Efficiency of methods to investigate PAHs exposure in fish

The aim of this study was to compare the efficiency of two methods for assessing PAH exposure in fish: measurement of the fluorescence intensity of PAH metabolites in bile (by Fixed Wavelength Fluorescence, FF), and determination of Ethoxyresourfin-O-Deethylase (EROD) activity in fish liver. In addition, we studied oxygen consumption rate and osmoregulation capacity, which are also used as indicators for PAH contamination in water. Nile tilapia (Oreochromis niloticus) was exposed to benzene, fluorene, anthracene, chrysene, and benzo[a]pyrene at non-lethal concentrations. The results showed that the fluorescence intensity, EROD activity, and oxygen consumption rate were significantly increased with increased exposure times and PAH concentrations. The maximum values were reached after 16 days' exposure. The measurement of fluorescence intensity of PAH metabolites by FF technique was more sensitive than determination of EROD activity; therefore the FF technique should be preferred in the study of long term exposure. However, the measurement of fluorescence intensity, EROD activity, and oxygen consumption rate can all be used to monitor PAH contamination in water.