Octocrylene

What it does

Chemical UVB filter and stabiliser for avobenzone.

Benefits

Absorbs UVB and short-UVA. Most often used to stabilise avobenzone, which would otherwise degrade quickly. Good water resistance.

Concerns & Risks

Has been studied for benzophenone formation as it ages — older bottles may contain trace impurities. Some individuals report irritation. Reef-safety concerns are debated.