Common Chemicals Activating Obesity

Common Chemicals Activating Obesity

Feb 2007 - Exposure 
to environmental chemicals found in everyday plastics and 
pesticides while in the womb may make a person more prone to 
obesity later in life, new research indicates. 
Obesity is generally discussed in terms of caloric intake - 
how much a person eats - and energy output - how much a person 
exercises. 
But now Frederick vom Saal, professor of biological sciences 
in University of Missouri-Columbia's College of Arts and 
Science, has found that when fetuses are exposed to these 
chemicals, the way their genes function may be altered to make 
them more prone to obesity and disease. 
Frederick vom Saal is a professor of biological sciences in 
the Endocrine Disrupters Group at the University of 
Missouri-Columbia's College of Arts and Science. 
Vom Saal presented his research today at the annual meeting of 
the American Association for the Advancement of Science, AAAS, 
in San Francisco. 
"Certain environmental substances called endocrine-disrupting 
chemicals can change the functioning of a fetus’s genes, 
altering a baby’s metabolic system and predisposing him or her 
to obesity," said vom Saal. 
"This individual could eat the same thing and exercise the 
same amount as someone with a normal metabolic system, but he 
or she would become obese, while the other person remained 
thin," he said. 
This is a serious problem because obesity puts people at risk 
for other problems, including cancer, diabetes, cardiovascular 
disease and hypertension. 
Using lab mice, vom Saal has studied the effects of 
endocrine-disrupting chemicals, including bisphenol-A, which 
the city of San Francisco has banned in children's toys from 
December 1, 2006. 
Some polymers used in dental fillings also contain 
bisphenol-A, while epoxy resins containing bisphenol-A are 
popular coatings for the inside of cans used for canning food. 

Toymakers and other companies affected by the ban have sued to 
block enforcement of the San Francisco ordinance, saying their 
products have been used safely for decades. 
But vom Saal found that bisphenol-A and other 
endocrine-disrupting chemicals cause mice to be born at very 
low birth weights and then gain abnormally large amounts of 
weight in a short period of time, more than doubling their 
body weight in just seven days. 
Vom Saal followed the mice as they got older and found that 
these mice were obese throughout their lives. 
Obesity is an increasing problem that may be linked to 
exposure to common chemicals. 
He says studies of low-birth-weight children have shown a 
similar overcompensation after birth, resulting in lifelong 
obesity. 
"The babies are born with a low body weight and a metabolic 
system that’s been programmed for starvation. This is called a 
thrifty phenotype, a system designed to maximize the use of 
all food taken into the body," vom Saal said. "The problem 
comes when the baby isn’t born into a world of starvation, but 
into a world of fast food restaurants and fatty foods." 
More research must be done to determine which chemicals cause 
this effect. According to vom Saal, about 1,000 of the 55,000 
human-made chemicals in the world might fall into the category 
of endocrine disrupting. 
These chemicals are found in common products, from plastic 
bottles and containers to pesticides and electronics. 
"You inherit genes, but how those genes develop during your 
very early life also plays an important role in your 
propensity for obesity and disease. People who have abnormal 
metabolic systems have to live extremely different lifestyles 
in order to not be obese because their systems are 
malfunctioning," vom Saal said. "We need to figure out what we 
can do to understand and prevent this." 
Fat children may have been exposed to endocrine disruptive 
chemicals in the womb. 
In the past 30 years, the prevalence of overweight and obesity 
has increased sharply for both adults and children in the 
United States, according to the Centers for Disease Control 
and Prevention, a federal agency. Between 1976–1980 and 
2003–2004, the prevalence of obesity among adults aged 20–74 
years increased from 15.0 percent to 32.9 percent. 
This increase is not limited to adults, the agency reports. 
Among young people, the prevalence of overweight increased 
from 5.0 percent to 13.9 percent for those aged 2–5 years, 6.5 
percent to 18.8 percent for those aged 6–11 years, and 5.0 
percent to 17.4 percent for those aged 12–19 years. 
Although one of the national health objectives for the year 
2010 is to reduce the prevalence of obesity among adults to 
less than 15 percent, current data indicate that the situation 
is worsening rather than improving. 
"Perinatal Programming of Obesity: Interaction of Nutrition 
and Environmental Exposures" is the title of vom Saal’s AAAS 
presentation. 
Also presenting with vom Saal at the AAAS symposium are Reth 
Newbold of the National Institute of Environmental Health 
Sciences, Bruce Blumberg of the University of 
California-Irvine, George Corcoran of Wayne State University 
and James O’Callaghan of the National Institute for 
Occupational Safety and Health.

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