The EU is considering introducing a blanket ban on the man-made chemicals called PFAS because of the risks they pose. Researchers have now found that these substances can even alter the genes of birds before they hatch.
These substances are called 'forever chemicals' because they break down very slowly in the natural environment. Some people may know them by the abbreviation PFAS, which stands for per- and polyfluoroalkyl substances. They are also very abundant.
"These substances are used in hundreds of products, ranging from frying pans and waterproof clothing to firefighting foam, food packaging and stain-resistant coatings," explained Anne-Fleur Brand, who until recently was a PhD research fellow at the Norwegian University of Science and Technology (NTNU).
As a result, PFAS can be found across large parts of the world. They have been found in drinking water and in cross-country ski tracks because PFAS was previously used in ski wax. It is a large group of chemicals, and some of them have already been prohibited because they are so toxic. But not all of them.
"Thousands of forever chemicals are still in use," said Brand.
Little is known about their harmful effects, but researchers have now discovered that these substances can harm ducklings even before they have hatched.
Investigated chemicals in duck eggs
"We studied two new PFAS chemicals that were recently found in wild duck eggs. These chemicals are known to exist in the natural environment, but very little is documented about their effects," said Professor Veerle Jaspers at NTNU's Department of Biology.
They conducted the experiments under controlled laboratory conditions. Carrying out these types of experiments in the great outdoors is very difficult because wild birds are exposed to so many influences. These include factors such as viruses, irregular food supply and changes in the environment.
"We therefore investigated mallard duck eggs in the laboratory," explained Jaspers.
The eggs were collected from a duck farm. The researchers drilled small holes in the eggs and injected them either with one of the two new chemicals or with the PFAS compound PFOS, which is already prohibited because it has been proven to be harmful.
The method replicates the way eggs are infected in the wild, where the chemicals are transferred from the mother to the egg.
The researchers then sealed the eggs with wax and placed them in an incubator for four weeks until they hatched.
Organs were affected
"As soon as the ducklings hatched, we collected samples from three important organs," said Brand.
The three organs were:
- The liver, where chemical metabolism and detoxification take place.
- The heart, which is vulnerable during development.
- The bursa fabricii, an organ unique to birds, which plays a key role in the development of the immune system.
"We investigated gene expression in these organs, meaning we looked at which genes were turned on and off," said Brand.
The three organs were affected differently.
The liver
The genes that regulate fat metabolism in the liver changed in the ducklings that were exposed to the two new PFAS substances. This is highly significant.
"Mallard ducks need to store and use fat according to a specific schedule that aligns with both the breeding season and migration. If their fat metabolism changes, it could reduce their chances of surviving or reproducing," explained Brand.
The heart
"The heart was largely unaffected. This surprised us because other PFAS compounds have previously been shown to affect heart development in other animals, including humans," said Brand.
However, she emphasizes that the tests were conducted so early in the development of the ducklings that some harmful effects might not have appeared until later instead.
The bursa fabricii
In the bursa fabricii immune organ, the researchers discovered something interesting. It applied to ducklings from all the eggs that were exposed to any of the three substances.
"We found increased activity in a gene that normally helps detect viral infections," said Brand.
This gene is part of a kind of alarm system that normally provides an early warning signal regarding viral infections. Computer simulations had already predicted this reaction, and the researchers were able to confirm that it also occurs in reality.
"We do not yet know if this helps or harms the birds," said Brand.
It can signal that the body has increased its readiness to fight infection, but it can also show that the body's immune system is stressed even if it is not necessary.
"To find out, we need to monitor the birds as they grow and see how they can withstand real viruses. This applies to viruses such as bird flu, which poses a major threat to wild birds.
Key findings
"Our findings show that even new forever chemicals can produce effects similar to those we already know from PFOS.
The EU is therefore considering regulating all PFAS as a group rather than each individual compound. This is simply because the whole group is potentially dangerous. All the substances have a very similar chemical structure.
"Our findings support the demands to regulate all forms of PFAS. Prohibiting them one by one is both expensive and time-consuming," explained Jaspers.
Before this can happen, however, researchers and decision-makers need more data, especially from experiments that resemble conditions in the natural environment. Therefore, this research will be very important.
The researchers highlight that since the substances remain in the natural environment for such a long time once released, caution is paramount.
"Forever chemicals do not just have long-term consequences. They are a problem right from the very beginning of life," wrote the researchers in their article.
Reference:
Anne-Fleur Brand, Silje Peterson, Louisa M S Günzel, Kang Nian Yap, Tomasz M Ciesielski, Céline Arzel, Veerle L B Jaspers, Gene expression changes in ducklings exposed in ovo to emerging and legacy per-/poly-fluoroalkyl substances , Environmental Toxicology and Chemistry, 2025;, vgaf213, https://doi.org/10.1093/etojnl/vgaf213
