Repeated measures of urinary polycyclic aromatic hydrocarbon metabolites in relation to altered reproductive hormones: A cross-sectional study in China.

<bold>Background: </bold>Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous environmental pollutants. In vivo and in vitro studies have demonstrated that PAHs can alter endocrine function, yet evidence from human studies is limited.<bold>Objectives: </bold>The objective of this study was to investigate whether environmental exposure to PAHs was associated with altered reproductive hormone levels, using repeated measures of urinary OH-PAHs as biomarkers.<bold>Methods: </bold>We measured 10 monohydroxylated PAHs (OH-PAHs) in repeated urine samples from 371 men in an infertility clinic in Wuhan, China. Multivariable linear regression models were used to estimate the associations between average urinary OH-PAH levels and serum reproductive hormones, and restricted cubic spline models were further used to examine the shapes of dose-response relationships.<bold>Results: </bold>We observed dose-response associations of urinary 2-hydroxynaphthalene (2-OHNa) with decreased serum free testosterone (fT) and urinary 1-hydroxypyrene (1-OHP), 9-hydroxyphenanthrene (9-OHPh), and 9-hydroxyfluorene (9-OHFlu) with decreased serum estradiol (all P for trends <0.05). These associations were linear and significant when these four OH-PAHs were modeled as continuous variables in restricted cubic spline models. Furthermore, a U-shaped association was observed across urinary 4-OHPh levels, with lower levels of serum sex hormone-binding globulin (SHBG) at median concentrations compared with 5th and 95th percentile concentrations.<bold>Conclusion: </bold>Environmental levels of PAH exposure in our study are associated with altered reproductive hormones. However, further research is needed to confirm our findings. [ABSTRACT FROM AUTHOR]