So long as...
Plugging a dynamic microphone into a mixer that has phantom power will not damage the microphone as long as you are using a balanced microphone. How can you tell? If you connect an unbalanced microphone to an input that is supplying phantom power, it goes BBBZZZZZZZZZZZZZZZ, and you'll probably rip it out of its input before you can seriously hurt the mic.
If you hear a soundguy say that it's dangerous, impress him by informing him that your dynamic microphone was made after about 1970, so it's balanced and, therefore, will not self-destruct.
Of course, I could be wrong about all of that and it could be more dangerous than napalm, but probably not.
Best Regards,
Chris