I read a lot about this (I can't remember the sites) and I learned that in general the #7 plastics are the unsafe ones. Avent and Dr. Brown's bottles, as well as Nalgene bottles are made from this plastic. It is any plastic that is hard and clear, whether it's colored or not. Opaque plastic bottles and sippy cups (like Gerber) are usually #5 plastic and are safe.
As far as microwaving and washing in the dishwasher, I understand that extreme heat causes the chemicals to break down faster and to leach into the food. However, the chemicals will break down over time whether they're heated or not, so even if you only hand wash, don't keep these bottles for long.
I also read that bottles with the plastic bag inserts, like Playtex, are safe. Avent also now makes a bottle like that so I might try it next time so I can still use the nipples I have.