Sunscreens, cancer, and protecting our planet
Authors: Jayden Galamgam, Natalia Linou, Eleni Linos
Journal: The Lancet Planetary Health (2018)

Beginning Jan 1, 2021, Hawaii will ban the sale or distribution of any sunscreens containing oxybenzone or octinoxate without a prescription from a licensed health-care provider. The ban is the result of concerns about the detrimental effects of these chemicals on coral and other marine organisms. Coral reefs are among the most important parts of marine ecosystems, providing food and shelter for ocean species, and offering vital services to human societies through their role in coastal protection, building materials, fisheries, and tourism. However, coral reef ecosystems have been threatened by climate change, ocean acidification, and coastal pollution.1Hoegh-Guldberg O Climate change, coral bleaching and the future of the world's coral reefs.Mar Freshw Res. 1999; 50: 839-866Crossref Scopus (2629) Google Scholar, 2Hoegh-Guldberg O Mumby PJ Hooten AJ et al.Coral reefs under rapid climate change and ocean acidification.Science. 2007; 318: 1737-1742Crossref PubMed Scopus (3904) Google Scholar Meanwhile, the incidence of malignant melanoma and non-melanoma skin cancers continue to rise,3Rogers H W Weinstock MA Feldman SR Coldiron BM Incidence estimate of nonmelanoma skin cancer (keratinocyte carcinomas) in the US population, 2012.JAMA Dermatol. 2015; 151: 1081-1086Crossref PubMed Scopus (1059) Google Scholar and public health efforts have focused on increasing sun protection practices. It is time to think about skin cancer and its prevention in the context of planetary health,4Whitmee S Haines A Beyrer C et al.Safeguarding human health in the Anthropocene epoch: report of The Rockefeller Foundation–Lancet Commission on planetary health.Lancet. 2015; 386: 1973-2028Summary Full Text Full Text PDF PubMed Scopus (1152) Google Scholar to balance the benefits to human health with the preservation of our environment and the ecosystems that underpin it. Excessive ultraviolet radiation exposure is a preventable cause of all types of skin cancer,5American Cancer SocietyCancer Facts & Figures 2018. American Cancer Society, Atlanta2018Google Scholar with numerous studies confirming that exposure in childhood and adolescence increases the risk of skin cancer later in life, especially when resulting in severe sunburn.6Grossman D C Curry S J Owens D K et al.Behavioral counseling to prevent skin cancer: US Preventive Services Task Force recommendation statement.JAMA. 2018; 319: 1134-1142Crossref Scopus (6) Google Scholar, 7Sánchez G Nova J Rodriguez-Hernandez A E et al.Sun protection for preventing basal cell and squamous cell skin cancers.Cochrane Database Syst Rev. 2016; 7 (CD011161.)Google Scholar Although long-term randomised trials of sunscreen on skin cancer prevention are still needed, it is widely established that broad-spectrum chemical and physical sunscreens reduce sunburn, one of the main risk factors for skin cancer. Several methods for effectively protecting skin from excessive ultraviolet radiation exposure and sunburn exist, including the use of protective clothing and hats, avoiding midday sun, and seeking shade. Broad-spectrum sunscreen of sun protection factor 30 or greater is an important supplement to these behaviours, especially for areas of the body that are not covered by clothing. Some dermatologists and public health professionals might therefore question whether Hawaii's decision to ban certain chemical sunscreens was the right one. We believe that based on the precautionary principle that encourages policies that protect human health and the environment in the face of uncertain risks and the fact that there are many safe alternatives that people can use until this uncertainty is resolved, this is not the wrong decision. We reviewed the scientific data on the effects of sunscreens on the environment. Overall, we identified very few studies on the topic, suggesting it might be too soon to draw firm conclusions. However, in laboratory conditions, oxybenzone was toxic to corals and led to coral bleaching,8Danovaro R Bongiorni L Corinaldesi C et al.Sunscreens cause coral bleaching by promoting viral infections.Environ Health Perspect. 2008; 116: 337-340Crossref Scopus (357) Google Scholar, 9Downs CA Kramarsky-Winter E Segal R 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.Arch Environ Contam Toxicol. 2016; 70: 265-288Crossref PubMed Scopus (311) Google Scholar a process by which corals that are stressed by changes in environmental conditions expel the symbiotic algae living in their tissues, causing them to turn white. Up to an estimated 14 000 tonnes of sunscreens, of which many contain as much as 10% oxybenzone, are washed off in tourist reef areas annually.9Downs CA Kramarsky-Winter E Segal R 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.Arch Environ Contam Toxicol. 2016; 70: 265-288Crossref PubMed Scopus (311) Google Scholar Ultraviolet filters might also enter the ocean through wastewater treatment plant effluent. In Brazil, oxybenzone and octinoxate were identified in both raw and treated water.10Pereira da Silva C Emdio ES Rodrigues de Marchi MR The occurrence of UV filters in natural and drinking water in São Paulo State (Brazil).Environ Sci Pollut Res. 2015; 22: 19706-19715Crossref Scopus (40) Google Scholar The effects of oxybenzone on other marine life have also been studied. In Japanese medaka and rainbow trout, exposure to high concentrations of oxybenzone led to decreased egg production, with significant reductions in egg hatchings and possible feminisation of male fish.11Coronado M De Haro H Deng X Rempel MA Lavado R Schlenk D Estrogenic activity and reproductive effects of the UV-filter oxybenzone (2-hydroxy-4- methoxyphenyl-methanone) in fish.Aquat Toxicol. 2008; 90: 182-187Crossref PubMed Google Scholar These documented effects on coral and marine life call the aforementioned precautionary principle into play.12Kriebel D Tickner J Epstein P et al.The precautionary principle in environmental science.Environ Health Perspect. 2001; 109: 871-876Crossref PubMed Scopus (453) Google Scholar Planetary health is an emerging field focused on the dual goal of protecting the health of humans while also protecting the health of our planet for today's and future generations. This approach was developed because of the threatened state of the environment and a realisation that human behaviours have led to a transgression of several planetary boundaries, putting the health of both humans and the planet at risk. Dermatologists should be familiar with this problem, given that stratospheric ozone depletion, as evident in the hole in the ozone layer, has put many humans at increased risk of malignant melanoma and other cancers. We clearly need further studies to better evaluate the potential environmental effects of sunscreen. In the meantime, both dermatologists and sunscreen sceptics agree on the benefits of other sun-protective behaviours, including avoiding indoor tanning, seeking shade, and wearing sun-protective clothing and sunscreens with physical filters including zinc oxide and titanium dioxide.13Schneider SL Lim HW Review of environmental effects of oxybenzone and other sunscreen active ingredients.J Am Acad Dermatol. 2018; (published online June 28.)DOI:10.1016/j.jaad.2018.06.033Google Scholar It is time for dermatologists to continue advocating for skin cancer prevention, while also being cognisant of the understudied but potential risks to our planet. And for Hawaiians, He po'i na kai uli, kai ko'o, 'a'ohe hina pūko'a. Though the sea be deep and rough, the coral rock remains standing. Hopefully, for generations to come. EL is supported by the National Cancer Institute (grants DP2CA225433 and R21CA212201) and the National Institute of Aging (grant K76AGO54631). All other authors declare no competing interests.