Profile of urinary phenanthrene metabolites in smokers and non-smokers

Phenanthrene metabolites (phenols and dihydrodiols) and 1-hydroxypyrene excreted in the 24-h urine of smokers, non-smokers and lung cancer patients, who after heavy smoking became light smokers, were determined and compared. In contrast to 1- hydroxypyrene, no significant differences of the absolute amounts of phenanthrene metabolites were found between smokers and non-smokers. A ratio phenanthrene metabolites/l-hydroxypyrene of 10.4 was observed for non-smokers and 9.9 for lung cancer patients, but 4.2 for smokers. Significantly different ratios for the regiospecific oxidation of phenanthrene were found for smokers when compared with non-smokers (1,2-oxidation vs 3,4-oxidation was 1.45 in the case of smokers, but 2.34 in the case of non-smokers) indicating a cigarette smoke - but not PAH - caused induction of CYP 1A2 in smokers. As a consequence of the degree of PAH exposure the ratio dihydrodiols/phenols depends on the total amount of metabolites excreted. Phenols predominate, equally in smokers and non-smokers after low exposure, while dihydrodiols become more prominent in highly exposed persons (coke plant workers). Both (i) the regiospecific oxidation of PAH and (ii) the ratio of dihydrodiol vs phenol formation may be recognized from the urinary phenanthrene metabolite profile. This pattern mirrors the enzymatic status (balance of the CYP isoforms and epoxide hydrolase) in individuals. Accordingly, more detailed information may be obtained from the urinary metabolite pattern than from 1- hydroxypyrene, commonly used in PAH biomonitoring.