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EMF Studies

08 November 2012

Obesogens : An Environmental Link to Obesity

Obesity has risen steadily in the United States over the past 150 years, with a marked uptick in recent decades. In the United States today more than 35 percent of adults and nearly 17 percent of children aged 2 to 19 years are obese. Obesity plagues people not just in the United States but worldwide, including, increasingly, developing countries. Convincing evidence suggests that diet and activity level are not the only factors in the rising obesity trend. Chemical "obesogens" may alter human metabolism and predispose some people to gain weight. The effects of early-life exposure, during fetal and infant development, may be irreversible which means these people will fight a life-long battle against weight gain. It is very unfortunate that certain health groups continue to talk about prevention in terms of diet and activity level. Too little attention is being paid to the environmental toxins in our lives which can cause obesity. Following are extracts from an article which appeared in Mother Earth News. (Click here for article in full.) 

Obesogens: An Environmental Link to Obesity
by Wendee Holtcamp for Environmental Health Perspectives, 21 February 2012

“Obesity has risen steadily in the United States over the past 150 years,with a marked uptick in recent decades. In the United States today more than 35 percent of adults and nearly 17 percent of children aged 2 to19 years are obese. Obesity plagues people not just in the United States but worldwide, including, increasingly, developing countries. Even animals — pets, laboratory animals, and urban rats — have experienced increases in average body weight over the past several decades, trends not necessarily explained by diet and exercise. In the words of Robert H. Lustig, a professor of clinical pediatrics at the University of California, San Francisco, “[E]ven those at the lower end of the BMI [body mass index] curve are gaining weight. Whatever is happening is happening to everyone, suggesting an environmental trigger.

“Many in the medical and exercise physiology communities remain wedded to poor diet and lack of exercise as the sole causes of obesity. However, researchers are gathering convincing evidence of chemical “obesogens” — dietary, pharmaceutical, and industrial compounds that may alter metabolic processes and predispose some people to gain weight.

“The idea that chemicals in the environment could be contributing to the obesity epidemic is often credited to an article by Paula Baillie-Hamilton, published in the Journal of Alternative and Complementary Medicine in 2002. Her article presented evidence from earlier toxicologic studies published as far back as the 1970s in which low-dose chemical exposures were associated with weight gain in experimental animals. At the time, however, the original researchers did not focus on the implications of the observed weight gains.

“The role of environmental chemicals in obesity has garnered increased attention in academic and policy spheres, and was recently acknowledged by the Presidential Task Force on Childhood Obesity and the National Institutes of Health (NIH) Strategic Plan for Obesity Research. “Over the past ten years, and especially the past five years, there’s been a flurry of new data,” says Kristina Thayer, director of the Office of Health Assessment and Translation at the National Toxicology Program (NTP). “There are many studies in both humans and animals. The NTP found real biological plausibility.” In 2011 the NIH launched a 3-year effort to fund research exploring the role of environmental chemical exposures in obesity, type 2 diabetes mellitus, and metabolic syndrome.”..

A Growing List of Potential Obesogens

“Obesity is strongly linked with exposure to risk factors during fetal and infant development ... These factors may also affect adults…

Potential obesogens include:

-chemical pesticides in food and water, particularly atrazine and DDE (a DDT breakdown product)
-certain pharmaceuticals, such as the diabetes drug Avandia® (rosiglitazone)
-dietary obesogens, including the soy phytoestrogen genistein28 and monosodium glutamate.

Most known or suspected obesogens are endocrine disruptors. Many are widespread, and exposures are suspected or confirmed to be quite common:

-designer handbags, wallpaper, vinyl blinds, tile, scented items such as air fresheners, laundry products, and personal care products.

-DES (diethylstilbestrol), a synthetic estrogen given to millions of pregnant women from the late 1930s through the 1970s to prevent miscarriage. The drug caused adverse effects in these women’s children, who often experienced reproductive tract abnormalities; “DES daughters” also had a higher risk of reproductive problems, vaginal cancer in adolescence, and breast cancer in adulthood. One study revealed that low doses of DES administered to mice pre- or neo-natally also were associated with weight gain, altered expression of obesity-related genes, and modified hormone levels.

-bisphenol A (BPA), found in medical devices, in the lining of some canned foods, and in cash register receipts. “BPA reduces the number of fat cells but programs them to incorporate more fat, so there are fewer but very large fat cells,” explains University of Missouri biology professor Frederick vom Saal, who has studied BPA for the past 15 years. “In animals, BPA exposure is producing in animals the kind of outcomes that we see in humans born light at birth: an increase in abdominal fat and glucose intolerance.” It was found that BPA affected rodent fat cells at very low doses, 1,000 times below the dose that regulatory agencies presume causes no effect in humans, whereas at higher doses he saw no effect.

-PFOA (perfluorooctanoic acid): “Pretty much everyone in the U.S. has it in their blood, kids having higher levels than adults, probably because of their habits. They crawl on carpets, on furniture, and put things in their mouth more often,” explains NIEHS biologist Suzanne Fenton. PFOA is a surfactant used for reduction of friction, and it is also used in nonstick cookware, Gore-Tex™ waterproof clothing, Scotchgard™ stain repellent on carpeting, mattresses, and microwavable food items. In 2005 DuPont settled a class-action lawsuit for $107.6 million after its factory outside Parkersburg, West Virginia, tainted nearby drinking water supplies with PFOA.

Eye on Prevention

Can diet and exercise ultimately make any difference? Bruce Blumberg, a biology professor at the University of California, Irvine, who first coined the term “obesogen” in 2006, does not consider the situation hopeless. “I would not want to say that obesogen exposure takes away free will or dooms you to be fat,” he says. “However, it will change your metabolic set points for gaining weight. If you have more fat cells and propensity to make more fat cells, and if you eat the typical high-carbohydrate, high-fat diet we eat [in the United States], you probably will get fat.”

Blumberg postulates that the effects of early-life exposure are irreversible, and those people will fight a life-long battle of the bulge. However, if such people reduce their exposure to obesogens, they will also reduce health effects that may arise from ongoing adulthood exposures. Blumberg believes it’s good to reduce exposure to all kinds of endocrine-disrupting chemicals. “Eat organic, filter water, minimize plastic in your life,” he says. “If there’s no benefit and some degree of risk, why expose yourself and your family?”

Jerry Heindel, who leads the extramural research program in obesity at the National Institute of Environmental Health Science, hopes the NIH’s new grant-making effort will yield important discoveries. “It’s a very new field, and people are always skeptical of new fields,” he says. “It’s up to us to get more data to show that chemicals are actually interfering with the endocrine system that controls weight gain and metabolism. And there’s still the question of how important is this to humans. We’re never going to know until we get more data.” 

“What if this was really true and chemicals are having a significant effect on obesity?” muses Heindel. “If we could show environmental chemicals play a major role, then we could work on reducing exposure during sensitive windows, and that could have a huge effect [on obesity prevalence].” It would change the focus from treating adults who are already obese to preventing obesity before it starts — a fundamental shift in thinking about obesity...

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