This story is part of a series, “Fighting ‘Forever Chemicals’: Women face pervasive PFAS risks.”

(The Hill) — For decades, physicians and scientists have touted breast milk as liquid gold for its immunological benefits.

But nursing parents with considerable exposure to cancer-linked “forever chemicals,” or PFAS, may unwittingly be exposing their babies to these compounds as well — presenting parents with a quandary scientists are still trying to unravel.

The data available on these substances in breast milk is minimal.

And in North America, there is little effort to test for exposure through milk or formula, no guidelines on what level of chemical is safe for babies to ingest and a general lack of education among medical professionals on the topic.

The Centers for Disease Control and Prevention’s (CDC) Agency for Toxic Substances and Disease Registry unequivocally states that “babies born to mothers exposed to PFAS can be exposed during pregnancy and while breastfeeding.” The agency advises lactating people to continue breastfeeding, however, stressing that the benefits of nursing likely outweigh the potential risk of PFAS exposure through breast milk. 

On the other hand, the agency also acknowledges that scientists are continuing to conduct research in this area and that nursing moms should contact their doctors “to weigh the risks and benefits” — doctors who may not be up to date on PFAS literature.

PFAS, which stands for per- and polyfluoroalkyl substances, persist in the body for years and have been linked to a variety of cancers and other illnesses. They are found in many common household products, certain kinds of firefighting foams and industrial discharge, and have become pervasive in the air, water and soil.

“I’m always stressing to people ‘breast is best,’ even if there’s contamination,” said Linda Birnbaum, the former head of the National Institute of Environmental Health Sciences and the National Toxicology Program. 

While she agreed that the specific nutrition and immune benefits babies get from breast milk remain important, Birnbaum affirmed that many people “are really concerned.” 

“And I don’t blame them,” she said. 

A February 2022 review from a team of U.S. and Canadian researchers — who compiled the existing, although minimal, data available regarding PFAS levels in breast milk — called for the urgent establishment of national breast milk monitoring programs in North America to prevent harmful impacts on babies who drink it. 

Such programs, the authors explained, could include studies that measure concentrations of PFAS in milk and blood serum samples taken simultaneously from breastfeeding women. The results could help contextualize current estimates of PFAS levels in breast milk, in order to minimize unwanted exposures of infants to such contaminants, according to the review.

Suzanne Fenton, one of the authors of the commentary, which was published in Environmental Health Perspectives, pointed out that “the U.S. has not, to date, participated in global milk monitoring efforts.”  

For example, the U.S. chooses to not be involved in a global monitoring plan established under the Stockholm Convention, explained Fenton, who at the time was a group leader in the Mechanistic Toxicology Branch of the National Toxicology Program at the National Institutes of Health. This past fall, she transitioned roles and took over as the director of North Carolina State University’s Center for Human Health and the Environment.

Among the outcomes of the 2001 Stockholm Convention on Persistent Organic Pollutants was a “human milk survey,” which tested 189 national pools of breast milk from 90 countries for 28 such pollutants, including certain types of PFAS. 

North America, in general, lacks both breast milk research collections and widespread access to testing for nursing parents. And while scientists and government agencies agree that PFAS are unsafe in drinking water, the U.S. government has not given specific guidance as to what concentrations of the substances pose a threat to infants consuming breast milk.

Fenton and her colleagues criticized the absence of such screening values for breast milk PFAS levels in both the U.S. and Canada. They contended that even if PFAS concentrations in milk surpass thresholds that have been set for drinking water, it is impossible to predict what harm could result. 

Contaminated water itself, meanwhile, could also be a potential source of PFAS in infant food supplies. Parents may be making formula with it — although the data available on the subject is sparse.

Fenton and her colleagues incorporated some available data on PFAS in both breast milk and formula in a December 2022 Environmental Research review, stressing that “an international monitoring effort and access to affordable testing are needed for breast milk, drinking water and infant formula to fully understand infant PFAS exposures.” 

