Many parents have heard the term “breast is best,” a saying to convey the health benefits of breast milk, over formula, for infants. Studies have shown it can protect babies from diseases, by providing antibodies from the mother, while also reducing the lactating parent’s risk of breast and ovarian cancer.
Yet studies have also shown that contaminants, such as pesticides and flame retardant chemicals, are in human milk. A recent study adds microplastics, or tiny microscopic plastic particles, to that list.
As a breastfeeding mom of two, I wondered: Should I be worried? Is breast milk still really best?
“It’s definitely concerning when we find chemicals in breast milk that are known to affect child development,” said Erika Schreder, science director for the advocacy group Toxic-Free Future and co-author of a 2023 study on brominated flame retardants (known as BFRs) in breast milk of U.S. women. “We know that breastfeeding is so important for the health of both the mom and the baby, and we need to do everything we can to make sure breast milk is safe.”
Environmental pollutants were first found in breast milk in a 1951 survey of 32 women. Thirty of the women had small amounts of the pesticide DDT in their breast milk. By 2008, DDT and its metabolites were reported “in essentially all human milk tested worldwide,” according to a research article published that year. (DDT was banned in the United States in 1972 but is still used in some countries.)
The Centers for Disease Control and Prevention says that “we do not know what level of exposure to pesticides is safe for breastfeeding” but that pesticides have been associated with a variety of diseases in humans, such as cancer, neurotoxicity and genotoxicity risks, and effects on the endocrine, reproductive and immune systems.
As for BFRs, which are used in such items as furniture, children’s products, vehicles and electronics, researchers began to find these chemicals in breast milk in the 1970s. A 1999 study reported that one of the most commonly used BFRs increased more than 5,000 percent in the milk of Swedish mothers between 1972 and 1997. BFRs have been found in breast milk in other studies based in other countries as well.
Schreder said these findings (as well as the fact that BFRs have been found in placentas and fetal blood) are not surprising given that these chemicals continue to be used in household products and can be easily transferred to our bodies.
“Incidental dust ingestion is the biggest route of exposure,” Schreder said, noting that “when BFRs are used in electronics like TVs, they migrate out of the plastic in the product” and “get into the dust that accumulates on it.”
Concerns about the impact of flame retardant chemicals on humans and the environment have led some chemical manufacturers to voluntarily stop their production, while some states and several European countries have banned some formulations altogether.
As for microplastics, a small 2022 study found tiny plastic particles, less than five millimeters in diameter, in 75 percent of 34 breast milk samples studied. (Previous studies found microplastics in placentas, heart tissue and blood.)
Antonio Ragusa, an obstetrician and lead researcher of the 2022 study, said that, for babies, the danger of microplastics lies less with the tiny plastic particles themselves and more with the chemicals used to create the plastic, including some that are known endocrine disrupters, which mimic or interfere with human hormones.
“Since hormones are so fundamental for everything from sleep to hunger to sex, chemicals that disrupt those messages can lead to a wide variety of issues – including fetal development, neurological disorders and even fat storage, leading to obesity,” Ragusa said.
Laurence Grummer-Strawn, unit head of food and nutrition action in health systems at the World Health Organization and a specialist on infant and child nutrition, said that despite these concerning findings, no one who is breastfeeding, or thinking of doing it, should conclude that it’s unhealthy for their child.
“After considerable analysis, the answer is almost always that in spite of the existence of trace elements appearing in the milk, breastfeeding should still be recommended over formula feeding,” he said.
“One reason for this is that the levels in the breast milk are still below what would be considered ‘safe’ levels,” he added. “Second, toxins that are ubiquitous in the environment may be found in infant formula or other baby foods as well as in breast milk. Third, the epidemiologic literature that compares breastfeeding and formula feeding have been done in populations that have been exposed to these toxins and so any ‘dampening’ of the benefits of breastfeeding are already accounted for, and still, breastfeeding is found to be superior.”
Philip J. Landrigan, a pediatrician and director of the Program for Global Public Health and the Common Good at Boston College, agreed that “for the general American population, the balance of evidence is breastfeeding is better than bottle-feeding or any other substitute” – provided a mother can breastfeed and wants to do it.
He noted that there are a few instances in which pediatricians advise moms not to nurse their babies “because the levels of chemicals are so high,” like for those who live near industrial factories and some native populations in the north of Canada. “Concentrations of some of the chemicals, like PCBs [chemicals used in industrial production that were banned internationally in 2001], are astoundingly high there in the region near the North Pole,” where they were blown or carried by the ocean.
So is breast milk best? The WHO, the American Academy of Pediatrics and the U.S. Preventive Services Task Force all recommend breastfeeding for those who can. That, plus the experts’ advice, convinced me to stay the course on breastfeeding.
However, the experts acknowledged the breast-bottle calculus could change in the future given the continuing and growing use of chemicals and plastics in the environment.
HOW TO REDUCE ENVIRONMENTAL CONTAMINANTS
Pediatrician Philip J. Landrigan said that there are ways people can cut down on their families’ exposure to environmental contaminants.
Landrigan said he advises families to opt for organic foods whenever possible because “studies have shown that people who eat a mainly organic diet have far fewer toxic chemicals in their body than people who eat a so-called conventional diet.”
He also suggests limiting or eliminating the use of pesticides around the house. “If you’ve got bugs around the apartment or the house, deal with them the old-fashioned way,” he said, “which is keeping things clean, picking up food residue, don’t leave the bugs any free food and water.”
Sherri A. Mason, a microplastics expert and director of sustainability at Penn State Behrend in Erie, Pa., said breastfeeding parents who are concerned about their babies’ microplastics exposure in particular should consider providing breast milk directly from the breast and not from a bottle.
Pumping milk, freezing it in plastic and then heating it up increases the shedding of microplastic particles. Likewise, heating plastic in a microwave causes “the thousands of chemicals that are used in the plastic to move,” which means they will migrate out of the plastic and into the liquid or food, Mason added.
Mason said nursing parents may want to avoid plastic water bottles themselves; her 2018 research showed that “bottles shed particles of plastic into the water, making the plastic content in the bottled liquid hundreds of times greater than simple tap water.” It’s one way they can potentially reduce the plastics in their body, and their breast milk.
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