Today’s beach outing is not the same as your grandparents’ beach outing: With intense summer heat waves now the norm due to climate change, and with the ozone layer still not fully healed, people need more and better sun protection when outdoors.
Sunscreen offers proven protection from sunburn and skin cancer — but it’s also often comprised of a cocktail of ingredients including chemicals that scientists warn are a growing source of environmental pollution.
Much of this concern focuses on a variety of ingredients known as ultraviolet (UV) filters. Sunscreens typically come in two forms: organic (using chemicals to absorb solar radiation), or inorganic (using zinc oxide and titanium oxide to reflect away solar radiation).
An estimated 6,000 to 14,000 metric tons of UV filtering chemicals are released annually into coastal regions with coral reefs. And in recent years, scientific evidence of sunscreen chemicals harming sensitive marine ecosystems has accumulated, resulting in a series of local, regional and national bans of some chemical ingredients to protect living reefs.
Experts now underline that these concerns go far beyond coral reefs.
In a 2025 paper, researchers at Plymouth Marine Laboratory in the UK outlined how some sunscreen chemicals impact a host of marine organisms at a molecular, cellular, individual or community level. Studies show that UV filters are linked to effects on enzyme growth, endocrine disruption, reproductive issues and more. UV filters can affect not only coral, but species of seagrass, fish and other marine life.
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There are multiple axes of toxicities associated with the petrochemical sunscreens, ranging from reproductive development toxicities to neurotoxicity to increased risk for mutagenicity and carcinogenicity and then endocrine disruption.
Craig Downs, executive director, Haereticus Environmental Laboratory
The researchers are calling for an “urgent investigation” of the wider impacts on marine life. “If there’s a risk that these chemicals can harm coral and other marine life, if there’s less harmful compounds out there that we can use instead, then we need to establish what they are,” says Anneliese Hodge, a Ph.D. student at Plymouth Marine Laboratory and lead author of the 2025 paper. “We need to research that … and figure out the alternatives.”
Experts emphasise that sunscreen ingredients number among the many thousands of other synthetic pollutants that leak into the environment annually, most of which haven’t been tested for safety. Scientists have already assessed that humanity has crossed a “safe operating space” for chemical pollution and release of these “novel entities.”
In addition, there are preliminary findings that some chemicals used in some sunscreens may also impact human health — though those findings are still cloaked in uncertainty due to a lack of long-term ecotoxicological testing. These early findings have given rise to an “anti-sunscreen” movement in the media that experts say must be addressed with caution to avoid misinformation.
Sunscreen’s environmental toll
UV filters are known as a “pseudo-persistent pollutant.” Over time, they will degrade, though some may break down into more toxic forms. However, the speed of degradation is being outpaced by the rapid and consistent rate at which they’re flowing into the environment.
Sunscreen chemicals wash off beachgoers’ or sunbathers’ bodies or enter the environment via wastewater. Many treatment facilities can’t remove them, meaning that potentially vast quantities of wastewater effluent contain UV filters. This pollution load reaches environmentally concerning levels during the Northern Hemisphere’s peak summer holiday season.
It’s not only sunscreens that are responsible; UV filters are present in an array of cosmetics and also released by various industries, says Lenka McGachy, professor of environmental chemistry at the University of Chemistry and Technology, Prague.
This ubiquity makes them a common pollutant in waters across the world, even in far-flung locales like Antarctica.
Numerous studies have outlined the ways in which corals, seagrass, fish and other marine organisms are susceptible to sunscreen chemical ingredients. Studies show they can prompt coral bleaching, impact zooplankton hatching or development rates, and cause impairments to the structure of sea urchin sperm. Other research has found UV filters in species like rainbow trout, threatened loggerhead turtles and dolphins.
But knowledge gaps remain, say experts. A 2025 paper notes “significant or complete data gaps for acute and chronic exposure data” of organic UV filters for freshwater “amphibians, sediment organisms, aquatic fungi and other rarely tested organisms.”
