No Microwaving food in Styrofoam containers is not dangerous to your health.
I've always microwaved food in Styrofoam containers for many years and never have had any health problems.
A Styrofoam container can safely be microwaved for at least 2 minutes and no longer than 2 minutes so keep an eye on the microwave during those two minutes and if you notice the Styrofoam starts to melt then remove it before it melts all the way through and you'll be safe.