(NaturalNews) Bisphenol-A could be making us fatter. Diet and too little exercise are the main culprits of what has been called the obesity epidemic, but the hormone mimicker bisphenol-A might be tipping the scales, so to speak.
Bisphenol-A (BPA) is mainly found in polycarbonate plastic, which is labeled with the number 7; in plastic food wrap, and in the resins that coat the inside of metal cans for food. It is so prevalent in today's products that it is even in refrigerator shelving, water bottles, plastic food storage containers, water pipes and flooring.
BPA is an endocrine disrupter that mimics the hormone estrogen. Studies have shown harmful biological effects on animals using low-doses of the chemical and harmful effects on humans have been observed outside of studies. Hormone disrupting effects have been shown to occur at levels of application as low as 2-5 pars per billion and many canned foods are within and over this range.  With such a low level of toxicity, it's easy to see how even a minuscule rate of bisphenol-A (BPA) leakage from plastics disturbs many people. The damaging effects of the chemical include impairment and unnatural changes to sex organs and their functions, increased tumor formation, hyperactivity, neurotoxin effects, and signs of early puberty have been observed. Clearly, BPA's toxic effects are diverse.
A recent study by the US Centers for Disease Control and Prevention discovered that about 93% of the United States population have bisphenol-A
in their body at a median concentration of 2.7 ppb. 
A group of BPA experts determined that the average levels seen in people are above those seen to cause harm to animals during laboratory experiments. 
The Health Canada provisional human
safe exposure limit is set at 25 parts per billion per day (ppb/day). Their American neighbors have set the human safe exposure limit to 50 ppb. Here comes the surprising part. Below the United States' maximum limit, animals have been observed to display hyperactivity (sounds like ADD/ADHD) and a reversal of normal sex difference in their brain structure at 30 ppb/day. Below the Canadian level for maximum exposure, there has been a notable increase in damage to DNA at 20 ppb/day, insulin resistance (often leading to metabolic syndrome and type 2 diabetes) at 10 ppb/day, early puberty at 2.4 ppb/day (at one tenth of the maximum safe limit), and other types of harm to sex organs even at levels of approximately 0.025 ppb/day, which is much lower than what was in more than half of the people in the CDC study. 
An infant that is fed canned formula with polycarbonate bottles can take in up to 13 ppb/ day of BPA
Many of the results of BPA exposure, at limits below what is in the average person, have resulted in animal impairments whose counterparts in humans have been growing in populations as the amount of BPA in the environment has increased. In recent decades, type-2 diabetes has increased, positive ADD/ADHD diagnoses have increased, and rates of early puberty have gone up. Perhaps BPA exposure causes similar impairments to humans as it does to animals at similar levels. 
In a recent study, researchers at the University of Missouri-Columbia fed quantities of BPA to mice during their early development that produced amounts in their bodies that were lower than levels found in most people by the U.S. C.D.C. study. A result of this was that the mice became significantly more obese as adults than their fellow mice that were not given BPA.  Tufts University researchers found a similar occurrence in rats. The chemical industry disagrees with these results.
This is the recent link between low-level BPA exposure and obesity. Frederick vom Saal, a BPA-studying biological scientist at the University of Missouri-Columbia said to the Boston Globe that exposure "can be critical on the front end of one's life where the rest of your life's physiology is being programmed." If BPA is present during fetal development, it may be part of the explanation for the trend of increased and younger rates of obesity. Its damaging effects seem to be permanent.
Vom Saal said, "The idea that this is a strong, durable product is an illusion. The chemists have known that the Bisphenol A chemical is constantly leaching and coming into contact with food or water. It's going to damage your body." 
This year, nine states have pending legislation that will limit BPA's use in containers. 
There are many other endocrine disruptors similar to BPA. Educate yourself and limit your exposure.
"Bisphenol A: Toxic Plastics Chemical in Canned Food." http://www.ewg.org/reports/bisphenola
"New Data from CDC Confirms Human Exposure to Bisphenol A in the United States is Far Below Safe Limits." http://www.bisphenol-a.org/whatsNew/20071101.html
"Chapel Hill bisphenol A expert panel consensus statement: integration of mechanisms, effects in animals and potential to impact human health at current levels of exposure." http://endocrinedisruptors.missouri.edu/pdfarticles/pdflist.html
Richter, C.R., Birnbaum, L.S., Farabollini, F., Newbold, R.R., Rubin, B.S., Talsness, C.E., Vandenbergh, J.G., Walser-Kuntz, D.R. and vom Saal, F.S. "In vivo effects of bisphenol A in laboratory rodent studies." Reprod. Toxicol. 24:199-224, 2007.
"Uncovering a Hidden Danger." http://atmizzou.missouri.edu/jun03/plastics.htm
"Parents Concerned Over Potentially Toxic Baby Bottles." http://www.abcnews.go.com/WN/story?id=4259036&page=1
About the author
Tom Mosakowski, B.S. Biochemistry.
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