BPA Exposure Underestimated

"There are a range of molecules that are natural, and some are incredible toxins. But when we start to make molecules that are not known to nature, we need to think a little more carefully about how they are going to interact with biological systems." - Zoeller (University of Massachusetts, Amherst)

This quote was obtained from an article in The New York Times titled, Study: Human Exposure to BPA 'Grossly Undersestimated'. The article was posted on September 20, 2010 and can be viewed at this link. Additional information from the article is discussed below:


Exposure Limits:

• Bisphenol A(BPA) can be found in 90% of the American population
• According to the U.S. Environmental Protection Agency(EPA), the human exposure limit for BPA is 50 micrograms per kilogram of body weight.
• It has been found that the average person is exposed to 400 micrograms per kilogram of body weight.

Since most people do not think in terms of micrograms and kilograms, let's do some math.

50 micrograms = 0.00005 grams = 1.10x10^-7 pounds BPA
1 kilogram = 1000 grams = 2.20 pounds of body weight
1.10x10^-7 pounds BPA /2.20 pounds of body weight = 5.00x10^-8 pounds BPA per pound of body weight
A person weighing 150 pounds should only take in 7.50x10^-6 pounds of BPA or 0.003 grams of BPA.



BPA Mimics Estrogen

• BPA is an "endocrine disrupter" because it mimics estrogen in the body.
• The estrogen receptor, male hormone receptor, and thyroid receptor can be bound by BPA.
• BPA's first use was as a "man-made estrogen substitute". This is why it resembles estrogen.

Two Studies of BPA

In 2002, a German scientist from the University of Wurzburg named Wolfgang Volkel conducted the only BPA study performed on humans. According to his study, 99% of BPA in the blood is removed by the liver. He also concluded that it is excreted from the human body in six hours. However, many researchers "say the the method Volkel used to measure BPA in the blood was not sensitive enough and that he likely overestimated the ability of the chemical to pass through without causing harm."

A recent study by a biologist from the University of Missouri named Julia Taylor was performed on mice and monkeys. The method she used is more sensitive for measuring BPA levels. Blood samples revealed that "biologically active" amounts of BPA were found in the mice and monkeys. She concluded that BPA circulates in the blood because the liver is not able to completely remove it. Furthermore, the BPA levels in blood "are cause for concern".

BPA and Politics

Senator Dianne Feinstein aims to amend the "FDA Food Safety Modernization Act". The amendment would ban BPA from the packaging used in children's food and drinks.

Dianne Feinstein

Analysis of the Article

While the article is not from a scientific journal, it uses evidence from scientific articles and studies. So, it uses strong evidence. The article is also unbiased because it discusses the subject from multiple viewpoints and considers several sources. The article gains credibility from being published in The New York Times, a widely accepted newspaper. However, the evidence was interpreted by a newspaper journalist instead of someone who has first hand knowledge of the subject. Some information obtained from the evidence is likely to be left out of the article in order to fulfill the journalist's arguments. Overall, the evidence provided in the article is reliable.