Science and Technology
10 April 2003
do peoples' PBDE levels vary widely?
by Kellyn Betts
Researchers suspect that old furniture may be responsible for some
people’s high levels of PBDEs.
is becoming increasingly clear that North American women are taking
up high levels of a relatively new persistent organic pollutant
(POP), polybrominated diphenyl ethers (PBDEs), and new data out
of the United Kingdom show that women there are accumulating more
than their peers on the continent. As the evidence grows, many scientists
studying the issue are observing that some people are taking up
far more of the flame retardant chemicals than others.
latest data come from England and three different areas of the United
and Texas. Arnold Schecter, a professor of environmental sciences
at the University of Texas at Houston’s School of Public Health,
revealed one of the largest collections of U.S. data amassed to
date at the Society of Toxicology meeting in March.
PBDE levels Schecter found are “strikingly high compared to
Europe,” he says. He analyzed 47 samples of milk from women
in Texas and looked for 13 different PBDE compounds, or congeners.
The samples contained anywhere from 6.2 to 419 parts per billion
(ppb) of the PBDEs per gram of milk fat. In comparison, Bert van
Bavel of Örebro University in Sweden reports that the lowest
level in Schecter’s sample is equal to the highest levels
reported in Europe for workers in electronics recycling facilities.
the PBDE levels recorded in the milk of 67 British women by a team
led by Kevin Jones of the University of Lancaster ranged from less
than 1 ppb to 69 ppb. More than half of the women in the study,
which has yet to be published, had levels of 6 ppb or above.
PBDE levels of North Americans are 10 times higher than the (non-U.K.)
European levels, and some North Americans have levels 10 times higher
than their peers, summarizes Linda Birnbaum, director of the Experimental
Toxicology Division of the U.S. EPA’s National Health and
Environmental Effects Research Laboratory, who says that the range
of the data that Schecter collected is roughly comparable to all
of the data she has seen showing levels in North Americans (Environ.
Sci. Technol. 2002, 36, 50A–52A).
European data also show that some individuals have significantly
higher levels than their peers, van Bavel says. He routinely finds
higher levels in 5% of the samples he analyzes from Sweden.
North American PBDE levels are notable for being orders of magnitude
higher than human levels of dioxins, in the parts-per-billion, rather
than the parts-per-trillion levels, says Schecter, who has studied
human exposure to dioxins. However, PBDE levels are generally an
order of magnitude lower than those for polychlorinated biphenyls
(PCBs), stresses Robert Hale, a professor in the Virginia Institute
of Marine Science’s Department of Environmental & Aquatic
Animal Health. Still, Birnbaum notes that the highest PBDE levels
may be similar to PCB levels.
data on health effects from PBDEs are far from complete, but the
chemicals are suspected endocrine disrupters, Birnbaum says. Rodent
studies show that PBDEs may impair neurological functioning, and
they appear to have additive effects with PCBs, she says. Although
most of the data are for women, exposures to PBDEs—like all
POPs—should be gender-blind, adds Myrto Petreas, one of the
California researchers who reported new data in March.
new study out of Indiana University suggests that mothers may be
transferring PBDEs to their babies in utero (Environ Health Perspect.
DOI 10.1289/ehp.6146). The researchers measured six different PBDE
congeners in the blood of 12 mothers and found that their levels
ranged from 15 to 580 ppb per gram of fat, and the levels in their
babies’ umbilical cords ranged from 14 to 460 ppb. Although
researchers were looking for impacts on the thyroid, no such correlation
between the PBDE levels and the infants’ thyroid levels was
found. However, they say that their study shows that U.S. babies
may be exposed to relatively high levels of PBDEs.
PBDEs have been banned in Europe, and levels in countries where
their use was already discontinued are dropping, which hints that
the same could hold true in North America if the substances were
banned, Schecter says.
the U.K. is subject to the same EU bans, the U.K.’s fire regulations
on the need for retardant treatments in furnishings, etc., were
particularly stringent,” Jones notes. “The U.K. has
also been a major manufacturer of PBDEs. Hence, the amounts 'present
in the U.K.' are likely to be high, relative to other European countries.”
He says that researchers in his lab have compared the level of PBDEs
in the air with data collected by a group led by Ron Hites at Indiana
University, and the levels are “very similar.”
of the continuing mysteries surrounding the widely varying levels
in humans is how these chemicals are taken up. Petreas speculates
that diet cannot be the only source of PBDEs.
number of scientists suspect indoor dust. Previous reports have
shown that levels of PBDEs in dust can be strikingly high, up to
the parts-per-million level (Environ. Sci. Technol. 2001, 35, 274A–275A).
The sources of PBDEs in dust include the “Deca” formulation
of flame retardants used in electronics products and the “Penta”
contained in some of the polyurethane foam used as cushioning, Hale
the polyurethane foam in an old piece of furniture is exposed to
the environment, it tends to crumble, Hale explains; this releases
the PBDEs embedded within the foam. Because PBDEs are used in percent
by weight concentrations in flame retardant-treated foam, modest
deterioration of such products could release and expose people to
significant amounts of the Penta formulation that has to date been
shown to have a great tendency to bioaccumulate, he says. For this
reason, a small amt of PBDE-containing ‘foam dust’ could
contribute significantly to the amount of the contaminant in household
dust, he adds.
people have nice, new furniture,” Hale points out. “Others
are sitting on couches that are falling apart. When they vacuum,
it re-suspends the material. If [someone is] chronically exposed
to that, you can predict a spike in the[ir] blood level,”