Melamine won't release BPA, which is the chemical to be concerned about in polycarbonate plastics, commonly marked with a number 7. Melamine is a nitrogen-containing chemical that is used as a fire retardant and when combined with formaldehyde forms a resin. Melamine products are not known to release formaldehyde gases and as far as we know are safe for food. But melamine dishes should not be used in the microwave. Before putting ANY dishes in the microwave, you should check the bottom to see if they are microwave safe and not marked with a number 7.
Here's more information about plastics in the microwave, if you're interested:http://www.simplesteps.org/content/view//334/37
I work for NRDC, an environmental organization. This information is from NRDC's website, www.simplesteps.org
, and has been vetted by our staff scientists and doctors. I hope it was helpful.