Exactly What Protection Do Sunscreen Products Provide?

Press of Atlantic City, Richard Harkness
Published July 29, 2007

Question: Will a high SPF sunscreen protect me against both sunburn and premature skin aging and wrinkling caused by the sun? Answer: Some background will help answer your question. The sun emits UVB and UVA radiation. UVB rays primarily affect the skin surface and are the main cause of sunburn. UVA rays cause premature skin aging and wrinkling. (Both types are thought to be linked to skin cancer.) The SPF (Sun Protection Factor) number you see on product labels refers to UVB protection only. The higher the SPF number, the longer you can stay in the sun without burning. For example, if your skin usually gets red after 20 minutes of sun exposure, an SPF 10 product allows you to stay in the sun for 200 minutes (10 times longer) before redness develops. To answer your question, then, a high SPF product will protect you against sunburn, but not necessarily against premature skin aging and wrinkling. The latter depends on the product’s UVA coverage. The big issue is that UVA coverage varies widely among sunscreen products. One reason is that manufacturers are allowed to claim UVA protection for products that cover only half of the UVA range. Many products fall short of even that. A 2004 analysis found that only 56 percent of UVB/UVA products blocked more than one-fourth of the UVA range. A product with an SPF of 15 or higher gives most people adequate protection against sunburn-causing UVB radiation. But which products are best at also warding off skin-aging UVA? Look for formulations containing titanium dioxide or zinc oxide. In the past, these products left an unsightly coating on the skin, but the use of modern nanotechnology has created particles fine enough to be more transparent. Avobenzone, oxybenzone, and dioxybenzone also work against UVA rays, but they are broken down rapidly in the sun. It is UVA rays that awaken the dormant virus responsible for cold sores or fever blisters. That’s why you can slather on all the high SPF UVB-blocking lip balm you want and still suffer these outbreaks. UVA also causes photosensitivity reactions in people taking certain drugs. Don’t defeat the purpose of a sunscreen by using it improperly. Follow these tips from the Skin Cancer Foundation (www.skincancer.org/): n Apply at least 1 ounce (about a shot glass full). n Apply 30 minutes before sun exposure. n Reapply the same amount every two hours. n Reapply immediately after swimming, toweling off, or sweating a lot. To help prevent cataracts and other eye damage, use sunglasses that block both UVB and UVA rays. For lots of other good information on sunscreens, including lists of products and ingredients, visit the Web site of the Environmental Working Group. (http://www.cosmetics database.com/special/ sunscreens/summary.php) Because UVB revs up the skin’s production of vitamin D (the “sunshine vitamin”), some clinicians recommend regular, brief periods of unprotected sun exposure. Others recommend avoiding the sun and meeting your needs through vitamin D-fortified foods and vitamin supplements.