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What are environmental chemicals doing in breast milk?

Posted on January 19th, 2011 by Alf | Print

What is free, cheap, non-processed, fresh, highly nutritious, perfect for babies, and readily available? Well, there are no prizes for guessing the answer is breast milk. It truly is a wonder food. Around 1% protein, 4% fat (including the omega-3 fats), 7% carbohydrate, minerals and vitamins all in a readily available form. Not only does it have all of the nutrients that are required for growth, it also contains factors that protect infants from infection and help educate the babies immune system.

The composition of breast milk can vary significantly from woman to woman. One important factor in this variability is the diet of the mother. For example, the fat composition of the breast milk is dependent on the types of fats in the mother’s diet. So, if the mother’s diet is rich in the special omega-3 fats in fish, or takes fish oils during lactation, the levels of these fats increase in the milk. Conversely, if the mother’s diet is deficient in vitamin A, an important nutrient, her breast milk may contain insufficient amounts of the vitamin to ensure optimal growth and development of her baby (1).

So, what is present or missing in the diet of the mother can affect the composition of their breast milk and in turn, have an impact on the health of the baby. Unfortunately, there are other substances often present in the maternal diet which are not normal components of food but are either contaminants in food, or deliberately added to food at some point. There are also many pollutants that can enter the mother’s body in other ways – for example through environmental exposure, skin contact, or through the lungs. Examples of contaminants detected in food include the pesticides used to control pests both before and after harvest, plastics components such as phthalates and Bisphenol A (BPA) and industrial waste products. The latter include the polychlorinated hydrocarbons (or PCBs), the polybrominated hydrocarbons (PBDEs), and heavy metals such as mercury. There are literally thousands of other substances we are exposed to in our daily lives and theoretically at least, many of these can be taken up.

Once these substances enter the mother’s body they may find their way into the mammary glands, which produce the milk, and then into the milk itself. There is no doubt that there are traces of environmental pollutants in breast milk. Pesticides, PCBs, PBDEs, mercury, arsenic, phthalates, and bisphenol A have all been found in breast milk, albeit in very small amounts. It is also clear what we are exposed to determines the levels detected in the milk (2,3,4,5, 6). What is alarming is the fact that breast milk from women who live in some of the most pristine places on the planet, where there is apparently little or no agriculture or industry, may also contain traces of pollutants. A good example of this is the Faroe Islands, which are situated in the North Atlantic close to the Arctic Circle and far removed from major European or North American industrial centers. The breast milk of women from these remote islands has been reported to contain high levels of industrial waste products, PCBs and PBDEs (6). The probable origin of these pollutants in Faroes’ women is the seafood in their diet, which may contain significant levels of a variety of pollutants such as mercury, arsenic, PCBs and PBDEs. The effects of diet and exposure on the levels and types of environmental chemicals in breast milk composition is not confined to Faroes women but is observed in breast milk taken from women throughout the developed and non-developed world.

The obvious question is – are these pollutants affecting the health of babies? Perhaps an even more important question is – should environmental chemicals, some of which are known to be potentially harmful, be present in breast milk in the first place? Most people would agree that the answer to this second question is an emphatic no. The answer to the first question – do these chemicals cause harm to babies? – is not yet clear. Certainly, the amounts in environmental chemicals in breast milk are very low, apparently too low to be toxic, at least as far as we can tell from animal toxicity studies. However, there are grounds for caution. Firstly, some babies are being exposed to a cocktail of environmental chemicals, not just a single chemical and the toxicity studies we do have mostly examine the effects of exposure to a single chemical, not a cocktail. Secondly, there are reports that tiny amounts of chemicals can produce unexpected effects via a process which scientists have termed “hormesis”. Thirdly, animals are not humans. This was dramatically demonstrated by birth defects caused by the anti-nausea pregnancy drug, thalidomide, defects that did not show up in the animal testing. Finally, some effects may be quite subtle and not expressed until later in life and if you don’t know what questions to ask, you won’t get the right answers.

