I was discouraged to see this recent study, which showed that as many as 93% of pregnant mothers would stop breastfeeding over concerns about toxins in their milk:
Of breastfeeding women, 78% to 93% of mothers reported that they would either discontinue breastfeeding sooner than intended or pump and discard their milk if they were told that they had "low" or "high" levels of phthalates in their milk, respectively. African American women were significantly more likely than Caucasian women to report that they would immediately wean if told of phthalates in their milk.
This demonstrates, I think, a lot of fear about environmental toxins in breastmilk. So I thought that this might be a good time to put out a few facts about this topic:
1) Levels of some toxins in breastmilk have been going down in recent years. Dr. Kathleen Arcaro, environmental toxicologist at the University of Massachusetts said in an interview for this blog, "the good news is that the concentration of some lipophilic (fat-loving) environmental pollutants in breast milk is decreasing. For instance the level of many pesticides (DDT and its metabolites) and polychlorinated biphenyls (PCBs) has greatly decreased over the last 30 years."
2) Toxins are in formula, too. Update: Please see this post on contaminants in formula. You obviously have to feed your baby something, and there's no reason to think that formula doesn't contain some contaminants as well. Dr. Arcaro notes that "pollutants are widely distributed [i.e. in the air, in water] and therefore are in cow’s milk and formula." Dr. Arcaro shared a study with me showing that one type of toxin (PAH) is found in the highest levels in formula and cow's milk, and lowest levels in breastmilk. If some degree of exposure exists in all of our choices, wouldn't we want to choose the food that offers many health and developmental advantages?
3) Recent research found no adverse consequences of dioxins in breastmilk. A recent study comparing the health and development of babies exposed to dioxins (nearly twenty years ago, when exposure to dioxins was more common) through breastmilk and those fed formula found no adverse health consequences for the breastfed babies, and significantly better developmental outcomes for those who were breastfed. This confirms the findings of prior research. The International Lactation Consultant Association states in their position paper (pdf) on this topic that, "with the exception of maternal poisoning, breast milk remains a safe, life-enhancing method to feed and nurture infants and young children."
4) Not everything in the environment or your diet makes it into your milk. Our bodies have several systems that regulate what gets into our milk. Some things we eat, for example, are destroyed in our digestive system, eliminated from our bodies, or held in our livers before they even enter our bloodstream, which is where they may transfer into milk. And not everything that enters our bloodstream makes it into our milk, either. Only substances that are small enough in molecular weight to squeeze in between our milk making cells, or fat-soluble enough to 'hitchhike' through the milk making cells, can make it into milk. And once the level in our bloodstream declines, substances that make it into milk actually move backwards into our bloodstream. Even when something harmful does make it into your milk, your baby's gut may destroy it or poop/pee it out before it can enter her bloodstream. Of course, these systems are not foolproof, and some substances can pose a threat to your baby. Much more on this topic can be found on Dr. Thomas Hale's website.
5) If you're concerned, you can make choices about products you use, and advocate for better regulation. Dr. Arcaro points out that some recently identified substances in milk (and therefore in our fatty tissue) are from household and personal care products. So, if you're concerned about this (and I'd again note the research above does not raise concerns), you can make some pretty simple choices about the detergents, cleaners, personal care products (soaps, shampoos, deodorant, lotions, etc.), and plastics you use, as well as the foods you eat. You can also advocate for tighter regulation of substances like BPA.