A new study indicates that the overall effect of so-called ‘forever chemicals’ is more detrimental to the environment when they are present together than when they are studied individually.
Researchers from the University of Birmingham explored how microplastics and PFAS impact the environment, finding that their combined presence can significantly harm aquatic organisms.
Microplastics consist of minuscule plastic fragments that originate from items like plastic bottles, packaging, and fabric fibers. PFAS (Per- and Polyfluoroalkyl Substances) refer to a category of chemicals commonly found in household products such as non-stick cookware, water-repellent apparel, firefighting foam, and a variety of industrial goods. Both microplastics and PFAS are referred to as “forever chemicals” because they resist decomposition and accumulate in the environment, posing risks to wildlife and humans alike.
Both PFAS and microplastics can be carried over long distances via water systems, reaching even remote areas like the Arctic. They often get released together through consumer products. However, the combined effects and their interactions with other environmental pollutants are still not well understood.
To gain insight into the joint impact of these pollutants, the researchers utilized Daphnia, also known as water fleas. These tiny organisms are effective for monitoring pollution since they are sensitive to chemicals, making them suitable for assessing safe chemical thresholds in the environment.
The study, published in Environmental Pollution, contrasted two groups of Daphnia: one that had not previously encountered chemicals and another that had been exposed to pollution in the past. This innovative method was made possible by Daphnia’s ability to enter dormancy for extended periods, enabling the researchers to “bring back” older populations with various pollution histories.
Both Daphnia groups were exposed to a mixture of irregularly shaped microplastics—reflecting natural environmental conditions—along with two PFAS substances at concentrations typically found in lakes, throughout their entire life cycle.
The research team found that the combination of PFAS and microplastics resulted in more severe toxic effects compared to when each chemical was tested alone. Particularly alarming were the developmental failures noted, along with delayed reproduction and reduced growth rates. The interacting chemicals led Daphnia to abort their eggs and yield fewer offspring. These adverse effects were more pronounced in Daphnia that had previously encountered pollutants, indicating that they had diminished tolerance to the tested forever chemicals.
Notably, the study revealed that the duo of chemicals inflicted more harm in combination—59% of interactions were additive, while 41% were synergistic across crucial fitness factors such as survival, reproduction, and growth.
Professor Luisa Orsini, the lead researcher, highlighted the significance of these findings: “It is essential to grasp the long-term effects of chemical mixtures, especially considering that past exposures to other chemicals and environmental pressures may impair organisms’ ability to cope with new chemical threats.
“Our research sets the stage for further investigations into how PFAS chemicals influence gene functionality, offering vital information about their long-term biological consequences. These results are pertinent not only to aquatic life but also to humans, emphasizing the urgent need for regulatory systems that consider the unintentional combinations of pollutants in the ecosystem. Regulating chemical mixtures poses a critical challenge for safeguarding our water resources.”
Dr. Mohamed Abdallah, co-lead of the research, stated: “Existing regulatory systems typically emphasize testing the toxicity of standalone chemicals, largely via short-term exposure methods. It is crucial to examine the combined effects of pollutants throughout the life cycles of wildlife to achieve a better understanding of the real-world risks posed by these contaminants. This knowledge is vital for guiding conservation initiatives and informing policy as we face the increasing challenge of emerging pollutants like forever chemicals.”
Recent advancements in chemical and biological screening, aided by artificial intelligence, enable us to analyze intricate chemical interactions in the environment. Therefore, revising current methodologies for evaluating environmental toxicity is not only feasible but necessary.”
