How well are sunscreen users protected

摘要: Previous studies have shown that people often apply less sunscreen than the recommended amount of 2 mg/cm . Our purpose in this study was to determine objectively how photoprotection varies with application thickness. The protection provided by differing quantities sunscreens containing varying amounts titanium dioxide measured vitro using excised human epidermis as substrate. It found thickness had a significant effect on sun factor (SPF), most users probably achieving mean SPF between 20-50% expected from product label. Underprotection due inadequate application, coupled overexposure sun, might partially explain why use has been reported be risk melanoma.