For my baby I'm choosing Bisphenol-A (BPA) and phthalate free baby bottles. Both of these chemicals are endocrine disruptor's that the body confuses for estrogen.
Over 95% of the baby bottles on the market are made from plastics that contain BPA which can leach out of the bottle particularly when heated. There is a large body of evidence showing that BPA exposure even in tiny amounts has harmful effects in lab animals. Effects include (but are not limited to) early puberty, hyperactivity, obesity, diabetes and lower sperm counts. Many environmental health organizations in the US and Canada are calling for an immediate moratorium on the use of BPA in food and beverage containers while the FDA reviews the safety of these products.
Many people are falling back on the idea that these products have been used for years and if they were good enough for me why aren't they good enough for my baby. I find this argument extremely short sighted. There was a time we didn't think cigarettes were that bad for us, and we obviously know the ending of that story. We have no idea what the long term effects are of these types of chemicals, but if there is one isn't better to take the 'ounce of prevention' route now while we wait and see?
There are more and more BPA free options becoming available so it is not impossbile to choose BPA free products. I've currently placed Evenflo glass bottles on my registry, since glass products do not have the same potentially harmful chemicals in them. There are plastic bottles made by Born Free that do not contain any BPA although they tend to be a little more expensive (but not outrageous).
In terms of breast milk pumping and storage the Medela Breastmilk storage and feeding set is made from polyproplyene and therefore is also BPA free (polycarbonate is the plastic that is potentially hazardous). I also registered for this type of pump even though they are very expensive. I feel strongly enough about this to pay the extra money myself and while some people may find it presumptive to register for such expensive gifts I don't actually expect anyone to purchase it for me. However, it is the kind of gift a group of people could go in together on if they wanted so it makes sense to me to leave it on there.
Generally products labeled with recycling symbols of 1,2,4,5 are thought to be safe while 3, 6,and 7 may contain harmful chemicals.
Also clear silicone nipples are free of all BPA as are the drop-in type liners (at least the playtex ones for sure I didn't look into all of them) used in many feeding systems (although obviously less environmentally friendly).
Both the Playtex and Avent company's have letters on the websites saying that the dangers of BPA are unproven and the FDA currently approves of all products they sell (They are the only ones I looked up at this point). These company's obviously have a lot to loose if their products get pulled from the market and therefore will certainly do everything they can to prevent the FDA from doing so.