Microplastics and PFAS: combined risk and increased environmental damage

Researchers from the University of Birmingham have studied the environmental effects of microplastics and PFAS and shown that, combined, they can be very harmful to aquatic life.

Microplastics are tiny plastic particles from plastic bottles, packaging and clothing fibers. PFAS (per- and polyfluoroalkyl substances) are a group of chemicals used in everyday items such as nonstick cookware, water-resistant clothing, firefighting foams, and many industrial products. PFAS and microplastics are known as “forever chemicals” because they do not break down easily and can accumulate in the environment, causing potential risks to wildlife and humans.

PFAS and microplastics can be transported through water systems over long distances, all the way to the Arctic. They are often released together from consumer products. Yet their combined effects, as well as how they interact with other environmental polluting compounds, remain poorly understood.

To better understand the combined impact of these pollutants, the researchers used Daphnia, commonly known as water fleas. These tiny creatures are often used to monitor pollution levels because they are very sensitive to chemicals, making them ideal for determining safe chemical limits in the environment.

In this study, published in Environmental pollution, The team compared two groups of water fleas: one that had never been exposed to chemicals and another that had experienced chemical pollution in the past. This unique approach was possible due to Daphnia’s ability to remain dormant for long periods of time, allowing researchers to “resurrect” older populations with different pollution histories.

The two groups of Daphnia were exposed throughout their life cycle to a mixture of irregularly shaped microplastics – reflecting natural conditions – as well as two PFAS chemicals at levels typically found in lakes.

The team showed that PFAS and microplastics together caused more serious toxic effects than each chemical alone. The most worrying finding was developmental failures, seen in conjunction with delayed sexual maturity and growth retardation. When combined, the chemicals caused Daphnia to abort their eggs and produce fewer offspring. These effects were more serious in Daphnia historically exposed to pollutants, making them less tolerant of chemicals tested forever.

Importantly, the study found that both chemicals cause greater damage when combined: 59% additive and 41% synergistic interactions were observed on critical fitness traits, such as survival, reproduction and growth.

Lead researcher Professor Luisa Orsini highlighted the importance of the findings: “Understanding the long-term chronic effects of chemical mixtures is crucial, especially considering that previous exposures to other chemicals and threats Environmental impacts can weaken the ability of organisms to tolerate new chemical pollution.

“Our research paves the way for future studies of how PFAS chemicals affect gene function, providing crucial information about their long-term biological impacts. These results will be relevant not only to aquatic species but also to humans, highlighting the urgent need for regulatory frameworks that address unintended combinations of pollutants in the environment. Regulating chemical mixtures is a critical challenge for protecting our water systems.

Dr Mohamed Abdallah, co-lead of the research, said: “Current regulatory frameworks focus on toxicity testing of individual chemicals, primarily using acute (short) exposure approaches. It is imperative that we study the combined impacts of pollutants on wildlife throughout their life cycle. To better understand the risk posed by these pollutants in real-world conditions, this is crucial to boost conservation efforts and inform policy in the face of the growing threat from emerging contaminants such as perennial chemicals.

New chemical and biological screening tools and advances in artificial intelligence allow us to understand the complex interactions between chemicals in the environment. Revising current methods for assessing environmental toxicity is therefore not only possible but imperative. »