POLYCYCLIC AROMATIC HYDROCARBON METABOLITES IN URINE AS BIOMARKERS OFEXPOSURE AND EFFECT

Humans are exposed to polycyclic aromatic hydrocarbons (PAHs) from var ious occupational, environmental, medicinal, and dietary sources. PAH metabolites in human urine can be used as biomarkers of internal dose to assess recent exposure to PAHs. PAH metabolites that have been dete cted in human urine include 1-hydroxypyrene (1-OHP), 1-hydroxypyrene-O -glucuronide (1-OHP-gluc), 3-hydroxybenzo[a]pyrene. 10-tetrahydroxy-7, 8,9,10-tetrahydrobenzo[a]pyrene, and a number of other hydroxylated PA Hs. The most widely used of these is 1-OHP-gluc. the major form of 1-O HP in human urine, by virtue of its relatively high concentration and prevalence in urine and its ease of measurement. This metabolite of py rene can be measured as 1-OHP after deconjugation of the glucuronide w ith beta-glucuronidase or directly as 1-OHP-gluc without deconjugation . Elevated levels of 1-OHP or 1-OHP-gluc have been demonstrated in smo kers (versus nonsmokers), in patients receiving coal tar treatment (ve rsus pretreatment), after workshifts in road pavers (versus before shi fts or versus controls), after shifts in coke oven workers (versus bef ore shift), and in subjects ingesting charbroiled meat (versus preinge stion). More importantly, this metabolite is found (at low levels) in most human urine, even in persons without apparent occupational or smo king exposure. Although measurement of these metabolites is useful in assessing recent exposure to PAHs, their value as predictive markers o f biological effect or health outcomes has not been rigorously tested and at present can only be inferred by association.