Background Phthalates are one of renowned endocrine-disrupting chemicals, although inconsistent results are present around their effect on onset of menarche. Our hypothesis is that pre-pubertal exposure to phthalates is associated with acceleration of menarche. Methods We analyzed a total of 236 middle school (7th to 9th grade) girls from Korean National Environmental Health Survey 2015 – 2017. We used multiple linear regression to investigate impact of eight phthalate metabolites on age of menarche. We also conducted logistic regression to evaluate association between phthalate metabolite concentrations and early onset of menarche, adjusting for grade, maternal age of menarche and body mass index (BMI). Results In linear regression analysis, no significant association was found for any phthalate metabolites. In logistic regression analysis, however, odds ratios (ORs) of early menarche were significantly increased for mono-n-butyl phthalate (MnBP) and for sum of all phthalates. When compared to group with the lowest level, high concentration group for MnBP presented significantly increased odds of early menarche (OR: 2.09; 95% confidence interval [CI]: 1.03, 4.23) after adjusting for grade, maternal age of menarche and BMI. Furthermore, high concentrations of sum of all phthalates were associated with significant increase of OR of early menarche (OR: 2.22; 95% CI: 1.10, 4.49) after adjustment, compared to the lowest concentration group. Conclusions Results of our study suggest that exposure to phthalates around puberty may be associated with increased risk of early menarche.

The effects of bisphenol A (BPA) on asthma have been reported in various in vitro, animal, and human epidemiologic studies. However, epidemiological studies on the effects of bisphenol S (BPS) and bisphenol F (BPF), which are substitutes of BPA, on asthma are lacking. The purpose of this study was to identify the association between BPA, BPS, and BPF and asthma. An asthma-related questionnaire; urinary BPA, BPS, BPF; and the possible confounders were analyzed among 922 adolescents aged 12–17 years who participated in the Korean National Environmental Health Survey 2016. In males, urinary BPA, BPS, and BPF did not show a significant relationship with the lifetime prevalence of asthma. In females, urinary BPS was higher in the asthma group (p < 0.01). High urinary BPS showed a significant relationship with a high odds ratio (OR) of lifetime asthma prevalence in the model adjusted for possible confounders (p < 0.05). High urinary BPS was particularly associated with an increase in the OR of asthma diagnosed after the age of 60 months (p < 0.01). Urinary BPS was significantly associated with asthma diagnosis, especially after the age of 60 months, among Korean adolescent females.