Low-level exposure to polycyclic aromatic hydrocarbons is associated with reduced lung function among Swedish young adults

Background: Exposure to polycyclic aromatic hydrocarbons (PAHs) has been linked to adverse pulmonary effects. However, the impact of low-level environmental PAH exposure on lung function in early adulthood remains uncertain. Objectives: To evaluate the associations between urinary PAH metabolites and lung function parameters in young adults. Methods: Urinary metabolites of pyrene, phenanthrene, and fluorene were analysed in 1000 young adults from Sweden (age 22-25 years) using LC-MS/MS. Lung function and eosinophilic airway inflammation were measured by spirometry and exhaled nitric oxide fraction (FeNO), respectively. Linear regression analysis was used to evaluate associations between PAH metabolites and the outcomes. Results: Median urinary concentrations of 1-OH-pyrene, EOH-phenanthrene, and EOH-fluorene were 0.066, 0.36, 0.22 mu g/L, respectively. We found inverse associations of EOH-phenanthrene and EOH-fluorene with FEV1 and FVC, as well as between 1-OH-pyrene and FEV1/FVC ratio (adjusted P < 0.05; all participants). An increase of 1% in EOH-fluorene was associated with a decrease of 73 mL in FEV1 and 59 mL in FVC. In addition, EOH-phenanthrene concentrations were, in a dose-response manner, inversely associated with FEV1 (B from -109 to -48 compared with the lowest quartile of EOH-phenanthrene; p trend 0.004) and FVC (B from -159 to -102 compared with lowest quartile; p-trend <0.001). Similar dose-response associations were also observed between EOH-fluorene and FEV1 and FVC, as well as between 1-OH-pyrene and FEV1/FVC (p-trend <0.05). There was no association between PAH exposure and FeNO, nor was there an interaction with smoking, sex, or asthma. Conclusion: Low-level PAH exposure was, in a dose-response manner, associated with reduced lung function in young adults. Our findings have public health implications due to i) the widespread occurrence of PAHs in the environment and ii) the clinical relevance of lung function in predicting all-cause and cardiovascular disease mortality.