Healthy Milk, Healthy Baby
Chemical Pollution and Mother's Milk
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Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants. They are added to the plastic material in televisions and computers and are also found in construction materials, furniture, and textiles.
The chemical structure of the PBDEs closely resembles the structure of PCBs, dioxins and furans. Rather than containing chlorine, however, these chemicals contain bromine. Unlike the PCBs and many of the organochlorine pesticides, the PBDEs are not banned anywhere, and are widely used throughout the world. The production and use of PBDEs have steadily increased since the 1970s.
PBDEs are persistent in the environment and have a high potential for bioaccumulation. PBDE contamination has been observed in the environment for years, particularly in marine mammals, and is a problem for humans as well.
Health Effects of PBDEs
Because PBDEs have been recognized as environmental contaminants only recently, they have not been extensively studied for health effects. As with most industrial chemicals, they were subject to no testing requirements for safety prior to their debut on the market and their release into the environment. The similarity of the PBDEs to the dioxins and PCBs gives many scientists cause for concern that their negative effects on health will prove similar. In fact, preliminary studies indicate that these chemicals may have many of the same properties as the banned toxicants. In particular, scientists have found indications that the PBDEs may affect hormone function and may be toxic to the developing brain. The PBDEs have been associated with non-Hodgkin's lymphoma in humans, a variety of cancers in rodents, and disruptions of thyroid hormone balance.
PBDEs in the Body
PBDEs can enter the environment during the production and disposal of materials containing PBDE flame-retardants, as well as during the lifetime of PBDE-containing products. PBDEs are not chemically bound to plastics, so they can evaporate into indoor air or the outdoor environment. Once released, PBDEs can build up in the environment and in living organisms, binding strongly to sediment and building up in fish and other aquatic organisms.
Human exposure to PBDEs mainly occurs as a result of eating PBDE-contaminated fish.  Worker exposure occurs during the production of PBDEs or PBDE-containing products. Consumers may also be exposed to PBDEs by breathing indoor air in the vicinity of electronic equipment or fabrics treated with these chemicals.
PBDEs were first found in sediment in the United States and in fish in Sweden in the early 1980s.  Since then, several studies have found PBDEs in different human tissues, including blood, fat, and breast milk. Still, only a few studies have sought to measure PBDEs in breast milk. The data regarding PBDEs is limited in part because PBDEs have only recently been acknowledged as a chemical class of concern. In future breast-milk monitoring studies, PBDE residues should be routinely examined.
Controlling Exposure: Bans and Restrictions
No known restrictions have been placed on the production and use of PBDEs. However, the Swedish government has announced its intention to ban PBDEs in products sold in Sweden, based partly on the detection of these chemicals in breast milk.[2, 4]
Benchmarks and Exposure Limits for PBDEs
Because PBDE contamination is a relatively newly understood phenomenon, no benchmarks or "safe" levels have been set for human exposure.
Breast-milk Monitoring Studies Looking at PBDEs
Very few breast-milk monitoring studies have measured PBDEs. Extensive data from Sweden, and some limited data from Germany have been collected. The data from Sweden sounded the first alarm about the potential for breast-milk contamination from PBDEs. In the Swedish study, archived samples collected between 1972 and 1997 were recently analyzed for the presence of PBDEs to get an overall summed total of PBDEs in milk. An average for each time period was calculated and is shown in Figure 34.[1, 4]
The data from Sweden show a drastic increase in the quantity of PBDEs detected in women's breast milk. Since no definitive data regarding the health effects of children's exposure to PBDEs in breast milk have been published, it is not possible to draw conclusions regarding the impact of these rising levels. However, enough is known to raise concerns. Like the dioxins, furans, PCBs, and organochlorine pesticides, PBDEs are bioaccumulative and persistent. Unlike these other chemicals, no serious international efforts are under way to ban these hazardous chemicals. The trend toward higher levels in breast milk signals a need for immediate action to stop human exposures, before the levels rise higher and risk compromising the safety of children's first food. Toward that end, other monitoring studies in other countries will help clarify the scope of the problem.
Related Site on the Web
Read an article by Drs. Kim Hooper and Thomas McDonald, published in the journal Environmental Health Perspectives, and titled "The PBDEs: An Emerging Environmental Challenge and Another Reason for Breast-Milk Monitoring Programs."
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1. Meironyte, D., K. Noren, and A. Bergman. Analysis of Polybrominated Diphenyl Ethers in Swedish Human Milk, A Time-related Trend study, 1972-1997. Journal of Toxicology and Environmental Health Part A 1999; 58: p. 329-341.
2. Darnerud, P.O., et al. Polybrominated Diphenyl Ethers: Occurrence, Dietary Exposure, and Toxicology, Environmental Health Perspectives Journal 2001; 109(Supplement 1): p. 49-68.
3. Hooper, K. and T.A. McDonald. The PBDEs: An Emerging Environmental Challenge and Another Reason for Breast-milk Monitoring Programs, Environmental Health Perspectives Journal 2000; 108(5): p. 387-392.
4. Noren, K. and D. Meironyte. Certain Organochlorine and Organobromine Contaminants in Swedish Human Milk in Perspective of Past 20-30 Years, Chemosphere 2000; 40: p. 1111-1123.
last revised 5.22.01