Current Breast Milk PFAS Levels in the United States and Canada: After All This Time, Why Don’t We Know More?

Abstract

Background: Despite 20 y of biomonitoring studies of per- and polyfluoroalkyl substances (PFAS) in both serum and urine, we have an extremely limited understanding of PFAS concentrations in breast milk of women from the United States and Canada. The lack of robust information on PFAS concentrations in breast milk and implications for breastfed infants and their families were brought to the forefront by communities impacted by PFAS contamination. Objectives: The objectives of this work are to: a ) document published PFAS breast milk concentrations in the United States and Canada; b ) estimate breast milk PFAS levels from maternal serum concentrations in national surveys and communities impacted by PFAS; and c ) compare measured/estimated milk PFAS concentrations to screening values. Methods: We used three studies reporting breast milk concentrations in the United States and Canada We also estimated breast milk PFAS concentrations by multiplying publicly available serum concentrations by milk:serum partitioning ratios for perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). Measured and estimated breast milk concentrations were compared to children’s drinking water screening values. Discussion: Geometric means of estimated breast milk concentrations ranged over approximately two orders of magnitude for the different surveys/communities. All geometric mean and mean estimated and measured breast milk PFOA and PFOS concentrations exceeded drinking water screening values for children, sometimes by more than two orders of magnitude. For PFHxS and PFNA, all measured breast milk levels were below the drinking water screening values for children; the geometric mean estimated breast milk concentrations were close to—or exceeded—the children’s drinking water screening values for certain communities. Exceeding a children’s drinking water screening value does not indicate that adverse health effects will occur and should not be interpreted as a reason to not breastfeed; it indicates that the situation should be further evaluated. It is past time to have a better understanding of environmental chemical transfer to—and concentrations in—an exceptional source of infant nutrition. https://doi.org/10.1289/EHP10359

Invited Perspective: Current Breast Milk PFAS Levels in the United States and Canada Indicate Need for Additional Monitoring and Actions to Reduce Maternal Exposures

“…In this issue of Environmental Health Perspectives, LaKind et al. ( 2021 ) discuss measured and estimated PFAS levels in breast milk in North America and evaluate the potential significance of these levels.…”

“…First, LaKind et al. ( 2021 ) reported that data on PFAS in breast milk in the United States and Canada are very limited; only three general population studies, with 95 U.S. and 13 Canadian participants in total, were identified. The four long-chain PFAS [i.e., perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonate (PFHxS)] that are ubiquitous in the blood serum of U.S. residents ( CDC 2021 ) were detected in breast milk in the two U.S. studies, whereas only PFOA was detected in a smaller study from Canada, possibly because of insufficient analytical sensitivity.…”

“…Next, LaKind et al. ( 2021 ) used mean breast milk:maternal serum PFAS ratios from the literature to estimate breast milk PFAS concentrations in the general population. They used serum PFAS data from two national surveys—the U.S. National Health and Nutrition Examination Study (NHANES) and the Canadian Health Measures Survey—and from exposure assessments conducted by the Agency for Toxic Substances and Disease Registry (ATSDR) in communities with contaminated drinking water.…”

“…2012 ; NJDWQI 2017 ) and 200:1 for PFOS ( NJDWQI 2018 ), PFNA ( NJDWQI 2015 ), and PFHxS [calculated from half-life and volume of distribution data from NHDES ( 2019 )] with the breast milk:serum ratios used by LaKind et al. ( 2021 )—PFOA: 0.073:1; PFOS and PFHxS: 0.013:1; PFNA: 0.03:1. To put the relationship between exposures to the mother and the breastfed infant into a broader context, data from mother–infant pairs from the general population indicate that, although serum levels of long-chain PFAS are similar or lower in the infant compared with the mother at birth, they increase several times from birth to 6 months of age in breastfed infants ( Fromme et al.…”

“…Finally, LaKind et al. ( 2021 ) compared measured and estimated breast milk levels of the four long-chain PFAS to child screening levels (environmental media evaluation guides, or EMEGs) set by the ATSDR for PFAS in drinking water ( ATSDR 2019 ). EMEGs are based on ATSDR minimal risk levels (toxicity factors for noncancer health effects)—which are similar in concept to reference doses set by the U.S. Environmental Protection Agency (EPA)—and the drinking water ingestion rate from birth to 1 year of age.…”