Monitoring benzo(a)pyrene exposure using laser-excited Shpol'skii spectroscopy of benzo(a)pyrene metabolites

Exposure to polycyclic aromatic hydrocarbons (PAHs) is considered a serious threat to the health of animals and humans and should be thoroughly monitored. Next to chemical analysis of PAHs in the various environmental compartments, PAH metabolites in body fluids (e.g., bile and urine) could be measured to determine the actual uptake. Although pyrene is not considered particularly toxic, its metabolite 1-hydroxy pyrene is often used as a biomarker because it is usually found at considerable concentrations and the analysis is relatively simple. As the result of differences in volatility and/or solubility, the uptake of more relevant carcinogens like benzo(a)pyrene may be some orders of magnitude lower and is far more difficult to measure. Determination of benzo(a)pyrene metabolites requires a very selective and sensitive method, and so far these compounds could only be detected after exposure to heavy pollution. In this paper it will be shown how several hydroxy benzo(a)pyrene metabolites are selectively determined using Shpol'skii spectroscopy. With this method, highly resolved fluorescence spectra are obtained upon cooling the sample in a suitable solvent to cryogenic temperatures. When a tunable laser system is employed as an excitation source, sub-femtomole amounts can be detected. Applications of the technique to marine monitoring (benzo(a)pyrene metabolites in fish bile) and to occupational hygienics (benzo(a)pyrene metabolites in workers' urine) are discussed. The data will be compared with 1-hydroxy pyrene concentrations to evaluate the routine use of the latter compound as a biomarker.