June 13, 2005
Avoid these 8 mistakes with sunscreen
By Laurel Naversen Geraghty
New York Times
Once limited to sticks, oils, and chalky creams, sunscreens now come in lotions, gels, sprays, wipes, mousses and powders. A sun protection factor, or SPF, is also found in foundations, moisturizers, bug sprays, laundry detergent and even a product that protects against jellyfish stings.
Still skin cancer continues to rise, according to the American Academy of Dermatology. Among Caucasians, the rate of melanoma, the deadliest form of skin cancer, more than tripled between 1980 and 2003.
Here are eight common sunscreen mistakes:
• Not knowing what SPF means: SPF is a multiplier that describes how much time a sunscreen allows a person to spend in the sun before getting burned by UVB rays. A product with an SPF of 15, the minimum doctors advise, lets you stay in the sun 15 times longer. The SPF says nothing about how well a sunscreen protects against UVA light.
• Not knowing what ingredients to look for: Among U.S. approved sunscreen ingredients, many protect against UVB light: benzones (like dioxybenzone and oxybenzone), for example, and the cinnamates (like octyl methoxycinnamate). But only one, avobenzone (Parsol 1789), specifically absorbs UVA light. The sunblocks zinc oxide and titanium dioxide reflect UVA and UVB light. But products that combine avobenzone with zinc oxide, titanium dioxide or one of the ingredients that absorb UVB light are better.
• Skimping: To get the SPF advertised on a bottle takes a full teaspoon slathered on the face and enough to fill a shot glass rubbed over the body. Yet people typically apply only 20 percent to 60 percent of that, a 2002 study found. The ears, the neck, the hands, the feet and even bald patches on the head are commonly missed sites.
• Applying it too late: Most sunscreens take 15 to 20 minutes to start working because they have to be absorbed by the skin first. ''If you put that sunscreen on when you're already at the beach, you're not getting that protection,'' said Dr. Darrell S. Rigel, a dermatologist at New York University.
• Not reapplying: There's no such thing as all-day protection because the active ingredients in sunscreens degrade in the sun after about two hours. (That is why you sometimes hear that an SPF of 45 is no more useful than an SPF of 30; both need to be reapplied after two hours.)
• Not wearing it daily: Many people wear sunscreen only at the beach. But subtle everyday exposure to UV light can add up to wrinkling or cancer.
• Continuing to use old products: ''Most sunscreens have a shelf life of three years,'' said Dr. Susan Weinkle, an assistant clinical professor of dermatology at the University of South Florida. (If you have kept one around that long, however, you are probably not using enough.) Products lose their potency even faster if bottles are left out in the sun or stashed in a hot car, where light and heat can degrade them.
• Not taking medications into account: Antibiotics like tetracycline can make the skin more photosensitive, leaving it more vulnerable to UV damage. So, too, can thiazide diuretics, drugs included in some blood pressure medicines, said Dr. Clay J. Cockerell, the president of the American Academy of Dermatology.
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