Sunscreens may be less harmful to aquatic ecosystems than expected

An interesting study from the University of Alberta is providing new insight into the impact of sunscreen on aquatic ecosystems.

The experts have found that sunscreens may be much less toxic to small aquatic creatures than what has been assumed in the past. The research paves the way for a better understanding of how chemicals interact in marine environments.

Sunscreen, an indispensable shield against the sun’s harmful ultraviolet rays, contains ultraviolet filters (UVFs) which are meant to protect our skin. These filters have been under scrutiny for the potential harm they can inflict on marine ecosystems. 

There is evidence suggesting that some UVFs are detrimental to corals, and as a result, places like Hawaii and Palau have implemented bans on certain types of sunscreen. 

Massive knowledge gap surrounding sunscreens

PhD candidate Aaron Boyd set out to examine the effects of these chemicals. Rather than solely focusing on individual chemicals, Boyd analyzed the interactions of the “chemical cocktail” in sunscreens.

“Researchers overwhelmingly perform studies testing the toxicity of UVFs in isolation by exposing test organisms to one chemical at a time,” said Boyd. He noted that only three percent of aquatic toxicology studies have actually investigated whole sunscreen mixtures, which he says leaves a “massive knowledge gap to be addressed.”

How the study was conducted on aquatic ecosystems

The study was focused on Daphnia water fleas, small invertebrates that are omnipresent in freshwater lakes around the globe. Daphnia serves as an indicator species that can be studied to learn how pollution may impact marine life.

Boyd compared the long-term toxicity of five different sunscreen mixtures as well as their individual UVFs on Daphnia.

Surprising results about impact of sunscreens

“We were very surprised to find that sunscreen mixtures are much less toxic to Daphnia than what would be expected based on the quantity of each UV filter present within the mixtures,” said Boyd. 

According to the study, the Daphnia could withstand long-term exposure to sunscreens containing octocrylene at concentrations over 50 times higher than what would be entirely lethal if exposed to the UVF alone.

Boyd noted that the rate of new chemical development and release is alarmingly faster than scientific investigation into the consequences of such contamination. He emphasized the importance of utilizing limited research resources judiciously by identifying which contaminants are truly harmful.

“We found that the other components of the sunscreen mixtures reduced the toxicity to such a large extent that perhaps these chemicals are not a contamination concern in most environments,” explained Boyd. This finding is significant as it suggests that previous studies may have been overestimating the toxicity of individual UV filters in aquatic environments.

“Regardless of any potential environmental toxicity of sunscreens, always wear sunscreen when going outside for an extended period of time,” said Boyd. “The threat of cancer is much more severe than the potential effects that sunscreen contamination may cause!”

Sunscreen and corals

Sunscreen and its potential impact on coral reefs have been a significant topic of concern in recent years. Many sunscreens contain chemicals, like oxybenzone and octinoxate, which are known to be harmful to coral reefs.

These chemicals are found in many popular sunscreens as they effectively protect our skin from harmful ultraviolet rays. However, once they wash off in the ocean, they can cause damage to marine life.

When people wearing sunscreen go swimming in the ocean, some of the sunscreen washes off and remains in the water. As a result, these chemicals can reach high concentrations, particularly in popular swimming and snorkeling spots.

Coral bleaching

Research has shown that these chemicals can exacerbate coral bleaching, a phenomenon that occurs when corals under stress expel the algae living within their tissues, causing them to turn white. 

Coral bleaching is primarily caused by rising sea temperatures due to climate change. Still, the presence of harmful chemicals such as those found in sunscreen can make corals more susceptible to bleaching and disease.

Stunted development 

Moreover, sunscreen chemicals can have a detrimental impact on the early developmental stages of corals. 

Studies have shown that these chemicals can deform and kill coral larvae, reducing the ability of coral reefs to recover from other threats such as climate change, overfishing, and habitat destruction.

Legislative action 

These discoveries have led to legislative action in several parts of the world. For instance, in 2018, Hawaii became the first US state to ban the sale of sunscreens containing oxybenzone and octinoxate, with the law taking effect in 2021. Palau, a Pacific Island nation, has also banned sunscreens containing these harmful chemicals.

To mitigate these harmful effects, researchers and companies are exploring alternatives to traditional sunscreens, such as “reef-safe” sunscreens, which do not contain oxybenzone or octinoxate. However, it’s crucial to understand that the term “reef-safe” is not regulated, and the effectiveness and safety of these alternatives are still under scrutiny.

While this issue is complex and multi-faceted, reducing the use of harmful sunscreen chemicals is one way that individuals can help protect our oceans and the diverse life they support. Nonetheless, it’s still crucial for us to protect our skin from the sun’s harmful rays, so finding a balance is key.

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