Fair-skinned people are at greatest risk, especially those who sunburn easily and have red or blond hair. People who live in sunny climates accumulate more exposure over time, so are at greater risk. But even dark-skinned people develop cancer, so while these clients don't have to worry as much about sun protection, some vigilance regarding changes in moles and other signs of cancer is required.

The sun's ultraviolet rays are the source of skin damage. Until recently, scientists and consumers were only concerned about UV-B rays, since they are the ones that cause sunburn and skin cancer. UV-A rays cause tanning, and were once thought to be harmless. But UV-A rays actually penetrate the skin more deeply and can damage the skin's connective tissue, causing sagging and wrinkling of the skin. UV-A rays also seem to increase the cancer-causing effects of UV-B rays.

Safer sun exposure

Protecting skin from the sun's damaging rays will help prevent both premature aging and cancers of the skin. Skin protection is the way to go outdoors. The most effective skin protection is some form of sun block. Tightly woven clothing (hold it up to light to see how much the sun shines through) helps keep the sun's rays from reaching the skin, and wide-brimmed hats provide some protection. Zinc oxide blocks the sun, and is good for noses and lips when long-term exposure is required.

When a sun block is not practical, a sunscreen should be used. Sunscreen does not shield the skin completely, but it does reduce the damaging effects of ultraviolet rays. Evidence suggests that the skin can repair some damage when sunscreens are consistently applied. But other researchers warn that sunscreens can provide a false sense of security. Since they prevent burning, they may lull us into thinking the sun is not hurting us, while damage may still be occurring.

A sunscreen's degree of protection is indicated by a numerical rating of sun protection factor (SPF). The SPF is the time a person can stay in the sun without burning when protection is used, divided by the time a person can stay in the sun when protection is not used. For example, if your skin burns after 10 minutes in the sun without protection, but after 100 minutes with protection, the SPF of your sunscreen is 10. In other words, the sunscreen allows you to stay in the sun 10 times longer before burning.

A sunscreen with SPF-15 is generally recommended, although people with fair skin may need something stronger. Sunscreens and blocks should be applied 30 minutes before exposure and used conscientiously whenever outdoors, even on cloudy days, since some radiation penetrates cloud cover. It is especially important to use sunscreen on your face, ears and shoulders, which are the most commonly burned areas.

Barriers to skin protection

Chemists have yet to invent a sunscreen that is fun to wear. Many exercisers can't take the grease, especially, as an avid bicyclist put it, "as it mingles with sweat and dead bugs." Advice for heavy sweaters is to exercise in the early or late part of the day, take as shady a route as possible, wear a hat and protective clothing, and use as much sunscreen as you can tolerate.

Swimmers should note that "waterproof" sunscreen stays on for only about 30 minutes in the water, and should be reapplied after that time.

Dry skin care

Although not life-threatening, dry skin can be very uncomfortable. Frequent showers and water exposure can strip the skin of its natural protective oils. The only solution is frequent moisturizing. Use of a good moisturizing cream immediately after drying off will counteract the drying effect of a "wash and wear" lifestyle.

By Barbara A. Brehm

REFERENCES

Munnings, F. Sun safety: Shedding light on the risks of exposure. The Physician and Sports-medicine. 19: 100-107, 1991.

Sunscreen can't give blanket protection. Science News, Jan. 22, 1994, pp. 54-55.