Urinary polycyclic aromatic hydrocarbons as a biomarker of exposure to PAHs in air: A pilot study among pregnant women

Recent studies have linked increased polycyclic aromatic hydrocarbons (PAHs) in air and adverse fetal health outcomes. Urinary PAH metabolites are of interest for exposure assessment if they can predict PAHs in air. We investigated exposure to PAHs by collecting air and urine samples among pregnant women pre-selected as living in “high” (downtown and close to steel mills, n=9) and “low” (suburban, n=10) exposure areas. We analyzed first-morning urine voids from all 3 trimesters of pregnancy for urinary PAH metabolites and compared these to personal air PAH/PM2.5/NO2/NOX samples collected in the 3rd trimester. We also evaluated activities and home characteristics, geographic indicators and outdoor central site PM2.5/NO2/NOX (all trimesters). Personal air exposures to the lighter molecular weight (MW) PAHs were linked to indoor sources (candles and incense), whereas the heavier PAHs were related to outdoor sources. Geometric means of all personal air measurements were higher in the “high” exposure group. We suggest that centrally monitored heavier MW PAHs could be used to predict personal exposures for heavier PAHs only. Urine metabolites were only directly correlated with their parent air PAHs for phenanthrene (Pearson's r=0.31–0.45) and fluorene (r=0.37–0.58). Predictive models suggest that specific metabolites (3-hydroyxyfluorene and 3-hydroxyphenanthrene) may be related to their parent air PAH exposures. The metabolite 2-hydroxynaphthalene was linked to smoking and the metabolite 1-hydroxypyrene was linked to dietary exposures. For researchers interested in predicting exposure to airborne lighter MW PAHs using urinary PAH metabolites, we propose that hydroxyfluorene and hydroxyphenanthrene metabolites be considered.