My first trip to the state of Hawaii, a family vacation in 2019, built up my excitement for a great deal of time in the sun, particularly snorkeling and SCUBA diving. During my vacation, I noticed signs advocating for the use of reef safe sunscreen at beaches, shops, and tourist attractions. Unaware of the ongoing battle against traditional sunscreen, and slightly shocked by the higher cost of the reef save variety, my family and I continued to use the sunscreen we had packed with us. But what were the environmental effects of using traditional “reef unsafe” sunscreen around corals? What are the ingredients in sunscreens that harm coral reefs?

Via Adobe Stock.

The American Academy of Dermatology strongly recommends that everyone, regardless of age or race, wear sunscreen daily when outdoors (1). Sunscreens contain UV filters, chemicals or materials which absorb ultraviolet (UV) light from penetrating into skin. Excess exposure to UV light may lead to uncomfortable sunburns, premature skin aging, and even skin cancer (1, 2). Thus it is important to apply sunscreen when skin cannot be covered by clothing, as is often the case during beach activities in tropical destinations.

Sunscreen also washes off from water activities, both in the ocean and terrestrially from bathing. Efforts to characterize quantify sunscreen chemicals in coastal waters have found increased concentrations in areas of busy water use (8, 13). The greatest concentrations of sunscreen ingredients are detected in calmer areas with the greatest intrusion of humans using sunscreen (i.e. popular beaches and tourist destinations (13).

The greatest concentrations of sunscreen chemicals are found at heavily used popular beaches. Via Adobe Stock.

Concern has spread over the deleterious consequences of sunscreens’ chemicals on corals. Coral reefs are more than stony structures that fish swim around – corals are living creatures, invertebrates within family Cnidaria. Already under stress from ocean acidification and warming (15, 18, 16, 10), they can also be harmed by anthropogenic chemical pollution. Oxybenzone and octinoxate, two common UV ray blocking ingredients in sunscreens (3, 14), have faced criticism for their reef safety (11, 14). Sunscreen chemicals may accumulate inside of coral tissues, leading to deformities, bleaching, increased susceptibility to diseases, and possibly death (5, 7, 8). When faced with natural or anthropogenic stress, corals are less capable of defending themselves against grazers and algal growth. Vibrant coral reefs can be transformed into algal dominated systems, changing the community structure as well (12). The bleaching and death of coral reefs create economic problems including reductions in tourism revenue from SCUBA divers and fisheries losses (9).

A bleached coral reef overgrown with algae looks much different than a healthy reef.  Via Adobe Stock.

To mediate coral reef losses, the state of Hawaii banned the sale and use of sunscreens containing the UV filters oxybenzone and octinoxate, effective January 1, 20214. This has driven market development for sunscreens which lack these ingredients and are deemed “reef safe.” Their objective is to replace the coral-stressing UV filters with other ingredients, while still providing adequate UV ray protection to the wearer. Ingredients such as zinc-oxide and titanium-oxide are popular amongst the reef safe sunscreens.

It is worth noting that oxybenzone and octinoxate are also found in other personal care products. Perhaps the reason these ingredients may have become infamous in sunscreens specifically is because of beachgoers and SCUBA divers bringing them within inches of coral reefs. That is, it may be easier for policy makers to identify one very specific activity as harmful to corals – applying sunscreen.

Via Adobe Stock.

Enforcement of the new sunscreen ban is complicated. It mostly came down to self-enforcement by shops and citizens before the legal ban. And there is continuing uncertainty over which products are truly reef safe. A 2019 study published in the Journal of the American Academy of Dermatology sought to better understand the ingredients of reef safe sunscreens. Of 52 commercially available products marketed as reef safe, two contained oxybenzone or octinoxate (17), the very ingredients banned by Hawaii. Another 23 products contained at least one other ingredient known to be toxic to corals (5), leaving just 52% of the reef safe products, reef safe (17). This lack of regulation makes it more difficult to make environmentally conscious purchasing purchases, leaving it consumers to identify ingredients and examine labels carefully (6, 17). Consumers have faced similar struggles with other marketable words such as “natural,” “green.” Creating a certifiable designation by an agency such as the Food and Drug Administration would help consumers identify reef safe sunscreen products at a glance, leading to better coral reef protection.

The National Oceanic and Atmospheric Administration (NOAA) identifies several chemicals as harmful to marine life, including corals. Via NOAA.

