Researchers caution against improper use of sunscreen
California researchers report that sunscreens are beneficial, but the lotion itself can actually generate compounds that damage the skin if they are not reapplied often enough to maintain a constant protective sun shield. When skin is exposed to sunlight, ultraviolet radiation is absorbed naturally by skin molecules that then can generate harmful compounds called reactive oxygen species or ROS molecules, according to lead researcher Kerry M. Hanson, a senior research scientist in the department of chemistry at the University of California at Riverside. "These are highly destructive molecules of oxygen that react with everything from lipids to cell walls to cause a lot of damage to a cell," Hanson said. Sunscreen blocks ultraviolet radiation from penetrating the surface of the skin, inhibiting sunburn. But the sunscreen compound seeps into the skin as it wears off and itself generates ROS molecules. The problem, Hanson said, is that people often apply sunscreen once and don’t re-apply. "What our data show is that … if you have too little sunscreen at your skin’s surfaces, they are going to generate free radicals both naturally and by the sunscreen itself," she said. Hanson said that studies have shown that this type of skin damage can contribute to many problems, including premature skin aging and, in extreme cases, skin cancer. She said more advanced sunscreen formulations are needed and are being studied by the industry. THE STUDY In the study, in the current journal of Free Radical Biology & Medicine, researchers used epidermal model tissue and applied sunscreen to the surface to test the effect of sunscreen penetration on the free radical levels in the deep epidermis. Researchers used their own sunscreen formulas using three ultraviolet filters, octylmethoxycinnamate, benzophenone-3 and octocrylene, all approved by the Food and Drug Administration and widely used in most sunscreens. They then compared images taken before and after skin was exposed to ultraviolet radiation and found that the more the sunscreen compounds wore off and penetrated the skin, the higher the level of free radicals. In a statement, Schering-Plough Corp. , the makers of Coppertone, said: "Dr. Hanson’s work shows that when sunscreens stay on skin’s outer surfaces, they prevent ROS formation by absorbing UV before it can reach the molecules inside the skin that cause ROS formation. Coppertone sunscreens are advanced formulations designed to stay on the skin’s surface and not to penetrate into the skin and therefore do not cause ROS formation." Article source: http://www.clarionledger.com/
