Per- and polyfluoroalkyl substances (PFAS) are found in everything from firefighting foam and textiles to food packaging. They are among the most persistent chemicals known and have been linked to several serious health problems. New research from Linköping University now shows that two highly similar PFAS compounds can affect the body in markedly different ways, a discovery that could prove important for future risk assessments and treatments.
“The only difference between these molecules is the length of the carbon chain. PFNA has one more carbon atom than PFOA. Despite this structural similarity, the molecules behave very differently in biological systems.”
“Our results showed that both PFOA and PFNA cause toxicity in Drosophila melanogaster. This manifests as a shortened lifespan and negative effects on the signaling system between nerve cells. PFNA had the strongest impact on survival, while PFOA exhibited greater neurotoxicity,” says Ann-Christin Brorsson.
PFAS Found in Nearly Everyone
PFAS are often referred to as “forever chemicals” because they break down extremely slowly in the environment. Research has shown that around 99 percent of the population, including fetuses, have measurable levels of PFAS in their blood. These chemicals have been associated with a range of toxic effects, says Brorsson.
“Among other things, we see an increased risk of cancer, damage to the liver and kidneys, as well as neurotoxicity that could contribute to neurodegenerative diseases such as Alzheimer’s disease.”
“For me, it is extremely important that we can live in a world where people can feel safe from becoming ill due to environmental toxins. That is why we need to stay one step ahead and identify potential toxic effects before a substance has spread through the environment to a degree that is almost impossible to stop,” says Ann-Christin Brorsson.
Two Similar Compounds, Two Different Effects
The results show that both PFOA and PFNA are harmful to the flies. Both compounds shortened lifespan and affected nervous system function. However, despite differing by only a single carbon atom, they displayed distinctly different toxicity profiles.
PFNA had the strongest effect on survival, causing a substantial reduction in lifespan. PFOA had a smaller impact on survival but caused greater damage to the nervous system. Activity of the enzyme acetylcholinesterase, which is essential for communication between nerve cells, was significantly reduced.
“What was particularly surprising was that two chemicals with such similar structures behave so differently in biological systems. This demonstrates that PFAS cannot be treated as a single uniform group when assessing health risks.”
Developing a Biological Sensor for Contaminated Water
The research group has now received continued funding from the Swedish Environmental Protection Agency to further develop the research. In addition to studying more PFAS compounds, the team aims to map the biological mechanisms underlying the differences between PFOA and PFNA.
Ann-Christin Brorsson also wants to investigate whether there are substances that can counteract PFAS effects and to further develop the fruit fly model into a biological sensing system that could be used to assess water quality in contaminated areas.
“To protect people and the environment from PFAS, we need to understand exactly how these substances affect biological systems. In the future, that knowledge could contribute to both improved risk assessments and new ways of reducing negative health effects.”
