Biomonitoring of bisphenol A (BPA) and bisphenol analogues in human milk from South Africa and Canada using a modified QuEChERS extraction method.

A sensitive modified QuEChERS extraction method was developed to assess the levels of free and conjugated bisphenols (BPs) in human milk collected between 2018 and 2019 from two regions of South Africa (the Limpopo Province Vhembe district, n = 194; Pretoria, n = 193) and Canada (Montreal, n = 207). Total BPA (free and conjugated) and BPS were the predominant bisphenols detected in samples from Vhembe and Pretoria, whereas total BPS was the predominant bisphenol detected in Montreal samples. The levels of total BPA in samples from Vhembe and Pretoria ranged between < MDL-18.61 and <MDL-19.38 ng/mL, with medians of 1.03 ng/mL and 0.69 ng/mL and detection frequencies of 73% and 68%, respectively. The speciation analysis of BPA revealed a predominantly conjugated form in South African samples. In contrast, total BPA was detected in only one milk sample from Montreal. Total BPS levels were lower than BPA in South Africa, with detection frequencies of 57% and 21% in Vhembe and Pretoria, respectively. In contrast, total BPS was the major BP detected (42%) in Montreal (up to 4.42 ng/mL). BPAF was found exclusively in South Africa, with detection frequencies for total BPAF of 40% and 9% in Vhembe (<MDL-12.41 ng/mL) and Pretoria (<MDL-0.11 ng/mL), respectively. To our knowledge, this is one of the first studies to detect bisphenols in human milk from data-scarce countries such as South Africa and to highlight the notable disparities in the types and levels of bisphenols detected across two distinct countries (Canada and South Africa).