Craig Downs, an ecotoxicologist and executive director of the Haereticus Environmental Laboratory in the US, emphasises that these contaminants are found not only in coastal waters but also in freshwater lakes and streams. “There are multiple axes of toxicities associated with the petrochemical sunscreens,” he says. “Ranging from reproductive development toxicities to neurotoxicity to increased risk for mutagenicity and carcinogenicity and then endocrine disruption.”
A troubling, largely unanalyzed brew
Sunscreen pollution poses a big problem for researchers: It isn’t happening in a vacuum. It exists in the environment alongside a host of other contaminants, and how they all interact remains unknown. “When you have a complex mixture of chemicals, like what you might have at a wastewater effluent site, it can potentially increase the overall impact on the organism,” Hodge says. Sorting out interaction impacts is challenging.
For example, one troublingly recent study found that sunscreen chemicals, including ethylhexyl methoxycinnamate (EHMC), can bind to plastics in the environment and slow their degradation.
“It’s as if [EHMC] acts like a ‘biofilm stabiliser,’ shielding the plastic and its microbial inhabitants from natural degradation processes,” study co-author Sabine Matallana-Surget, a professor of environmental molecular microbiology at the University of Stirling, UK, wrote in an email. “Plastic already takes up to a century to degrade in the ocean; if it’s covered by stabilising biofilms triggered by co-pollutants like EHMC, its persistence could be even longer.”
Equally worrying is that this comingling can create a “co-pollution scenario” with the microbial communities that cling to plastic-UV filter surfaces, posing a risk to marine ecosystems and human health. If marine organisms ingest these plastics, they not only face harm from the physical plastic, but also from the chemicals coated and absorbed by it.
There’s still another concern, says Awadhesh Jha, a professor of genetic toxicology and ecotoxicology at University of Plymouth: The bioaccumulation of UV filters and other chemicals in marine species may end up being consumed by people.
An estimated “4.3 billion people are reliant on fish for 15 per cent of their protein intake,” he says. “Safeguarding production of healthy seafood in the changing environment is crucial for the sustainability of aquaculture industries.”
Coral- and reef-safe, or not?
Experts are urging stricter regulation of sunscreen marketing, noting that while some readily available sunscreens branded as “reef-safe” or “coral-safe” don’t contain chemical UV filters, these brands often don’t come with actual evidence of meeting safety goals.
These labels, in some instances, amount to little more than greenwashing, according to experts. Studies suggest that a number of sunscreens branded reef- or coral-safe are “a bit less toxic than the not environmentally friendly sunscreens,” but are still toxic, says Pedro Echeveste De Miguel, a marine microbial ecologist at the University of the Balearic Islands, Spain.
For many products, these claims are made without adequate toxicity testing or proof to validate them. “That’s really concerning. It misleads consumers into thinking that they’re doing the right thing,” Hodge says.
There’s also a need to challenge assumptions and claims that inorganic mineral-based sunscreens are always better for the environment than formulas using organic UV filters. A recent paper found that “coral-friendly” sunscreens containing zinc oxide (a mineral formulation) caused severe impacts to soft and hard corals, as compared to “reef-safe” formulas containing organic UV filters that caused mild or no effects.
“This shows why credible, standardised testing is urgently needed,” says Johanna Leonhardt, director of operations at Soneva Conservation & Sustainability in the Maldives, who was part of the study. She also emphasises that ecotoxicology testing must not only include individual ingredients, but also full formulation testing, and that companies should fully disclose active filter ingredients.
A sensitive topic
While sunscreens can have real environmental impacts, misinformation is also rife. Social media has recently given rise to an avid anti-sunscreen movement spreading unsubstantiated claims that these products cause a range of diseases, including cancer.
That being said, there are concerns among experts regarding studies finding that chemicals used in sunscreens (such as avobenzone, oxybenzone, octocrylene and ecamsule), when applied to the skin, can enter the bloodstream. Similarly, research suggests inorganic sunscreens containing nanoparticles can get into the blood. But still other studies suggest these chemicals may have no impact and are safe, though more research is needed.
A major health concern for both people and marine life is the potential for endocrine disruption linked to some chemicals. As with the environmental concerns, much of the human health focus has coalesced around two ingredients: oxybenzone and octinoxate.
