PFAS concentrations in breast milk exceed screening values for drinking water

ByMaria Marabito

Mean concentrations of perfluorooctanoic acid and per- and polyfluoroalkyl substances in women’s breast milk exceeded drinking water screening values for children, according to findings published in Environmental Health Perspectives.

However, researchers said the clinical implications of their findings are unclear “and should not be interpreted as a reason to not breastfeed.”

“The higher the PFAS levels in the mother’s blood, the higher the milk PFAS levels.”

“Per- and polyfluoroalkyl substances (PFAS) are just one class of pollutants that may be present in infant nutrition (be it breast milk or the contents of formula), and there is little to no way to judge what levels are ‘safe’ for the infant to consume,” Suzanne E. Fenton, PhD, a group leader in the mechanistic toxicology branch of the NIH’s National Institute of Environmental Health Sciences, told Healio. “Research, enhanced monitoring of these food sources and policies to limit pollutants in these food sources could improve child health.”

Data collection

Fenton and colleagues initially conducted a literature review of papers published in the U.S. and Canada on PFAS concentrations in breast milk. Only three papers were eligible for inclusion. To counteract this limited dataset, the researchers estimated nationally representative breast milk concentrations of PFAS in the U.S. using the most recent available data on serum perfluorooctanoic acid (PFOA), perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS) and perfluorononanoic acid (PFNA) from the 2017 to 2018 NHANES survey of women aged 18 to 44 years, as well as nationally representative plasma data from the 2016 to 2017 Canadian Health Measures Survey of Canadian women aged 12 to 79 years.

Fenton and colleagues also analyzed geometric mean serum concentrations from communities with known histories of PFAS drinking water contamination, as documented by the Agency for Toxic Substances and Disease Registry. This documentation included blood samples collected in 2019 and 2020 from residents living in communities near current or former military bases that were known to have had PFAS in their drinking water. Additionally, the researchers used publicly available data from New York’s health department on the Hoosick Falls and Petersburgh areas as well as blood samples collected from residents between June 2018 and March 2019, about 2.5 years after most exposures to PFOA from drinking water ended.

Monitoring contaminants

All estimated and measured mean breast milk concentrations of PFOA and PFAS exceeded drinking water screening values for children, sometimes by more than two orders of magnitude, according to the researchers. Overall, estimated and measured mean breast milk concentrations of PFHxS and PFNA were below the drinking water screening values for children. However, the geometric mean estimated breast milk concentrations were close to or exceeded children’s drinking water screening values for certain communities.

When pregnant women ingest water with contaminants, the PFAS stay in their body, accumulating in both their blood and liver to levels much higher than what was in the water, according to Fenton.

“During late pregnancy and into the lactational period, nutrients and fluids from a woman’s bloodstream are sent to the breast and are incorporated in the milk that is then transferred to the infant,” she said. “This transfer of circulating nutrients and pollutants to the breast milk happens each time the infant nurses, which can be many times a day. The higher the PFAS levels in the mother’s blood, the higher the milk PFAS levels.”

Consuming breast milk with PFAS levels that exceed children’s drinking water screening values does not indicate that adverse health effects will occur, and the findings should not be interpreted as a reason to not breastfeed, the researchers said.

Formula alternatives and breast milk bank donations are not screened for PFAS, according to Fenton.

“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,” Fenton and colleagues wrote.

Primary sources of PFAS include manufacturing sources (pollution), landfill and wastewater treatment plant waste fields, aqueous film-forming foams used to extinguish fuel-based fires (airports, military bases) and consumer products among other causes, according to Fenton.

Women who breastfeed may be able to have their serum or milk levels measured, she added.