Association between environmental exposure to benzene and oxidative damage to nucleic acids in children

Objectives: To evaluate the association between environmental exposure to benzene and oxidative damage to nucleic acids in children, also considering the role of Environmental Tobacco Smoke (ETS). Methods: 396 children living in central Italy were recruited in districts with different urbanization and air pollution. All biomarkers were determined in spot urine samples by mass spectrometric techniques to assess exposure [benzene (U-Benz), and its metabolites (t,t-muconic and S-phenylmercapturic acids, t,t-MA and S-PMA, respectively), cotinine] and nucleic acid oxidation [8-oxo-7,8-dihydro-2'- deoxyguanosine (8-oxodGuo), 8-oxo-7,8-dihydroguanosine (8-oxoGuo), and 8-oxo-7,8-dihydroguanine (8-oxoGua)]. Results: Biomarkers of exposure and nucleic acid oxidation increased with urbanization and were correlated with each other (r>0.18, p<0.005). In a multiple linear regression model, benzene exposure, assessed by S-PMA and t,t-MA, was associated (p<0.0001) with both 8-oxodGuo (R2=0.392) and 8-oxoGuo (R2=0.193) in all areas of residence, with similar slopes. Conclusions: (i) Biomarkers of exposure to benzene increased as a function of environmental air pollution and urbanization level; (ii) U-Benz clearly distinguished both exposure to ETS and areas of residence, whereas benzene metabolites were associated only with the latter; (iii) the variance of 8-oxodGuo and 8-oxoGuo was accounted for by environmental benzene exposure, thus suggesting that benzene is a good tracer of other components of complex mixtures of pollutants causing oxidative damage to nucleic acids.