Unless your oven is a combination microwave/regular oven or combination microwave/convection oven and you use it on those other settings, no, you can't cure polymer clay in a microwave oven. Not for health reasons but because microwaving doesn't work to cure clay.
You CAN bake clay in a food oven, but if you do a lot of it, you will find that baking the clay vaporized oils that can build up on the oven walls so you will want to clean it more often. This stuff is more messy than dangerous.
I prefer a small countertop convection oven (mine cost $100 years ago, still going strong) and I only use it for clay. I find it more convenient, cheaper than using the "big" oven for my small projects, and I don't have to clean it. But if I wanted to bake a cookie-sheet sized veneer, for instance, I would use my food oven. I think I would put foil over it to reduce the off-gassing in the big oven, though.
If you want to play it extra safe, many people bake in their home ovens in foil broiler pans tented with foil to create a "sealed" container within the actual oven. So that's an option, too.