Monday, January 18, 2010

BPA shown to be toxic to humans (again!)

I pee Bisphenol-A (BPA). I’m sure you do as well. About 90% of Americans have measurable concentrations of BPA and its metabolites present in their urine.

BPA is one of the world highest produced chemicals (>2 million metric tonnes produced in 2003) and we have a nearly ubiquitous exposure to it daily. Because BPA is so water soluble, the half-life for human oral intake is only a few hours. So the fact we are measuring it in urine means we have a nearly constant exposure to BPA. Exposure to BPA comes mainly through dietary means since it is a constituent of plastics and used as a lining for canned goods (so the food doesn’t actually touch the metal).

There are many health concerns though about BPA because it is a known endocrine disruptor, acting as both an estrogen mimic and androgen antagonist. Anytime chemicals alter hormonal function, it can often lead to a cascade of effects. With BPA this includes liver and pancreatic dysfunction, thyroid disruption promoting obesity and also feminizing effects in males studied. More so, these effects are observed at daily intake concentrations lower than the recommended safe exposure level. Never a good sign.

And producers of BPA and BPA-containing products have gone through great lengths to try and cover up these findings and try and sell BPA as if it were safe product. Such findings come from minutes and memos from closed door BPA industry and advocacy groups:

“Internal notes from the meeting obtained by the Post state that industry representatives discussed "using fear tactics [e.g. 'Do you want to have access to baby food anymore?]." The notes also state that the group focused on "befriending people that are able to manipulate the legislative process. According to the Journal-Sentinel, industry officials "hammered out" a public relations strategy they hoped would include the "holy grail" of "showcasing a pregnant woman to talk about the chemical's benefits.”


These letters gained the attention of both Connecticut and California whom are both considering bans on BPA with the Conn attorney general concluding:

“The chemical industry used "confusion and concealment" and possibly violated Connecticut law in its unsuccessful attempt to kill legislation banning the use of bisphenol-A in baby bottles and infant food jars, Attorney General Richard Blumenthal charged Monday.

Blumenthal, during a news conference with legislators and environmental and public-health activists, said he was concerned by an apparent strategy that was developed during a meeting of packagers and chemical lobbyists in Washington early this year. Misleading consumers, he said, is a violation of state law.”

Just this month however, a new study published in PLoS one confirms a previous survey that elevated BPA urinary concentrations are associated with heart disease. The previous study, National Health Nutrition Examination Survey (NHANES), a large scale and high quality dataset representative of the US adult population, for 2003/04 was the first association found between BPA exposure and coronary disease, diabetes and an increase in specific liver enzymes. Such important findings needed to be confirmed by independent data however.

With the NHANES 2005/06 report just released, looking for the same associations and adjusting for the same variables as the 2003/04 survey, BPA urinary concentrations were again found to be associated with heart disease. Using an independent survey group than the 2003/04, the new study found the overall urinary concentrations to be lower but the heart disease correlation remained virtually the same. BPA exposure and incidence of diabetes and liver enzymes did not prove to be significant in the new data set (though diabetes was sooo close, but alas, not significant). In the pooled data between 2003/04 and 2005/06, heart disease, diabetes and increased liver enzymes were all significant.

While this is confirmation that BPA may cause heart disease further testing is needed. These new findings do however add to the growing body of literature that shows the adverse health effects of BPA exposure.

It’s about time we phase this chemical out.

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