Is Regular Sunscreen Killing Our Coral Reefs?

Slip, slop, slap, and welcome to the most recent ‘sucks to be a coral reef’ fact.

Made of chemicals arrogant enough to pick a fight with the sun, it turns out sunscreens are also tough enough to have a go at the most bullied plant at school for ten years in a row now.

Sunscreen, an unlikely badboy of the cosmetic world, has been caught in laboratory situations being a big old ‘endocrine disruptor’, transforming planulae (jellyfish, corals, sea anemones) into a ‘deformed, sessile’ state, and promoting ‘viral infections’ too.

According to a study of local mediterranean stony corals conducted by the Italian Dipartimento di Scienze of Università Politecnica delle Marche,“Sunscreen products commonly used by tourists to protect their skin… can affect tropical corals causing extensive and rapid bleaching.”

Cinzia Corinaldesi, one of the researchers, talked to Dreamland about the situation.

Cinzia says her team is increasingly proving sunscreens are harmful and when introduced into marine coast areas, especially during summer.

“[Sunscreens] cause a threat to biodiversity and ecosystem function, which can further increase their vulnerability to climate change,” she said.

What ingredient in sunscreen is doing this?

There are two ingredients that come up when you Google this issue: Oxybenzone and octinoxate.

Most recently, Hawaii introduced a bill (to come into effect in 2021) banning sunscreens containing these two chemicals from their State:

“The legislature finds that two chemicals contained in many sunscreens, oxybenzone and octinoxate, have significant harmful impacts on Hawaii’s marine environment and residing ecosystems.” [S. B. NO. 2571]

The bill proposes it to be unlawful to sell any hygiene or personal care product which contain the two chemicals without requiring a prescription.

The move will affect “at least 70% of the sunscreens” on the United States market today, according to the Consumer Healthcare Products Association.

The advice now is to switch to mineral sunscreens which rely on UV blocking natural ingredients such as zinc oxide (ZnO) and titanium dioxide (TiO2) to work.

Good advice five years ago… not the best today.

The study mentioned at the start of this article, which was released in October 2018, examined whether the above mineral ingredients had the same effect as oxybenzone and octinoxate.

“Our results demonstrate that uncoated ZnO [zinc] induces a severe and fast coral bleaching due to the alteration of the symbiosis between coral and zooxanthellae… Conversely, Eusolex® T2000 and Optisol™ [modified forms of zinc] caused minimal alterations in the symbiotic interactions and did not cause bleaching, resulting more eco-compatible than ZnO,” it said.

Basically, not all zinc-based sunscreens are good for the environment. See the difference effects threes popular zinc products have on coral health below.

Before and afters: The Control (no chemical), Zinc Oxide (used in mineral sunscreens), Eusolex T2000 (a modified form of titanium-dioxide), Optisol (a modified form of titanium-dioxide)
 Credit: Impact of inorganic UV filters contained in sunscreen products on tropical stony corals (Acropora spp.) (2018) Credit: Impact of inorganic UV filters contained in sunscreen products on tropical stony corals (Acropora spp.) (2018)

Mr Screen’s assorted crimes

It is also important to note, that toxic UV blockers in sunscreens are not just entering waterways off the backs of swimmers, but through sewage when sunscreen is showered off.

At least one study has taken the ‘ability to cause coral bleaching’ trait and theorised sunscreen ‘potentially’ plays ‘an important role in coral bleaching in areas prone to high levels of recreational use by humans’.


Why isn’t this being taken as seriously at home?

Closer to home, the outlook on sunscreen is a bit more laid-back, with the Australian Institute of Marine Science telling Dreamland they are not currently undertaking any research into sunscreen’s toxic effects.

Yes, they are aware of sunscreen’s toxic classification, but the AIMS considers this “low on the list of toxic issues for coral on the Great Barrier Reef”.

Bleaching from warming waters, crown-of-thorns starfish, and cyclones are all considered greater threats to local reefs than the collective sunscreen runoff of a measly five million Queenslanders.

This is partly because Hawaii receives double that number per year in visitors alone – and all those people are crammed in a far fewer beaches than we enjoy on the Australian east coast.

We talked to someone smarter than us on this point: Ecotoxicologist Dr Andrew Negri.

“Given that sunscreens are only moderately toxic (where data is available) and the likely exposure to most tropical marine life is low, a ban on sunscreen use in Australian now would be premature.” Dr Negri said.

“The Australian scientific community has been aware that sunscreens are potentially an emerging risk for a decade. However, other potential stressors such as climate change, nutrients, sediments and pesticides have been considered to represent more of a threat to coral reefs.”

“More research is needed to test the toxicity of a wide range of sunscreens, including “natural” sunscreens to relevant marine species. When these toxic “threshold” are compared with concentrations measured in the sea we will be able to properly assess their comparative risk,” Dr Negri said.

For the record: The threshold at which guilty chemicals start having an effect is recorded in a 2015 Israeli study as one drop per six-and-a-half Olympic-sized swimming pools.

Wait a minute, it’s been a thing for a decade, you say?

The first study to demonstrate sunscreen’s effect on corals begun many, many years ago now – 2003 to be exact.

It took five years for the study to be completed and published in 2008 in the U.S. peer-reviewed publisher Environmental Health Perspectives.

That first study concluded: “Sunscreens cause the rapid and complete bleaching of hard corals, even at extremely low concentrations. The effect of sunscreens is due to organic ultraviolet filters, which are able to induce the lytic viral cycle in symbiotic zooxanthellae with latent infections.”

In that same year, when these sunscreen allegations first hit the broader scientific communities desks, Mexico begun restricting sunscreen use in closed waterways such as their underground rivers and near popular reefs.

In 2020, Palau, one of the wealthiest island nations in the pacific, will become the first country to ban reef-toxic sunscreens completely.

So what are we to do?

The official advice on sunscreen use is conflicting.

Australian scientists see no problem with continuing to use regular sunscreen:

“We have no idea if switching between sunscreens makes any difference to sea life,” Dr Negri said when we asked him if changing sunscreens was recommended.

“Cover up as much as possible with clothing and continue to use effective sun protection on exposed skin.”

Associated Professor Cinzia Corinaldesi offers her own suggestions for choosing sunscreens:

“I’m confident that things will change in the future but we all must be more careful in reading the ingredients before buying a sunscreen that could cause severe harm to marine life.”

“Eco-compatible products (containing only ingredients which do not affect marine organisms) are already available in the market. So, it is possible to combine the need for healthy human skin and the conservation of marine environment. We have just to use effective, alternative and eco-compatible sunscreens or protecting ourselves using a nice long-sleeve t-shirt!”

Professor Corinaldesi also offers one final piece of parting advice:

“Beware of fake commercial sunscreens labelled as ‘reef safe’, ‘eco-friendly’ or ‘biodegradable’! Sometimes, most of them are not safe at all for marine life, and indeed they have been never tested on marine organisms.”

This article was written by Daneka Hill.

Outside of attempting to get a solid ten hours sleep, Daneka enjoys looking at books (not reading, looking), eating all manner of stone fruit, and finding herself in unbelievable situations (you wouldn’t believe how many times that’s happened). She’s from North Queensland and is currently working in the Pilbara.

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