“This isn’t just about damaging coral. These compounds have the potential to damage health, to cause problems with human health,” says Greg Kearns, associate dean for research at Texas Christian University’s Burnett School of Medicine in the US
“No studies been done to say this amount of this sunscreen and this chemical causes this injury or illness,” Kearns cautions. “But we know the potential exists. And if the potential exists, that begs the question in science, do we need to know more about this? I think the answer is, yes.”
Studies suggest that a range of chemicals — including oxybenzone, ethylhexyl methoxycinnamate (octinoxate) and 4-methylbenzylidene camphor — should be avoided during pregnancy due to their endocrine-disrupting potential. Research published last year found that sunscreen ingredients like phenols and parabens could also increase the risk of hypertension during pregnancy.
In 2021, the US Food and Drug Administration assessed that only zinc oxide and titanium oxide are “generally recognised as safe and effective,” noting that 12 other ingredients didn’t meet FDA criteria due to lack of data. Elsewhere, the EU has placed limits on the use of oxybenzone and homosolate. Recently, the Australian government flagged the same chemicals for restrictions due to health concerns.
All these data put users worried about environmental and potential health effects in a tricky spot, especially given that specific ingredients and concentrations are often not listed on product bottles or squeeze tubes.
David Andrews, acting chief science officer at the Environmental Working Group, a research and advocacy nonprofit, says that ultimately it’s not “an all-or-nothing type equation” for sunscreen users. “We know getting sunburned is bad and sunscreen is one of those tools against that,” he says.
His organisation suggests using mineral-based sunscreens first as the safest option — both from a health and environmental perspective — but also stresses that, ultimately, decisions on use should be based on what works best for each person.
Others such as Hodge agree that although several studies suggest mineral UV filters may be less acutely harmful than some organic filters, but uncertainties about particle behaviour and sub-lethal effects mean further research is required.
“Sometimes the narrative when we discuss sunscreens and its impact on marine life, it quickly … steers towards people thinking that we’re telling them that they can’t wear sunscreen, and that they think it needs to be a choice between harming marine life or getting skin cancer,” she says. “I think it’s important that consumers do know that we’re not telling them to not wear sunscreen.”
Screening your sunscreen
Experts Mongabay spoke to agree that changes are needed in the way sunscreens are made and regulated to better protect people and Earth. Industry and manufacturers also must do much more to ensure and prove the safety of their products.
“We support much needed efforts to do a more comprehensive review of health and environmental concerns,” Andrews says. “That includes substantiating the safety and toxicity of these sunscreens during long-term usage.”
He underlines that this is not a call for people to abandon sunscreen use, but for consumers to educate themselves and scrutinise ingredients, and make use of traditional techniques to manage exposure to the sun. “You don’t want to overly rely on sunscreen,” he notes, stating that appropriate clothing, sun hats and seeking shade are important in sun protection.
Downs, from the Haereticus lab, says more urgent innovation is needed to formulate safe sunscreen. “If you want to make sunscreen safe, then you need an active ingredient that can be [used] at high doses, doesn’t absorb systemically into the skin and doesn’t cause toxicity,” he says. “Some of the mineral sunscreens, if they’re made correctly, could meet that demand.”
Others emphasise the use of “green chemistry” principles to ensure ingredients don’t persist or cause harm. New formulations, some using natural ingredients, hold promise.
But in Downs’ view, real change won’t happen without prompting from governments and regulatory bodies. “If you were to say in four years or five years, we’re going to ban petrochemical sunscreen chemicals, like they’ve done in Palau [a Western Pacific island nation], you would get a serious investment and activity in true green chemistry innovation to find a hopefully toxicologically safer ingredient and one that doesn’t persist in the environment.”
An industry move is currently underway to add sun protection factor (SPF) boosters to products to reduce the volume of UV filters used. While this would cut the UV filter pollution load, shifting from one chemical to another without testing for impacts is potentially problematic. “We don’t really know the full extent that some of these compounds can also have on the marine environment,” Hodge says.
“We really need more evidence and more research to fully know exactly what we need to be switching to,” she says. “And we need to find that healthy balance between providing sufficient sun protection whilst also ensuring that our sunscreen ingredients are environmentally conscious.”
This story was published with permission from Mongabay.com.