Butyl Methoxydibenzoylmethane

Butyl methoxydibenzoylmethane is a synthetic sunscreen ingredient that provides sun protection in the UVA range. This type of radiation is present all day long, and penetrates deeply into skin, where it causes a cascade of damage that leads to many signs of ageing.

Better known as avobenzone, butyl methoxydibenzoylmethane is globally approved. In fact, it’s one of the most widely used UVA filters in the world and has been rigorously tested for safety and efficacy, with further safety studies ongoing.

In the United States, it may be used as an over-the-counter sunscreen active up to 3%. Its maximum permitted concentration extends to 5% within the European Union, where it’s been in use since 1978 (it was FDA-approved in 1996).

Many studies have shown that avobenzone becomes unstable when exposed to UV light, one reason reapplication during long periods of time outdoors is necessary. To increase its photostability, UV absorbers such as octocrylene and non-UV filters (e.g., diethylhexyl 2, 6-napththalate) often accompany avobenzone in a sunscreen formula.

Synthetic and natural antioxidants (such as vitamin E ubiquinone, glutathione, and diethylhexyl syringylidenemalonate) have can also improve avobenzone’s photostability, as can the proper choice of emollients, one example being caprylic/capric triglyceride. Other ingredients used to stabilize avobenzone and allow it to be used with other filters such as octinoxate include polyester-8 and ethylhexyl methoxycrylene.

Avobenzone is one of several sunscreen ingredients currently undergoing further safety testing under the purview of the United States Food and Drug Administration (FDA). This testing is to gain a better understanding of the systemic absorption, metabolism, and elimination of these sunscreen actives when small amounts enter the body via topical use. It’s important to know that the presence of this or other sunscreen actives in the body does not mean your health is at risk. It is anticipated that the additional testing being done will reaffirm the safety of these ingredients; however, those who remain concerned can choose sunscreens with mineral actives (titanium dioxide and zinc oxide) which are not included in the FDA’s new call for additional testing.

Note: this UV filter is also known as Parsol 1789, but avobenzone is the official name when used in sunscreens.