Breast milk bisphenol concentrations in Canada and South Africa and associations with body size among South African infants

Abstract

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, Canada (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 BP predictors, and linear marginal structural models were used to estimate associations between BP concentrations and infant size. RESULTS : BP 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 BP exposure in rural Africa and suggest that exposure to BPA and BPAF may be related to altered growth among South African infants.

HIGHLIGHTS • BPA, BPS and BPAF breastmilk levels were higher in Vhembe vs Pretoria and Montreal • Microwaving plastics and diet were associated with higher concentrations • Free and total BPAF were associated with greater length and head circumference • Total BPA was associated with smaller head circumference