Does exposure to PM 10 decrease age at menarche?

There has been a consistent decrease in age at menarche in South Korea. A potential risk factor for early menarche is exposure to particulate matter (PM), because endocrine-disrupting compounds emitted into air from anthropogenic sources may be incorporated into PM. The objective of this study was to examine the association between pre-menarcheal exposure to PM ≤ 10 μm in diameter (PM ) and age at menarche in adolescents of South Korea using Korea National Health and Nutrition Examination Survey (KNHANES) 2010-2012 data. We used self-reported age at menarche of 639 girls aged 13-17 years in this study. The cut-off age for early menarche was set to 12 years. Based on each subject's address, 1-year, 2-year, and 3-year averages of annual mean PM concentrations (models 1-3) were linked to KNHANES. Models were adjusted for body mass index (BMI), city size, household income level, maternal age at menarche, and second-hand smoke exposure at home. SURVEYREG and SURVEYLOGISTIC procedures were used to address the complex survey design of KNHANES. Overall analysis showed that exposure to PM has a significant effect on decreasing age at menarche. Multiple linear regression results suggested that each 1 μg/m increase in 1-year, 2-year, 3-year averages of annual mean PM concentrations accelerated age at menarche by 0.046 years (95% CI: -0.064, -0.027; p