With the long days of summer upon us, many of us are hitting the beaches and getting suntans.  Southern California is obsessed with both beauty and health, and tanning sits at the intersection of the two.  Suntans have become symbols of status, health and beauty. But why?  There are certainly no health benefits to tanning, and many health risks.  Dermatologists have been warning us for over a generation that sun exposure increases our risk of melanoma, the most dangerous form of skin cancer.  I...