Environmental▼News PERSPECTIVE tested in the new study had detectable levels of PBDEs, and the mix of individual PBDE compounds, or When the manufacturers of two of Brominated flame retardants are congeners, found was consistent the world’s most widely used bromiconcerns because of their potential with the recently discontinued nated flame retardants agreed to for liver toxicity, disruption of thyPenta formulation. withdraw their products from the roid hormone levels, developmental “The Penta formulation is added U.S. market last year after California neurotoxicity, and reproductive toxto polyurethane foams at such high and the European Union (EU) icity based on animal studies, says levels—5–30%, by weight—essenbanned the products, environmenKen Moss, a policy analyst for the tially, it’s like having the pure chemtal scientists around the globe herU.S. EPA’s Office of Pollution Prevenical just sitting there, volatilizing to alded the action as a victory. But tion and Toxics. Although EPA is acthe air, all over the house,” says Tom new evidence suggests that the detively collecting toxicology data, Harner, a research scientist with cision may not go far enough to there’s not enough evidence to supEnvironment Canada, the country’s protect public health. Because the port regulatory action via the Toxic environmental protection agency. major sources of these Harner is the correchemicals are products in sponding author of the new homes and workplaces, sciES&T research into PBDE entists are beginning to reallevels in indoor air, which is ize that the pathways to the the most extensive study health risks posed by the conducted on the topic to discontinued flame-retardate. In the paper, he and dant formulations—as well colleagues at Lancaster Unias by others that are still versity and Health Canada used—may be very different also calculate the maximum from those of older persisdaily human exposure likely tent organic pollutants to result from breathing in (POPs) such as dioxins and PBDEs at the levels they PCBs. recorded. The median levels Study after study shows found in the tested homes that a class of flame-retardcorrespond to 1.9 nanoing polybrominated grams per day (ng/day) for diphenyl ethers (PBDEs) are females and 2.0 ng/day for traveling throughout the males. globe instead of staying inHowever, the situation is side the consumer products very different for the most they are meant to protect. contaminated homes, which The fat-soluble chemicals harbor PBDE levels that are Researchers believe that PBDEs, which are being found in have been discovered in a an order of magnitude highbreast milk, food, indoor air, and house dust, could put wide array of animals, as er. The women living in the young children at risk. well as in plants, air, algae, most highly contaminated and sediments from the North to the Substances Control Act, he says. “We homes could be inhaling up to 66 ng South Poles. However, perhaps the can’t act on the precautionary prinof PBDEs each day, while the men biggest concern is the rapidly rising ciple at this point, as much as some might be taking up 71 ng/day, acPBDE levels found in people living of us would like to,” he adds. Arnold cording to the study. Harner says in North America, which are curSchecter, a public health physician that the results of the study are likely rently 10–70 times higher than the at the University of Texas Health Scito apply across most of North levels of people in Japan or Europe ence Center in Dallas, deems the America. (Environ. Sci. Technol. 2002, 36, lack of published human health PBDE researchers consistently 50A–52A). Although scientists still studies very disturbing. report that 5–10% of the people they haven’t pinpointed exactly where The fact that products found test have significantly higher PBDE those PBDEs are coming from, two in almost every North American levels in their fat or blood than the studies published in this issue of home—including upholstered rest of the population (Environ. Sci. ES&T help flesh out the picture by couches, chairs, curtains, carpet Technol. 2003, 37, 164A–165A). By providing strong evidence that inpadding, and mattresses—contain documenting that the air in some door air can be a significant source high levels of brominated flame rehomes has PBDE levels that are of PBDEs in North American homes tardants is one of the reasons that more than 10 times higher than the (pp 5306–5311) and suggesting that scientists like Schecter are so conmedian levels, Harner and his colU.S. food is broadly contaminated cerned. All 74 of the randomly seleagues say that their findings may with PBDEs (pp 5312–5318). lected homes in Ottawa, Canada, help explain why. KELLYN BETTS
PBDEs and the environmental intervention time lag
