Is it safe to heat food in plastic containers?

Salt Lake Tribune: "A five-month investigation by Good Housekeeping Research Institute, working with an independent laboratory, found that none of the food samples tested had BPA or phthalates in them after storage or microwaving. But there is more to understand. 

Technicians analyzed 31 containers, lids, bags, wraps and slow-cook liners to see whether BPA and phthalates were present. Four items had low levels of the chemicals - Rubbermaid Premier containers, Rubbermaid Easy Find Lids containers, Glad Storage Gallon Zipper Bags and Glad Press 'n Seal plastic wrap."