Environmental Contaminants and Human Milk
Ithaca NY USA
From: LEAVEN, Vol. 39 No. 6, December 2003 - January 2004, pp. 123-25.
Recent headline reports in news media such as USA Today and CNN have made public several studies concerning chemicals in human milk. The most publicized of these studies was performed by the Environmental Working Group, a nonprofit organization in the United States that recently completed the first nationwide test for chemical fire retardants in human milk. Each of the women in the sample showed unexpectedly high levels of brominated or bromine-based fire retardants in their milk.
When studies such as these are publicized, Leaders can expect the subject to come up at meetings and during phone calls. First and foremost, Leaders can assure mothers that human milk is still the best for babies and that all of the research available indicates that women should continue to breastfeed.
Environmental Contaminants Are the Problem, Not Mother's Milk
When discussing such studies with breastfeeding mothers, Leaders can point out that the reason researchers test mother's milk is not to condemn breastfeeding, but to find out the level and types of pollutants in our bodies.
Bio-monitoring (testing humans for pollutants) is being done more often because of recent breakthroughs in the ability to test human tissues. The easiest bio-monitoring tests are done using human milk. Other bio-monitoring tests can be performed using blood or fat tissues, but those samples are harder to acquire, and may require larger samples for accurate results. Some chemicals don't show up in blood samples, only in tissue samples containing fat. Testing human milk means that the mother can pump it herself, and volunteers are not subjected to needle pricks or invasive procedures to remove fat tissues.
Bio-monitoring of human milk provides an easy way to collect data about which chemicals are retained in body tissues. Researcher Kim Hooper states in his article, "Levels of chemicals in humans (body burdens) are useful indicators of environmental quality and community health." Like other researchers, Hooper says that the bio-monitoring of human milk should not be used to discourage breastfeeding, stating that, "body-burden monitoring using breast milk should include educational programs that encourage breastfeeding" (Hooper 2002).
Sandra Steingraber, PhD, ecologist, and author of the book Having Faith: An Ecologist's Journey to Motherhood, explains that toxins, including heavy metals such as mercury and lead, bind to milk proteins, and other chemicals, such as flame retardants, become trapped inside the milk fat, which is then carried by the liquid fraction of milk "like so many bath-oil beads."
Humans store environmental contaminants in their fat tissues over their lifetime, and at least 60 percent of the fat in milk-globules is drawn from reserves scattered throughout the mother's body. Hence, human milk carries with it the chemicals the mother has been exposed to and stored her whole life. It is also, therefore, one of the easiest tissue samples to use for monitoring the "body burden" of chemicals for an average adult. Particularly worrisome are the persistent organic pollutants (POPs) including DDT, PCBs, and dioxins, which remain in the environment for years.
The Environmental Working Group's Study of Flame Retardants in Human Milk
The Environmental Working Group (EWG) tested the milk of 20 first-time mothers from all over the United States, and found that every mother showed unexpectedly high levels of bromine-based flame retardants in their milk. Flame retardants are neurotoxic chemicals (chemicals that are poisonous to nerve tissue) used in hundreds of industrial, automotive, and household products, from bedding to computers, carpets to foam padding, wastewater pipes to electrical connectors. The study confirmed that American women have far higher levels of flame retardants in their body tissues than women in Europe (Lunder 2003).
There are many types of flame retardants with varying levels of toxicity. The most potentially dangerous type still being manufactured today is a group of brominated fire retardants called polybrominated diphenyl ethers, or PBDEs. PBDEs are the chemical cousin to PCBs and, like PCBs, they are persistent in the environment and bioaccumulative, meaning they build up in people's bodies over a lifetime. While PCBs have been banned in the United States, the United States Environmental Protection Agency has set no safety standards on the manufacture, use, or disposal of flame retardants. Earlier studies that showed PBDEs rapidly accumulating in the human milk of Swedish mothers prompted a ban on their use in Sweden, Germany, and the Netherlands in the mid-1980s and early 1990s. Since the ban, the level of fire retardants in Swedish mothers' milk has declined, and the European Union has banned their use starting in 2004. It is therefore likely that a similar ban in the US would have a similar effect.
What the Studies Show and What Remains Unknown
While the EWG found high levels of PBDEs in American mothers' milk, the research on what the effects are on babies remains unclear. While low exposures of PBDEs in laboratory animals have been linked with thyroid hormone disruption, permanent learning and memory impairment, behavioral changes, hearing deficits, delayed puberty onset, decreased sperm count, fetal malformations and, possibly, cancer, it is difficult and unpredictable to transfer those findings to humans.
It's important to note that numerous studies of laboratory animals and humans show that many of the problems associated with exposure to environmental contaminants occur in utero and not during breastfeeding or after. Sonya Lunder, an environmental analyst for the Environmental Working Group, writes:
Several long-term studies have followed groups of babies exposed to PCBs (polychlorinated biphenyls) in utero and found that the breastfed babies appear to be less impacted by the chemical exposures than their formula-fed counterparts. One study of Michigan [USA] babies found significant improvements in babies breastfed for at least six weeks. The researchers concluded that PCB exposures in the womb were responsible for the neurological impacts, and that breastfed infants showed far fewer effects of PCB exposure (Lunder 2003).
