A morbidly obese child
In the United States, 68% of the population are overweight; 34% of those are obese. It’s true we eat too much, don’t exercise enough and consume too many processed foods.
But how do we explain the growing epidemic of obesity in 6-month-old babies? Have they been slacking off at the gym? Snacking on too many Whoppers? Not likely.
What is likely is that there are factors other than calorie intake and calorie burning that are affecting our girth.
As early as 2007, the Washington Post reported that “Several recent animal studies suggest that environmental exposure to widely used chemicals may also help make people fat.
“The evidence is preliminary, but a number of researchers are pursuing indications that the chemicals, which have been shown to cause abnormal changes in animals’ sexual development, can also trigger fat-cell activity—a process scientists call adipogenesis.”
And it was also in 2007 that Bruce Blumberg , professor in the School of Developmental and Cell Biology in the School of Biological Sciences at the University of California, Irvine, coined the word “obesogen.”
When asked by Steve Curwood on a recent PRI interview how he came up with the word, Blumberg answered, “. . . when we were writing our story about the chemical that we worked on—tributyltin—it seemed absolutely obvious to us that a chemical that makes animals fat should be called an obesogen, and I didn’t realize it wasn’t a word.
“Tributyltin used to be used on ship hulls and it’s used as a fungicide in paints*, and it keeps marine life and fungus from growing on various surfaces. We found, accidentally, that tributyltin makes animals fat.”
Blumberg further explained that there are a number of pharmaceutical obesogens that make us gain weight. Actos and Avandia are diabetes drugs that improve insulin sensitivity but also make a person fat, as do many antidepressants.
The earlier-mentioned Washington Post article discussed childhood and in utero exposure to obesogens. Mice exposed to obesogen chemicals, particularly pesticides, became obese adult mice, remaining obese even when placed on reduced calorie and increased exercise regimes. Like tributyltin, DES, which for decades was added to animal feed and routinely given to pregnant women, permanently disrupted the hormonal mechanisms regulating body weight.
Retha Newbold of the National Institute of Environmental Health Sciences in North Carolina has a grim prognosis for those exposed early to obesogens: “Once these genetic changes happen in utero, they are irreversible and with the individual for life.”
Blumberg concurs. He told Curwood, “What our research and the research in other laboratories suggests that prenatal and early life exposure to obesogens can reprogram the metabolism of the individual that’s exposed, so that they use calories differently. Our prenatally exposed mice get fatter on an absolutely normal diet.”
A study conducted by the Centers for Disease Control and Prevention found another obesogen, this one a petroleum-derived chemical, bisphenol A (BPA), in 95% of the people tested at levels at or above the levels that affected animal development. When the findings were presented at the annual meeting of the American Association for the Advancement of Science, a representative of the chemical industry dismissed concerns.
Jerry Heindel, an official of the National Institute of Environmental Health Sciences (NIEHS), said the suspected link between obesity and to “endocrine disrupters (so called because of their hormone-like impacts) is plausible and possible.”
Frederick vom Saal, professor of biological sciences at the University of Missouri at Columbia says, “Exposure to bisphenol A is continuous.” The chemical appears in refillable water containers and baby bottles, in the lining of food cans, in dental sealants and on store receipts. In 2003, US industry added about 2 billion pounds of BPA into our consumer products.
Vom Saal’s research indicates that exposure during development to low doses of BPA activates genetic mechanisms that promote fat-cell activity. Vom Saal’s conclusions match Newbold’s: “These in-utero effects are lifetime effects, and they occur at phenomenally small levels.”
For more about the sources and dangers of BPA, see http://mytakeontoday.wordpress.com/2011/12/14/canned-soups-linked-to-greatly-elevated-levels-of-bpa/
*According to The Lund Report, February 17, 2012, the chemical is also used in PVC pipes.
from Washington’s Blog, March 17, 2012 Public Radio International’s (PRI) Living on Earth, transcript, June 1, 2012 Washington Post, March 12, 2007
Coming up: Obesogens: Fighting Back
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