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Are PBDEs harmful to human health?

The health effects of PBDEs have not been studied in humans. Instead, studies with laboratory animals provide information on the toxic effects of PBDEs. In these animal studies, PBDE exposure before and after birth caused problems with brain development. These studies observed problems with learning, memory and behavior. They also show that exposure to PBDEs during development can decrease thyroid hormone levels and affect reproduction.

These effects are observed mainly in studies with Penta forms of PBDEs. Some similar toxic effects are seen with Octa and Deca forms of PBDEs, but at higher levels than for Penta. There is some evidence from animal studies that Deca PBDE may cause cancer at high levels. Penta and Octa have not been tested in cancer studies with animals. 

PBDEs have a similar chemical structure to PCBs (polychlorinated biphenyls), which have been studied in humans. PCBs are no longer used in the United States. For more information on PCBs, see ATSDR's ToxFAQs on PCBs. This suggests that PBDEs may be similar to PCBs in terms of toxic effects and their ability to build up in the environment and in people. PCBs are believed to cause skin conditions in adults and affect the nervous and immune systems of children. At high levels they may cause cancer.  Studies are needed to determine if PBDEs have similar effects on human health.

Measuring levels of PBDEs in humans
PBDEs find their way into our bodies and are stored for a long time in body fat or other tissues.  PBDEs have been measured in blood, fat and breast milk collected from people around the world. The PBDEs found in human tissue samples are mostly Penta PBDEs. Octa and Deca PBDEs are also found, but at generally lower levels. 

The highest levels of PBDEs among the general population are found in the U.S. and Canada—10 to 100 times higher than levels reported for Europe and Japan.  One reason for the higher levels of PBDEs in U.S. and Canadian may be because most of the world’s supply of Penta PBDE is used here.  While levels in people in Japan and some European countries are decreasing, levels in people in the U.S. appear to be increasing.                                                                                    

PBDEs in breast milk
Some of the first information about PBDEs in people came from studies of breast milk in Sweden.  Between 1972 and 1997, PBDE levels in human breast milk from Sweden increased rapidly, doubling every five years.  Recently, breast milk levels in Sweden have begun decreasing, probably related to decreased use of PBDEs in that country.

Important information for breastfeeding women
Nursing mothers should be aware that studying breast milk for PBDEs does not mean that there is a greater health risk to their infants from breastfeeding. Nursing women should continue to breastfeed their babies, since breastfeeding has many benefits. Breast milk contains components that appear to protect babies from the effects of prenatal exposure to toxic chemicals. Nursing also helps to boost a baby’s immune system and develop brain tissue.

Scientists study breast milk to look for PBDEs and other chemicals that tend to build up in fatty tissue, because breast milk is high in fat compared to other body tissues and it is easy to collect. Measuring chemicals in breast milk shows whether they are present throughout the population, in people of all ages.

Babies are exposed to PBDEs and other toxic chemicals during pregnancy. They are already carrying a "body burden" of toxic chemicals when they are born.

The Washington Department of Health encourages mothers to breastfeed their infants. Breastfeeding is the best thing a mother can do for her baby. There is nothing better than breast milk to help infants build their immune system. Breastfeeding results in better outcomes for the health and development of the child. For more information about breastfeeding, contact the Healthy Mothers, Healthy Babies Coalition of Washington.