Subscribe to North America's Longest Established Scuba Diving Magazine

The Truth About Sunscreens and Coral Reefs

By Jean-Michel Cousteau

Photo: Carrie Vonderhaar – Ocean Futures Society

It’s often called ‘The Law of Unintended Consequences’. The simple explanation for this law is when we do something we believe is good or helpful but there is a counter, unexpected reaction that is not always so good.

That is exactly the case with human sunscreens and the increasingly degraded coral reefs in our oceans. No one can contest that sunscreens are a vital means of protecting our skin from sunburn and skin cancers. We are more aware than ever about the dangerous effects of UVA and UVB rays, and the bronzed bodies some wanted are increasingly a thing of the past.

For divers, fishermen, boaters and those who recreate on our oceans and lakes, this is particularly important because of the reflected and intense direct sunlight to which they are exposed.

When you buy sunscreen, look at the ingredients. The main components of most sunscreens are zinc oxide and titanium dioxide—ingredients that will never biodegrade and have the potential to harm corals and sea life. Some also contain mineral oil (petroleum) which has a low solubility rate in water, is slow to biodegrade and is known to be harmful or fatal to some aquatic life and birds.

You are probably asking yourself, “How can the thin layer of sunscreen I put on my body do significant damage to coral reefs and sea life?” In this case, dilution is not the solution. An estimated 4,000 to 6,000 metric tons of sunscreen washes off swimmers’ bodies annually with the potential to cause damage to fragile ecosystems.

My team and I use sunscreen and thus have wondered what are the options for people who want to minimize their impact on the ocean.  We have discovered that there are companies working to create sunscreen and skin care products that will have minimal impact on aquatic life.  One of these companies is Reef Safe, based in Ormand Beach, Florida, has stated that their products do give people all the SPF benefits of regular sunscreen but are non-toxic to marine and sea life and also will not kill or contaminate bait used by fishermen.  In discussions with Reef Safe my question was, “What about the effects of these products on corals?”  From those discussions Reef Safe is now conducting tests, overseen by an independent lab, to determine what impact, if any, these products have on coral health.

Today we are bombarded with claims from a growing array of companies that their products are safe. Terms like “biodegradable,” “natural” or “eco-friendly” are being used on more and more products but are these claims true?  Its difficult to know where truth ends and green wash begins.

In the case of products that will end up in the ocean these issues are critical. The 2011 World Resources Institute report on reefs at risk shows that reefs seriously threatened have doubled to 60 percent since they did that same study in 1998. They conclude that by 2030, 90 percent of reefs will be threatened. For divers and anyone who loves the ocean, these are staggering figures.

Photo: Carrie Vonderhaar – Ocean Futures Society

I would not suggest that sunscreen products are the primary reason our reefs are collapsing. We know that climate change, ocean acidification, overfishing and destructive fishing, coastal development and watershed-based pollution are the biggest culprits. But, like so many issues surrounding the degradation of ecosystems, everything is connected. Everything we put into or take out of our environment adds to a cumulative impact we are having on our planet.

As consumers of so many products, it’s up to us to make reasonable choices from the seafood we eat to the fertilizers we put in our gardens to the appropriate disposal of plastics, and even to the sunscreen we put on ourselves and our children. You have often heard me say, “Protect the ocean and you protect yourself.” When it comes to buying truly biodegradable sunscreens, it’s “Protect yourself and you can also protect the ocean.”

31 Comments Leave A Reply

31 Responses to “The Truth About Sunscreens and Coral Reefs”

  1. K Eden

    Thank you for this article. I am a dive master and have been passionate about informing every diver I can about the dangers of sunscreen to our precious reefs. Why slather up with sunscreen right before you go under water anyway I’ve always wondered. Often people think it is an exaggeration on old wives tale but in actuality they need to be more informed and aware and accept the reality of the delicacy of nature and our responsibility to think of it on it’s own terms and the capability we have to so easily destroy something we need to survive, thus harming ourselves. Every dive shop in the world should carry the message about people’s rampant sunscreen and it’s poison effect on the very life they go to visit in the seas.

