A losing battle against sun damage?

April 1, 2005

Current concepts on sunscreen use still support recommendations for choosing a broad-spectrum sunscreen that has an SPF of 15 and contains titanium dioxide, zinc oxide, avobenzone or oxybenzone for UVA protection.

Results of recent studies indicate that sunburns and tanning bed usage continue to be common among adolescents, teens and adults, and that persons who do use sunscreen often apply it inadequately, notes Dr. DeLeo, chairman, department of dermatology, St. Luke's/ Roosevelt and Beth Israel Medical Centers, New York.

"We need to continue with our efforts to encourage sun-sensible behavior, including appropriate sunscreen use," he tells Dermatology Times. "The importance of that message is supported by results from many animal studies demonstrating the efficacy of sunscreens for preventing photoaging, ample evidence that broad- spectrum sunscreens prevent squamous cell carcinoma and a preponderance of data strongly suggesting that sunscreen usage is helpful for preventing basal cell carcinoma and malignant melanoma."

Sixteen percent of 15-year-old girls had visited a tanning parlor, and the proportion of tanning bed users rose to 35 percent among females aged 17 years.

Economic impact Another recent report highlights that acute sunburn carries a significanteconomic impact. Based on survey findings from a convenience sample of 56 beachgoers in Galveston, Texas, Warthan and colleagues calculated the cost from sunburn-related missed days of work and treatment may exceed $10 million a year in the Galveston area alone, Dr. DeLeo says.

Sunscreen recommendations Current concepts on sunscreen use still support recommendations for choosing a broad-spectrum sunscreen that has an SPF of 15 and contains titanium dioxide, zinc oxide, avobenzone or oxybenzone for UVA protection. However, accompanying that advice must be clear instructions about adequate application.

"The SPF value is determined in studies using 2 mg of product per square centimeter body surface area. On that basis, adults should use two tablespoons of sunscreen to cover their entire skin surface, and a family of four at the beach should use an entire 8-ounce bottle in two days. However, studies show most people use only 25 to 75 percent of the quantity used for SPF testing," Dr. DeLeo notes.

Dermatologists who are concerned that an individual is not using enough sunscreen might suggest use of a higher SPF product (ie., 30) as a means of compensation. In addition, they might recommend that persons with photosensitivity disorders for which the action spectrum is in the long-wave UVA range obtain a sunscreen containing mexoryl (L'Oreal) from outside the United States.

"Mexoryl provides significantly better UVA protection than any of the organic and inorganic sunscreens available in this country, and that extra protection can be valuable for certain patients," Dr. DeLeo says.

Addressing vitamin D issue A potential detrimental effect of photoprotection on normal vitamin D metabolism has been another area of recent controversy and was one of the subjects discussed at a consensus conference in August, 2004, that was jointly sponsored by the U.S. Food and Drug Administration and the American Academy of Dermatology (AAD). Dr. DeLeo participated in that meeting and notes that there is continuing debate over several questions, including measurement of serum vitamin D metabolites and the prevalence of vitamin D deficiency.

However, it was suggested that the current RDA for vitamin D intake is too low and should be about 1000 IU rather than 400 IU. While relatively minimal sun exposure is an effective means for achieving adequate vitamin D levels by stimulating endogenous synthesis from precursors in the skin, it is not necessary for people to go out into the sun to maintain normal vitamin D.