Breast Milk Bisphenol Concentrations in Canada and South Africa and Associations with Body Size among South African Infants.

Objective: Infants may be exposed to bisphenols (BP) via breastfeeding. These chemicals are known endocrine disruptors and may interfere with infant growth. However, their presence in breast milk and their associations with infant size remain unexplored in South Africa, where infants may be especially vulnerable to toxic effects.

Methods: We measured BPA, BPS, and BPAF in breast milk samples obtained 4-8 weeks postpartum from mothers residing in rural (Vhembe district; n=193) and urban (Pretoria; n=189) areas of South Africa and compared them to samples from Montreal (n=206). Infant length and head circumference were measured in South Africa, with z-scores computed based on World Health Organization (WHO) growth charts. Random forest plots were used to identify top-ranked predictors of bisphenols, and linear marginal structural models were used to estimate associations between bisphenol concentrations and infant size.

Results: Bisphenol concentrations were highest in Vhembe relative to Pretoria; in Montreal, only BPS was detected. Microwaving food in plastic containers and maternal diet were important determinants of exposure. In the combined South African sites, total BPAF detection was associated with greater infant length (β=0.38 SD, 95% CI: 0.09, 0.68) and head circumference (β=0.52 SD, 95% CI: 0.23, 0.81). Associations were strongest in Pretoria. In contrast, a tenfold increase in total BPA concentration was associated with a 0.20 SD decrease in head circumference (95% CI: -0.39, -0.01) in Vhembe.

Conclusion: Findings point to high exposure to bisphenols in rural Africa and suggest that exposure to BPA and BPAF may alter growth among South African infants.