Sunscreen contains compounds that contribute to marine ecosystem degradation. It is for this reason that in 2021, Hawaii banned sunscreens containing the chemicals oxybenzone (BP-3) and octinoxate (Suh, et al., 2020). These two chemicals are damaging to coral reefs, which are already compromised due to anthropogenic factors, like pollution. This discussion is centred around BP-3 in particular, as it poses a genotoxicity (DNA damaging) threat to marine ecosystems due to its metabolic byproducts.
The sun emits different wavelengths of radiation. One category concerns ultraviolet (UV) light, which is composed of UVC, UVB, and UVA rays. While Earth’s atmosphere blocks most UVC rays, UVA and UVB radiation is still significant. Exposure to this type of radiation can increase the likelihood of skin cancer, atrophy, and more (D’Orazio, et al., 2013). Thus, sunscreen is used as topical protection to mitigate the impact of UVA and UVB rays. Commercial sunscreens are usually chemical-based, which operate by converting UV rays to thermal energy, or mineral-based, which operate by reflecting UV rays (Santander Ballestín and Luesma Bartolomé, 2023).
BP-3 is often found in chemical sunscreens due to its UV filtering properties, but also in products such as cosmetics and shampoos (Zhang, et al., 2023). The wide-use of BP-3 has led to residue build-up in aqueous environments and sediments, which is detrimental to aquatic life.
BP-3 is a concern particularly due to its metabolic products. For example, BP-3 can be metabolized by sea anemones, which are venomous Cnidarians that are soft-bodied, and are often found in symbiotic relationships with coral reefs (van der Burg and Prentis, 2021). One such anemone called Aiptasia, breaks down BP-3 to form phototoxic glucoside conjugates (Vuckovic, et al., 2022). Simply put, phototoxicity involves molecules that are excited to triplet states through exposure to light. These molecules can then degrade to reactive oxygen/halogen species. A research study funded by the National Science Foundation involved using BP-3 and UV light to observe Aiptasia mortality rates (Vuckovic, et al., 2022). Some of the results can be seen in Figure 1 below.
Results showcased that asymbiotic Aiptasia died quicker than symbiotic Aiptasia at 8.8 μM of BP-3. Additionally, the presence of BP-3 and UV caused the greatest drop in mortality rates, highlighting the phototoxicity dangers of BP-3.
Altogether, if organisms like Aiptasia are susceptible to chemicals like BP-3, coral reefs will undergo a similar impact as they have a symbiotic relationship. To protect coral reefs and mitigate the impact of anthropogenic factors, it is vital to consider how these factors affect smaller, yet equally as important, organisms. Steps such as limitation of tourists in endangered marine environments, and the use of reef-safe sunscreen, can be taken to attenuate the presence of BP-3 in ecosystems.
References
D’Orazio, J., Jarrett, S., Amaro-Ortiz, A. and Scott, T., 2013. UV Radiation and the Skin. International Journal of Molecular Sciences,14(6), pp.12222–12248. https://doi.org/10.3390/ijms140612222.
Santander Ballestín, S. and Luesma Bartolomé, M.J., 2023. Toxicity of Different Chemical Components in Sun Cream Filters and Their Impact on Human Health: A Review. Applied Sciences, 13(2), p.712. https://doi.org/10.3390/app13020712.
Suh, S., Pham, C., Smith, J. and Mesinkovska, N.A., 2020. The banned sunscreen ingredients and their impact on human health: a systematic review. International Journal of Dermatology, 59(9), pp.1033–1042. https://doi.org/10.1111/ijd.14824.
van der Burg, C.A. and Prentis, P.J., 2021. The Tentacular Spectacular: Evolution of Regeneration in Sea Anemones. Genes, 12(7), p.1072. https://doi.org/10.3390/genes12071072.
Vuckovic, D., Tinoco, A.I., Ling, L., Renicke, C., Pringle, J.R. and Mitch, W.A., 2022. Conversion of oxybenzone sunscreen to phototoxic glucoside conjugates by sea anemones and corals. Science, 376(6593), pp.644–648. https://doi.org/10.1126/science.abn2600.
Zhang, K., Shen, Z., Yang, W., Guo, J., Yan, Z., Li, J., Lin, J., Cao, X., Tang, J., Liu, Z., Zhou, Z. and Lin, S., 2023. Unraveling the metabolic effects of benzophenone-3 on the endosymbiotic dinoflagellate Cladocopium goreaui. Frontiers in Microbiology, 13, p.1116975. https://doi.org/10.3389/fmicb.2022.1116975