Health effects of PFAS exposure through breastmilk largely unknown
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Key takeaways:
- Maternal exposure to PFAS chemicals is associated with decreased lactation duration.
- The biological mechanism in humans remains unknown.
BOSTON — Women exposed to a class of endocrine-disrupting chemicals known as PFAS may be more likely to struggle with breastfeeding, whereas the health effects of infant exposure to PFAS via breastmilk remain unknown, a speaker said.
Breastfeeding offers benefits for both the lactating parent and the child and the American Academy of Pediatrics recommends exclusive breastfeeding for 6 months, though breastfeeding rates remain low globally, Megan Romano, PhD, MPH, associate professor of epidemiology at Dartmouth Geisel School of Medicine, said during a presentation at ENDO 2024. Social and cultural barriers can affect breastfeeding duration; however, less is known about the effects of environmental exposures, Romano said.
“The hormonal regulation of lactation should suggest for us that lactation is an endpoint that is potentially very sensitive to endocrine-disrupting chemicals,” Romano said.
PFAS exposure and mammary gland development
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a large group of highly fluorinated persistent synthetic chemicals found in a very wide range of stain-, oil- and water-resistant consumer products. The chemicals have very long half-lives in the body and about 1,000 PFAS have current industry uses, but the class is much larger, Romano said.
Experimental animal studies support the hypothesis that PFAS exposure disrupts mammary gland development and lactation. Involved pathways likely include peroxisome proliferator-activated receptor (PPAR)-alpha activation, interference with mammary gland differentiation, disruption of hormones, and alterations in milk protein gene expression. Researchers have also noted some transgenerational effects, Romano said.
“There is a lot to unpack here in terms of what might be going on biologically and how PFAS might be influencing these lactation outcomes,” Romano said.
Impact on breastfeeding duration
A growing body of literature suggests that PFAS may be associated with shorter duration of breastfeeding, Romano said.
In a study published in the International Journal of Hygiene and Environmental Health in May, Romano and colleagues quantified PFAS concentrations in maternal plasma collected during pregnancy in the New Hampshire Birth Cohort Study (2010-2017). Participants completed standardized breastfeeding surveys at regular intervals until weaning (n = 813). Researchers estimated associations between mixtures of five PFAS chemicals, measured at about 26 weeks’ gestation, and risk for stopping exclusive breastfeeding before 6 months or any breastfeeding before 12 months. For individual PFAS, researchers calculated RRs and HRs for stopping breastfeeding.
Researchers found that PFAS mixtures were associated with stopping exclusive breastfeeding before 6 months, primarily driven by perfluorooctanoate (PFOA). Romano said they observed statistically significant trends in the association of perfluorohexanesulfonic acid (PFHxS), PFOA and perfluorononanoic acid (PFNA) with stopping exclusive breastfeeding. Women in the highest PFOA quartile had a 28% higher risk for stopping exclusive breastfeeding before 6 months compared with those in the lowest quartile. PFAS were not associated with stopping any breastfeeding before 12 months.
“What this indicates to us is that greater overall PFAS exposure is associated with increased risk for stopping breastfeeding,” Romano said. “PFOA is likely to be the primary bad actor, but this underscores the need to consider the combined influence of multiple PFAS when thinking about these endocrine-sensitive outcomes.”
The biological mechanism in humans remains unknown, Romano said.
“It may be a disruption of prolactin, oxytocin, estrogen or other hormones that influence lactation,” Romano said. “There is some evidence that [PFAS exposure] may be associated with challenges with initiation, but it is challenging to study the initiation of breastfeeding in populations.”
Other possible mechanisms could include an association between PFAS exposure and abnormal mammary gland development or insufficient quantity of milk or that exposure to PFAS influences the quality of milk or milk composition, Romano said.
Should women avoid breastfeeding?
Human milk is a route of PFAS excretion and people living in communities with high PFAS exposures are often concerned about breastfeeding infants, Romano said, calling the question “the giant elephant in the room.”
“WHO recently conducted a risk-benefit analysis of breastfeeding and while there are toxicants present in milk, they found that, unequivocally, the benefits of breastfeeding far outweigh the risk of early-life toxicant exposure,” Romano said. “The CDC also echoes this recommendation.”
Romano said breastfeeding remains the optimal nutrition for an infant’s changing needs during early life; however, there is “no one-size-fits-all answer.” Infant formula and baby food also contain PFAS and guidance for new parents is lacking, Romano said. Additionally, the health effects in infancy and childhood of PFAS exposure through human milk are largely unknown.
“There are sparse studies on the influence of PFAS exposure via human milk on child health, but we are working on changing that as well,” Romano said. “Ultimately, what this work emphasizes is the need for continued environmental stewardship and to prevent these exposures from happening in the first place.”
Reference:
Romano ME, et al. Int J Hyg Environ Health. 2024;doi:10.1016/j.ijheh.2024.114359.
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Romano M. Endocrine-disrupting chemicals in reproductive endocrinology. Presented at: ENDO annual meeting; June 1-4, 2024; Boston.
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