| Summary: | Polycyclic aromatic hydrocarbons (PAHs), mainly from petroleum products, are a source of worldwide contamination, and it is in the present study, we exposed Nile Tilapia in aquaria to No-Observed-Effect-Levels (NOELs) of naphthalene, phenanthrene and pyrene for periods up to 9 days in a continuous flow system. Additional studies were carried out on fish exposed to lubricating oil, gasoline and diesel oil. Two methods were used to measure the levels of these PAHs: determination of ethoxyresorufin-O-deethylase (EROD) activity in liver extracts, and fixed wavelength fluorescence (FF) of PAH in bile. Optimal excitation wavelengths for FF analyses were determined to 290, 260 and 341 nm for naphthalene, phenanthrene and pyrene, respectively. The optimal emission wavelengths were 335, 380 and 383 nm, respectively. EROD activity and fluorescence intensity increased with increasing PAH concentrations and increasing exposure times. Similar results were obtained after exposure to lubricating oil, gasoline, or diesel oil. There was a high and significant correlation between the two methods. In view of its higher accuracy, lower cost, and convenience FF offered better possibilities than EROD determination to monitor PAH contamination in fish.
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