So what does all this mean? While there may be disputes about the effects of pollution on global warming, there is absolutely no doubt that pollutants can and do enter our bodies and find their way into a food that is critical for the growth and development of our babies and children. That many of these pollutants are toxic in larger amounts is also beyond dispute. While governments around the world do not seem concerned at the levels of these toxic materials in breast milk, presumably because they believe that the amounts are insufficient to cause harm, these same governments also warn us of the dangers of eating certain foods containing these same pollutants when we are pregnant or nursing mothers (7). Governments’ ambivalence over this issue is best described by the old expression as “having a bob each way”.

Of course, the real question is what can we do about it? If we believe that pollutants should not be present in breast milk at all then we have to lobby government to introduce tougher laws and regulations further restricting the release of chemicals into the environment. Alternatively, some of us may believe that having trace amounts of environmental chemicals in breast milk in amounts that are considered non-toxic is a price we have to pay for an improved standard of living and is worth the risk. Whichever view we believe, the good news is that we can through sensible lifestyle choices, reduce our exposure to environmental chemicals and this will reduce their levels in breast milk.

Promoting Good Health is concerned about the potential health effects of environmental chemicals: How you are exposed; how they enter your body; the possible effects on your health and how to reduce your exposure. It is for this reason we have written “The Silent Threat” which provides detailed information on environmental pollutants in our food and water. “The Silent Threat” is available for purchase through our website. In the next few months, Promoting Good Health will be releasing other resources on environmental chemicals and contamination, including a new book on pollutants generated by industrial and other human activities and how they may be affecting your health and wellbeing.

Meanwhile stay healthy and happy!


(1) Tansuğ, N., Polat, M., Ceşme, S., Taneli, F., Gözmen, S., Tokuşoğlu, O., Yılmaz, D. and Dinç, G. (2010) “Vitamin A status of healthy children in Manisa, Turkey.Nutr. J., 9, 34.
Abstract available online at:  http://www.ncbi.nlm.nih.gov/pubmed/20809963
Full article available : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2940924/pdf/1475-2891-9-34.pdf
(2) Krysiak-Baltyn, K., Toppari, J., Skakkebaek, N. E., Jensen, T. S., Virtanen, H. E., Schramm, K. W., Shen, H., Vartiainen, T., Kiviranta,H., Taboureau, O., Brunak, S. and Main, K. M. (2010) “Country-specific chemical signatures of persistent environmental compounds in breast milk.Int. J. Androl. Apr;33(2):270-278, 2010. Epub 2009 Sep 24.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/20496936
(3) Ennaceur, S., Gandoura, N. and Driss, M. R. (2008) “Distribution of polychlorinated biphenyls and organochlorine pesticides in human breast milk from various locations in Tunisia: Levels of contamination, influencing factors, and infant risk assessment. Environ. Res. Sep;108(1):86-93. Epub 2008 Jul 9.
Abstract available online at:  http://www.ncbi.nlm.nih.gov/pubmed/18614165
(4) Lin, S., Ku, H. Y., Su, P. H., Chen, J. W., Huang, P. C., Angerer, J. and Wang, S. L. (2011) “Phthalate exposure in pregnant women and their children in central Taiwan.Chemosphere Feb;82(7):947-955. Epub 2010 Nov 13.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/21075419
(5) Kuruto-Niwa, R., Tateoka, Y., Usuki, Y. and Nozawa, R. (2007) “Measurement of bisphenol A concentrations in human colostrum.Chemosphere. Jan;66(6):1160-1164. Epub 2006 Aug 14.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/16904728
(6) Fängström, B., Strid, A., Grandjean, P., Weihe, P. and Bergman, A. (2005) “A retrospective study of PBDEs and PCBs in human milk from the Faroe Islands. Environ Health. Jul 14;4:12.
Abstract available online at: http://www.ncbi.nlm.nih.gov/pubmed/16014177
Full article available online at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1226148/pdf/1476-069X-4-12.pdf
(7) US Food and Drug Administration Health Advisory: “What You Need to Know About Mercury in Fish and Shellfish (EPA-823-R-04-005). 2004 EPA and FDA Advice For:
 Women Who Might Become Pregnant, 
Women Who are Pregnant, 
Nursing Mothers and 
Young Children. March 2004.
Available online at: http://www.chifountain.com/studies_Folder/MercuryJune04.pdf

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