If you are paying any attention to the news I am sure you have heard a lot about plastic safety in the last few months. In what I have read and seen, one source says a certain "number" is safe while another source says it isn't . I have come to the conclusion that we will start phasing plastics out of our house, starting with plastic cups! We have made the switch to all glass for us, but for the littles they still have plastic. Our daughter doesn't do "sippy" cups but rather uses a straw. I haven't yet found one that is either glass or metal.
Glass storage containers are expensive, so we will be buying these gradually as our budget allows. There are a few places were you can buy stainless steel "sport bottle" type cups. Of course plastic is the cheap version of all of these but instead of having a cabinet full of plastic ones, one or two stainless steel cups will do. I always carry a bottle of water with us when we go anywhere, two if hubby is going (he drinks mucho amounts of water and isn't good at sharing!).
To see if your plastics are safe go here.
If you are looking for baby bottles or sippy cups born free is a good resource.