Urinary biomarkers of polycyclic aromatic hydrocarbons in pre- and peri-pubertal girls in Northern California: Predictors of exposure and temporal variability

These results confirm diet and environmental tobacco smoke exposure as the main sources of PAHs. Controlling for these sources, differences in concentrations still existed by race for specific PAH metabolites and by income for 2-naphthol. The modest temporal variability implies adequate exposure assignment using concentrations from a single sample to define a multi-year exposure timeframe for epidemiologic exposure-response studies.