SUNBATHERS APPLICATION OF SUNSCREEN IS PROBABLY INADEQUATE TO OBTAIN THE SUN PROTECTION FACTOR ASSIGNED TO THE PREPARATION

The sun protection factor (SPF) is a ratio that estimates the protective efficacy of a sunscreen against sunburn. The generally accepted methods used to determine the SPF of a sunscreen require that the formulation be applied in a thickness of 1.5 mg/cm(2) (Deutsches Institut fur Normung) or 2 mg/cm(2) (US Food and Drug Administration). The applied thickness of a sunscreen is important for the degree of photoprotection. Forty-two volunteers on a beach applied their own sunscreen all over the body. The amount of the applied sunscreen was on average 0.5 mg/cm(2). This indicates that the labelled SPF is probably considerably higher than the obtained degree of protection against sunburn.