Still, according to some Dutch studies, mothers whose milk is more contaminated have children with more mental and psychomotor deficits, although less than there are in formula-fed infants.
In reading and evaluating any study, it is important to consider who conducted the study and their methodology. For example, recent Dutch research on toxins in human milk, specifically PCBs and dioxin, which used pooled milk and were conducted by labs connected to the formula industry, linked high levels of contaminants in human milk with some mothers' inability to even produce milk. The US Natural Resources Defense Council, in commenting on dioxin in human milk, states the following:
A group of women may all donate samples that are then combined into one sample for analysis. This means that individual levels, and the variability (range) of dioxin levels, may not be known. Not knowing the range can be problematic because outliers (extremely high or low values) can indicate unique exposure scenarios.
How Leaders Can Help Mothers
As bio-monitoring studies using human milk gain popularity, we can expect media outlets to report more stories concerning pollutants in human milk. As La Leche League Leaders, we need to be prepared for helping mothers who call with concerns regarding the safety of their milk.
First, we can, as Leaders, reassure mothers that all available data show that human milk remains the best even in a polluted world. We can help mothers by acknowledging their fears and pointing out that environmental pollution is a reason to get rid of toxins from the environment, not to get rid of breastfeeding. As stated in "Towards Healthy Environments for Children," a FAQ (frequently asked questions) sheet published by WABA:
The existence of chemical residues in breastmilk is not a reason for limiting breastfeeding. In fact, it is a reason to breastfeed because breastmilk contains substances that help the child develop a stronger immune system and gives protection against environmental pollutants and pathogens. Breastfeeding can help limit the damage caused by fetal exposure (WABA 2003).
If mothers are looking to take specific action to reduce the level of chemicals in their body, research shows that not smoking cigarettes and not drinking alcohol helps reduce pollutants in the body. Also, limiting fish intake from waters reported as contaminated and limiting exposure to chemicals such as solvents in paints and gasoline fumes can help reduce environmental contaminants. (See the box on page 124 for more suggestions on limiting exposure to potentially hazardous chemicals.)
Mothers do not need to have their milk tested, according to "Towards Healthy Environments for Children,"
Individual testing of breastmilk should never be used as a basis for making decisions about breastfeeding, except in the rare case of an emergency short term response to an industrial accident (WABA 2003).
Breast Is Still Best
No discussion on chemicals in human milk would be complete without looking at the risks of not breastfeeding. Although soy-based and cow's milk-based infant formulas are generally lower in the contaminants found in human milk, they are hardly contaminant-free. In many areas of the midwestern United States, artificially fed infants are exposed to high doses of weed killers and nitrate fertilizers when powdered formula is mixed with tap water (Steingraber 2001). An artificially fed baby born in those regions will have absorbed 25 percent of his or her lifetime allowable dose of atrazine in his first year (EWG 1999). Most water treatment plants cannot filter these contaminants out. Also, formula tends to be more contaminated with lead than human milk. Human milk is, and always will be, a living, changing fluid that adapts to the needs of the infant. Leaders can help support a mother by helping her be aware of potential exposures and how they can be avoided, thereby providing milk of the highest quality to her baby.
Unless a mother's exposure to contaminants is extremely high-as in high-level occupational exposures-the benefits of human milk far exceed the risks of low levels of contaminants in human milk (Schrieber 2001). In fact, there is evidence that human milk with its species-specific optimal nutrition and its anti-inflammatory agents, including antioxidants, helps a child develop a stronger immune system and other potential protection against environmental pollutants and pathogens. In regard to organochlorine compounds (organic compounds containing chlorine), a recent study in Pediatrics states: "Long-term breastfeeding was found to be beneficial to neurodevelopment, potentially counterbalancing the impact of exposure to these chemicals through breast milk" (Ribas-Fito 2003).
Though each person carries some body burden of chemicals, human milk is the perfect food for babies, species specific, and designed for optimum growth and development. It is pollution, not breastfeeding, that needs to be stopped at its source.
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Minimizing Exposure to Contaminants: What You Can Do
It is impossible to reduce exposure to all contaminants. However, for those who would like to reduce contact with chemicals, especially before pregnancy and during pregnancy and lactation, the following suggestions may be helpful.
10 Simple Steps to Help Reduce the Level of Chemicals in Your Body
1. Avoid smoking
cigarettes and drinking alcohol. The levels of contaminants
have been found to be higher in those who smoke and drink
Because of the efforts of many women's groups, environmental groups, health activists, and breastfeeding advocacy groups, some well-known toxic chemicals (such as DDT and PCBs) have been banned in the United States and elsewhere in the world. For more information on creating a healthier environment, visit the following Web sites:
Baby Milk Action
Food Action Network
on Environments and Women's Health
for Breastfeeding Action
Elizabeth Bauchner is a wife, mother, writer, and La Leche League Leader living in Ithaca, New York, USA. Her weekly column, "Mothering Matters," appears in the Ithaca Journal and addresses the concerns of women and children. Visit her Web site at www.elizabethbauchner.info. Special thanks to Contributing Editor, Norma Ritter, who originally received this article for the regular Leaven column, "Keeping Up-to-Date."