Bisphenol A

[Butters]

A friend of my is starting to become obsessive about contaminants in his food and drink, and recently has decided that using a plastic kettle to boil water for tea is building up toxic levels of Bisphenol A in his body. I am less convinced that this is anything more than a media beat-up, but I have no evidence to base this on. This is not his only theory, and he tends to believe in a lot of so-called alternative medicines and other far more obviously bogus science, so that may colour my perception of this latest obsession.

 

My question is as follows. Is Bisphenol A a problem in the levels most people are exposed to, and even if it is, is the plastic used to make a kettle the right type of plastic to release this chemical into the water?

 

 

[CharonY]

That is not easy to assess. Theoretically one would have to measure each source of contamination and then figure out whether the intake could cumulatively lead to adverse effects. In most cases the levels are not high enough for acute effects and most likely infants or small children are more affected by it (due to the endocrine disrupting properties).

Unless very unusually made something like a water cooker alone should not a sufficient source for toxic effects.

[CaptainPanic]

A nice way to get both objective data (if you know what you talk about) or reason to freak out (if danger symbols and names of diseases scare you) is the Material Safety Data Sheet of a chemical. Google will often provide one if you type MSDS (and the name of the chemical).

 

In this case, we see that the oral LD50 varied for different animals from 2200 mg/kg to 6500 mg/kg. If your friend is an average 70 kg, he must digest at least 150 g of bisphenol A in one go to have 50% chance of dying from it. In short, he can probably eat the entire kettle in one go, and survive.

 

That said, other effects, less immediate, are much harder to measure. For example, the Bisphenol A concentration in the water of the kettle... you'd need professional lab methods to measure that concentration.

 

I personally think that the most components (unreacted precursors for the plastics, and for example plasticizers) that are harmful will come out immediately during the first (few) times you boil water. I would recommend to boil water a few times, and throw that away. Whatever doesn't come out in the first few times, probably won't come out at all, since this will work a little bit like diluting those components out of the kettle.

 

The other question that I cannot answer straight away is whether bisphenol A is found in the plastic at all. It is used for polycarbonate, and in some epoxy resins. I don't know the material for kettles.

[CharonY]

One should add that the concerns for BPA are not based on acute toxicity and hence the LD50 is less informative than one might think. the basic idea is that it disrupts normal endocrine signaling, leading to problems during development and, but the evidence is far less here, possibly also to various health issues in adults.

 

In general exposure analyses do not deal with acute toxicity but rather with long-term and accumulation effects.

[JGK]

National Post Article

 

Seems to be based on hysteria not actual science

[CharonY]

The media coverage definitively is. There is also an interesting comment from Shape (2010) discussing this issue. The main points being that the toxic effects of BPA have contrasting results in two large studies, with the newest one challenging the older. It has to be noted that all results on humans will, by necessity, be association studies. Right now the evidence is not strong enough to support any acute concerns.