Sun, Sunscreen and Coral Reefs

I just spent a week on the beach near Cancun, Mexico which reminded me of an issue with sunscreen and coral reefs. Coral reefs are a very delicate ecosystem that has been suffering in recent years. Ocean acidification, climate change, sedimentation/pollution and destructive fishing are partly to blame for the increasing collapse of coral reefs but it is also thought that sunscreens that wash off swimmers bodies’ are also to blame.


Benzophenones and coral

Sunscreens can contain benzophenones, a common UV blocker. A recent study looked at Benzophenone-2 and found that this substance can harm coral reefs in 3 ways:

kill very young coral
can bleach adult coral and
can cause mutations in the DNA of coral

While benzophenone-2 is not allowed in sunscreens in the US, other, related benzophenones are used. Benzophenones are also found in colored cosmetics and fragrances where they are used to prevent breakdown of the product by UV light. Interestingly, they can also be found in inks to prevent their degradation. So if you are having a UV coating on your printed material you might ask if the ink contains benzophenones.

It appears that how sunscreens bleach the reef is indirectly by activating a virus that disrupts the micro algae that help support the reef biome.

Even natural sunscreen ingredients like zinc oxide and titanium dioxide are not recommended. These mineral particles do not biodegrade. The particles block sunlight and can be ingested by fish.

While sunscreen use is very important for some of us to prevent cancer, I challenge you to use less. I see people slathering on so much excess sunscreen on their body at the beach and doing it with undo frequency. I challenge you to wear protective clothing; a lightweight blouse and a wide brimmed hat. I challenge you to let the sun very lightly tan your skin. As far as I know there is no evidence that a light tan is related to cancers. I challenge you to use moderation with sunscreen for the sake of our reefs.

Did you know that coral are actually colonies of tiny animals that secrete calcium carbonate to form the coral skeleton? Many people think coral is a plant. They grow very slowly, multiplying and laying down more calcium carbonate each year. Many of them live symbiotically with microscopic algae that live on the coral’s tissue. These algae produce energy through photosynthesis for the coral to benefit from the energy produced. This is why sunlight is so important for survival of the coral reefs.

coral reef



Downs CA1, Kramarsky-Winter E, Fauth JE, Segal R, Bronstein O, Jeger R, Lichtenfeld Y, Woodley CM, Pennington P, Kushmaro A, Loya Y., Toxicological effects of the sunscreen UV filter, benzophenone-2, on planulae and in vitro cells of the coral, Stylophora pistillata. Ecotoxicology. 2014 Mar;23(2):175-91. doi: 10.1007/s10646-013-1161-y. Epub 2013 Dec 19.

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