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A variety of polycarbonate bottles, including the popular Nalgene shatter-free bottles contain the chemical bisphenol A. In sufficient quanitities the chemical is believed to disrupt hormones, but the FDA concludes in an early report that the levels in plastics are low enough not to be harmful.
FDA continues its insistence that the plastic is safe, says its studies on mice more accurate than recent human study

Last month, DailyTech reported that in a preliminary review, the U.S. Food and Drug Administration had declared the plastic Nalgene safe.  While Nalgene and other products contain the hardening agent bisphenol A (BPA), a known disruptive agent of human physiology, the FDA concluded that sufficient quantities of the chemical did not leach into the liquids stored inside the bottles to cause harm.  Critics blasted the ruling, pointing out that studies have indicated that small, but significant quantities did leach into the water.

Now the first major study on the effects of bisphenol A has been completed and it indicates a clear link between the compound and diabetes and heart disease.  In the study, researchers from Britain and the University of Iowa examined a U.S. government health survey of 1,455 adults who had given urine samples.  The adults were then split into different groups based on the levels of BPA found in their urine.  All the adults were within the "safe" levels of BPA, according to the FDA's standards.

The study discovered that in the highest BPA group there were more than twice as many people with diabetes and heart disease.  No correlation between BPA and cancer was shown.

While the study certainly seems to indicate a clear link between BPA and these diseases, it raises a chicken and egg sort of debate.  If the findings hold true in additional tests, there are two possibilities.  One possibility is that the disease came first and somehow raised the body’s absorption of BPA.  The other possibility is that the BPA came first and somehow interact with the patients' bodies, putting them at higher risk of diabetes and heart disease.

Despite the fact that the largest study to date now suggests a link between "safe" BPA levels and disease, the FDA is refusing to change its stance.  In a scientific review the FDA declared that BPA is "safe" within suggested guidelines.  Laura Tarantino, head of the FDA's office of food additive safety, states, "Right now, our tentative conclusion is that it's safe, so we're not recommending any change in habits."

Tarantino says that if customers want to voluntarily avoid the chemical; that is their decision.  She says that bottles bearing the recycling symbol 7 are BPA-containing, and that heating food in these containers helps to release the BPA.

Ms. Tarantino and the FDA also argued that the agency's own studies on mice were more thorough and extensive than the recent human study.  The American Chemistry Council, an industry trade group, agreed and was quick to blast the study, saying it was flawed, substantially limited, and "proved nothing".

Several states are restricting BPA use, and there is legislation that may soon ban BPA use in baby bottles in Canada.  On a national level in the U.S. and in the European Union, the government food and health agencies have suggested that the compound is safe.  The FDA has acknowledged in the past that its own studies indicate "some concern" of the possible effects of BPA exposure on the brain in fetuses, infants and children.  BPA is commonly used in baby bottles in the U.S. and EU.



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RE: Is that because of lunch boxes?
By masher2 (blog) on 9/17/2008 3:43:45 PM , Rating: 2
Looks like a 95% confidence was used. Source paper is here:

http://jama.ama-assn.org/cgi/content/full/300/11/1...

The American Chemical Council also has an interesting bit to say about the study:
quote:
The new study is a statistical analysis that attempts to correlate urinary concentrations of bisphenol A, which reflect very recent exposure, with the incidence of cardiovascular disease and diabetes. However, the onset and development of these diseases occurred over time periods well before the bisphenol A exposure measurements were made . Because of this and other inherent limitations, the study is not capable of establishing a cause and effect relationship between bisphenol A and these health effects.
http://www.americanchemistry.com/s_acc/sec_news_ar...


RE: Is that because of lunch boxes?
By clovell on 9/17/2008 6:14:46 PM , Rating: 2
Great point there, Michael - which is why the entire idea of using NHANES, rather than prospective data is a bad one. The only other large national database that comes to my mind that might shed further light on this is LSAO, conducted by the CDC. LSOA is a longitudinal study, but it focuses on the elderly.

The fourth sensitivity analysis seems most prudent, as it actually adjusts for potential confounders rather than simply demographics (favorite among epidemiologists).

> Models adjusted for levels of triglycerides plus LDL-C had a reduced number of participants (data for the fasting subsample only), but overall trends were similar: a 1-SD increase in BPA concentration was associated with increased odds of reporting diabetes (n = 635; OR, 1.40; 95% CI, 1.02 to 1.93; P = .04). However, the association with cardiovascular disease became nonsignificant, although the trend was similar (n = 546; OR, 1.22; 95% CI, 0.80 to 1.88; P = .33).

Which really seems to put this in a bit more perspective. When adjusted for confounding factors, they're analyses yield only a single significant result. I see no mention of adjustments for multiple testing, and, as you pointed out, the nature of the study seems to preclude any causal conclusions - at least those in the direction of what we're hearing.


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