I am looking into how to distinguish what is what in the plastics world. Its actually fascinating. The numbers on the bottom of bottles are not intended to give us safety information but to describe what type of plastic is used and how to sort and recycle them. They do describe what type of plastic or the combination of plastics used in the making of them, they are called resin ID codes, For example:
1. PET is used mostly in beverage bottles and then when recycled, used in carpets, textiles, etc:ie as polyester.
2. HDPE: is used for its stiffness and good barrier qualities, also holds up well in various temperatures -ie milk bottles and household cleaning items.
3. PVC: can be used as both rigid and flexible plastics, anything from shrinkwrap to pipe siding.
4. LDPE: mostly used in flim and some flexibile lids and bottles, packaging
5. PP: used with hot liquids, high melting point and strong, used for yogurt containers and condiment botttles, caps etc.
6. PS: again, can be rigid or soft, low melting point, used for packaging, bottles, food containers
7. OTHER: this is used to describe a package made of resin, more than one type of plastic or a combination of some of the other 6 listed above (these are all from the americanchemistry.org website)
I intially heard there were 11 kinds but I only found descriptions of 7.
So, you have to know in your area what kinds the recycle truck will pick up and recycle, you can look it up.
My big question is about safety and how to make sense of which kinds are safer than others, and can we really heat up food or drinks in these containers without having it leach into our bodies or give us cancer? In my searching, I got overwhelmed unsurprisingly.
I liked this practical question and answer series from the washington post (http://www.washingtonpost.com/wp-dyn/content/discussion/2008/04/15/DI2008041502361.html)
I gleaned some basics: BPA, not so good and now can probably be avoided by using certain number plastics (i know what I said before but these reccomendations are consistent over websites that # 1,5 6 id codes describe a type of plastic that are better for BPA content than the others). Why is BPA not cool? It seems recent research has indicated there is some concerns that exposure BPA had negative effects on the brain, behavior, and prostate gland in fetuses, infants, and children at current levels of exposure. There is also talk about it causing breast cancer, prostate cancer and early puberty. Also it seems, microwaving plastic-don’t do it because why should you do it when there are other alternatives such as glass that are known to be perfectly safe.
When I was freaking out about the baby bottle question, I use this website to replace all my bottles and tupperware with BPA free plastics by type
http://safemama.com/2007/11/22/bpa-free-bottle-and-sippy-cup-cheat-sheet/
I also just found this site that looks interesting and reviews sippy cups and bottles
http://www.naturemoms.com/blog/2008/01/21/bpa-free-sippy-cups-part-two/
Thats an update for now. I decided to do plastics for two months partially because it is a huge undertaking and kind of crazy to sort out what the heath issues are and the environmental issues without oversimplifying which I tend to do anyway. I will say that I gave up on the glass milk container already and its mostly because of the congealing fat clumps that make it seem there are butter lumps in my coffee. No can do. Wax paper half gallon containers can be mulched in the green bin.