Household dust is the main route of exposure to flame retardants

Household dust is the main route of exposure to flame
retardants for people — from toddlers to adults — followed by eating animal
and dairy products, according to a report in the July 15 issue of the American
Chemical Society’s journal Environmental Science & Technology. ACS is
the world’s largest scientific society. Until this study, which is based on
a computer model developed by Canadian researchers, scientists have been unsure
exactly how people are being exposed.

PBDEs (polybrominated diphenyl ethers) — used widely as flame-retardant
additives in electronics and furniture — have been detected in humans across
the globe, with especially high levels in North America. Little is known
about the specific toxic effects of brominated flame retardants, but some
researchers say that the increasing presence of the compounds in human tissue
is cause for concern because they have been associated with cancer and other
health problems in animal studies.

“Our work is good news and bad news,” says the study’s
lead author, Miriam Diamond, Ph.D., an environmental chemist at the University
of Toronto. “Good news because we’ve identified the main route of exposure
to PBDEs — house dust; bad news because we need more action to remove PBDEs
from household products and replace them with alternatives that are effective
in reducing hazards related to fires and that do not accumulate in the environment.”

PBDEs are released into the environment at their manufacturing
sources and also through everyday product wear and tear, which is the presumed
source of the chemicals in house dust, according to Diamond. Asked if drinking
water could be a possible source, Diamond said: “No, it’s not a significant
route of exposure.”

A small study published earlier this year in ES&T found
PBDEs in the dust of 16 homes tested in the Washington, D.C., area and one
home in Charleston, S.C. The work of Diamond and her co-authors builds on
that research with a more complete analysis of all potential exposure pathways,
including food, soil, dust and inhalation of indoor and outdoor air. Using
a combination of measured concentrations and computer modeling, she and her
coworkers estimated the emissions and fate of PBDEs in the Toronto area.

Toddlers tend to have high levels of PBDEs, which is most
likely because they are frequently bringing toys and other objects from the
floor to their mouths, the researchers suggest. Breast-feeding infants have
higher levels of PBDEs than all other ages, which is consistent with earlier
research revealing high levels of PBDEs in the breast milk of women across
North America.

“We hypothesize that women with very high PBDE concentrations
in breast milk may be super-exposed,” Diamond says. “Given evidence from
the literature, it seems likely that if one reduces one’s exposure, then
presumably the breast milk concentrations will fall.”

Diamond suggests a number of steps that people can take
to minimize exposure, such as frequent house cleaning and improved ventilation.
“It seems to me that any measures one takes to minimize dust will reduce
exposures,” she says.

Officials in the United States and Canada are still debating
the fate of flame retardants, although the main U.S. manufacturer has discontinued
production of two types of PBDEs — the penta and octa formulations — as part
of a voluntary agreement with the U.S. Environmental Protection Agency. The
European Union has banned the penta and octa formulations and is currently
considering a voluntary phase-out and further study on a third type, the deca

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