What's in Your Breast Milk? (and Is It Safe for Baby?)

Phthalates are one of the most common pollutants out there and the more press they get the more paranoid I’m starting to feel about what they may or may not being doing to my young daughters. I can take some measures to keep them away from my 15 month-old – no rubber duckies in our tub – but after hearing about a recent study it’s actually the daughter who’s breastfeeding I’m really starting to worry about.

Dr. Susan P. Phillips is a family physician and a professor in the school of medicine at Queens University in Kingston, Ontario, Canada who recently compared the levels of phthalates in breast milk to those in powdered infant formula. Rat studies have shown phthalates to have endocrine disrupting properties, but, even though there are less toxic and equally effective substitutes, in the U.S. they are still fairly ubiquitous. Water, soil, consumer products, medical equipment, dust – you name it, no category seems untouched. They’re in everything from CD’s, sunglasses and computers, to teethers, baby lotions and nail polish. When Phillips heard about the significant association between premature breast development in young Puerto Rican girls and the negative effects on sperm morphology from phthalate esters she decided to measure the milk of lactating mothers, determine how much their babies were being exposed to, and compare it with what they were being exposed to in formula. She found the levels of phthalates in breast milk were 37-times the levels in formula.

Phillips told me that the doctors she works with didn’t want her to do the research for fear it would discourage women from nursing their babies, but she feels strongly that women should be given as much information as possible. “My response was that women have a right to know,” said Phillips on the phone from Canada. “We would be implying they could not balance the pros and cons if you wanted to block them from having the full knowledge.”

The 21 women who volunteered from a prenatal education class to be part of the project gave samples of hand-expressed breast milk (when they were done nursing) at two weeks, one month, two months, four months and six months, for a total of 86 samples. Kingston, Ontario is a small, non-industrialized city and not an area where you'd think about pollution particularly.

When I asked Phillips if she would still recommend breastfeeding she said, yes. Bottom line: “there’s more we don’t know about phthalates than we do know.” Even if there’s a level of 10 parts per billion in breast milk, we still don’t know exactly what that means.

In the paper that she wrote with Jiping Zhu based on the study she acknowledges the superiority of breast milk as a source of infant nutrition, but also suggests that efforts to lower maternal exposure to phthalate esters could decrease the load of a potentially harmful chemicals transferred to the baby. She concludes: “Further research on the determination of phthalate esters and their metabolites in the body fluids of infants is needed to fully understand the potential health risk to infants exposed to phthalate esters through either breastfeeding or formula feeding. Risk management strategies also need to be developed to minimize the infants’ exposure to these endocrine disrupting chemicals, while maximizing the benefits of breastfeeding.”

In the meantime, you can check out what the Environmental Working Group has to say about the chemical safety of your personal care products of choice in their thorough database.