Polycyclic Aromatic Hydrocarbon (PAH) Metabolites in Atlantic Cod Exposed via Water or Diet to a Synthetic Produced Water

Abstract

Bile metabolites are widely accepted as measures of exposure to polycyclic aromatic hydrocarbons (PAH) and have also been used to assess exposure to alkyl phenols (AP). The aim of this study was to clarify relationships between exposure (through water or diet) and subsequent accumulation of specific PAH and AP metabolites in Atlantic cod (Gadus morhua). Atlantic cod were exposed through water or diet to a synthetic mixture of PAH, alkylated PAH, and AP, simulating the composition of North Sea produced water (formation water; separated from oil or gas on the platform). Fish were exposed through water for 11 mo and the results reported here are from 2 and 8 mo. Fish were subjected to one of four exposures: “control,” “low,” “high,” or “pulsed high.” Bile samples were analyzed by gas chromatography/time-of-flight mass spectroscopy (GC/MS-ToF) for identification of PAH and AP metabolites. Cod exposed through diet were divided into six groups receiving different groups of compounds (AP, PAH, or alkylated PAH), a mixture of all compounds, a low-concentration mixture, and controls. A dose-dependent relationship was found for metabolites for most of the PAH and AP, although results were less clear for the more volatile substances such as phenol and naphthalene. The concentration of bile metabolites from fish exposed through water rose with increasing lipophilicity, but this relationship was less clear for fish exposed through diet. Overall, data indicated that bile metabolites of AP and PAH in fish are reliable markers of both water exposure and dietary exposure to such substances, although with the possible exception of the more volatile species such as phenol and naphthalene.