Wednesday, April 16, 2008

Polycarbonate redux

I am listening to NPR’s All Things Considered – it’s a story about bisphenol A, a common chemical that many of us have heard about by now. You know the estrogenic chemical that’s in those colorful polycarbonate clear plastic bottles that we all bought when we didn’t want to use bottled water, as well as in the linings of food tins and clear plastic baby bottles – that yes, I’m sure I used with my kids. And I’m thinking maybe we all ought to drink a little bisphenol A if it’s true that a little estrogen is good for improving memory.

Here’s why.

There is no question that exposure to estrogenic contaminants is problematic – particularly when exposure occurs during fetal development and in young children. There are reams of data that demonstrate adverse impacts on the development of reproductive organs, timing of puberty, and other effects on both male and female offspring of test animals exposed in utero and during lactation. Then there is the unfortunate example of diethylstilbesterol or DES, the synthetic estrogen prescribed to women back in the twentieth century to stem complications during pregnancy. It was found to be ineffective in the 1950’s but prescribed until the ‘70s (go figure) when the consequences of exposure to extraneous estrogenic chemicals during development first reared its ugly head in the form of clear cell adenocarcinoma in the daughters exposed in utero.

But did you know that at one time, back in the 1930’s scientists seeking synthetic estrogens like DES found that bisphenol A also behaved as a weak estrogen? That’s right. Back in the 30s this was known. Then some genius discovered that it could be linked together to make plastic. And voila – perimenopausal women like me just have to drink from our polycarbonate bottles to replenish our estrogen. Apparently back then no one figured anyone would be drinking from the plastic, or storing food in it, or sealing children’s teeth – and then when they did discover these uses of the plastic they must have forgotten that it was a known estrogen.

Seriously, we could all use a memory boost. Here’s a Science News article from back in 1999 by Janet Raloff which, besides being so last century, is so similar to recent reports about leaching of bisphenol A from polycarbonate that I did a double take when I came across it on the web (actually I probably read it back then, being a fan of Ms. Raloff, but have since forgotten.) It’s uncanny. Right down to reports that bisphenol A is more likely to leach from well-used polycarbonate and when liquids are heated in polycarbonate.

If that was then, why has it taken us ten years to toss our bottles? Maybe it’s because as Raloff pointed out, the jury was out. Well, almost ten years later it has returned in the form of a report by the National Toxicology Program’s Expert Panel evaluation of bisphenol A, here’s what they conclude (their emphasis):

“The NTP concurs with the conclusion of the CERHR Expert Panel on Bisphenol A that there is some concern for neural and behavioral effects in fetuses, infants and children, at current human exposures. The NTP also has some concern for bisphenol A exposure in these populations based on effects in the prostate gland, mammary gland and an earlier age for puberty in females.”

“The NTP has negligible concern that exposure of pregnant women to bisphenol A will result in fetal or neonatal mortality, birth defects, or reduced birth weight and growth in their offspring.”

Although I’ve confiscated my kids bottles I might keep them around for a few years in case I’m needing a little extra estrogen – if I can remember where I’ve stashed them!

1 comment:

clearsight said...

Isn't it amazing how scientific knowledge cycles in and out of the collective consciousness? Of course, there's the disinformation factor coming out of corporate-funded research, but beyond that it seems that we often forget what we know!

Did you read that Nalgene pulled their bottles? Link: