So, a song by Willow Smith called 'i whip my hair' is harmful to human kind.
I was with my friend Sarah the other day, and we were making videos of us dance to songs...which are harmful to your eyes, so i don't suggest looking for them (:
Anyway, we were doing the head dance to that song, and i did it for 3. straight. minutes!
And now i have whip lash.
So...its defiantly harmful to people.