Pyrene metabolites in the hepatopancreas and gut of the isopod Porcellio scaber, a new biomarker for polycyclic aromatic hydrocarbon exposure in terrestrial ecosystems

The object of this study was to investigate the formation of pyrene metabol ites by the isopod Porcellio scaber as a possible tool in the environmental risk assessment of polycyclic aromatic hydrocarbon (PAH) exposure in terre strial ecosystems. The formation of pyrene metabolites was studied after ei ther pulse exposure to a single high dose, or prolonged exposure (14 d) to a lower dosage. Exposure studies were carried out with unlabeled or radiola beled pyrene, ion pair chromatography was used for analysis, and reference conjugates were synthesized. We also measured pyrene metabolites in field-e xposed animals, to explore their use as biomarkers of PAH exposure. Analysi s of the hepatopancreas and gut of single isopods revealed the formation of five products, one of which was 1-hydroxypyrene. Four of the remaining pro ducts were identified as phase II metabolites of 1-hydroxypyrene, with UV a bsorption and fluorescence characteristics similar to that of pyrene. One m etabolite was identified as pyrene-1-glucoside, which is in accordance with high rates of glucosidation, reported for these isopods. Another conjugate was identified as pyrene-l-sulfate. None of the metabolites coeluted with a pyrene 1-glucuronide reference obtained from Fish bile. A fifth metabolit e detected by on-line scintillation detection did nor exhibit any absorptio n at 340 nm, possibly because one of the aromatic rings of pyrene had lost its aromatic character. Although pyrene is not known for its toxicity, it u sually co-occurs with other PAHs that are transformed into toxic products. Investigating the metabolism of pyrene can provide information with regard to the biotransformation capacity of invertebrate species and uptake and el imination kinetics. Because pyrene is one of the most predominant PAHs in t he environment, analysis of its metabolites provides an extra tool for the environmental risk assessment of ecosystems with regard to PAH exposure, bi oavailability, and biotransformation.