Relationship between BPA exposure and physical growth among two-year-old children: Based on Laizhou Wan Birth Cohort

Background Studies have shown that bisphenol A (BPA), a typical environmental endocrine disrupting chemical, may affect children's growth and development. The stage of toddlerhood is critical for physical growth, which indicates that children in this period might be more susceptible to the potential risks of BPA exposure.

Objective This study examines the BPA levels in urine of two-year-old children in Shandong Laizhou Bay Area, and to explore their relationships with children's physical growth in early childhood.

Methods A total of 219 two-year-old children who were followed up in Laizhou Wan Birth Cohort (LWBC) were finally enrolled. The BPA levels in children's urine samples were detected; their growth indices including body length, body weight, head circumference, chest circumference were measured, and body mass index (BMI) was calculated; their mothers' demographic variables and prenatal health related factors and their basic information and dietary data were collected with a questionnaire. Overall and sex-stratified generalized linear models were used to analyze the associations between children's BPA exposure quartiles (Q1-Q4) and physical growth.

Results The median of children's urinary BPA concentration was 0.26μg·L^-1 or 1.07μg·g^-1 (creatinine-adjusted). According to the generalized linear models, children's BPA exposure levels were positively associated with their chest circumference (b=0.152, 95% CI:0.028-0.275, P_trend=0.016). Compared with the Q1 group, children's body length and weight decreased significantly of the Q2 and Q3 groups (P<0.05). The length and weight of the Q2 group decreased (95% CI) by 1.29 (2.25-0.32) cm and 0.49 (0.94-0.03) kg, and those of the Q3 group decreased (95% CI) by 1.32 (2.30-0.35) cm and 0.49 (0.95-0.03) kg, respectively, even though the two variables showed variability with insignificant trend (P_trend>0.05). No significant changes were found in other physical growth indicators. Among boys, compared with the Q1 group, the body length, weight, and BMI decreased significantly of the Q2 group (P<0.05), and all indicators of the Q3 group decreased significantly (P<0.05), but no significant associations were found between BPA exposure and physical growth (P_trend>0.05). Among girls, compared with the Q1 group, the BMI increased significantly of the Q2 and Q4 groups, but the two variables show variability with insignificant trend in girls (P_trend>0.05); BPA concentration was positively associated with their chest circumference (b=0.173, 95% CI:0.012-0.333, P_trend=0.035) but no significant changes were found in other indicators (P_trend>0.05).

Conclusion Children's BPA exposure in urine at two years old may be associated with their physical growth and differ between boys and girls. BPA concentration is positively associated with children's chest circumference, especially among girls. But some non-linear associations are found in boys, and higher BPA exposure levels may reduce their physical growth.