Healthy coral reefs play a key role in everything from protecting coastlines, providing food and income for coastal communities, and even medical research, but they are facing an existential crisis as a result of climate change and other threats, leading to a widespread stress response known as ‘bleaching’. More than half of the world’s reefs are estimated to have been lost since the 1950s, and according to a recent report, 1.5°C of warming would be catastrophic for those that remain. And the comfort we may feel in using ‘reef-safe’ sunscreen is somewhat misleading — perhaps more a marketing ploy than first suspected.
To start, there is an estimated 6,000 tons of sunscreen entering reef areas every year, and emerging studies suggest the UV-filtering chemicals being discharged into waters by beachgoers are having adverse effects on marine life. This has led to ingredients being banned in some locations, and has prompted a surge in ‘reef-safe’ sun protection on store shelves.
But what ‘reef-safe’ really means is unclear, and while there is ample proof that UV filters are in the ocean, the damage their presence is causing remains unsettled. Concerned consumers who want to protect their skin while doing right by the planet face a lack of clear guidance on what’s safe. To shed some much-needed light on the issue, experts weigh in on the threat sunscreen poses, what’s really safe for reefs, and how you can protect your skin without harming the sea.
The Sunscreen Chemicals Causing Concern
Two common chemical culprits, oxybenzone and octinoxate — which are part of a category of active ingredients that absorb the sun’s rays and convert them to heat — are featured prominently in a growing body of studies on their detrimental effects on marine organisms. These chemicals are bad news for corals, according to environmental engineer Dr. Tracy Fanara, harming them by damaging their DNA, disrupting hormonal processes, and causing deformities leading to decreased defenses against bleaching.
A recent study exposed anemones and mushroom corals to oxybenzone in artificial seawater with and without simulated sunshine. The anemones under simulated sunlight all died within 17 days, whereas the ones without light remained viable. This suggests that oxybenzone can render sunlight toxic to corals.
According to Dr. Craig Downs, Executive Director of Haereticus Environmental Laboratory and Invited Professor at Sorbonne University, octocrylene is another chemical that poses a threat to fish, corals, and other invertebrates. A 2021 study showed that octocrylene degrades into benzophenone, which according to Dr. Downs is a suspected carcinogen and endocrine disruptor.
Can Lab Studies Tell The Whole Story About ‘Reef-Safe Sunscreens?’
Others challenge the research, noting that the studies conducted in the lab can’t tell the whole story. The question is whether organisms in a lab setting are being exposed to a level of a chemical they would ever actually see in the marine environment. “The lab experiments are designed to test whether sunscreen chemicals could in theory affect corals, not whether real-world conditions pose a threat to corals,” says Simon Donner, Climate Scientist and Professor at the University of British Columbia. Lab studies don’t always correlate with field studies, according to Dr. Fanara; however, lab studies are necessary to control variables and target cause and effect. “We need to know realistic exposure levels to these compounds and how long they last in the marine environment to determine safe limits,” she says.
Donner believes that “unless you are in a small, crowded bay with poor water circulation, the concentration of chemicals from sunscreen will not be high enough to have the effect that is seen in the lab.” At Hanauma Bay — one of the most densely populated swimming locations in the Hawaiian Islands — a study conducted by Dr. Downs measuring the concentrations of oxybenzone in near-shore waters found that levels ranged from 30 parts per trillion to 27,880 parts per trillion, and that the chemical’s retention time in the water was as long as 50 hours. According to Downs, oxybenzone has demonstrated to be toxic to coral at levels as low as 72 parts per trillion in less than 24 hours, suggesting the concentrations present at Hanauma Bay pose a significant threat.
Because the term ‘reef-safe’ has no standard or regulated meaning behind it, it can give consumers a false sense of security.
The Definition Of ‘Reef-Safe’ Is Murky
Some sunscreens claim ‘reef-safe’ status simply for being oxybenzone-free, while others adopt the designation for having replaced the principal offenders with ‘clean’ alternatives such as avobenzone, octisalate, and homosalate. But is this new crop of UV filters any safer for reefs? According to Dr. Downs, independent science on avobenzone doesn’t paint a positive picture.
