The truth about sunscreen

Will sunscreens protect me?
They can help, the FDA says. Some brands say "waterproof" on their front label even though their back labels say, "Rinse with water to remove." So don't count on "sunblock" to block the sun, and don't count on "waterproof" products to stay on in the water. Be sure to reapply often.

What SPF should I use?
You need an SPF (sun protection factor) of at least 15. Use an SPF of at least 30 if you're at the beach, pool or tennis court. It takes two shot glasses of lotion to cover the average bather, and most people put on only about half that amount. So the higher SPF can help.

Is SPF the only factor I should consider?
No. An SPF rating measures a sunscreen's protection against UVB (ultraviolet B) rays but not against UVA (ultraviolet A) rays, which can also cause wrinkles and skin cancer. For UVA ray protection, check the sunscreen label for the ingredient avobenzone or mexoryl.

When should I apply sunscreen?
Apply 30 minutes before getting into the sun so your skin can soak up your sunscreen, and reapply every 90 minutes -- more often if you go in the water, sweat a lot or towel off.

Can I put sunscreen on my baby?
Sunscreen is OK after about 6 months of age. Still, keep babies out of the sun as much as possible, and re-apply often. If you must take an infant younger than 6 months to the beach, keep him or her in a stroller and use a "baby sun protective cover" with a UPF (ultraviolet protection factor) rating.

Is it safe to go to the beach?
Wear sunscreen when you go in the water. When you get out, get under an umbrella.

Can dark-skinned people get sunburns?
Dark-skinned people are less susceptible because the melanin that gives their skin its color absorbs UV radiation, Keri says, "but they can still burn."

What about tanning lotions that bronze the skin?
They're OK, Keri says, as long as the active ingredient is dihydroxyacetone (or DHA), which reacts with dead cells on your skin to turn you tan. Some tanning creams include protective ingredients with SPFs of 15 or higher.

Can I get a safe tan at a tanning salon?
The Skin Cancer Foundation warns against them altogether.

I hear the human body needs Vitamin D and gets it from unprotected exposure to the sun. Will I get enough if I take so many protective measures?
This is a matter of debate in the medical community. Some doctors, including rheumatologist James Dowd, author of the "The Vitamin D Cure," advise at least some unprotected exposure to the sun. The known benefits of Vitamin D -- which can be blocked by SPFs rated 8 or higher -- include helping calcium build strong bones, and researchers have looked in the vitamin's role in staving off colon cancer, multiple sclerosis, diabetes and heart disease.

Many dermatologists, say the risks of damage from unprotected exposure outweigh the potential benefits, and that Vitamin D can be obtained in foods and supplements. Good sources include salmon, mackerel, sardines, fortified milk or cereals such as Kashi or Total.