Highlights of Sightline’s study of persistent toxics in northwesterners.
What was the purpose of this study?
Sightline Institute’s original study–released in September, 2004–analyzed 40 samples of breastmilk from first-time breastfeeding mothers who live in British Columbia, Montana, Oregon, and Washington. The samples were analyzed for the presence of several kinds of PBDEs (polybrominated diphenyl ethers), a family of flame-retarding chemicals widely used in computer plastics, furniture foams, and textiles; and for PCBs (polychlorinated biphenyls), industrial chemicals used as lubricants and insulators, which were banned in North America in the late 1970s.
On August 25, 2005, Sightline and California/EPA released a new analysis of the study results, comparing levels of PBDEs and PCBs.
Why be concerned about PBDEs and PCBs?
PBDEs and PCBs degrade slowly in the environment and build up in living things, magnifying in concentration as they move up the food chain. Although banned decades ago, PCBs are still present in our bodies and the environment. In recent years, PBDE levels in wildlife, soil samples, and human tissues have been doubling every two to five years, and have reached high concentrations in North America, where PBDE use is highest.
What are the health risks of PBDEs and PCBs?
PCBs interfere with the body’s hormone systems, can impede children’s mental development, and cause a range of effects on the immune system, reproductive system, and nervous system. They are a known carcinogen. PBDEs are structurally similar to PCBs and show similar toxic effects in laboratory studies. Studies on laboratory animals have shown that PBDEs can impair memory and learning, alter behavior, delay sexual development, and disturb thyroid hormone levels. Scientists have found that PBDEs and PCBs work in similar ways, and may even act together to impair development. (See related fact sheet.)
What were the results of the study?
All 40 samples from Northwest mothers contained both PBDEs and PCBS. PBDE levels ranged from 6 to 321 parts per billion (ppb), as measured in milk fat. The average level was 96 ppb and 16 of the 40 women had at least 100 ppb of PBDEs in their milk. These levels were comparable to levels found in other studies in North America, but 20 to 40 times higher than levels found in Sweden and Japan (see related Flash animation).
PCB levels ranged from 49 to 1,454 parts per billion (ppb), with an average level of 180 ppb in milk fat. The analysis found that 13 of the Northwest women had higher levels of PBDE than PCBs, one of several new studies showing this trend.
Also, some samples contained elevated levels of deca-PBDE, a type of PBDE that is widely used in commercial applications, but has not received the same intense regulatory scrutiny as other types of PBDEs. Though deca-PBDE was long believed to be only minimally toxic, new studies suggest deca-PBDE can break down into other forms of PBDE that are more harmful and more readily absorbed.
How are people exposed to PBDEs and PCBs?
PCBs are believed to enter the body through food, particularly from consuming fish. The EPA analysis of the results found no correlation between PBDE and PCB levels in the women, suggesting that the two chemicals enter people in different ways. Scientists are still determining exactly how people are exposed to PBDEs, but several recent studies suggest that house and office dust is a primary exposure pathway. The fact that PBDEs were found in all 40 samples suggests that there is no way to completely avoid contamination. Recent studies have detected PBDEs in orcas and other marine mammals, salmon, osprey, as well as types of supermarket food that contain animal fat.
Why test breastmilk?
Testing human breastmilk is a good way to determine levels of these contaminants in people’s bodies. Unlike blood or tissue samples, breastmilk can be collected without needles or other invasive medical procedures. Breastmilk is also high in fat, and both PCBs and PBDEs collect in fat, which makes it possible to run comprehensive tests with a small amount of milk. Breastmilk, particularly from first-time mothers with very young infants, can provide a useful picture of the exposure of the general population.
Should women continue to breastfeed?
Yes, breastfeeding remains the healthiest choice for moms and babies (see related fact sheet). Breastmilk is perfectly suited to nourish developing infants, and protects them from illnesses including pneumonia, diarrhea, ear infections, and diabetes. Breastfeeding also reduces the risk of ovarian and breast cancers in mothers. As with many chemical contaminants, the biggest concern is exposure in the womb, rather than through breastfeeding. Breastfeeding may actually reduce the health risks associated with chemical exposures in the womb: in one study, breastfed babies exposed in utero to PCBs did not exhibit PCB-related learning deficits, while their bottle-fed counterparts did.
Has there been government action on PBDEs?
In 2003, the US Environmental Protection Agency announced an agreement to remove the two most troubling forms of PBDE from the market in the United States. This action is likely to limit the use of PBDEs throughout North America. However, it allows for the continued manufacture of a third form of PBDEs-deca-that is widely used in computers and consumer electronics.
Regional groups are seeking bans on the use of all forms of PBDEs and other persistent chemicals. Washington and Oregon have banned some forms of PBDEs, penta and octa, but not the deca type, though both are considering it. Both states also have formal statewide strategies to phase out persistent toxic chemicals, including mercury, dioxins, and PCBs. Sweden was the first government to phase out some of the most toxic forms of PBDEs, followed by the European Union.
What else can be done?
Northwest jurisdictions should ban all forms of PBDEs from commerce, including deca-PBDE, and develop programs and recommendations for removing products that contain PBDEs from homes and workplaces. (See related fact sheet on what Northwest jurisdictions are doing.) Economically viable and effective alternatives to PBDEs exist and companies such as Ikea and Volvo have already eliminated PBDEs from their products.
Northwest jurisdictions should also conduct comprehensive screens of human blood and breastmilk for chemical contaminants, both as an early warning system for emerging toxic threats, and as a means to monitor progress in cleaning up existing pollution. Finally, the United States and Canada should require industrial chemicals to undergo more rigorous scrutiny for health effects and the potential to collect in the bodies of humans and wildlife before the compounds are used.
Published: September 7, 2005