Sunscreen and Coral Reef Conservation (Guest Post)

Guest post by One People One Reef

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We are a group of communities and scientists working together to keep the reefs, culture and people of the Micronesian Outer Islands healthy. We are bringing traditions and modern science together in a revolutionary approach to sustainable ocean management.

Micronesian Outer islanders from the remote atolls of the Yap and Chuuk outer islands in the Western Pacific have sustainably managed their oceans for centuries, even millennia. Their culture, traditions and livelihoods are intimately linked to the reefs that surround their islands. However, their future is threatened by rapid environmental and cultural change. In 2010, they recognized a decline in fish populations and reef health, along with human health challenges. They asked for help to learn more about how to manage a sustainable food supply from their oceans in the face of these changes, a critical issue for their present and future wellbeing.

We brought together a team of scientists to respond to the outer islanders’ call for assistance. The result was a revolutionary approach in which communities lead through traditional management, backed and informed by modern science. Our work, which began on a single atoll–Ulithi–has now expanded across Yap State and into neighboring Chuuk State, at the request of local communities. Explore our website to learn more about our program’s history, approach and achievements.

Reef conservation and sunscreen

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In our work studying and helping manage coral reefs in the outer islands of Yap State, Micronesia, our team spends long hours snorkeling and diving in the intense tropical sun. For coral reefs this strong sunlight is essential: Reef-building corals have single-celled algal partners called zooxanthellae that need plenty of sunlight to photosynthesize. It is the products of their photosynthesis that give the corals the energy they need to build their skeletons, which are what form the structure of the reef. For us, the UV radiation in this strong sunlight presents a serious risk of skin damage and related cancers. Both sun-protective clothing and sunscreens can offer effective protection from UV rays. However, the possible effects of sunscreens on coral reefs are a cause for concern.

Coral reefs are already under great stress from climate change-related ocean warming and ocean acidification, destructive fishing, coastal development and pollution. Recent research is now showing that certain ingredients in sunscreens pose an additional threat. Estimates of the amount of sunscreen entering reef areas annually range from 4,000 to 14,000 tons.[1] This either washes off people’s skin when in the water or reaches the ocean via water treatment plants. Importantly, it is estimated that 90% of snorkeling/diving tourists are concentrated on 10% of the world’s reefs, so any environmental impact is likely to be concentrated in a few heavily visited areas.[2]

“Chemical” vs “mineral” sunscreens

There are two main types of sunscreen: Those that use carbon-based chemicals, and those that use zinc or titanium oxides to protect our skin. The former are often referred to as “chemical” sunscreens, and work primarily by absorbing UV radiation through their chemical bonds, and releasing the energy as heat. The latter are referred to as “mineral” sunscreens. They contain zinc oxide and/or titanium dioxide, which work primarily by scattering and reflecting UV light off the skin.

Chemical sunscreens—oxybenzone

Many sunscreens contain the carbon-based chemical oxybenzone (also called benzophenone-3 or BP3). It has been the focus of much of the research into sunscreen effects on corals to date. A 2015 study[3] found that:

  1. Exposing coral larvae to the chemical deformed and immobilized them
  2. The more corals were exposed to oxybenzone, the more likely they were to bleach (lose their algal symbionts, which they need to survive)
  3. Oxybenzone damaged coral DNA
  4. It also caused abnormalities in the coral larval skeleton

The same study found concerning concentrations of oxybenzone on coral reefs in Hawaii and the U.S. Virgin Islands. The authors conclude “Oxybenzone poses a hazard to coral reef conservation and threatens the resiliency of coral reefs to climate change.” On May 1, 2018, Hawaii became the first State to pass a bill banning the use of sunscreens containing oxybenzone and a second ingredient—octinoxate—based on such studies.

Other ingredients of concern

In 2008, Danovaro et al linked a number of carbon-based UV filters to coral bleaching and viral infections.[4] In an article for Alert Diver Online, the lead author of this study recommends avoiding all of the following ingredients because of their potential environmental impact:

  • parabens (common preservatives such as butylparaben)
  • BMDBM (4-tert-butyl-4-methoxydibenzoylmethane benzophenone
  • BZ (benzophenone-3)
  • MBC (4-methylbenzylidene camphor)
  • OMC (ethylhexyl methoxycinnamate)
  • OCT (octyl methoxycinnamate)
  • BEMT (bis-ethylhexyloxyphenol methoxyphenyl triazine)
  • any component that includes the term –benzene

None of these ingredients known to be of concern are found in Goddess Garden products.

