As summer approaches, so does the annual dilemma: which sunscreen to use? Will it be good for the skin? Can it be used long-term? We know that while the sun is essential for life, excessive and improper exposure to it can be highly harmful. In fact, according to data from the Spanish Association Against Cancer, the incidence of skin cancer has increased by nearly 40% in the last four years, with approximately 78,000 new cases diagnosed annually in Spain. These figures underscore the importance of making an informed decision about sunscreen while also adopting other vital measures, such as avoiding prolonged exposure during peak hours, wearing protective clothing, hats, and sunglasses.
Amid this array of questions and the countless products available on the market, a growing concern has emerged over recent years—one as relevant as personal health but less familiar to many consumers: the environmental impact of many sunscreens on aquatic ecosystems.
The Environmental Impact of UV Filters
UV filters, the chemical compounds that protect us from UVB and UVA radiation, have been detected in the most remote corners of the planet, from Antarctica to Pacific coral reefs. Closer to home, these substances have been found in the eggs of wild birds in Spain’s Doñana National Park, according to a 2017 study by IDAEA-CSIC.
White Stork | Florian Dormann
“This is a significant finding because it shows that the contaminant was transferred by the mother before laying the eggs, even before the bird developed and was exposed to the environment,” explains Dr. Silvia Díaz Cruz, lead author of the study and a Principal Scientist at the Institute of Environmental Assessment and Water Research (IDAEA-CSIC).
The issue goes beyond sunscreens. UV filters are also found in cosmetics, paints, textiles, and other products, contributing to their increasing presence in our environment and their direct impact on both our health and natural surroundings. IDAEA has recently, for the first time, detected 11 chemical compounds in the umbilical cord blood of newborns, including UV filters and parabens commonly used in sunscreens and other cosmetics. This study builds on previous research by Dr. Díaz Cruz that identified these compounds in placentas and breast milk.
What does the presence of these compounds in organisms mean?
Effects on Ecosystems
The global impact of UV filters is especially evident in vulnerable ecosystems like coral reefs and shallow waters. Increased tourism and water activities concentrate these products, causing coral bleaching, growth deformities, and other alterations. UV filters also reduce algal density by restricting photosynthesis, deform bivalve shells, disrupt immune systems, and impair fish fertility and mobility, among other effects.
In the Mediterranean, UV filters pose a serious threat to Posidonia oceanica, an endemic seagrass essential for maintaining clear waters, preserving sediment dynamics, and acting as a habitat for numerous marine species. Studies have shown that chlorophyll inhibition reduces the density and size of Posidonia meadows in the Balearic Islands, which decreases CO₂ absorption and oxygen production. Smaller meadows leave marine organisms with fewer places to live, while exposed seabeds become more vulnerable to erosion, impacting both marine environments and coastlines.
Posidonia oceanica. Benjamin Jones | Coral reefs. Naja Bertolt Jensen
Impact on Human Health
Research indicates that some UV filters are endocrine disruptors—chemicals that interfere with hormonal systems. These disruptors can mimic, block, or alter the action of natural hormones, potentially leading to adverse health effects. Hormones regulate essential body functions, including growth, development, metabolism, and reproduction.
“Chemical filters like benzophenone-3 (oxybenzone), previously the most widely used UV filter globally, increase the risk of endometriosis, infertility, and complications during pregnancy and childbirth,” notes Dr. Díaz Cruz.
The researcher also points out that avobenzone, another common filter in sunscreens and other personal care products, may interfere with the natural action of oestrogen and promote the development of childhood obesity.
What to look for on sunscreen labels?
Scientific evidence identifies certain compounds commonly found in mainstream products that should be avoided. While banned in places like Hawaii, Palau, Bonaire, Thailand, Mexico, the Marshall Islands, and the Virgin Islands, substances such as benzophenone-3 (oxybenzone or BP3), ethylhexyl methoxycinnamate (octinoxate or EHMC), and octocrylene (OC) remain legal in Europe. Octocrylene is currently under review by the European Chemical Agency (ECHA), with France considering reducing its permissible levels in sunscreens.
Dr. Díaz Cruz recommends using products with inorganic (mineral) compounds like titanium dioxide (TiO₂) and zinc oxide (ZnO), provided they are not in nanoparticle form, as nanoparticles can penetrate cell barriers. If not indicated on the label, consumers need not worry about this issue.
It is contradictory to use potentially hazardous products to shield ourselves from the sun when science offers the tools to develop safer alternatives for both consumers and the environment. While legislation moves to eliminate harmful substances, consumers can make proactive choices about which products to buy and avoid, exerting additional pressure on industries and policymakers. It is crucial to remember that human, animal, and plant health are interconnected and directly tied to ecosystems. Therefore, it is best to use products scientifically proven to be safe.
If public initiatives, such as the free distribution of sunscreens in public spaces being considered by Spain’s Ministry of Health, are implemented to reduce melanoma and other skin cancer rates, they should also account for environmental considerations. Informed decisions, guided by scientific research, will be key to ensuring both human and environmental health.
Iria Sambruno
Communication and Outreach
