Those who do not need to tan, dark or black-skinned people, are naturally highly resistant to the sun's ultraviolet radiation. They have and produce lots of melanin. For those people, the production of more melanin in response to sun exposure-tanning-is protective, according to Madhu A. Pathak, a research dermatologist at Harvard University Medical School. (However, the American Academy of Dermatology urges Americans of every skin shade to protect themselves from too much sun.)

While skin cancer is rare among dark-skinned people, it is exploding among light-skinned Americans, and sun exposure is the main culprit. Final figures have not been computed, but the New York-based Skin Cancer Foundation estimates that more than 600,000 new cases of skin cancer were diagnosed in 1991 and that 8,500 Americans died of the disease last year. And depletion of the Earth's protective ozone layer is making sun exposure more troublesome, because thinning ozone lets more ultraviolet radiation hit the Earth's surface. Last year the Environmental Protection Agency estimated that ozone loss could create 12 million additional cases of skin cancer among Americans alive today or born before 2030.

You can see why dermatologists encourage everyone to use a sunscreen with an SPF of 15 or higher. Some suggest that light-skinned individuals start with SPF 30; it doubles the amount of sun exposure they can safely receive. The Federal Drug Administration will come out with new proposed regulations involving sunscreen later this year that will, among other things, encourage fair-skinned Americans to use products with SPFs higher than 15.