Current breast milk PFAS levels in the US and Canada: After all this time why don’t we know more? (SETAC Abstract)

Background. Despite twenty years of biomonitoring studies of per- and polyfluoroalkyl substances (PFAS), we have a limited understanding of concentrations in breast milk from the US and Canada. The lack of information on PFAS levels in breast milk and the implications for breastfed infants and families were brought to the forefront by communities impacted by PFAS.  Objectives. To: 1) review published PFAS breast milk concentrations in the US and Canada; 2) estimate breast milk PFAS levels from serum concentrations in national surveys and communities impacted by PFAS; and 3) compare measured/estimated milk PFAS concentrations to screening values. Methods. We identified three studies reporting breast milk concentrations in the US and Canada. To estimate breast milk PFAS concentrations, we multiplied publicly available geometric mean (GM) and 95th percentile serum PFAS concentrations from two national surveys (only women) and six communities impacted by PFAS (men and women) by milk:serum partitioning ratios for four PFAS: perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), and perfluorononanoic acid (PFNA). Milk:serum ratios were identified from four previous studies with sample sizes ranging from 12 – 100 paired milk and serum samples. Breast milk concentrations were compared to Child Environmental Media Evaluation Guides (EMEGs) developed by the Agency for Toxic Substances and Disease Registry (ATSDR) for drinking water.  Discussion. All measured breast milk concentrations of PFOA and PFOS exceeded the Child EMEGs, while most measured PFNA and PFHxS concentrations in breast milk were below the Child EMEGs. All estimated GM and mean breast milk PFOA and PFOS concentrations exceeded the Child EMEGs. For two of six communities, the estimated GM concentrations of PFHxS and PFNA were close to – or exceeded – the Child EMEGs. Exceeding a Child EMEG does not necessarily mean that adverse health effects will occur but indicates that further evaluation is needed. Milk concentrations may be overestimated because the serum data is not limited to lactating women. This analysis is limited by the paucity of adequate data to fully characterize partitioning of PFAS into breastmilk. As breast milk may be the only source of hydration for the first months of life for many infants, a better understanding of environmental chemical transfer to – and concentrations in – an exceptional source of infant nutrition is needed.

Impact/Purpose

Per- and polyfluoroalkyl substances (PFAS) are a large class of more than 9,000 structurally different compounds that have been used in industry and consumer products since the 1950s. They do not occur naturally, are widespread and persistent in the environment, and have been detected in people, wildlife, and fish all over the world. There is widespread exposure to PFAS, even a decade after one legacy PFAS, perfluorooctane sulfonate (PFOS), was taken off the market in the U.S. Despite twenty years of biomonitoring studies of these chemicals in both serum and urine, we have an extremely limited understanding of PFAS concentrations in breast milk of women in the US. The lack of robust information on PFAS concentrations in breast milk and the implications for both the breastfed infants and their families creates a dilemma for those who are trying to make informed decisions regarding the risks and benefits of breastfeeding. This information is also essential for public health agencies, including the EPA, for making recommendations to individuals, clinicians, and communities. In this work, we estimate concentrations of four PFAS (PFOA [perfluorooctanoic acid], PFOS, PFHxS [perfluorohexane sulfonate], PFNA [perfluorononanoic acid]) in breast milk in the US and Canada using milk/serum partitioning data in conjunction with serum PFAS concentrations and compare measured/estimated milk concentrations to public health screening values to illustrate the need for further research into this important topic.

Citation

LaKind, J., M. Verner, R. Rogers, H. Goeden, D. Naiman, S. Marchitti, G. Lehmann, E. Hines, AND S. Fenton. Current breast milk PFAS levels in the US and Canada: After all this time why don’t we know more? (SETAC Abstract). SETAC Annual Meeting, Virtually, NC, November 14 - 18, 2021.