Exposure of Perfluorinated Chemicals through Lactation: Levels of Matched Human Milk and Serum and a Temporal Trend, 1996–2004, in Sweden

TLDR

Limited data exist on lactation as an exposure source of persistent perfluorinated chemicals for children. The study investigated the occurrence and levels of PFCs in human milk relative to maternal serum and examined temporal trends in milk levels between 1996 and 2004 in Sweden. Matched individual milk and serum samples from 12 primiparous women were analyzed alongside composite milk samples (25–90 women per year) from 1996 to 2004, detecting eight PFCs in serum and five in milk. PFOS and PFHxS were present in all milk samples at mean concentrations of 0.201 ng/mL and 0.085 ng/mL, respectively, with milk levels constituting about 1 % of maternal serum concentrations and showing strong correlations (r² = 0.7–0.8) that remained stable from 1996 to 2004, indicating lactation delivers roughly 200 ng/day of PFCs to infants and underscoring the need for reference concentrations.

Abstract

Only limited data exist on lactation as an exposure source of persistent perfluorinated chemicals (PFCs) for children.We studied occurrence and levels of PFCs in human milk in relation to maternal serum together with the temporal trend in milk levels between 1996 and 2004 in Sweden. Matched, individual human milk and serum samples from 12 primiparous women in Sweden were analyzed together with composite milk samples (25-90 women/year) from 1996 to 2004.Eight PFCs were detected in the serum samples, and five of them were also above the detection limits in the milk samples. Perfluorooctanesulfonate (PFOS) and perfluorohexanesulfonate (PFHxS) were detected in all milk samples at mean concentrations of 0.201 ng/mL and 0.085 ng/mL, respectively. Perfluorooctanesulfonamide (PFOSA), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were detected less frequently.The total PFC concentration in maternal serum was 32 ng/mL, and the corresponding milk concentration was 0.34 ng/mL. The PFOS milk level was on average 1% of the corresponding serum level. There was a strong association between increasing serum concentration and increasing milk concentration for PFOS (r(2) = 0.7) and PFHxS (r(2) = 0.8). PFOS and PFHxS levels in composite milk samples were relatively unchanged between 1996 and 2004, with a total variation of 20 and 32% coefficient of variation, respectively.The calculated total amount of PFCs transferred by lactation to a breast-fed infant in this study was approximately 200 ng/day. Lactation is a considerable source of exposure for infants, and reference concentrations for hazard assessments are needed.