Bisphenol A substitutes and childhood obesity at 7 years: a cross-sectional study in Shandong, China.

Bisphenol A (BPA) substitutes, such as bisphenol S (BPS) and bisphenol AF (BPAF), are increasingly used due to restrictions on BPA usage, a known endocrine disrupting chemical and putative obesogen. However, little is known about the obesogenic effects of exposure to BPA substitutes in children. A total of 426 children aged 7 years old originally recruited from Laizhou Wan Birth Cohort in Shandong, China, during 2010-2013 participated in the 2019-2020 survey. Urinary BPA and its substitutes including BPS, BPAF, bisphenol B (BPB), bisphenol AP (BPAP), bisphenol Z (BPZ), and bisphenol P (BPP) were determined. Anthropometric measures including height, weight, waist circumference, and body fat percentage were assessed, and overweight/obesity was defined as BMI z-score ≥ 85th percentile. Linear and logistic regressions were used on continuous and binary obesity measures, respectively, and weighted quantile sum (WQS) regression was further used to estimate the mixture effects of exposure to diverse bisphenols, and sex-stratified analysis was performed. BPA substitutes were widely detected (> 75%) in children's urine samples. A positive association with obesity measures was consistently observed for urinary BPS and BPAF, i.e., BMI z-score, waist circumference, and overweight/obesity. Further analysis from the WQS regression model demonstrated a positive association between bisphenol mixtures and all measures of obesity, with BPAF contributing the greatest weighing to the observed associations. Sex difference might exist as the positive associations were only significant in boys. No significant association was found between obesity and BPA or other BPA substitutes. Our study adds to mounting evidence that BPA substitutes BPS and BPAF are linked to obesity in children, especially in boys. Further longitudinal studies with larger sample size with continued biomonitoring these chemicals and their obesogenic effects are necessary.