mg/l, equivalent to 1/50-EC(50(48)), whereas exposures to Oxone and sodium bromide did not induce DNA damage at the maximal concentrations tested (1/10-EC(50(48))). These results confirm the suitability of this method for the screening of genotoxic effects of this type of aquatic pollutants, and we suggest their use in environmental risk assessment procedures.