Is Sunscreen Protecting Us at the Cost of Corals?

Illustration by  Angelo Esperanzate

Illustration by Angelo Esperanzate

Some scientists believe that sunscreens can do more damage to coral reefs than climate change.

Coral reefs are home to nearly one million species of fish, invertebrates, and algae. Today, bleaching caused by global warming is a major problem for reefs around the world.

But another insidious threat is damaging corals and reefs: sunscreen.

A typical bottle of sunscreen can has chemical or mineral ingredients that serve as ultraviolet (UV) filters. These mix into ocean water, washing off when the user goes swimming. Recent studies have detected these UV filters in coastal waters, sediments and marine life, including fishes, mollusks, and corals.

While there’s no exact magic number on the damage coral bleaching sunscreens have caused so far, about 6,000 to 14,000 tons of sunscreen get into coral reef areas annually. It doesn’t take a scientist to know it has a tremendous impact. (Although they can tell you.)

What makes sunscreen damaging?

The first study on the impact of sunscreens on coral reefs proved the observation that large human presence in beaches in has negative effects on marine ecosystems. 11 years since then, the indications that sunscreen, whether organic or mineral, adversely affects coral reefs are mounting.

Oxybenzone and octinoxate are just a couple of the active chemical ingredients that stunt coral growth and speed up coral bleaching. Oxybenzone, in particular, has been intensely scrutinized for its effects, outlined by the International Coral Reef Institute (ICRI).

What about “reef-friendly” alternatives?


The increasing studies on sunscreen’s impacts on marine ecosystems are undeniably crucial.

The label “reef-friendly” surfaced with the awareness of reef-toxic sunscreen ingredients. Chemicals were replaced with minerals that were reportedly eco-friendly. But does the science back it up?

Mineral ingredients are particles that sit on top of the skin, blocking UV rays instead of being absorbed.

Marine ecologist Cinzia Corinaldesi says that even mineral-based UV filters can result to coral bleaching. Together with other researchers, she found that some mineral-based, eco-friendly sunscreens are just as harmful to coral reefs as the chemical ones. Their recently published study showed that zinc oxide actually causes “severe coral bleaching, damaging hard corals and their symbiotic algae.”

The debate on protection

In response to the sunscreen findings, Hawaii became the first state to prohibit the sale of sunscreens with oxybenzone and octinoxate. The bill, passed in May 2018, will become law by January 2021.

Six months later, Palau, which has one of the largest marine reserves in the world, followed suit. It would ban the sale or use of chemical sunscreens that damage coral reefs. Key West in Florida and Bonnaire in the Caribbean have voted for similar bans while certain destinations in Mexico have asked tourists not to use chemical sunscreens.


But the sunscreen bans amid an inchoate body of research have some medical experts taking a cautious approach on the issue. Dermatologists are especially concerned that more people will be at risk of skin cancer if sunscreens are continued to be negatively associated with reef damage.

Clinical assistant professor of dermatology Seemal Desai says the environmental damage is not a reason to skip the sunscreen, given the alternative human cost. “There is no denying the link between UV rays and skin cancer, so not wearing sunscreen would certainly be harmful to the individual patient.” Other groups also say that such bans are premature unless adequate, extensively-researched and approved alternatives are needed before such bans are put in place.

There are no sunscreens really proven to be safe for corals or marine ecosystems. And the unfortunate truth is that there aren’t many sunscreen options that can address the issues outlined earlier—yet.

In the Pharmacy at the University of Florida, a group of researchers is working on a “natural sunscreen” made from shinorine, a UV-absorbing ingredient collected from algae. Another research team from Puerto Rico is creating “biodegradable beads that could soak up oxybenzone from oceans” which could help in high-tourism areas. Scientists are also exploring a thin film made from the DNA of salmon sperm, which was found to block UV rays.


What can we do?

Protection of our reefs by reducing the amount of harmful sunscreen in our waters will require the cooperation of governments, conservationists, scientists, reef managers, travelers, divers, snorkelers and swimmers, and the tourism and pharmaceutical industries.

But as travelers, we can also do our part. Here are some tips from National Geographic and Chasing Coral.

Research your accommodation. Does your resort have strategically shady spots or beach tents that suits your activities? Or do they provide awnings or rent umbrellas you can use? You can also check if your resort offers eco-kits that may include sunscreen with ingredients with less or minimal impact.

Make our outfit your first line of SPF defense. Hats, head covers, shirts, cover-ups and other UV-protective clothes can trim down the amount sunblock you need by up to 90%—plus they’re reusable!

Be a conscious sunscreen buyer. Read the ingredients and make sure that oxybenzone and octinoxate are not present. Your chosen product should have no nanoparticles: particles must be above 100 nanometers in size so that corals can’t ingest them. You can consult the Consumer Products Inventory for this. Avoid buying spray sunscreens or aerosols since a good chunk of the particles settle on the sand and get to the water easily.

Keep yourself updated on the studies and on the important lists. As we’ve mentioned, this is a developing field. While what truly is reef-safe is still being verified, Haereticus Environmental Lab publishes an annual list of sunscreens with less environmental consequences. The Environmental Working Group scored sunscreens and moisturizers with SPF values considering their environmental footprint.

Protection of our reefs through reducing the amount of harmful sunscreen in our waters will require the cooperation of governments, conservationists, scientists, reef managers, travelers, divers, snorkelers and swimmers, and the tourism and pharmaceutical industries.