Sun Care Science Part One

All it takes is one trip to the sunscreen aisle of the local drug store to realize not all sunscreens are created equal. But, with so many labels making similar claims, how does one judge? The best way is to know a little something about the chemistry behind this class of products.

Seventeen (17) active ingredients are currently FDA-approved for sunscreen use in the U.S. They fall into two categories: chemical absorbers (a.k.a. organic chemical ingredients) and physical blockers (a.k.a. inorganic physical ingredients). Chemical absorbers work by absorbing UV radiation before it can penetrate the skin; physical blockers work by scattering and reflecting UV radiation.

Each ingredient has demonstrated some level of effectiveness, but all are subject to some degree of limitation. No single ingredient provides every benefit possible. Some protect against a larger range of the light spectrum than others. Some have been associated with skin irritation. Some feel more comfortable. Some chemical absorbers become unstable and lose their protective capability after a certain time in the sun; others can penetrate the epidermis and generate free-radicals, leading to cell damage. The sunscreens we see on store shelves are actually formulations that, with varying degrees of success, combine actives with a variety of inactives in an attempt to increase efficacy and achieve cosmetic desirability


Sunscreen active Ingredients:
Aminobenzoic acid (PABA) up to 15 percent
Avobenzone up to 3 percent
Cinoxate up to 3 percent
Dioxbenzone up to 3 percent
Ecamsule up to 10 percent
Homosalate up to 15 percent
Menthyl anthranilate up to 5 percent
Octocrylene up to 10 percent
Octyl methoxycinnamate up to 7.5 percent
Octyl salicylate up to 5 percent
Oxybenzone up to 6 percent
Padimate O up to 8 percent
Phenylbenzimidazole sulfonic acid up to percent
Sulisobenzone up to 10 percent
Titanium dioxide up to 25 percent
Trolamine salicylate up to 12 percent
Zinc oxide up to 25 percent