There are already 2 recent post about this that you can refer to:
One on 04/14/08 titled "Bottles that leak poison into milk"
AND
One on 04/08/08 titled "What do you think about negative press over plastic baby bottles & sippy cups"
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I have read a good bit about this subject after I discovered that the bottles I have used (warmed in the steam warmer, in the microwave, and washed in the dishwasher) for the past YEAR is considered by some to be on the "bad list". (We have used the Breastflow bottle made by The First Years.) Some scientist say that BPA (Bisphenol-A) causes cancers such as breast in women and prostate in men and that we should stop using this material especially if you warm things up in it or wash it in the dishwasher. The theory is that over time, this type of plastic breaks down and leaks more BPA into the milk, and that this exposure can cause cancer.
Other scientist believe that this is hogwash, and that though some BPA is leaked out over time, that the very small amount cannot cause harm. The controversy is that BPA has been harmful to lab animals when subjected to it (but the amount they are getting is much greater than what a baby is exposed to by bottle use - 5 to 8 parts per billion). These scientist believe that plastics made with Bisphenol-A is a very strong plastic and quite durable over time, even with repeat warming and dish washer washing.
The reports are that this needs more testing. Different scientist have ran the SAME report and got DIFFERENT outcomes, and their recommendations for the use of this plastic vary quite drastically.
I am not going to change bottles or sippy cups. We are working on going off the bottle and onto a sippy cup. We do not heat liquids in the sippy cup (Nuby - also on the "bad list"), but I do wash them in the dishwasher. Millions of kids have used this type of plastic. We receive toxins from literally almost everything we do, touch, drink out of, eat off of, package food in, etc. I believe the body is able to process through most of this.
http://www.bisphenol-a.org/whatsNew/20080205.html