Environmental Health Conference Focuses on How Toxic Chemicals Influence Obesity

Known as obesogens, these chemicals influence weight gain by disrupting hormones that drive appetite and physical activity

February 17, 2012 -- Next time you struggle to put down that extra slice of pizza or get off the couch you might not feel so guilty about your lack of motivation, but new research suggests you may want to consider the role the environment may have played in your eating habits.

A growing on the role so-called obesogens — chemicals increasingly suspected to influence weight gain by disrupting hormones that drive appetite and physical activityplay in our country’s increasingly costly obesity epidemic became the center point of the fourth annual Northwest Environmental Health Conference. Hosted by the Oregon Environmental Council, the Oregon Chapter of Physicians for Social Responsibility, Health Care Without Harm, Josiah Hill III Clinic and the Oregon Public Health Association, the event explored emerging research into obesogens alongside discussions of environmental justice, workplace health, water quality and other discussions of the relationship between public health and environmental conditions in the Northwest.

Genetics alone can no longer be counted on to explain why some people overeat and avoid exercise, said Jerrold Heindel, the reproductive and developmental toxicology expert who was one of two keynote speakers at the February 10 event. The acting chief of the cellular, organs and systems pathobiology branch of the National Institute of Environmental Health Sciences told a few hundred conference attendees that while it doesn't take much thought to understand that overeating and little exercise are responsible for the prevalence of obesity in this country, the reasons some people are able to eat in moderation and remain active are complex.

“There are real differences between people who gain weight and don't,” Heindel said.

Genetics, diseases and certain drugs — particularly steroids, antiodiabetics and antidepressents — all shape the way the body metabolizes fats and other substances. Now it's becoming clear that external factors may be wreaking havoc on diets.

As many as 287 synthetic chemicals can be found in the cord blood — blood present in the placenta and umbilical cord — of everyone living in the United States. This suggests a common “chemical body burden” that has grown alongside production of and exposure to industrial and consumer chemicals.

As many as 20 chemicals are known to contribute to obesity later in life. These include the high-profile and increasingly toxic substance known as bisphenol A, or BPA, and tributyltin, a substance often used in PVC pipes and pesticides. A prevalence of the latter, for example, can nudge stem cells that might otherwise develop into bone cells to become fat cells. Thousands of synthetic chemicals, meanwhile, have yet to be studied.

“While it's important to pay attention to food intake and exercise, I think these chemicals are altering the set point for how much you can exercise and how much you eat,” Heindel said. Chemical exposures at birth and in development stages affect our “programming,” he said and shift the Hedonic pathways in our endocrine system that influence hormonal “rewards” for our actions. We're born exposed to these endocrine disruptors, Heindel theorizes; moreover, chemical exposures throughout life continue to stress already-altered systems.

“I think it's the perfect storm,” Heindel said.

Researchers have studied genetic roots for obesity for 40 years, he says, enough time for it to become clear that something beyond DNA has influenced weight gain. Meanwhile, it's still too early for scientists to completely understand the influence wrought by chemical exposures on obesity. Obesogens have only been examined for a decade or so. This new area of study, Heindel said, will change treatment of obesity from its focus on genetics and treatment through medication, to prevention.

“Currently there's nobody paying any attention to this,” Heindel said. A shift might mean a hefty price tag in a country where 17 percent of all medical costs come from obesity-related diseases. Children who are obese at age 12 who remain obese through their lives will cost the U.S. government more than $6 billion. That doesn't take into account emotional costs associated with obesity, Heindel said.

Despite growing attention focused on obesogens, highlighted by a feature article in the journal Environmental Health Perspectives, Heindel said more emphasis should be placed right now on research than publicity.

“It couldn't be a worse time to try to move an area of science forward when the funding levels are going down and are predicted to get worse,” Heindel said. “We're at a point now when we should stop talking a little and start doing a little more research.”

Disproportionate impacts

The public health officials, medical professionals, professors, students and activists who participated in the conference also heard a keynote from José Bravo, who leads the Just Transition Alliance. That organization convenes environmental justice advocates and labor groups to identify the disproportionate impact pollution and other environmental problems pose on low income and minority communities. Such environmental justice concerns are often neglected by white and higher-income communities to the extent that when organized environmentalists get toxic products removed from store shelves they end up at discount retailers in poor communities, he said.

Bravo, who served on President Obama's transition team, said the First Lady's encouragement to become more active is great news, but not sufficient for communities with limited affordable food options and surrounded by toxic facilities.

“I think it's very important to us to just look a little deeper than just make blanket statement to get up and move,” said Bravo, who later led a breakout session focused on the link between obesity and environmental justice.

Obesity wasn't the only topic on the agenda. Other sessions focused on the relationship between water quality and fish consumption in the Northwest, and a panel discussion on radon. Finally, before participants met to determine environmental health-related priorities on which to focus in the Northwest, Congressman Earl Blumenauer (D-Portland) brought the conference's focus back to food, with a speech about the Farm Bill.

Blumenauer said that complex legislation, set to expire September 30, is one of the “most important” pieces of health-related federal policy, as well as one that could have a tremendous economic impact for Oregon, but only if it doesn't concentrate too many subsidies among large agribusiness concerns.

“If we had a fair farm bill, even one that caused a third as much, but was fair, it would be an amazing shot in the arm for Oregon agriculture, Oregon tourism and the Oregon fish and wildlife community,” Blumenauer said.

Beginning February 24, presentations from the conference will be available on the Oregon Environmental Council's Web site at http://www.oeconline.org/our-work/healthier-lives/healthprofessionals/2012-4th-annual-nw-environmental-health-conference/.

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