Is Your Sunscreen Killing Coral Reefs?

In July 2018, Hawaii passed a law to ban the future sale of sunscreens containing benzophenone and octinoxate because it allegedly contributes to coral bleaching. 

So let’s look at how coral reefs work before we look at the data suggesting that sunscreen is damaging coral. Colorful corals have a symbiotic relationship with algae which is called “zooxanthellae”. This relationship is symbiotic which means that there are mutual benefits to both parties: the coral and the algae. The algae helps out coral by capturing sunlight and converts it into energy to feed the coral. This process is what gives coral its beautiful colorful hues. Algae provides around ninety percent of the energy that coral needs. Meanwhile, the coral gives algae a safe place to live within the coral tissue. Stress such as rising temperatures and  acidity are contributors to coral bleaching. Some people believe that sunscreen also puts stress on coral and thus contributes to bleaching.  

Consumers are very concerned with world-wise searches for “reef-safe sunscreen” having quadrupled over the last five years. While well-intentioned, this is dangerous for both consumers and the reef because (a) consumers may feel scared of sunscreen thus suffer with skin cancers and (b) the impact of climate change on the reef has been underestimated. 

Rising temperatures has especially put a lot of stress on this symbiotic relationship resulting in coral bleaching. Coral bleaching occurs when corals expel their symbiotic algae which leaves behind a white coral skeleton. The footprint of bleaching in the Great Barrier Reef is 1998, 2002, 2016 and 2017 matches with  the heat in the reefs, not the amount of tourists/sunscreen in those areas. Coral bleaching has even occurred in some of the most isolated, but the hottest parts of the Great Barrier Reef.

Director of the ARC Centre of Excellence for Coral Reef Studies, Professor Terry said that “people make a long list of bad things that human beings do to coral reefs — I would place sunscreen at number 200.Climate change and agriculture are far more harmful for coral reefs. If you look at any coral bleaching textbooks - these are what is mentioned, not coral reefs. Anyone with internet access and a little basic knowledge can tell people to stop wearing sunscreen so you can save the planet!

The research that has been done has been very limited in scope. The evidence out there is done in simulated laboratory conditions. A review of research performed by the Coral Reef Institute concluded that “there is a lack of firm evidence of widespread negative impacts at reef community and/or ecosystem level”. Similarly, Many of the studies done on coral reefs are performed on small environments, like a popular small coral reef, where many tourists swim.

If you are concerned about sunscreen then cover up. I minimise my use of sunscreen when swimming is by wearing a wetsuit or swimming leggings and a long sleeve top at the beach. As a result, I only have to put sunscreen on my hands, feet and face.

If you want to do something to truly help save not only coral reefs but the ocean in general, sunscreens should not be high on your radar - reduce your ecological footprint. Carpool or ride a bike next time you go to the beach! That will reduce carbon emissions and allow you to keep the beach beautiful! 

Thank you so much for reading this blog post. Coral bleaching is one of the main issues that people have with sunscreen. I’m very passionate about sunscreen use and a big motivation of my blog is to educate people on sunscreen use so I thought I should cover this issue. To be honest, all the research to date is generally inconclusive so let’s watch this space and see how the research progresses and the formulation of sunscreen changes.

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