UV Sunscreens are over-the-counter pharmaceutical products specifically designed for sun protection. They are regulated by the Food and Drug Administration (FDA), but no prescription is needed.
There are currently seventeen active sunscreen ingredients approved by the FDA for use in sunscreens in the United States. Ecamsule, marketed under the name Mexoryl, was the most recent addition to the list. It was approved by the FDA in July, 2006.
Active ingredients fall into two broad categories. Most are chemical absorbers for either UVB or UVA. A few are reflectors, sometimes also called "blockers".
Absorbers create a chemical reaction within the skin that allows the sunscreen to absorb the UV before it penetrates the skin. For example, octyl methoxycinnamate (OMC), homosalate, and octocrylene absorb UVB, while oxybenzone, avobenzone and ecamsule absorb UVA. Reflectors are physical barriers to the UV rays and block or reflect them away from the skin. Zinc oxide and titanium dioxide are examples of reflectors. In the past, zinc oxide looked like a thick white paint often seen on the nose of people at the beach. Today, advances in technology have led to micronized zinc oxide with much smaller particles that mean it is much closer to being invisible on the skin.
Many sunscreens contain a mixture of absorbers and reflectors. The choice of sunscreen ingredients is the primary determinant of the SPF rating of a sunscreen. While a SPF number only rates the level of protection against UVB rays, scientists now agree that UVA also does significant damage to the skin. (One way to remember the difference is UVB is for burning while UVA is for aging). So one sunscreen may have a very high SPF number and will therefore give great protection against UVB but it may provide no protection against UVA. Coolibar recommends selecting sunscreens with a SPF 30 rating that also provide excellent UVA protection (by including 6% or more zinc oxide and/or titanium dioxide, or 3% or more avobenzone/Parsol 1789, or ecamsule/Mexoryl).