Fine particulate matter components and reproductive hormones in female adults: A 15-year longitudinal cohort study

Few cohort studies have evaluated the long-term impacts of ambient fine particulate matter (PM_2.5) and its components on reproductive hormone levels in female adults.

We conducted a 15-year retrospective cohort study in Taiwan between 2003 and 2017. The two-year average concentrations of PM_2.5 and its components, including sulfate (SO₄^2-), nitrate (NO₃^-), ammonium (NH₄⁺), organic matter (OM), and black carbon (BC), were assessed at each participant's addresses. Linear mixed models were used to examine the associations of PM_2.5 and its components with reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), estradiol (E2), and prolactin (PRL). Stratified analyses were conducted to identify vulnerable populations.

17,152 female adults were included. Each interquartile range (IQR: 3.545 μg/m³) increase in PM_2.5 was associated with a 0.585 mIU/mL [95% confidence interval (CI): 0.190-0.980] increase in FSH levels. Among the five components of PM_2.5, BC had the strongest positive association [each IQR (0.272 μg/m³) increase was associated with a 0.863 mIU/mL (95% CI: 0.476-1.250) increase in FSH levels], followed by OM, SO₄^2-, and NH₄⁺. Similar associations were found for LH, with a 0.483 mIU/mL (95% CI: 0.225-0.742) and 0.684 mIU/mL (95% CI: 0.431-0.938) increase in LH levels per IQR increase in PM_2.5 and BC, respectively. The pollutants were marginally associated with decreased E2 levels and increased PRL levels. Non-linear associations between PM_2.5 and its components and the levels of FSH, LH, E2, and PRL were observed. These pollutants were also positively associated with T levels among young adults. Post-menopausal women were more susceptible to the chronic impacts of PM_2.5 and its components.

Our study highlighted the adverse impacts of long-term exposure to PM_2.5 components on hormonal homeostasis, revealing the biological mechanism of air pollution-reproductive health associations in females. Implementing stringent control of air pollution levels can benefit reproductive health in female adults, even in moderately polluted regions.