Urinary 1-hydroxypyrene and t,t-muconic acid as biomarkers of exposure to environmental pollutants in two areas in Italy (EPIC-Florence and Ragusa)

Several chemical compounds included in the group of polycyclic aromatic hydrocarbons (PAH) and benzene are well-known human carcinogens present in the atmosphere of polluted urban areas. Major sources include vehicle traffic and industrial emissions, but also cigarette smoke. Genotoxic damage derived from exposure to PAHs can be measured in healthy adults by specific assays as PAH-DNA adducts. In the frame of EPIC-Italy, we recently carried out a cross-sectional study in different areas of the country (Palli et al., Int J Cancer, 87: 444-451, 2000) and showed that mean DNA adduct levels varied considerably among different centers, being highest in Florence (a large metropolitan area in Tuscany) and lowest in Ragusa (a small town in Sicily). A subgroup of EPIC volunteers, representative of these two local cohorts, agreed to collect 24-h urine samples, and we measured the excretion of two potential biomarkers of exposure to environmental pollutants: t,t-muconic acid (MA), a metabolite of benzene, and 1-hydroxypyrene (1-OHP), a metabolite of pyrene. Overall, 69 24-h urine samples were available for analyses. The absolute amounts of 1-OHP and MA excreted in the 24-h urine samples were 169.6 ng and 33.8 microg, respectively. Urinary excretion of both metabolites did not vary according to age or area of residence. Strongly significant differences emerged when current smokers were compared to non-smokers for 1-OHP (P = 0.0001) and MA (P = 0.01), thus confirming that smokers are directly exposed to PAHs and benzene from tobacco smoke, with a dose-dependent effect particularly evident for MA. Multivariate analyses showed positive associations of 1-OHP excretion with male sex, low education and being overweight but not with residence in two areas with contrasting levels of urban pollution; MA excretion tended to be higher in Florence. These two urinary metabolites are strongly related to tobacco smoke and do not appear to represent reliable biomarkers of exposure to environmental pollutants in the general population.