Other ‘reef-safe’ sunscreens use only minerals (titanium dioxide and zinc oxide) to deflect the sun’s rays. But not all mineral sunscreens are created equal. The particle size is a key factor in reef safety, with the minerals being either ‘nano’ (smaller than 100 nanometers) or ‘non-nano’ (larger than 100 nanometers). Dr. Fanara points out that nano particles can be ingested by marine life, including coral, causing internal damage; and can react with UV rays to generate hydrogen peroxide which can be toxic to phytoplankton — a vital nutrient for many reef and coral species.
The problem is, most mineral sunscreens don’t indicate the particle size on the tube, though the viscosity of the lotion may be an indication. Typically, nano-sized particles can be blended more easily, disappearing into the skin, whereas non-nano particles typically sit on top of the skin. Brands like Beautycounter and Hawaii-based Project Reef advertise their use of non-nano minerals to consumers, and are reimagining the pasty, heavy formulations of the past, with sun protection that is more user-friendly. “I think the definition of ‘reef-safe’ is becoming murky, but we believe mineral is the new reef-safe,” says Matt Roomet, Founder of Project Reef.
One Part Of A Bigger Problem
Some scientists are of the view that while it’s easy to single out sunscreen as the cause of all harm, it’s only one part of a bigger problem — and that problem is climate change. “Human-caused climate change is an existential threat to the world’s coral reefs,” says Donner. “The warming of the oceans is causing the frequent ‘bleaching’ of corals, which effectively starves them to death.” Analysis by The UNESCO World Heritage Centre predicts that all 29 coral-containing World Heritage sites would cease to exist as functioning coral reef ecosystems by the end of this century unless carbon emissions are curbed. Beyond climate change, Donner points out that coral reefs are threatened by things like sewage pollution, coastal development, overfishing, invasive species, and marine viruses.
Donner believes focusing on sunscreen is like rearranging the furniture when your house is on fire. “If you want to help preserve coral reefs, start by urging your leaders to take action on climate change,” he says, adding, “then work to reduce your and your community’s footprint by thinking about the vehicle you drive, the places you stay on vacation, and the businesses you support.”
Skipping Sunscreen Isn’t The Solution
Experts are concerned consumers may be skipping sunscreen out of fear or a lack of information. The recent benzene contamination scare coupled with fear-mongering environmental headlines, it’s no wonder consumers are unclear about what is and isn’t safe. Dr. Caroline Robinson, MD, FAAD, and dermatologist and founder of Tone Dermatology feels that the impact of sunscreen bans need to be considered, as they may create premature and unnecessary fear. The discussion of safe versus unsafe, and fear-based skin care marketing disproportionately impacts those of lower socioeconomic status who still need to protect their skin. Robinson is seeing increasing concern from her patients about how products may impact their skin as well as the environment. “I think these concerns are coming from a good place, but I worry about the publicity and marketing of sunscreens lately and whether this is discouraging people from using it altogether,” says Robinson.
More Research Needs To Be Done On ‘Reef-Safe’ Sunscreens
Experts feel that the sunscreen discussion is still a gray area that requires more research. A review in the Journal of Environmental Toxicology and Chemistry looked at data from a dozen studies on the effect of sunscreen ingredients on coral, and concluded that while there is extensive proof that UV filters are found in the ocean, evidence that their presence is causing significant damage is limited. It goes on to note that it would be premature to conclude that UV filters do not negatively impact coral reefs, and that more research needs to be done to assess the impact in the marine environment. The National Academy of Sciences has convened a committee of experts to review the current research and provide an impartial assessment of where the current science is. A report of their findings is expected sometime this year.
The Bottom Line On ‘Reef-Safe’ Sunscreens
Until science delivers more definitive answers, there’s no saying with certainty what can truly be considered reef-safe, but experts agree that non-nano mineral protection is the best option for consumers. Of course, it’s second only to Ultraviolet Protection Factor (UPF) apparel, which is in fact truly reef-safe. “If you can wear a sun shirt, you are reducing by as much as 50 percent, the amount of sunscreen that ends up in the water,” says Dr. Downs. “Not only is this a conservation victory, but it is sun protection that doesn’t fail you while you are wearing it.”
Below, the best non-nano mineral sunscreen options to protect your skin without worrying about killing coral (and a vetted UPF shirt for your summer beach time).
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