Benzene exposure in childhood: Role of living environments and assessment of available tools.

Benzene is a widespread air pollutant and a well-known human carcinogen. Evidence is needed regarding benzene intake in the pediatric age group. We investigated the use of urinary (u) trans,trans-muconic acid (t,t-MA), S-phenylmercapturic acid (SPMA), and unmodified benzene (UB) for assessing exposure to low concentrations of environmental benzene and the role of living environment on benzene exposure in childhood. u-t,t-MA, u-SPMA, u-UB and u-cotinine were measured in urine samples of 243 Italian children (5-11 years) recruited in a cross-sectional study. Analytical results were compared with data obtained from questionnaires about participants' main potential exposure factors. u-UB, u-t,t-MA and u-SPMA concentrations were about 1.5-fold higher in children living in urban areas than in those in the rural group. Univariate analyses showed that u-UB was the only biomarker able to discriminate secondhand smoke (SHS) exposure in urban and rural children (medians=411.50 and 210.50 ng/L, respectively); these results were confirmed by the strong correlation between u-UB and u-cotinine in the SHS-exposed group and by multivariate analyses. A regression model on u-SPMA showed that the metabolite is related to residence area (p<0.001), SHS exposure (p=0.048) and gender (p=0.027). u-UB is the best marker of benzene exposure in children in the present study, and it can be used as a good carcinogen-derived biomarker of exposure to passive smoking, especially related to benzene, when urine sample is collected at the end of the day. In addition, it is important to highlight that SHS resulted the most important contributor to benzene exposure, underlining the need for an information campaign against passive smoking exposure.