Mineral sunscreens—“nano” vs “non-nano”

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Less research is available on the effects of mineral sunscreens on coral reefs. However, some attention has been paid to the effects of nanoparticles of zinc oxide and titanium oxide, now used in many mineral sunscreens since they help the product appear clear on the skin. Studies have raised a number of concerns about them, both environmental and human health related. One such study found that nanoparticles of zinc oxide damaged the exoskeletons of the small crustaceans at the base of the coral reef food web.[5] Another found that zinc oxide nanoparticles were toxic to sea urchin embryos.[6]

We recognize that Goddess Garden is using particles that meet Australian and EU guidelines for “non-nano” size in response to these studies.

More research is needed

According to both the International Coral Reef Initiative (ICRI)[7] and the Environmental Working Group, more research on the environmental effects of all UV filters and other sunscreen ingredients is needed. Currently, the Environmental Working Group (EWG) considers that “the weight of evidence indicates that both zinc oxide and titanium dioxide pose a lower hazard (to the environment) than most other sunscreen ingredients approved for the U.S. market.”

Our approach to sunscreen

In the field, our team uses sun-protective clothes like rash-guards and swim leggings, along with sunscreen to cover still exposed skin like faces and hands. Our team uses non-nano, zinc and titanium-based sunscreens, as the evidence points to those being the best options given our current state of knowledge.

As the ICRI briefing states, “Considering the many stresses already faced by reefs and current concerns about the toxicity of certain components of sunscreens to corals, a proactive and precautionary approach to dealing with this issue may be required. Reducing the amount of harmful sunscreen components that reach the reef environment is a high priority and will require the involvement of governments, reef managers, divers, snorkelers and swimmers, and the tourism and pharmaceutical industries.” We recognize and appreciate that companies like Goddess Garden are doing their best to develop products that are as ocean-friendly as possible, given the lack of conclusive data, and are responding to developments in the research as they become available.

We want to thank Goddess Garden for their generous donation of sunscreen to our team and the local people of the Yap outer islands for our summer 2018 field season. We feel a responsibility to share what we know not only about marine science and the management of sensitive coral reef ecosystems, but also about secondary impacts to these systems–and sunscreens are definitely part of this. For more on our work, please visit onepeopleonereef.org.

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[1] Wood, Elizabeth “Impacts of Sunscreens on Coral Reefs”, ICRI Briefing, Feb 2018. www.icriforum.org Web. Accessed June 4 2018.
[2] National Park Service. “Protect Yourself, Protect the Reef!”, Sunscreen Bulletin. n.d. www.cdhc.noaa.gov. Web. Accessed June 4 2018.
[3] Downs 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 2015 Oct 20. doi: 10.1007/s00244-015-0227-7.
[4] Danovaro, Roberto, “Sunscreens linked to Coral Bleaching.” Alert Diver Online. Winter 2014. www.alertdiver.com Web. Accessed June 4 2018.
[5] Wong, S. W. Y., Leung, K. M. Y., Djurišić, A. B., & Leung, P. T. Y. (2010). Toxicities of nano zinc oxide to five marine organisms: Influences of aggregate size and ion solubility [electronic resource]. Analytical and Bioanalytical Chemistry, 396(2), 609-618. doi://dx.doi.org/10.1007/s00216-009-3249-z
[6] Sonia Manzo, Maria Lucia Miglietta, Gabriella Rametta, Silvia Buono, Girolamo Di Francia, Embryotoxicity and spermiotoxicity of nanosized ZnO for Mediterranean sea urchin Paracentrotus lividus, Journal of Hazardous Materials, Volumes 254–255, 2013, Pages 1-9, ISSN 0304-3894,https://doi.org/10.1016/j.jhazmat.2013.03.027.
[7] Wood, Elizabeth “Impacts of Sunscreens on Coral Reefs”, ICRI Briefing, Feb 2018. www.icriforum.org Web. Accessed June 4 2018.

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