Assessment of RTG-W1, RTL-W1, and PLHC-1 fish cell lines for genotoxicity testing of environmental pollutants by means of a Fpg-modified comet assay.

In a context of growing awareness of aquatic pollution impacts, there is an increasing need to develop methods for hazard and risk assessment of pollutants. For this purpose, in vitro models such as fish cell lines warrant to be evaluated as possible alternative to in vivo fish testing, and new toxicity endpoints such as genotoxicity deserve to be considered. This study assesses the interest of the formamido pyrimidine glycosylase (Fpg)-modified comet assay applied to three fish cell lines (RTL-W1, RTG-W1, and PLHC-1) regarding the sensitivity of the system for measuring genotoxicity of various classes of pollutants. Cytochrome P450-dependent EROD activity has also been measured to evaluate the importance of the biotransformation capacity of the cell lines in genotoxicity assessment. For all cell lines and chemicals tested, a concentration dependent genotoxic effect was observed with a 10- to 1000-fold increased sensitivity when using the Fpg-protocol compared to the standard comet assay. Such a modified assay led in particular to improve the detection threshold of oxidative and alkylating DNA damages following exposure at environmentally relevant contaminant concentrations and could partly compensate for the lower sensitivity of cell lines versus whole organism testing often cited as a limit of in vitro testing.