Is 1-hydroxypyrene a reliable bioindicator of measured dietary polycyclic aromatic hydrocarbon under normal conditions?

Five healthy volunteers consumed similar amounts of identical foods for 5 consecutive days. The concentration of pyrene and of benzo(a)pyrene was determined in each of the 15 meals by a short analytical method that included sample saponification, solvent extraction, and HPLC analysis. The volunteers also provided three daily total volume 8-h urine samples for the duration of the study for the assessment of 1-hydroxypyrene, a biomarker of pyrene and polycyclic aromatic hydrocarbon (PAH) exposure. Mean recoveries were 83 and 75%, respectively, for pyrene and benzo(a)pyrene in food. Daily dietary pyrene doses varied from 0.7 to 3 microg. Excluding two outliers consisting of meals containing charbroiled pork and beef, pyrene content in the meals estimated from the published literature data was correlated to the measured pyrene, but overestimated the actual concentration by ca. 70%. Despite the identical ingested doses of pyrene, there was a 50-76% (coefficient of variation) interindividual variability in the daily-excreted amount of 1-hydroxypyrene. Urinary excretion of this metabolite was not correlated with ingested dose of pyrene under the normal feeding conditions used in this study. Bioavailability, enzymatic polymorphism, and differences in enterohepatic cycling of the metabolite may contribute to the observed variability. It was calculated that dietary pyrene intake accounts for between 87.5 and 99.8% of the sum of dietary and inhalation intake. From the presented data, unless the above-mentioned factors are taken into account, 1-hydroxypyrene might not be a reliable bioindicator of ingested pyrene (PAHs) under normal feeding conditions.