“Currently, our understanding of demonstrable methods for reducing exposures to emerging PFAS is limited, making this research and the communications surrounding it even more important,” the authors concluded. 

A second literature review overseen by Fenton, published in Toxics in March 2023, examined the issue from another angle: Rather than evaluating PFAS levels in milk, the authors sought to determine whether these compounds have any effect on how long a parent ends up nursing.

The researchers flagged human epidemiological studies that have examined this potential link, narrowing down their search to six studies — five of which identified a link between certain types of PFAS and shorter breastfeeding duration. 

Stressing that health authorities have long promoted the benefits of nursing, the authors noted that there has been little focus on “environmental exposures that might impair breastfeeding, the functional aspect of the breast.”

Some action has been taken by individual states, such as New Jersey and Minnesota, and by the Environmental Protection Agency (EPA) to develop hazard evaluations of individual types of PFAS in infant formula, according to Fenton. These assessments are based on “drinking water intake-body weight values” — an exposure factor adjusted for body weight — and aim to protect the health of sensitive populations, such as children younger than 5 years, Fenton explained. 

Part of the problem in establishing what concentration of PFAS in breast milk may be harmful, in addition to the lack of available milk samples, was a past lack of adequate technology that could analyze “low enough concentrations to detect what is in milk,” according to Erin P. Hines, a researcher in the EPA’s reproductive toxicology division. But as analytical chemistry techniques have improved and researchers have begun amassing local repositories of milk, Hines said she remains hopeful that such efforts could be replicated on a national scale.  

In the meantime, Hines stressed that people who are lactating should turn to their clinicians for guidance.

But testing options remain limited, and a gap still exists between scientific research on the effects of PFAS on breast milk and the awareness of clinicians who treat nursing parents. 

Asked whether the American Academy of Pediatrics (AAP) provides official guidance regarding PFAS exposure and pregnancy and nursing, Lisa Black, a spokesperson for the organization, sent The Hill a relevant book chapter available to clinicians. The chapter, within the AAP’s “Pediatric Environmental Health Fourth Edition” focuses on PFAS and routes of exposure to these compounds, as well as potential health impacts and clinical effects. 

While stressing that animal studies that incorporate high doses of certain PFAS compounds “have demonstrated acute and chronic toxicities,” the chapter warns that human epidemiological findings “have been inconsistent or have uncertain clinical relevance.” 

As far as treatment of potential symptoms is concerned, the chapter explains that “no proven therapy or approved medication is available to speed up the body’s natural but slow elimination of PFAS.” Instead, the guidance suggests switching to bottled water in the case of drinking water contamination.

The National Academies of Sciences, Engineering and Medicine in July 2022 released a report that provides some information to health care professionals and their patients who may have been exposed to PFAS, Fenton noted. While this guidance is based on adult exposures, it may be updated in a few years to offer advice on infants and children if the relevant data becomes available, she explained. 

The report identifies an increased risk of certain health impacts associated with PFAS exposure, some of which apply to infants and children. Among these effects are decreased antibody response, decreased infant and fetal growth and dyslipidemia — abnormally elevated levels of fats or cholesterol in the blood — as well as possible changes in liver enzymes. 

“The recommendations in this report will be most protective of the public’s health if they are part of a national effort toward increased biomonitoring, exposure surveillance, and clinicians’ and public health professionals’ education on environmental health issues,” the authors concluded.

Following the NASEM report publication, the AAP issued a press release highlighting its findings and offering some recommendations to pediatric health care providers. 

Chief among those were exposure reduction efforts, such as filtering contaminated water, following local food advisories for fish and game, replacing nonstick cookware with stainless steel or cast iron and avoiding stain-resistant textiles and waterproofing sprays. 

The AAP emphasized the utility of administering PFAS blood tests to those individuals with a likely history of elevated exposure — listing specific thresholds that could indicate further action.  

“While there is evidence that PFAS is present in breastmilk, it is uncertain whether such exposure constitutes a threat to the infant’s overall future health,” the AAP press release stated. “Breastfeeding is the best option for babies in most cases.”