Contrary to popular belief in some circles, breastmilk is not the pure and magical serum of the Earth goddess which ensures an eternal life of prosperity and good health to all who partake. That’s unicorn milk — it doesn’t exist. And now a new study seems to claim breastmilk passes so many toxic chemicals onto your baby that maybe you should stop early? So we're swinging the whole other direction now? Not quite. Let's look closer at the hyperbole on both sides and what that study actually found.
The benefits of breastfeeding — which I not only strongly support but have done for both my children — are not infrequently exaggerated. Yes, your body calibrates your milk to include precisely the nutritional proportions your growing baby needs. Yes, nursing confers undeniable benefits seen at the population level, such as reduced rates of breast cancer among mothers and reduced ear infections and GI infections in infants, among other advantages. But at the individual level, with the exception of certain groups such as preemies, breastfeeding your baby cannot guarantee your child will be thinner, fatter, smarter, healthier, faster or stronger than a baby fed any of the increasingly more sophisticated baby formulas on the market.
One of the few benefits that can be quantified at the individual level is the transfer of maternal antibodies, the suspected main reason for those reduced GI problems and ear infections. Yet, in an ironic twist, it may be that very property that chemicals in breastmilk threaten to undo. Or so claims a new study about a commonly used group of industrial compounds called perfluorinated alkylate substances, or PFASs. But that's not the whole story.
These two breastmilk samples from the same woman show foremilk on the left and fattier hindmilk on... [+]
Manufacturers have used PFASs for more than a half century in products ranging from waterproof clothing to food packaging to paints and lubricants. These compounds make products waterproof or grease- or stain-resistant. But, like many other compounds designed to improve people’s lives in some way or another, these chemicals stick around for a really long time in the environment and in animals’ bodies, including those of humans. And, like a variety of other classes of manmade compounds, PFASs have been linked to a range of unsettling health effects, such as interference with reproduction in animals, disruption of hormones in human endocrine systems and, yes, interference with human immune systems.
“Perhaps most importantly, we have recently found that children respond more poorly to vaccinations if they have elevated levels of PFOS, PFOA and other perfluorinated compounds in their blood,” said the study’s lead author, Phillippe Grandjean, a professor of environmental health at Harvard School of Public Health. “So there is a risk that the vaccination will not ‘take’ and help protect the children against the diseases.”
Whoa, whoa, whoa — so breastfeeding now hurts kids’ immunity? That is, in fact, what Grandjean suggests. Yet the only evidence cited in his paper for that is a single study... that he conducted and that was criticized in a letter to the journal (paywall). The World Health Organization, CDC and American Academy of Pediatrics all recommend exclusive breastfeeding for six months and continued breastfeeding for up to one to two years, but Grandjean claims the best evidence for breastfeeding only lasts through the first three months (the evidence actually shows it lasts longer). He therefore recommends supplementing breastfeeding with formula after three months and hopes that the CDC, WHO and other agencies “will reassess the situation and revise their recommendations.”
“I find it paradoxical that we have to worry about industrial chemicals in human milk,” Grandjean said. He points out that the Toxic Substances Control Act of 1976 does not require industrial chemicals to be tested for effects on human health even though we have the ability to test whether a compound can be secreted through milk. “It is absurd that we allow toxic chemicals to find their way to the most sacred form of nourishment and put the health of the next generation in danger.”
Say what? That sounds like serious chemophobia. And it is. Let’s back up.
First, what did Grandjean and his colleagues actually find? They found that the build-up of PFASs in children’s blood increased by 20% to 30% for each additional month of exclusive breastfeeding. Children supplemented with formula had lower levels, and the levels dropped when exclusively breastfed children were weaned. But here’s the thing: the study is very small and very geographically limited: the researchers tracked just 81 children living in the Faroe Islands and tested their PFAS blood levels when the children were 11 months, 18 months and 5 years old. That's not even a 100 kids.
“This was a study of a very specific group of women, with very specific diets, which may have led to increased exposure of their infants to PFAS through breastmilk,” said Dr. Henry Farrar, a clinical pharmacologist at Arkansas Children’s Hospital in Little Rock. “Therefore, this study may present a setting in which there are valid concerns in a very specific group of people.”
But that’s one small population — in an island nation, much less — whose breastmilk composition cannot necessarily be extended to that of women living elsewhere in the world. “This is a well-done study but more studies need to be done in other groups of women before there can be concern that the risks outweigh the benefits of breastfeeding,” Farrar said. “Currently there are very few circumstances in which the risks of exposure of an infant to chemicals in breastmilk outweigh the many benefits of breastfeeding.”
Further, the data we have on PFASs and their effect on humans is sparse and inconsistent — and the risks appear quite modest. Although Grandjean provided a hefty list of concerns that these compounds have been linked to, the epidemiological evidence base in humans shows small and inconsistent effects in those populations with the highest levels of exposure, such as industrial workers in manufacturing plants and communities near industry who consumed contaminated drinking water. In fact, more than 95% of people in the U.S. have PFASs in their blood because it’s pretty hard to avoid them in modern society.
It seems more than a little paranoid, then, to suggest that women the world over should cease exclusive breastfeeding at three months on the basis of a single study involving fewer than 100 people that found increases in compounds that may or may not have serious health effects.
The real take-away, it would seem, is that there is no perfect, “right” way to feed a baby. There are risks and benefits and advantages and drawbacks to breastfeeding and formula feeding and mixed feeding. We have a lot more to learn about the compounds in our environment, how they affect our children, the interactions of gut bacteria in breastfed and formula-fed children and a host of other scientific questions. But breastfed and formula-fed children all across the world are all leading happy, productive lives. So carry on. Feed your baby.
Note: This study was funded by the National Institute of Environmental Health Sciences, the U.S. Environmental Protection Agency, the Danish Council for Strategic Research and the Danish Environmental Protection Agency. No other funders supported this study.
My book, The Informed Parent, with co-author Emily Willingham, is available for pre-order. Find me on Twitter here.
