Actually, Simple Green is non toxic, you can drink it(not recommended) and if you rince the pipe thoroughly, it's perfectly safe. When I was a diesel mechanic, the district rep for the company that makes it came to my shop to do a demo, he drank 4 ounces of it, and other than a horrific taste, he suffered no ill effects.

Mouthwash will do the trick too, although I'm not sure if an alcohol based cleaner is the safest thing to microwave, since when it's heated the alcohol becomes very flammible.