  2. Robert

    What is the best brand to use? or can you make your own?

    • Milla

      Non Nano Zinc Oxide Subscreen is the safest not Oxybenzone. Its been studied and published and is the only one allowed in Mexico & Florida now. This article is outdated

      • Dave

        1. “Safe” is a loaded term. The study (yes, there was only one) linking oxybenzone and coral bleaching has several very serious flaws in its methodology. It has also not been replicated, and did not control for water temperature as a cause.
        2. There has been no rigorous independent assessment of zinc oxide’s impact on corals. Calling it safe is premature.
        3. Only Key West has outlawed the sale (not use) of sunscreens containing oxybenzone and octinoxate, not the state of Florida. Other sunscreens, including homosalate and octocrylene, are unaffected by this ban.

  3. Irene

    With all due respect to Jean-Michel Cousteau, it appears that he didn’t actually read the only scientific paper that has been published to date on the effects of sunscreens on coral. It is the seminal paper by Roberto Danovaro et al. that sparked this entire conversation in the first place. In the paper, the scientists list 4 sunscreen chemicals that caused coral bleaching. They are: butylparaben (a preservative), oxybenzone (a sunscreen), octinoxate (a sunscreen) and 4-methylbenzylidene camphor (a sunscreen). If your sunscreen has any of these ingredients you are possibly harming coral. There is no mention of zinc oxide or titanium dioxide in their research.

    According to the paper, most of the harm was done to the corals within 48 hours of exposure to the chemicals, so even if a sunscreen is biodegradable the chemicals will have done their damage well before the sunscreen biodegrades.

    • Heidi

      Thank you, Irene, for looking this up. I was about to throw my hands up and give it up. Just recently, there was also talk about not using sunscreen with oxybenzone, octinoxate, etc., because they actually chemically alter our skin cells to not absorb UVB/UVA. Some doctor (this was on Dr. Oz) cautioned us about using these products as they may affect our hormone system and this is further worrisome since you have to reapply those sunscreens more often than the products with zinc oxide and titanium oxide. And, they wanted us to use the products that contain zinc oxide or titanium dioxide because those compounds do not get absorbed into our bodies while doing just as good a job preventing UVA/UVB absorption.

    • Rob

      You have it exactly right. Oxybenzone and octinoxate are the harmful active ingredients found in most all commercial sunscreens. It is the sunscreens with zinc oxide or titanium dioxide that not only block the suns harmful rays, but do not kill the corals. Danovaro’s white paper proves this.

    • Ava

      Thank you for this important contribution! Yes, let’s remember that first and foremost, we want to discourage use of chemical sunscreens as harmful to ecosystems, while limit the use of physical sunscreens as a balancing act.


    • Jean

      Reef safe contains oxybenzone…

      We work with sunscreen for the last 20 years and my honest reply would be that NO one can reply to a biodegradable problem issue.

      Let me argument, a plastic bottle is biodegradable in 1 million years, aluminium 200, … are they ok to throw in the sea? No

      Buy sunscreens that are very water resistant that have a ribosome technology that encapsulates the ingredients. No zinc or titan…

      Sunscreens without Oxybenzone! Common! Don’t publish such a good article with this mistake… a few drops in a swimming pool Olympic size would make all the coral suffocate!

      Lobby your governments to rise the list of SPF chemicals accepted USA has 15 ingredients less on their list than European Union.. which leaves you with no choice of products.

      And don’t forget what’s not know yet to arm environment might become one day!

  4. Pissed off

    Hi I just came to say that your printing button is very very very broken. In fact it seems to me as if you are in league with the printer companies, as mine printing 10 whole pages of ocean, wasting half my cartridge before I could stop it. At the same time, it did not even print half the article. Fix. Your damn. Button.

