Coral reefs, which provide food and shelter to close to one quarter of all marine life, are under attack from an unlikely source: chemical sunscreens.

In addition, since we’ve all heard about the myriad potential effects of global warming, it’s no surprise that a new UCLA study1 suggests that as the oceans heat up, coral reefs are likely to grow slowly, putting even more marine life in jeopardy.

So, between our judicious use of certain sunscreens and global warming, we may be creating a double whammy with a pronounced downside for the health of our coral supply.

The Data

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Specifically, when there are lots of sunscreen-coated swimmers in bays and coves, in which chemicals don’t dilute out into the open ocean quickly, concentrations of a common sunscreen ingredient, Benzophenone-3, rise above the concentrations shown to be toxic to coral in the lab. The effect can be anything from making it more difficult for coral to spread and reproduce to directly bleaching and killing the adult coral.

The obvious problem is that we know the health benefits of using sunscreen to prevent sunburns on the beach.

So are we stuck with having to choose between killing coral with sunscreen or cooking our skin without sunscreen?

Fortunately, no. The good news is that physical blockers, namely titanium dioxide and zinc oxide, are pretty harmless to coral, probably because they are naturally present in sea water at low levels. Thus, the best way to protect skin from skin cancer and premature aging without jeopardizing our coral supply is to stick to wearing sunscreens that only have zinc and titanium as active ingredients and support rules enforcing this at beaches near reefs.

Dr. Zirwas originally presented this talk at Cosmetic Surgery Forum 2017 in Las Vegas.

Cosmetic Surgery Forum 2018 will be held November 28 to December 1 at the Cosmpolitan Las Vegas. For information or to register, visit

Matthew J. Zirwas, MD is a dermatologist in private practice in Bexley, OH, Director of the Ohio Contact Dermatitis Center, and a Member of the North American Contact Dermatitis Group. 

1. Gold Z, Palumbi SR. Long-term growth rates and effects of bleaching in Acropora hyacinthus. Coral Reefs March 2018, Volume 37, Issue 1, pp 267–277,