Is it safe to reheat food in any type of plastic container or are there only some types of plastic ware that are safe to use?
There has been quite a lot of discussion regarding the safety aspects of cooking/reheatin foodstuffs in plastic microwave containers. I'm not sure there is, as yet, any conclusive evidence one way of the other.
If you have to reheat food in plastic containers, make sure they're labelled specifically for that purpose. Personally, I'd use glass or ceramic.