The Obesity Epidemic: Is Plastic Making Us Fat?
Plastic and its link to obesity: Information, Research, Causes, Symptoms and Treatment
BETH DALEY / Boston Globe
14 Jan. 2008
Researchers are exploring whether exposure to common chemicals during early development could set us up for a lifetime battle with the bulge
Being fat has long been seen as a personal problem, fixed only by struggling against the proliferation of fast food restaurants, unlucky genes, and a sedentary life.
But could something in the environment also be making Americans fat in epidemic numbers?
Animal studies in recent years raise the possibility that prenatal exposure to minuscule amounts of common chemicals — found in everything from baby bottles to toys — could predispose a body to a life of weight gain. The chemicals, known as endocrine disrupters, mimic natural hormones that help regulate, for example, how many fat cells a body makes and how much fat to store in them.
These findings have led some scientists to put forth a provocative argument: They say diet and too little exercise clearly are key reasons for the worldwide rise in obesity in the past 20 years, but they may not be the only ones. Food intake and exercise just haven't changed that much in that period, they argue. And while genetics obviously play a role — just think of someone you know who can eat three Big Macs a day and never gain an ounce — these researchers say it would be impossible to see such widespread genetic change in just two decades, giving them more reason to suspect the environment.
"This is a really new area... but from multiple labs on multiple levels we are getting preliminary data that all say the same thing: Chemicals can play a role. We know that nutrition and exercise are very, very important, but underlying that could be environmental exposures during development that alter your physiology, including how you respond to food and exercise."
— Jerry Heindel, National Institute of Environmental Health Sciences
Thousands of chemicals have come on the market in the past 30 years, and some of them are showing up in people's bodies in low levels. Scientists studying obesity are focusing on endocrine disrupters — which have already been linked to reproductive problems in animals and humans — because they have become so common in the environment and are known to affect fat cells.
New Term: "Obesogens"
One key researcher in the field, Bruce Blumberg of the University of California, Irvine, has even coined a new word for chemicals that can make you fat: Obesogens.
Bisphenol A Study
A CDC study found 93% of the US population had bisphenol A in their body. University of Missouri studies showed mice fed bisphenol A during early development became markedly more obese as adults.
Industry Response
The chemical industry disputes these studies, with the American Chemistry Council stating that "dozens of studies showed no weight gain" from bisphenol A.
Bisphenol A is only one of the chemicals scientists are studying. Blumberg's lab has also studied tributyltin, an endocrine disrupter that is used as an antifungal agent in agriculture and in marine paints to keep ship hulls free of barnacles. Female mollusks exposed to the chemical were seen to grow male sex organs. Lab mice exposed to tiny levels of tributyltin during prenatal development became fatter adults than those not given the chemical.
Critical Development Window
These scientists are focusing on early development because it is a critical time for determining a baby's long-term health and weight. Studies show that babies born underweight are likely to be fatter later in life, possibly because undernourished fetuses learn to use fat cells more efficiently.
"It predisposed them for life" — Bruce Blumberg
"Exposure can be critical on the front end of one's life where the rest of your life's physiology is being programmed."
— Frederick vom Saal, University of Missouri-Columbia
Growing up with more fat cells isn't necessarily a problem if you are running around a lot, says Pete Myers, chief scientist for Environmental Health Sciences. But in a world where exercise is down and poor diets abound, it could exacerbate a weight problem.
How to Minimize Exposure
For those who don't want to wait until all the evidence is in, here are some tips from researchers:
- • Avoid buying plastics with recycling number 7 marked on the bottom
- • Be aware that similar chemicals are in carpet fibers, PVC piping, and many other products
"These compounds are everywhere" — Felix Grun, UC researcher
Scientists say years of research into diethylstilbestrol (DES) — a synthetic hormone once given to women to prevent miscarriages until it was linked to cancer — also bolsters their belief that chemical exposure during early development can affect weight later in life. Research shows that mice exposed to DES in utero are fatter than those not given the chemical.
"What else are we waiting for? There is evidence these chemicals have a multitude of deleterious effects in animals... We should be worried."
— Ana Soto, Tufts University professor
Source: www.boston.com: Is Plastic Making Us Fat: 29jan2008