Avobenzone

Avobenzone is an organic ultraviolet A (UVA) filter used in many sunscreen formulations. It is chemically known as 4-tert-butyl-4'-methoxydibenzoylmethane and is sold under trade names such as Parsol 1789. Avobenzone absorbs UVA radiation, spanning roughly 320 to 400 nanometers, and contributes to protection against photoaging and some skin cancers when combined with UVB filters.

Avobenzone is inherently photounstable; exposure to sunlight can cause it to degrade, reducing UVA protection. To address this, formulators stabilize avobenzone by using stabilizers or other filters. Common approaches include incorporating UVB absorbers such as octocrylene or employing stabilization technologies (for example, Helioplex) that enhance UVA protection by stabilizing the molecule when exposed to UV light.

Avobenzone is approved for use in many countries and is commonly found in combination with other UV filters to provide broad-spectrum protection. In the United States, it is typically used at concentrations up to 3%. It is widely included in creams, lotions, and cosmetics intended for sun protection.

Avobenzone has generally been regarded as safe for topical use when used as directed. Some individuals may experience skin irritation or allergic reactions, though such cases are rare. Data on environmental impact are limited; as with other sunscreen agents, care should be taken to minimize environmental release.