Exposure to bisphenol A among school children in eastern China: a multicenter cross-sectional study

Bisphenol A (BPA) is one of the highest production and consumption volume chemicals in the world. Although exposure of children to BPA has been studied in Western countries, little is known about its level in China. In this study, total BPA was measured in the morning urine samples of 666 school children aged 9-12 years from three regions in eastern China in 2012. A rapid and sensitive ultraperformance liquid chromatography (UPLC) tandem mass spectrometry (MS/MS) method was used for the measurement and urinary concentrations of BPA were presented as unadjusted (ng/ml), creatinine-adjusted (μg/g creatinine) and specific gravity (SG)-adjusted (ng/ml) forms. BPA was detected in 98.9% of urine samples with their unadjusted concentrations ranging from 0.1 to 326.0 ng/ml (LOD=0.06 ng/ml), indicating that the exposure of BPA was common for school children living in eastern China. The geometric mean and median of BPA was 1.11 ng/ml (creatinine-adjusted: 2.32 μg/g creatinine; SG-adjusted: 1.17 ng/ml) and 1.00 ng/ml (creatinine-adjusted: 2.22 μg/g creatinine; SG-adjusted: 1.07 ng/ml), respectively. The highest urinary BPA level was found in the age group of 12 years with GM concentration of 1.55 ng/ml, and it decreased with decreasing age (11 years: 1.18 ng/ml; 10 years: 1.05 ng/ml; and 9 years: 0.99 ng/ml), but there was a lack of consistency for age associated with BPA levels in three study areas. The estimated daily intake of BPA (0.023 μg/kg bw/day) was much lower than the tolerable daily and reference dose of 50 μg/kg bw/day recommended by either the European Food Safety Authority or the US Environment Protection Agency. There was no significant difference in urinary BPA concentrations between children who were overweight or obese and those with normal weight (P=0.26), whereas BPA daily intake was unexpectedly higher among normal-weight children (P=0.003). Compared with creatinine correction, the correction method of specific gravity is preferred to evaluate BPA exposure for children.