Tourists at Hawaii Kai Beach. (Photo by Marufish. 2004) CC BY-SA Tourists at Hawaii Kai Beach. (Photo by Marufish. 2004) CC BY-SA

The U.S. state of Hawaii passed a bill this summer banning sunscreens posing ecological risks to delicate coastal coral reefs. First proposed in the summer of 2017, the bill is in response to massive bleaching events in coral reefs throughout the Pacific Ocean.

“Hawaii’s reefs have been slowly dying over the past 20 years, and that death spiral has been accelerating with the impact of an El Niño-induced mass bleaching events and increased local pollution impacts from both tourism and development,” Craig Downs, the executive director of the Haereticus Environmental Laboratory, told the New York Times in May.

“Everyone has come together to support this legislation, from local nurses and doctors, to resorts and airlines, as well as the entrepreneurial spirit of new sunscreen companies to supply reef-safer products.”

Specifically, the aloha state is prohibiting the sale and distribution of oxybenzone and octinoxate, two of the most common active ingredients in chemical sunscreens.

While chemical sunscreens have already been banned at marine eco-parks in Mexico, popular tourist destinations, including tropical islands in the Maldives, French Polynesia and the Philippines, have long issued quiet reminders to visitors to avoid chemical sunscreens if possible.

Though these viruses brought on by parabens et al are miniscule in size, their impacts on marine ecology are huge.

Sunscreen under the microscope

Sunscreen ingredients have been subject to scrutiny before. Research in 2008 by Roberto Danovaro from the Department of Marine Sciences at the Polytechnic University of the Marche in Italy have shown UV filters like parabens, benzophenones and camphor can cause viral infections in coral populations.

Since all sunscreens (including water resistant types) dissolve in seawater after 80 minutes, as little as 10 microlitres of these chemical compounds per litre of seawater can facilitate the destruction of zooxanthellae, a species of symbiotic algae that captures sunlight and converts it into energy for corals. When zooxanthellae die or flee coral when stressed by chemicals contained in sunscreen, coral bleaching can occur within days.

Though these viruses brought on by parabens et al are miniscule in size, their impacts on marine ecology are huge. Increased concentrations of viral abundance in seawater can influence global biogeochemical cycles by interfering with population dynamics of phytoplankton, microscopic organisms vital to aquatic food chains. The release of viruses caused by chemicals in sunscreen can directly cause massive changes in algal composition, affecting species dependent on phytoplankton for food and the flow of nitrogen and phosphorous throughout marine environments.

Moreover, many investigations into oxybenzone have revealed its lethalness to coral larva, preventing its growth and reproduction. While most bleaching events are caused by warming habitats brought on by climate change, oxybenzone contamination leads to coral bleaching even at colder water temperatures.

Protecting coral reefs

Coral reef systems offer a diverse range of ecosystem services, including shoreline protection, maintenance of habitats and nitrogen fixation. And for the people of Hawaii, these reefs are also crucial money-makers. The state’s most popular reef areas of the main Hawaiian Islands are worth nearly $10 billion US to Hawaiian culture and biodiversity. Reefs remain the most productive ecosystem type on Earth, sustaining both marine biodiversity hotspots and terrestrial human life, since many Hawaiian locals depend on reefs for food and income.

Leaving your chemical sunscreen at home is no solution given the dangers sun exposure can cause. And even if you restrict harmful sunscreens for use away from beaches, there is no guarantee oxybenzone and octinoxate won’t make it to the seas eventually, as these contaminants have been found to reach the ocean via sewer systems. This makes it all the more crucial that tourists, where possible, abstain completely from using chemical sunscreens at tropical locales even when they’re away from the beach.

Hawaii’s ban on oxybenzone and octinoxate is expected to come into effect in 2021, but there are still many ways for beach-lovers to protect themselves and reefs. Water resistant physical sunscreens containing “non-nanosized” zinc oxide are the safest option for water sports and sunbathing. Yet these sunscreens are notably more expensive than their chemical-laden alternatives, making their use unrealistic for low-income families. Moreover, many mineral sunscreens are incredibly thick and rarely designed for use by people of colour. This too, along with making safer sunscreens more affordable, needs to change.  

Until then, for consistent protection against UVA and UVB in the water, a wetsuit may be the best choice for your next tropical vacation. Think of the coral.

Hai Lin studies Conservation Biology and Biodiversity at University of Toronto. She’s interested in sustainability, green economies and baking. In her spare time, she likes to visit botanical gardens and pretend she lives in a tropical forest rather than a concrete jungle.

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