Sunscreen pollution is invading the ocean - with unknown consequences 

The chemicals in sunscreens are increasingly present in the ocean, but much about their impact on marine life remains poorly understood. This is the conclusion of a new study from Plymouth Marine Laboratory and the University of Plymouth. 

With sunscreen now integral not only to health care but also to various products – ranging from personal care to industrial materials – experts worry about the large-scale release of these compounds into coastal waters and the long-term consequences for aquatic ecosystems.

“This review highlights the mindboggling range of sunscreen-derived chemicals that we know are released into coastal marine environments – and demonstrates that our understanding of the effects of these toxic compounds on marine organisms is surprisingly limited,” said co-author Frances Hopkins, a marine biogeochemist at the Plymouth Marine Laboratory.

How sunscreen pollution enters the ocean

Sunscreens use UV filters – either organic (chemical-based) or inorganic (mineral-based) – to absorb or scatter ultraviolet rays. Beyond sunscreens, such filters are added to various items including shampoos, moisturizers, lipsticks, plastics, rubber, paint, and cement, helping protect them from solar damage.

Because of modern lifestyles, these compounds inevitably find their way into marine environments through direct and indirect exposure. 

Direct exposure occurs when people swimming or diving carry sunscreen-laden water off their skin directly into the sea. Indirect exposure happens when residue is washed off during showers, laundering towels, and even through urine. 

Additionally, recycled wastewater plays a role, as some agricultural practices use treated water or sludge, which can deposit UV filter contaminants into soil and eventually run off into rivers and coasts.

Enormous scale of sunscreen pollution

Traditional wastewater treatment cannot effectively remove many UV filter chemicals. Data show organic UV filters in 95% of wastewater effluents and 86% of surface waters worldwide. 

They have been found not only in tourist-heavy beach areas but also in remote regions like Antarctica and the Arctic, highlighting their pervasive reach.

As global sunscreen sales are projected to reach $13.64 billion by 2026, researchers estimate 6,000-14,000 tons of UV filters wash into coral reef zones every year. 

Many filters, especially benzophenones, have been deemed persistent, bioaccumulative, and toxic. Benzophenone-3, in particular, is on the European Chemical Agency’s watch list as a potential hormone disruptor.

“There are increasing amounts and varieties of sunscreens entering the environment, and contaminants occur in all possible combinations,” said Awadhesh Jha, a professor in genetic toxicology and ecotoxicology at the University of Plymouth and the study’s senior author. 

“It is therefore imperative that we understand their bioaccumulation potential across the food chain, and the mechanisms through which they act at molecular and cellular levels, alone and in combination with other stressors.”

Complex chemistry with unknown effects

A single sunscreen can contain three to eight UV filter compounds, adding up to 15% of the product’s mass. Organic filters – up to 55 different types exist – work by absorbing UV radiation, while inorganic filters like titanium dioxide (TiO₂) and zinc oxide (ZnO) reflect it. 

Each compound has different properties, toxicities, and solubilities, complicating efforts to understand how these chemicals behave once in the ocean.

The study, published in the journal Marine Pollution Bulletin, involved a review of over 110 publications related to sunscreen, UV filters, and their ecological or toxicological impacts. 

The researchers note that at least 25% of a sunscreen’s UV filters wash off during swimming, and a single busy beach can see up to 35 kilograms of sunscreen deposited into the water per day.

“We are essentially sitting on a ticking time bomb,” said study co-author Mahasweta Saha, a marine chemical ecologist at Plymouth Marine Laboratory. “It is crucial to exercise caution in introducing new substances, as they could exacerbate existing challenges.”

More research is urgently needed

Despite broad commercial use, little is known about the long-term ecotoxicological effects of these compounds, especially regarding their potential to bioaccumulate in the food chain. 

Marine ecosystems already face pressures such as ocean warming, acidification, marine heatwaves, and eutrophication. The addition of poorly understood chemicals could worsen the strain on marine organisms.

“It is therefore imperative that we understand their bioaccumulation potential across the food chain, and the mechanisms through which they act,” Jha emphasized.

This includes gauging effects at the molecular level – understanding if they disrupt hormones, reproductive cycles, or growth – and how multiple stressors might interact to amplify harm.

Precautionary measures are needed

The scientists call for coordinated, science-based policy actions to address the threats of sunscreen pollution.

They recommend improved wastewater treatments to remove UV filters, the development of biodegradable sunscreens, and enhanced monitoring to track sunscreen-derived pollutants in global coastal areas.

The study further recommends adopting a precautionary approach, acknowledging that while sunscreens protect human health, they also risk harming fragile marine life including corals, fish, and other sea creatures vital to the ecosystem.

Thus, as oceans become repositories for countless chemical compounds, unraveling the complex interactions among UV filters is critical. Failing to act could intensify existing stresses on marine habitats, with possible ramifications for seafood safety and the broader health of our planet’s waters.

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