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 IC₅₀ 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-EC₅₀₍₄₈₎, whereas exposures to Oxone® and sodium bromide did not induce DNA damage at the maximal concentrations tested (1/10-EC₅₀₍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.