Reef-Safe Sunscreen, Explained: What Hawaii's Act 104 Bans, What the National Academies Said About the Coral Data, and Why the Label Is Not a Standard

What Hawaii's Act 104 actually bans

Act 104 of 2018 (Senate Bill 2571) made it unlawful, beginning 1 January 2021, to sell, offer for sale or distribute for sale in Hawaii any sunscreen that contains oxybenzone or octinoxate, or both, unless the buyer has a prescription from a licensed healthcare provider. The law is ingredient-specific. It names two chemicals and says nothing about a general standard that other products must meet to call themselves reef friendly. A sunscreen can therefore be legal in Hawaii because it contains neither ingredient and still have never been tested on a single marine organism. On an ingredient list, look for Benzophenone-3 (oxybenzone) and Ethylhexyl Methoxycinnamate (octinoxate).

What the National Academies concluded in 2022

In August 2022 the US National Academies of Sciences, Engineering, and Medicine published a review of sunscreens in aquatic environments. NOAA summarizes its conclusion this way: specific UV filters found in chemical sunscreens can harm aquatic life, including corals, and a more comprehensive ecological risk assessment of all UV filters in chemical sunscreen is needed. The report describes uneven data: oxybenzone has received the most attention, while some other filters have almost no data beyond their physical and chemical properties. It also notes that there is enough information to build acute species sensitivity distributions for oxybenzone, octinoxate, titanium dioxide and zinc oxide, but significant gaps remain for marine species, long-term studies and sediment.

Why the coral evidence is called limited

A 2021 critical review in Environmental Toxicology and Chemistry, by Mitchelmore and colleagues, examined 14 organic UV filters, with oxybenzone and octinoxate studied most because of the bans in Hawaii, the US Virgin Islands and Palau. It reported that seawater concentrations near reefs were mostly in the nanogram-per-liter range, with medians roughly between 1 and 100 ng/L, while laboratory toxicity responses appeared in the microgram-per-liter to milligram-per-liter range. The authors found only 12 monitoring studies of seawater, only 2 that measured UV filters in coral tissue, and 9 toxicity papers with significant methodological issues. They also noted that no standardized guidelines exist for coral toxicity testing. Their conclusion was that limited and variable monitoring data, plus limited toxicity information with methodological problems, have led to limited and unreliable risk assessment.

That does not show the ingredients are harmless to reefs, and it does not show they are harmful at real-world levels. It shows that a firm number on "how much damage" is not yet available, which is exactly why a label that sounds certain deserves a second look.

What the FDA has and has not said about the same two ingredients

The US Food and Drug Administration approaches the topic from the human-use side. In a notice of intent published in the Federal Register, it said it would prepare an Environmental Impact Statement because of questions about the extent to which oxybenzone and octinoxate may affect coral or coral reefs. Its 2021 proposed order (OTC000008) listed both among ingredients with insufficient data to be classed as generally recognized as safe and effective for sunscreens. The agency states that this proposal does not represent a conclusion that those ingredients are unsafe. Zinc oxide and titanium dioxide are proposed as eligible at up to 25%. The two questions, human safety data and reef effects, run on separate tracks, and a gap in one is not an answer to the other.

Mineral does not automatically mean "reef safe"

NOAA suggests choosing a sunscreen without chemicals that can harm marine life, and describes mineral sunscreen as a better option because there are fewer effects on aquatic organisms. The same NOAA page, however, lists nano-sized titanium dioxide and nano-sized zinc oxide among the substances that can harm marine organisms. So the useful question is not just "mineral or chemical" but which specific filters and what particle form. Our zinc oxide versus organic UV filters explainer covers what a mineral-only formula gives up in texture and UVA coverage, and our bemotrizinol article covers a newer filter the FDA recently added.

Reading a label without trusting the slogan

A practical checklist follows from the sources above, not from any ranking. First, check the active ingredient panel for oxybenzone and octinoxate if you will be in Hawaii or another jurisdiction with a ban. Second, treat phrases such as reef friendly or ocean safe as marketing language unless the brand shows what it tested and on which species. Third, if you choose a mineral formula, check whether the label says non-nano, since the NOAA page flags the nano forms. As with other front-of-pack claims, the logic is the same one we walk through in our label claims guide: a phrase on the front tells you less than the panel on the back.

Protection still matters more than the claim

NOAA also lists shade between 10 am and 2 pm and UV-protective clothing as ways to cut the amount of product needed. Whatever you pick, the amount applied is what the SPF number depends on, as shown in our 2 mg/cm² sunscreen dose guide. Swapping to a different filter while applying a quarter of the tested dose does not improve protection.

Before you switch products

Any new sunscreen can irritate, including mineral ones with added fragrance or botanical extracts. Test a small area first, following our patch testing guide, and stop using it if a reaction appears.

This article summarizes published research and regulatory documents and is not medical advice. Patch test any new product first, and see a dermatologist if you have a rash, a history of sunscreen reactions or any concern about skin cancer risk.