The Food and Drug Administration on Tuesday expanded its list of allowed sunscreen ingredients to include the chemical compound bemotrizinol.

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The change has been eagerly anticipated for years: Bemotrizinol has long been popular in Europe, Australia and some Asian countries.

It also marks the first time in more than 20 years the FDA has permitted a new compound onto its sunscreen ingredient list.

Why the excitement?

Bemotrizinol is a UV light filter, meaning it blocks out harmful ultraviolet rays from the sun.

To be most effective, these filters need to be broad-spectrum, meaning they block UVA and UVB rays. UVA rays cause aging and wrinkles, while UVB rays cause sunburn, according to the American Academy of Dermatology. Both contribute to skin cancer, according to the Skin Cancer Foundation.

UV filters come in two formats: mineral or chemical. The mineral sunscreens — which contain zinc oxide or titanium dioxide — block both UVA and UVB rays but often leave a white cast on the skin.

Currently, the chemical filters available in the United States protect against either UVA or UVB. None are broad-spectrum on their own, and products often contain a mix to block both types of rays. Chemical sunscreens also break down in the sun and need to be regularly reapplied.

Bemotrizinol is broad-spectrum and far more stable, so it doesn’t break down in the sun. It also has low levels of absorption into the body, according to the FDA. There has been concern that other sunscreens may seep into the bloodstream, though it remains unclear whether this is harmful.

The Environmental Working Group, an activist group that advocates for stricter sunscreen regulations, praised the FDA’s move and said that bemotrizinol offers better protection against UVA in particular.

“This is a great day for American consumers and everyone who has fought to improve sunscreen options and close the UVA protection gap in U.S. sunscreens,” David Andrews, the organization’s chief science officer, said in a statement.

Sunscreens with bemotrizinol are expected to be available by the end of the year, according to the ingredient manufacturer DSM-Firmenich.