Focusing conservation efforts on sunscreen derived UV filters may be skirting around a greater threat at play – climate change. Anthropogenically released carbon dioxide stresses corals by making the oceans warmer and more acidic, pathways which lead to coral bleaching. Certainly though, exposure to oxybenzone and octinoxate certainly isn’t beneficial to corals. Whether these two ingredients are banned or not, choosing sunscreens that does not contain them can help make a difference when around coral reefs. And using UV protective clothing such as wetsuits and rash guards can lessen the total amount of sunscreen contamination an individual contributes to the ocean. Still, wearing sunscreen of any variety on exposed skin is highly recommended for protection against harmful skin effects.

A thin, warm water wetsuit can offer exposure protection from UV rays and reduce the amount of sunscreen a surfer or SCUBA diver needs to apply. Via Adobe Stock.

References

1.     https://www.aad.org/public/everyday-care/sun-protection/sunscreen-patients/sunscreen-faqs

2.     https://www.mayoclinic.org/diseases-conditions/skin-cancer/symptoms-causes/syc-20377605

3.     https://pubchem.ncbi.nlm.nih.gov/compound/Oxybenzone

4.     https://www.sciencedaily.com/releases/2019/01/190109110048.htm

5.     https://oceanservice.noaa.gov/news/sunscreen-corals.html

6.     https://savethereef.org/about-reef-save-sunscreen.html

7.     Danovaro R, Bongiorni L, Corinaldesi C, Giovannelli D, Damiani E, Astolfi P, Greci L, Pusceddu A. Sunscreens cause coral bleaching by promoting viral infections. Environmental Health Perspectives. 2008;116(4):441–447. doi:10.1289/ehp.10966

8.     Downs CA, Kramarsky-Winter E, Segal R, Fauth J, Knutson S, Bronstein O, Ciner FR, Jeger R, Lichtenfeld Y, Woodley CM, et al. Toxicopathological Effects of the Sunscreen UV Filter, Oxybenzone (Benzophenone-3), on Coral Planulae and Cultured Primary Cells and Its Environmental Contamination in Hawaii and the U.S. Virgin Islands. Archives of Environmental Contamination and Toxicology. 2016;70(2):265–288. doi:10.1007/s00244-015-0227-7

9.     Graham NAJ, Wilson SK, Jennings S, Polunin NVC, Robinson J, Bijoux JP, Daw TM. Lag effects in the impacts of mass coral bleaching on coral reef fish, fisheries, and ecosystems. Conservation Biology. 2007;21(5):1291–1300. doi:10.1111/j.1523-1739.2007.00754.x

10.  Hughes TP, Kerry JT, Álvarez-Noriega M, Álvarez-Romero JG, Anderson KD, Baird AH, Babcock RC, Beger M, Bellwood DR, Berkelmans R, et al. Global warming and recurrent mass bleaching of corals. Nature. 2017;543(7645):373–377. doi:10.1038/nature21707

11.  McCoshum SM, Schlarb AM, Baum KA. Direct and indirect effects of sunscreen exposure for reef biota. Hydrobiologia. 2016;776(1):139–146. doi:10.1007/s10750-016-2746-2

12.  McManus JW, Polsenberg JF. Coral-algal phase shifts on coral reefs: Ecological and environmental aspects. Progress in Oceanography. 2004;60(2–4):263–279. doi:10.1016/j.pocean.2004.02.014

13.  Mitchelmore CL, He K, Gonsior M, Hain E, Heyes A, Clark C, Younger R, Schmitt-Kopplin P, Feerick A, Conway A, et al. Occurrence and distribution of UV-filters and other anthropogenic contaminants in coastal surface water, sediment, and coral tissue from Hawaii. Science of the Total Environment. 2019;670:398–410. doi:10.1016/j.scitotenv.2019.03.034

14.  Raffa RB, Pergolizzi J V., Taylor R, Kitzen JM. Sunscreen bans: Coral reefs and skin cancer. Journal of Clinical Pharmacy and Therapeutics. 2019;44(1):134–139. doi:10.1111/jcpt.12778

15.  Rosenberg E, Ben-Haim Y. Microbial diseases of corals and global warming. Environmental Microbiology. 2002;4(6):318–326. doi:10.1046/j.1462-2920.2002.00302.x

16.  Spalding MD, Brown BE. Warm-water coral reefs and climate change. 2015;350(6262):769–771.

17.  Tsatalis J, Burroway B, Bray F. Evaluation of “reef safe” sunscreens: Labeling and cost implications for consumers. Journal of the American Academy of Dermatology. 2020;82(4):1015–1017. http://dx.doi.org/10.1016/j.jaad.2019.11.001. doi:10.1016/j.jaad.2019.11.001

18.  Kleypas JA, Yates KK. Coral reefs and ocean acidification. Oceanography. 2009;22(SPL.ISS. 4):108–117. doi:10.5670/oceanog.2009.101