Obesity And Environmental Chemicals: Research Probes Potential Link
By Beth Potier, Media Relations
March 7, 2007
Could your couch be making you fat?
A team of researchers at UNH is investigating whether the increasing ubiquity
of chemical flame retardants found in foam furniture, carpeting, microwaves
and computers might be related to the climbing rate of obesity in the United
States.
“Environmental chemicals are a possible third component to the obesity
epidemic, along with diet and exercise,” says Gale Carey, professor
of nutrition and a leader of the research project, along with professor
of nutrition Anthony Tagliaferro and Deena Small, assistant professor of
molecular biology and biochemistry. The trio received funding for the project
from the President’s Excellence Initiative Awards, which provide
support for interdisciplinary research.
The flame retardants, called polybrominated diphenyl ethers (PBDEs), have
been produced since the 1960s; they’re now found in consumer products
like carpeting, upholstered furniture, computers and hair dryers, where
they retard the combustibility of these products. It’s estimated
that American consumers come into contact with up to 100 products containing
PBDEs per day.
While chemical manufacturers say PBDEs can reduce by 45 percent the risk
of death and injury by fire, they are an emerging environmental chemical – and
an emerging concern, as their impact on the human body becomes documented.
Their persistence in the environment has PBDEs compared to now-banned toxins
like PCBs and DDT; the use of two types of PBDEs is prohibited in European
Union countries.
Carey, Small and Tagliaferro, working in collaboration with clinical assistant
professor of animal science Alice Roudabush, D.V.M., and 11 undergraduate
and graduate student researchers, are exploring how PBDEs affect fat storage
and production. “We know PBDEs are fat-soluble – they dissolve
in fat tissue,” says Carey. “What are they doing in the fat
as they sit there? Nobody has asked that question yet.”
Building on research conducted by two of Carey’s graduate students,
the faculty trio will expose laboratory rats to PBDEs through pregnancy
and lactation, stages Carey describes as critical windows for exposure.
At the molecular level, Small will examine what PBDEs are doing to stem
cell populations within the adipose tissue and the effects of PBDEs on
gene expression. Does exposure to PBDEs, which mimic estrogen and thyroid
hormones in the body, make cells more likely to develop into fat cells? “Everything
I do has to do with how changes in signaling result in changes in gene
expression,” she says.
Carey’s work is at the cellular level. Isolating the fat tissue
of these animals, Carey will explore the insulin sensitivity of fat cells.
Preliminary data from her lab suggest that chronic exposure to PBDEs could
cause fat cells to become less sensitive to insulin, which is a forerunner
to developing Type II diabetes. The fat cells of growing male rats that
were fed PBDEs daily for a month acted metabolically like the fat cells
of obese rats, although the PBDE-fed rats weighed the same as a control
group.
Tagliaferro, whose research interests concern whole-body energy and metabolism
questions, will assess sensitivity of all body tissues to insulin, as well
as examine the food intake, body weight changes, and energy metabolism
of the rat pups once they are weaned from their mothers. PBDEs, the researchers
note, seem to interrupt thyroid hormone levels, which may impact caloric
expenditure.
“There’s much more to obesity than eating too much McDonald’s
and not exercising,” says Small. “PBDEs may be one of the confounding
factors to obesity.”
With the research just getting underway, the scientists are duly cautious
about predicting outcomes. If findings implicate PBDEs in obesity, Carey
notes, the news would be good and bad.
“From a scientific standpoint, it would be very interesting if these
animals began to put on weight,” she says. “But part of me
hopes they don’t, because these chemicals are all around. But that’s
the good thing about science: You try to get to the truth, and then when
you get the truth, you can do something about it.”
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