Find us on...
By Francesca Rapolla, Senior Affairs Manager, Science, CTPA
Introduction
Sunscreens play an essential role in protecting our skin from the harmful effects of UV rays, allowing us to enjoy the sunshine safely. Not only do sunscreens keep us safe, but as with all cosmetic products, their ingredients must also be safe. Cosmetics companies employ teams of expert scientists to ensure safety, and they also work with independent academics to contribute to cutting-edge scientific research. One topic which has become of interest to consumers is the potential impact of sunscreen on the environment, and particularly, the ocean ecosystem. This blog explores the current science of how UV filters interact with aquatic environments, why the issue is more complex than it may first appear, and why robust research which is relevant to the real world is essential to be able to reach evidence-based conclusions on safety.
The key message is that current scientific evidence does not show that UV filters in sunscreens are responsible for coral damage or bleaching.
Why coral bleaching happens?
Scientists, environmental organisations and governmental agencies identify climate change, particularly rising sea temperatures, as the main cause of coral bleaching1,2,3. Other factors include pollution, coastal development and overfishing, which can also contribute to the decline of coral reef ecosystems1,4.
This sets the scene for the major causes of global coral bleaching events.
There is currently no proven link between the use of UV filters in sunscreens and coral reef damage under real-world conditions. Some laboratory studies have investigated whether certain UV filters could affect corals or other aquatic organisms. However, before we can use the results from laboratory studies to conclude on what is happening in real-life, we must consider whether these studies accurately represent the real environment in which corals live.
‘The challenge of studying corals in the lab’
Corals are delicate organisms that require very specific conditions to remain healthy. In the ocean, factors such as light, temperature, water movement, food availability and water quality all influence coral health. Replicating these conditions in a laboratory is difficult, and if corals are already stressed by the test environment, it becomes harder to determine whether any observed effect is caused by the substance being tested, or by the fact that the corals are no longer in their natural habitat and are struggling to survive.
Another challenge is that many UV filters do not dissolve easily in water. This is helpful for water-resistant sunscreens which provide consumers with sun protection even when swimming in the sea, because they do not wash off. However, it creates difficulties for laboratory testing. Scientists may use other substances to help the UV filters dissolve in water, but these other substances can alter how much of the UV filter is available to corals and therefore can cause toxicity to the coral to an unrealistic extent. Many laboratory studies do not include appropriate controls, meaning that it can be difficult to know whether any observed effect is due to the UV filter, the substance to help it dissolve, or the test conditions themselves.
Concentrations are also important. Some studies use levels of UV filters that are much higher than those actually measured in the marine environment, particularly at the depths where corals live. If test concentrations are not environmentally realistic, the findings will overestimate the amount of UV filters that corals would come into contact in real life.
Finally, current conclusions about the effects of UV filters on corals are uncertain because most experiments have not been repeated to make sure that the same results happen again.
Making sense of the science
The relationship between UV filters and the marine environment remains an active area of scientific research. More studies are needed which use realistic exposure levels, suitable controls, standardised methods and repeated experiments to confirm whether results are reliable and comparable.
The cosmetics industry is actively contributing to this scientific discussion by supporting research on how UV filters enter the environment, how they behave in water, sediment and living organisms, and how laboratory testing methods can be improved5,6,7,8,9.
This work is important because conclusions about environmental impact must be based on robust scientific evidence that reflects real-world conditions.
Just one example of the cosmetic industry’s work in this area is a major global project, funded by the industry and led by the International Collaboration on Cosmetics Safety (ICCS), to accurately model how UV filters behave in both freshwater and marine environments. This work is being conducted with input from environmental scientists, regulatory bodies, and independent researchers to ensure credibility and transparency. You can read more in this scientific poster here.
Conclusion
Protecting our skin from the sun remains essential. Sunscreens are an important part of sun protection, alongside seeking shade, wearing protective clothing and avoiding excessive sun exposure during the hottest parts of the day. At the same time, it is crucial to continue improving our understanding of how UV filters interact with the environment.
Good environmental decision-making depends on sound science. For sunscreens and corals, this means recognising the major drivers of coral reef decline while continuing to investigate potential local environmental pressures using reliable and realistic research methods. The cosmetics industry is actively contributing to this scientific work because the most responsible approach is to support strong science, ensure conclusions remain proportionate to the evidence, and continue promoting safe and effective sun protection.
References
1 Hughes, Terry P., et al. "Coral reefs in the Anthropocene." Nature 546.7656 (2017): 82-90.
2 Heron et al. 2017. Impacts of Climate Change on World Heritage Coral Reefs: A First Global Scientific Assessment. Paris, UNESCO World Heritage Centre.
3 U.S. EPA. 2022. Action Plan for Restoration of Coral Reef Coastal Protection Services: Case Study Example and Workbook, Supplement to A Manager’s Guide to Coral Reef Restoration Planning & Design. Office of Research and Development, Center for Public Health and Environmental Assessment, Washington, DC; EPA/600/R-21/306. Available online at http://www.epa.gov/research.
4 Walpole, Lisa, and Wade Hadwen. "Extreme events, loss, and grief—an evaluation of the evolving management of climate change threats on the Great Barrier Reef." Ecology and Society 27.1 (2022).
5 Mitchelmore, C. L., et al. “A Critical Review of Organic Ultraviolet Filter Exposure, Hazard, and Risk to Corals”, Environmental Toxicology and Chemistry, Volume 40 (2021): 967-988
6 Moeller, Mareen, et al. "Challenges in Current Coral Reef Protection–Possible Impacts of UV Filters Used in Sunscreens, a Critical Review." Frontiers in Marine Science 8 (2021): 383.
7 Burns, Emily E., and Iain A. Davies. "Coral Ecotoxicological Data Evaluation for the Environmental Safety Assessment of Ultraviolet Filters." Environmental toxicology and chemistry 40.12 (2021): 3441-3464.
8 Duis, Karen, Thomas Junker, and Anja Coors. "Review of the environmental fate and effects of two UV filter substances used in cosmetic products." Science of The Total Environment 808 (2022): 151931.
9 Saxe, Jennifer K., et al. "Development of a novel rinse‐off method for improved sunscreen exposure assessment." Integrated environmental assessment and management 17.5 (2021): 961-966.
