Vitamin D (your body makes it from sun exposure between 11am and 3pm) seems to more beneficial than the sun is dangerous.
Still not a good idea to get sun burned. 8-10 minutes in the middle of the day is tolerable for most people and beneficial for D making.
http://realfarmacy.com/scientists-blow-the-lid-on-cancer-sunscreen-myth/
Toms Blog on Life and Livingness