Determination and assessment of human dietary intake of per and polyfluoroalkyl substances in retail dairy milk and infant formula from South Africa

Dairy milk and infant formula play important roles in the diet of adolescents, adults and infants, respectively, in the South African population. However, data on the occurrence of legacy and emerging contaminants such as PFAS in these important food sources is lacking. In this study, the concentration of fifteen PFAS were measured in 23 pooled retail dairy milk and 7 pooled infant formulas by means of an ultrahigh performance liquid chromatography tandem mass spectrometric method. The concentrations of Σ₁₅PFAS ranged from 0.08–15.51 ng mL⁻¹ and 0.42–5.74 ng mL⁻¹ in dairy milk and infant formulas, respectively. PFBA, PFPeA, PFuDA, PFTrDA and PFDoA were the most prevalent PFAS in both matrices with detection frequency > 96%. Highest PFAS concentrations of 2.02 ng ml⁻¹ and 2.76 ng ml⁻¹ were recorded for PFDoA in infant formulas and dairy milk, respectively. The concentrations of legacy PFAS –PFOA and PFOS, shows resemblance with global data, however, elevated concentrations of long chain C₉ – C₁₄ PFAS were observed in this study. Though, higher concentrations of PFAS were measured in full cream dairy milk, no statistical significant difference (P = 0.546) was observed for the various classes of dairy milk. The EDI of Σ₁₅PFAS through infant formulas were 184.92, 329.47 and 166 ngkg⁻¹BWday⁻¹ for partially breastfed, exclusively formula fed and older infants, respectively. Similarly, the EDI of PFAS through dairy milk for toddlers, adolescents, female and male adults for the rural population were 14.17, 1.09, 2.59 and 3.16 ngkg⁻¹BWday⁻¹ respectively while they were 20.41, 3.84, 4.13 and 4.26 ngkg⁻¹BWday⁻¹ respectively in the urban population. Although, the EDI of PFAS through the consumption of infant formulas and dairy milk are lower than the daily tolerable limits, the relative importance of long-term exposure and the cumulative effects of multiple exposure pathways cannot be overemphasized.