The Iron Ring

I found three lengthy and impressive articles on the health effects of bisphenol A (BPA) pictured here on the left. I decided to narrow my focus a bit. For example, it may take much less BPA to cause those sad alligators to have smaller penises than it does to cause breast cancer in people. Further, as the cellular mechanisms that cause these effects are WIDELY varying, I decided to focus on the BPA-carcinogenic (particularly breast cancer) question. I narrowed my questions to three main issues:

1) Is BPA carcinogenic?

2) If so, at what levels is it dangerous?

3) What levels are present nowadays anyway?

I found the answer to 1 and 2 in the same article (R.A. Keri et al. / Reproductive Toxicology 24 (2007) 240–252) and the answer to 3 in a different article (W. Dekant, W. Völkel / Toxicology and Applied Pharmacology 2008).

Basically, naturally occurring estrogens (at least estradiol 17β) are carcinogenic, which is why women whose have early onset of menstruation or late menopause have a greater risk for breast cancer (news to me!). In any case, as we establish this link between estrogen and cancer (see how I carefully word my sentences), the question of ‘is BPA carcinogenic?’ really becomes, ‘does BPA function as an estrogenic endocrine disruptor?’ which, translated, means ‘can BPA trick your body into thinking it is estrogen’?

This question, in turn, becomes ‘does the receptor that recognizes estrogen also recognize BPA’ (whew! Still with me?). The answer (at least what I can glean from here as I did not read the entire article) is that yes, BPA can be an agonist for the estrogen receptor, at high (100 mg/kg/day) doses. Again, to translate, that means at an exposure of 100 mg per kg of your body weight per day. A quick google search tells me that for women, weight is around 65 kg, which means you would need to be exposed to 6500 mg/ day for BPA to act as an agonist to the estrogen receptor. Of course, this is not the end of the story, but it is a place to begin to think about which levels of exposure might be dangerous.

The authors conclude that there is too little literature to indicate that BPA is definitely carcinogenic (this is a healthy skepticism on the part of scientists). This brings me to my final question, just how much BPA is hanging around anyway?

Apparently, scientists are not in agreement on how best to measure BPA. I will spare you all the details and say that a group in Germany measured BPA in urine and determined an approximate daily exposure of <>

Should we be worried? Probably not

Will I continue to research this as I am not satisfied with these few papers? Yes

Will I post what I find even though I have few readers and it seems I am the only person interested? Of course.

Do we need more research into this subject? YES

Interested in how BPA gets in us anyway? Look here and here and also here. Can’t vouch for verity in all three but it’s a starting point.

# posted by Sarah : 9:18 PM