How Does Sunscreen Affect Freshwater Ecosystems?

There’s a good chance you’ve never heard of avobenzone, octocrylene or oxybenzone, but ultraviolet (UV) filtering chemicals like these are essential components of sunscreen, helping to protect your skin from the most damaging effects of prolonged exposure to sunlight. But what happens when these chemicals leach off the skin and infiltrate freshwater ecosystems?

One recent study from the University of Alberta in Canada attempted to find out. By examining the effects of exposure to UV filters on a single crustacean species – a water flea known as Daphnia magna – the team were able to better understand the debilitating effects that such substances can have on marine organisms. The results suggested that even brief exposure could have a detrimental impact on the animal, while prolonged exposure could lead to its death.

Unwanted side-effects of skin protection

The adverse effects of human activity on water quality is a well-trodden area of research, with the impact of agricultural run-off a particular topic of concern. However, less is known about how everyday chemicals like those which are contained in sunscreen affect the natural environment, despite the fact that swimming in both freshwater and marine environments is a common occurrence.

To learn more about this underexplored subject, researchers from the University of Alberta concentrated on how Daphnia magna coped under exposure to UV filters. Their study showed that just 48 hours of exposure interfered with the fleas’ directional awareness, preventing them from effectively navigating their environment. Two weeks in an area containing high concentrations of the substances (a not uncommon event in beach environments) resulted in their deaths.

Domino effect

While the Daphnia magna itself is a very small crustacean, the debilitating effects of sunscreen chemical exposure could potentially be felt much further up the food chain, according to the authors of the study. “This is particularly bad for a freshwater ecosystem as a whole, as Daphnia are an important part of the food chain for many smaller species of fish,” explained Aaron Boyd, lead author on the paper.

“Losing a Daphnia population would put all of the species that rely on them at risk of starvation, and in certain conditions could cause the local ecosystem to collapse.” However, Boyd did point out that the fleas were able to recover if they were removed from the affected area if their immune systems had not already been totally overwhelmed, spelling encouraging news about the resilience of such freshwater habitats.

More research needed

As is so often the case with these types of preliminary studies, the authors stress the need for further research to corroborate their findings. Future studies should concentrate on more species over a greater area and over a longer period of time to allow us to gain a greater insight into the long-term effects of UV filter exposure in such environments.

In the meantime, authorities can ensure river conservation by conducting high resolution monitoring on a continual basis. This can help to create and maintain a safe habitat for the flora and fauna living in our rivers, lakes and waterways. Meanwhile, the scientific community continues to search for UV filters which do not prove toxic to other forms of life.