Banned Sunscreens and Coral Reef Health

Hawaii recently passed legislation that restricts products containing the sunscreen agents oxybenzone and octinoxate. Why? These sunscreen agents have shown, in lab studies, to cause harm to coral reefs. Coral reefs are only a fraction of a percent of the world’s ocean surface but provide a home for over 20% of all marine species; therefore, there is understandable concern for maintaining the safety and protection of this crucial ecosystem.

Assorted-color Corals

Oxybenzone is an effective sunscreen that absorbs a range of UV wavelengths, providing UVA and UVB protection. Octinoxate has a narrower range of protection, primarily fending off UVB radiation. These are 2 examples, among many others, of chemical sunscreen agents which protect against the harmful ultraviolet rays of the sun by absorbing them before they can damage the skin. Although many sunscreen agents are available throughout the world, there is a limited number of them that are available in the US due to the FDA studies that are required to approve these agents and the lack of studies needed to verify that there is no harm from chronic exposure, especially in children and pregnant women. There is continued discussion that oxybenzone may have anti-androgenic and pro-estrogenic properties due to animal studies demonstrating such effects(1). Further research has shown this concern to be nearly insignificant (2).

There is concern and evidence in lab studies that chemical sunscreens, and these two agents in particular, may be having an impact on the delicate ecosystem of the coral reefs.

Estimates show that nearly 25% of sunscreen that is applied to the skin is washed away within 20 minutes of submersion in water; this translates to thousands of tons of sunscreen being released into the water that is inhabited by coral reefs. In Hawaii, the water filtration systems are not effective in filtering out organic sunscreen agents, so there is additional contamination from sewage.

Green Coral In Aquarium

You may have heard the term “coral bleaching” which refers to the response of coral exposed to oxybenzone and octinoxate. Coral and zooxanthellae algae have a close symbiotic relationship; the coral provides a safe haven for the algae to exist. The algae the provides nutrients and compounds needed by the coral when the coral later consumes the algae. When the algae is exposed to oxybenzone and octinoxate, the algae loses the integrity of its membranes and also lose photosynthetic pigments. This leads to the algae separating from the coral and thus the coral losing the nourishing benefits of the algae. Oxybenzone and octinoxate may also directly damage coral larvae DNA. The net effect of this is compromised viability of the coral due to the effects of these 2 sunscreen agents.

Further research is needed to make a definite decision in sunscreen recommendations. We all recognize the importance of sunscreens in skin protection and sunburn avoidance. Moving towards biodegradable sunscreens may provide a safer alternative that is effective in protecting skin without potential damage to our valuable coral reefs.

  1. Wang SQ, Burnett ME, Lim HW. Safety of oxybenzone: putting numbers into perspective. Archives of Dermatological Research. 2011 Jul 147(7):865-6
  2. Janinua NR, et al. Systemic absorption of the sunscreens benzophenone-3, octyl-methoxycinnamate, and 3-(4-methylbenzylidene) camphor after whole-body topical application and reproductive hormone levels in humans. Journal of Investigative Dermatology 2004 July. 123(1):57-61.

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