Chemical UVB sunscreen/sunblock: Benzophenone-3 (Oxybenzone), Benzophenone-4 (Sulisobenzone)

Generic name: Benzophenone-3 (Oxybenzone), Benzophenone-4 (Sulisobenzone)

Brand(s): Various

Type: Chemical

Range of UV spectrum covered: UVB, short UVA (UVA-2) but not long UVA

Wavelengths covered: 290-360 nm

Stability:
Highly stable, do not degrade in sunlight. Protect other UV blocking agents from UV-induced degradation.

Summary:
Benzophenone-3 (Oxybenzone) and Benzophenone-4 (Sulisobenzone) are chemical UV absorbers solid (powder) at normal temperature. Both cover UVB and short UVA (UVA-2) range but are relatively weak sunscreens, inadequate when used alone. They are both very stable and protect and augment other UV absorbers. Benzophenones are absorbed into the skin and have been shown in some studies to promote generation of potentially harmful free radicals. The health implications are unclear but some experts have raised concerns that warrant further research.

Details:
Benzophenones are weak chemical UV absorbers. Benzophenone-3 (Oxybenzone) and Benzophenone-4 (Sulisobenzone) are the benzophenones most commonly used is sunscreen products. They are chemicals solid (powder) at normal temperature. Oxybenzone is water insoluble. Sulisobenzone is water insoluble in its acid form, but can be dissolved in water if neutralized. Both cover UVB and short UVA (UVA-2) range but are relatively weak sunscreens, inadequate when used alone. They are both very stable and protect and augment other UV absorbers.

Benzophenones are relatively easily absorbed into the skin and have been shown in some studies to promote generation of potentially harmful free radicals. Implications of these finding for typical use are unknown but some experts have raised concerns that warrant further research. (See our article on possible risks of absorbable chemical sunscreens.)