ok just to clear stuff up - sharpie on your arm is not going to kill you. I'm positive there are more chemicals in your food that could kill you than there are in your sharpie. (assuming you don't eat the sharpie)
A lot of things won't kill you, and it is still not a wonderful idea to put theose chemicals into your skin. Besides, there are most certainly not more chemicals in your food that could kill you than there are in your sharpie. Unless you are eating some stuff from Chernobyl, your food should be quite safe. TO CONCLUDE:
Sharpie on skin - doesn't do much, but still not a positively wonderful idea
Chemicals in food > Chemicals in sharpie - No.