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We examined possible early-effect biomarkers and polymorphisms of susceptibility in primary school children living near the Atoyac River in central Mexico, which receives waste from multiple industries. We observed a significant increase in micronucleated reticulocytes associated with the oxidative stress index (OSI) and the OGG1 GG (S326C) genotype, and a significant decrease of reticulocytes carrying the transferrin receptor, inversely correlated with OSI.

a b s t r a c t Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous pollutants presenting a public health risk, par- ticularly to children, a vulnerable population. PAHs have genotoxic and carcinogenic properties, which depend on their metabolism. Many enzymes involved in PAH metabolism, including CYP1A1, CYP1B1, GSTM and GSTT are polymorphic, which may modulate the activation/deactivation of these compounds. We evaluated PAH exposure and DNA damage in children living in the vicinity of the main petrochem- ical complex located in the Gulf of Mexico, and explored the modulation by genetic polymorphisms of PAH excretion and related DNA damage. The participants (n = 82) were children aged 6-10 y attend- ing schools near the industrial area. Urinary 1-hydroxypyrene (1-OHP; a biomarker of PAH exposure) was determined by reverse-phase-HPLC; DNA damage by the comet assay (Olive Tail Moment (OTM) parameter); CYP1A1*2C and CYP1B1*3 polymorphisms by real time-PCR; and GSTM1*0 and GSTT1*0 by multiplex PCR. The median value of 1-OHP was 0.37 mol/mol creatinine; 59% of children had higher 1- OHP concentrations than those reported in environmentally exposed adults (0.24 mol/mol creatinine). A stratified analysis showed increased DNA damage in children with 1-OHP concentrations greater than the median value. We observed higher 1-OHP concentrations in children with CYP1A1*2C or GSTM1*0 polymorphisms, and a positive influence of CYP1A1*2C on OTM values in children with the highest PAH exposure. The data indicate that children living in the surroundings of petrochemical industrial areas are exposed to high PAH levels, contributing to DNA damage and suggesting an increased health risk; fur- thermore, data suggest that polymorphisms affecting activation enzymes may modulate PAH metabolism and toxicity.