Research links common chemicals to obesity (Reuters)

GENEVA (Reuters) - Exposure in the womb to common chemicalsused to make everything from plastic bottles to pizza boxliners may program a person to become obese later in life, U.S.researchers said on Wednesday.

Their studies of mice showed animals exposed to even tinyamounts of the chemicals during development were fatter whenthey grew older compared with mice not exposed to thecompounds, they told the 2008 European Congress on Obesity.

"We are talking about an exposure at very low levels for afinite time during development," said Jerry Heindel of the U.S.National Institute of Environmental Health Sciences.

"The fact that it is such a sensitive period, it may bealtering the tissue and making people more susceptible toobesity."

The World Health Organization estimates some 400 millionpeople are obese, a problem that raises the risk of conditionslike type 2 diabetes and heart disease.

Previous studies have linked these chemicals -- also foundin water pipes -- to cancer and reproductive problems,prompting a number of countries and U.S. states to considerpotential bans or limits of the compounds, the researcherssaid.

One of the chemicals is called Bisphenol A, found inpolycarbonate plastics. Past research has suggested it leachesfrom plastic food and drink containers.

A team at Tufts University in the United States showed thatfemale mice whose mothers were exposed to this chemical earlyin pregnancy gained more weight in adulthood even though theyate the same amount of food and were as active as other mice.

A similar effect occurred with perfluorooctanoic acid -- agreaseproofing agent used in products such as microwave popcornbags. These animals were unusually small at birth then becameoverweight later in life.

"One of the problems we are finding is we don't know whereall these chemicals are," said Suzanne Fenton, a researchbiologist at the U.S. Environmental Protection Agency, whoseresearch focused on perfluorooctanoic acid.

The chemicals appear to disrupt the endocrine system byaltering gene and metabolic function involved in weight gain,said Bruce Blumberg, a University of California biologist.

The result is the offspring store fat cells moreefficiently, which makes them gain weight, he said. Blumbergstudied tributylin, a chemical used in boat paint, plastic foodwrap and as a fungicide on crops.

The findings suggest some people may be programmed toobesity before birth and underscore the need to identifybiomarkers scientists can use to identify people at risk, theresearchers said.

"We are calling this an emerging hypothesis," Heindel said."Most of the data is in animals and we want to develop somebiomarkers that could be used in humans.

(Editing by Matthew Jones)