    • Editor at Diver Magazine

      Well I’m sorry to hear you’re having problems. It seems to be working fine for me across three different browsers, so I would suggest you copy the text you wish to print, paste into a text or Word doc and print from there. That should fix the problem.
      Thanks for your email

    • dho

      Oh my – so Rude.

  5. Steph

    I’ve been reading about the SPF in certain essential oils, such as carrot seed oil & red raspberry seed oil. Do we know what effect these essential oils might have on oceans and marinelife? Thanks!

    • Jane

      No natural oils have any useful UV filtering properties. The best ever measured was one sample of raspberry seed oil which came out at around SPF 3. Most of the samples showed little or no UV filtering properties. If you rely on any of these products you are sett9ing yourself up for serious sunburn.

  6. Julie

    I am doing a project to test if sunscreen impacts toxicity levels in the ocean. Can anyone refer me to studies and papers to help me build my research paper?

  7. HoneyBadget

    Use a rash guard so you don’t need to use sunscreen. Really worth it.

  8. Dara

    this is totally confusing and makes it difficult as a consumer to do the right thing. I think the difference is the ingredients that are harmful to coral reefs and can cause bleaching (per the peer study report cited above) and ingredients that are harmful to fish and other species, for example zinc oxide (which may be fine for coral, but not other mammals. I would love to get clarification on this and understand if there is a sunscreen that is safe for both coral reefs + other forms of marine life.

  9. Snorkeling and SUP 4 life

    This is misinformation.

  10. Wil

    Right now, besides all the sun blocking gear, non-nano zinc oxide still seems to be the most reef safe sunscreen option (re: UV apparel it’s also good to check they’re treated with chemicals). Raw Elements USA is committed to making the safest most efficient broad spectrum sunscreen; engineered for extreme athletes (gentle for infants). Tested & used by surfers, divers, fishermen, paddlers around the world. 23{c383baab7bef8067e8c9786a45d8006c492489841a98fe37723e304bb1ddd030} non-nano recycled (not mined) zinc in an organic certified natural nonGMO base. Non-migrating, never stings. So water-resistant you can apply under water.

  11. Liz Smith

    I’d love to see an update on the findings of the Reef Safe sunscreen. And yes, I’ve also heard that Raw Elements is great!

  12. Marilyn

    Hi. Thank you for this article. I see that in the 4th paragraph it says that titanium dioxide, and zinc oxide never biodegrade, and have potential to harm coral and sea life. I had purposefully purchased “goddess garden” sunscreen (which has both of those ingredients 6.4 and 6.0 {c383baab7bef8067e8c9786a45d8006c492489841a98fe37723e304bb1ddd030} respectively) because it APPEARED to be eco safe with its “organics” labeling, and states on the bottle “Reef Safe.” How terribly upsetting if this is not the truth. And if this proves to be such false advertising, then I wish for the company to fix this immediately, and/or suffer the consequences with their business.

    • Chelsea

      Actually, Marilyn, the author of this article is wrong saying that titanium dioxide and zinc oxide are harmful ingredients. Its oxybenzone and others which are actually the harmful non-coral safe ingredients.

      • Jade

        Remember that reef safe and coral safe are two different things. Reef includes the coral and marine life. Coral safe, not so much. There are more considerations that just the coral.

  13. Aaron

    For reference to anyone viewing this site, the Reef Safe brand is decidedly NOT reef-safe. Their MSDS sheet specifically calls out that they use the chemicals mentioned above, OCTINOXATE and OXYBENZONE, that are known to be hazardous to reefs.

    • Milla

      Those are not high enough SPF’s. Those provide a 4 at best spf.

  14. Chelsea

    Diver Magazine: you need to delete this misinformed article. You’re purposefully steering sunscreen consumers towards non-reef safe sunscreens…

    • Milla

      Exactly. This article is incorrect. Zinc Oxide is the best: oxybenzone is the worst: proven scientifically We use Me and a Tree brand

  15. Zinc

    Such a well-written article about zinc. I had no idea this happened.


Leave a Comment

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.