Dr. Bruce N. Ames Addresses Sun Exposure
Most skin cancers you just cut off, and it isn't much of a problem. But UV (ultraviolet) light from the sun—particularly burns during the first 10 or 15 years of your life—damages DNA and causes skin cancer.
It's bad if you're fair-skinned and have too many burns; then your risk of getting skin cancer or melanoma is much higher. Melanoma is a really nasty cancer that spreads easily. That's the dangerous one and the incidence is going up. The highest rates in the world are in places like Australia.
There's no sunshine in England to speak of, and all these fair-skinned people went off to Australia and burnt themselves to a crisp. It has the highest melanoma rate in the world. Now Australia has a big campaign: "Wear hats. Wear clothes. If you're fair-skinned, wear sun block and don't get so much sunshine." Obviously there's a genetic component: Dark skin protects you. Dark skin in the tropics protects you from UV-induced cancer.
On the other hand, the Swedes are as white as they can be because they're not getting enough UV. You need UV to make vitamin D in your skin. If you don't get your vitamin D, you're really in trouble for osteoporosis, cancer, and other things. And the Swedes aren't getting enough sunshine. They need to get as much sunshine as they can in these Northern climates.
In fact, most Americans are probably getting too little UV, particularly in the North. It's the people up in Minnesota, North Dakota, the northern tier of the United States, and Canada, who are really in trouble if they don't get enough ultraviolet light or take a vitamin pill to get their vitamin D.
If you're going out to fry yourself on the beach, you should put a sun block on because you don't want to get burned. But you need a little sunshine, even though sunshine is a carcinogen. You can't put an umbrella up every time you go outside. You will get a vitamin D deficiency . . . and you might poke somebody's eyes out or not see a car coming. Life is full of these trade-offs.