Excuse the cut and paste job - but back when I played ultimate and wasted time on rec.sport.disc (i.e. before I started doing tris and wasting my time on slowtwitch) a similar discussion started up.
The whole thing is at
http://groups.google.com/group/rec.sport.disc/browse_thread/thread/568690a4bd757678/eb6cf42a5a9b1ed1?lnk=gst&q=nalgene&rnum=2#
But the most interesting entry was from a grad student in the sciences, who wrote this:
I read , and my interest was piqued. My
Nalgene bottle was sitting next to me on my desk, and I had been steadily
drinking from it all day. As a biologist who studies hormones, I’ve heard
a lot about “environmental estrogens” like BPA, and their effects on
reproduction and development, so the studies described weren’t entirely
surprising. But I’ve also read a lot of science articles, and I have to
say that a lot of crappy research gets published in respected science
journals, particularly when it deals with a very media-friendly topic. So
I set off on a completely nerdy 5-hour quest through about 150 abstracts
and at least 20 journal articles to try to figure out how compelling the
relationship is between Nalgene bottles, BPA, and biological effects.
And now that I’ve spent all that time, and missed my workout and various
other things I was planning to get done tonight, I feel the need to burden
your inbox with my results. Feel free to stop reading now and delete this
(if you haven’t already).
There is no question that BPA is what's called an "endocrine
disruptor," or a chemical that either mimics or interferes with (or both)
the normal action of hormones like estrogen and testosterone. In lab
animals and cultured cells, high doses of BPA have effects similar to
those of estrogen. They can disrupt reproductive develoment and possibly
contribute to cancer. These doses are on average about 1,000 times higher
than the highest reported level of leaching from any polycarbonate
plastic.
The big question is whether low doses of BPA (or other endocrine
disruptors), such as you might experience in your average daily
plasticized environment, also have significant harmful effects. The
answer is, as far as I can tell, “maybe.” Several studies have shown an
effect of low doses on things like uterine weight and sperm count in mice.
Several other studies, in other labs, have failed to replicate those
results (using as close to the same methods as possible, and often using
larger sample sizes). Also, there’s some evidence that BPA gets
metabolized (broken down and removed from the body) pretty quickly, so
we’re not talking about a DDT-type accumulation effect. I’m not saying
that the original studies were bad or wrong, but science is all about
replication, i.e. if the effect isn’t consistent, is it really meaningful?
In the end, I didn’t come away convinced that there’s a solid effect (but
that doesn’t mean there isn’t one).
The other big question is whether your **Nalgene** is leaching gobs of
BPA into your drinking water. The folks at ourstolenfuture do a nice job
of pointing out that the Lexan used in Nalgene bottles hasn’t been
specifically tested, but there have been tests done on other polycarbonate
plastics like lab animal cages and baby bottles. All of those studies
have shown some amount of leaching under some conditions, particularly
when subject to high heat over long periods of time. However, one study
reports detectable leaching from brand-new polycarb animal cages at room
temperature, whereas another reports no leaching from baby bottles
subjected to typical use. Another study reports miniscule amounts of BPA
in water that was sitting in a polycarb container for 39 weeks. Again,
the answer seems to be, “maybe.”
To put this into perspective, If you take the highest BPA amounts
from the 39-week experiment above, and assume that you’re getting that
much BPA in your water every time you fill up your Nalgene, and figure
you drink 2 bottles a day, you’re still getting less than one-hundredth of
the lowest dose used in animal experiments. Now, since no one has
specifically studied Lexan, and I hope that someone does that test soon, I
don’t know whether that’s a realistic scenario. Regardless, I can tell
you that it’s probably more likely to leach BPA if you repeatedly stick it
in the dishwasher versus gently rinsing it out with warm water.
By raising the scientific controversy, I don't mean to detract
from the concern, or from the hard work of the folks who are trying to
understand the effects of environmental estrogens. I believe that it is a
problem, and requires more research. And of course, it’s easy for
regulatory agencies and industries to say that there isn’t clear evidence
for , rather than trying to do something
about it.
As far as the Nalgene bottles go, it’s not a bad idea to switch if
you care about this kind of thing - if nothing else, it will make you feel
safer, and there’s a chance that it might make some difference to your
kids. It certainly won’t hurt to switch to an HDPE or metal water bottle
(at least, not until someone finds something that leaches out of them).
Just because you’re ingesting way more BPA from covering your food in
plastic wrap than you probably are from your Nalgene doesn’t mean that
it’s ok. But at this point I’m not going to freak out about the fact that
I’ve been drinking out of mine for years. In fact, all this typing is
making me thirsty…
