Biomonitoring and temporal trends of bisphenols exposure in Japanese school children.

The widely used chemical bisphenol A (BPA), applied in various consumer products, has been under scrutiny in the past 20 years due to its widespread detection in humans and potential detrimental effects on human health. Following the implementation of restrictions and phase-out initiatives, BPA has been replaced by other structurally similar bisphenols, which have not yet received the same level of research attention. In this study, we aimed to 1) investigated the internal exposure to seven bisphenols in morning void urine samples (n = 396) from 7-year-old children from Hokkaido, Japan and 2) assess possible time trends in the concentrations of bisphenols between 2012 and 2017. Information on demographic, indoor environment and dietary characteristics of participants were acquired through a self-administered questionnaire. All bisphenols were detected in the study population, with BPA, BPF and BPS showing detection frequencies >50%. Concentrations of bisphenols measured in the Japanese children in our study were generally lower compared to studies worldwide. We found that BPA concentrations decreased significantly over the study time period (average 6.5% per year), whereas BPS rose with 2.8% per year. Levels of BPA and BPF were higher in autumn compared to winter. Higher urinary BPF levels were significantly associated with higher concentrations of the oxidative stress biomarker, 8-hydroxy-2'-deoxyguanosine (8-OHdG). BPA and BPF levels were higher in children from families with lower household income. Bisphenol concentrations were significantly influenced by some other personal (e.g. household income), food intake (e.g. vegetables and cow milk) and indoor housing characteristics (e.g. flooring). This is the first study to report longitudinal time trends of bisphenols in Japan. The presented findings imply that further research on bisphenols is warranted in the future to monitor whether these time trends continue.