Protection from the damaging ultraviolet rays of sunlight.

Scientists have found a strong link between exposure to direct and reflected sunlight and a number of health risks. Ultraviolet (UV) radiation, a component of sunlight, causes damage to the skin and increases the risk of skin cancer. UV radiation comes in two forms—ultraviolet A (UVA) and ultraviolet R (UVB). UVB is the radiation sunscreens are designed to screen out. The United States Food and Drug Administration has not approved a rating system for UVA protection because experts have not reached a consensus as to what constitutes a good test. Manufacturers can claim protection against "broad spectrum" radiation if their product contains one of the following ingredients: benzophenone, oxybenzone, sulisobenzone, titanium dioxide, zinc oxide, and butyl ethoxydibenzolmethane (also called avobenzone and known by the trade name Parsol 1789).

One of the factors that increases the risk of skin...