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Because home ventilation systems send the pollutants outside, “the indoors is polluting the outdoors, essentially,” Harner says. This differentiates PBDEs from most other POPs, such as dioxins and chlorinated pesticides like DDT, which are far more abundant in outdoor air. “Standard POPs are outdoor chemicals that come in,” says Kim Hooper, who heads the Biomonitoring Group operated by the California EPA’s Hazardous Materials Laboratory in Berkeley, Calif. The fact that household goods may be a major source of people’s exposure is another way that PBDEs are significantly different from most other POPs, Schecter says. For POPs such as PCBs and dioxins, food accounts for more than 95% of human exposure, he explains. Schecter is the lead author of the food survey, which is the first published “market basket” survey of PBDEs in U.S. food. Schecter and his colleagues analyzed 32 samples of food from 3 major supermarket chains in Dallas, Texas. They selected foods mainly of animal origin likely to represent the dietary sources of PBDEs for the women who participated in an earlier study that found that the levels of PBDEs in U.S. women’s breast milk are 10–100 times higher than numbers reported anywhere else. The researchers also analyzed soy infant formula. The PBDE levels that Schecter and his colleagures are reporting for U.S. food are 9–20 times higher than those reported for food from Spain or Japan, where lower amounts of PBDEs are used in commercial products. Schecter’s report is also notable for showing that congeners associated with the Deca flameretardant formulation are found in U.S. food. This formulation is added to the plastics used in home electronics such as televisions and computers, and it is the most heavily used brominated flame retardant in the world. To date, the Deca formulation has not been discontinued or banned anywhere. The Bromine Science and Environment Foundation (BSEF), an industry group, says that the levels of PBDEs found in food are “well
within the levels identified as safe by national and international experts.” The organization also contends that Deca formulation poses no threat to human health and maintains that the discontinued Penta and Octa formulations are not harmful. The benefits that all these chemicals provide far outweigh their risks, according to the organization’s website, which says “brominated flame retardants probably save more lives, by preventing and limiting fires, than most other chemical substances.” Dust may prove to be a third major source of the PBDEs that people are taking up. Scientists have been reporting high levels of PBDEs in dust for some time (Environ. Sci. Technol. 2001, 35, 274A– 275A), but a number of scientists interviewed for this story say persuasive evidence that dust plays a major role should soon be published. “The dust that we’re finding has pretty high levels of both the Penta and the Deca mixture,” says Heather Stapleton of the National Institute of Standards and Technology in Gaithersburg, Md. Stapleton is referring to data from unpublished studies. While people of all ages may be taking up PBDEs from house dust, children under the age of 4 are disproportionately at risk because studies show that they tend to eat a lot more dust than older people. “I think that the children are of concern especially because of their developmental stages. They can get exposures from mother’s milk, from the air, and from the dust in the homes,” says Stapleton. Researchers have estimated that infants nursing on mother’s milk may be taking in up to 1700 ng/day of PBDEs, Stapleton says, characterizing this as “quite high”. The presence of the PBDE congeners associated with the Deca formulation in house dust also raises questions about whether they could be the source of the lighter congeners that are more likely to volatilize into the air and be taken up by people. A growing number of published and unpublished studies are showing that Deca degrades
fairly readily and breaks down in sunlight, sediments, and sludge. Researchers have previously shown that animals like carp and rats are able to break Deca down into smaller brominated compounds (Environ. Sci. Technol. 2004, 38, 8A– 9A), but no one knows how many other animals can do this—or whether humans can. Although the presence of the Deca in Schecter’s food study was a surprise, the biggest surprise was finding the Deca congener in the soy infant formula, Schecter stresses. He says that to the best of his knowledge, this is the first time that a POP has been found in a vegetable product. The Deca congener’s presence could be attributable to a route similar to the one by which dioxins enter cow’s milk through the grass on which the animals graze. Bryony Wilford of Lancaster University, a coauthor on the home PBDE level study, suggests that another explanation for the presence of Deca BDE in infant soy milk may be because of contamination from processing or packaging materials. Despite all the unanswered questions about PBDEs, researchers complain that U.S. funding has never been sufficient for this work and is growing scarcer. “Unlike dioxins and PCBs, which were funded very well… we’ve found it incredibly difficult to get funding for brominated flame retardants,” Schecter says. Hooper says that the brominated flame retardant industry has no incentive to fund work that could show that their products harm people, because such data could fuel lawsuits. One area that is being funded is the search for alternatives. The EPA’s Design for the Environment program is working with the American Fire Safety Council and furniture manufacturers to develop environmentally preferable approaches for achieving fire-safety standards. In the meantime, regulatory agencies like EPA must carefully evaluate the substitutes the industry is proposing, which include other brominated substances as well as chlorinated compounds and non-halogenated phosphorous-based chemicals, says EPA’s Moss. —KELLYN BETTS
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