An Assessment of the Adequacy of Sunscreen Usage

Sunscreens are in widespread use as a form of skin protection against solar ultraviolet radiation. Previous studies provide some data to show that the amount of sunscreen applied is less than manufacturers' recommendations, although studies have often used indirect measurement techniques. This study comprised 50 volunteers who applied a standard aqueous cream as a hypoallergenic analogue for sunscreen to one of their forearms. Two novel methods of directly measuring forearm area were used, based on a mathematical model and the use of a helically wrapped cloth belt. Application amounts ranged from 0.05 mg.cm-2 to 8.38 mg.cm-2. The distribution was heavily skewed, with a modal value in the range 0.5-1.0 mg.cm-2. Of the volunteers 69% applied less than the generally accepted quantity of 2.0 mg.cm-2, with 61% applying less than 1.5 mg.cm-2, and 37% applying less than 1.0 mg.cm-2. The study confirms previous findings that most sunscreen application is not sufficient to achieve the stated sun protection factor. The use of higher factor sunscreens, a reassessment of the definition of sun protection factors and/or further public education campaigns are warranted. (author)