Scientists at the Norwegian University of Science and Technology (NTNU) have found that PFAS can interfere with gene expression during duck embryo development, altering the activity of vital organs and affecting long-term survival after hatching.
Growing global concerns
PFAS (per- and polyfluoroalkyl substances) are synthetic chemicals valued for their resistance to heat, water, and grease.
Due to its durability, it is widely used in everyday items such as nonstick cookware, waterproof clothing, food packaging, firefighting foam, and antifouling coatings. However, the same durability means it lasts for decades in nature.
Thousands of PFAS variants continue to circulate around the world, even though the toxicity of some well-known compounds has already led to bans.
These chemicals have been found in a variety of environments, including drinking water supplies and snow-covered surfaces at ski resorts, and are a remnant of their former use in ski wax.
Despite their ubiquity, the biological risks posed by many of these new PFAS compounds remain largely unknown.
Testing PFAS effects directly in duck eggs
To understand how new PFAS variants affect early development, NTNU researchers turned to mallard duck eggs.
Studying wild populations is notoriously complex because birds in the wild are exposed to a variety of external pressures, from fluctuations in food availability to virus outbreaks, and these variables can obscure the effects of chemical exposure. Clearer vision was obtained in a controlled laboratory environment.
The research team obtained eggs from duck farms and introduced two recently detected PFAS compounds directly into the eggs. The third group was exposed to PFOS, a well-known variant of PFAS that is already banned due to its toxicity.
After drilling small holes and injecting chemicals, the researchers sealed the shells with wax and incubated the eggs for four weeks.
The goal was to mimic natural exposure. In the wild, PFAS pass from hens to eggs. This means that contamination starts from the earliest stages of life.
3 organs, 3 different reactions
Once the ducklings hatched, the researchers analyzed three organs essential for healthy development: the liver, the heart, and the sac fabricus, an organ unique to birds that is central to building the immune system.
By examining changes in gene expression, they were able to pinpoint which genes were switched on or off as a result of PFAS exposure.
Liver: disruption of fat metabolism
The liver showed the most obvious signs of destruction. Ducklings exposed to the new PFAS variant showed changes in genes that regulate fat processing.
The timing of fat storage is critical for mallards, which must conserve energy prior to breeding season and long migrations. Interference with these metabolic pathways can reduce a bird’s ability to reproduce and survive in harsh conditions.
Heart: surprisingly stable
In contrast to previous findings in other species, little immediate change in gene activity was seen in the heart.
The relative stability in this study was unexpected, as other PFAS compounds have been linked to heart development problems in animals, including humans. However, researchers note that subtle or long-term effects may only emerge later in life.
Immune system: early warning signals
The dough sack told a different story. All ducklings exposed to one of the three PFAS substances had abnormal activation of genes associated with early detection of the virus.
This gene typically acts as a front-line sensor for infectious diseases, raising the possibility that PFAS will put the immune system into a potentially unnecessary state of alarm.
It is not yet clear whether this response strengthens resistance to disease or burdens the body with chronic stress.
The next step will be to monitor birds’ resilience to real pathogens, such as avian influenza, which is a major global threat to wild bird populations.
Impact on EU regulations
This discovery came at a pivotal moment. The EU is considering whether to regulate PFAS as an entire class, rather than seeking to phase out individual compounds.
There are thousands of variants that share similar chemical structures, so testing and restricting them one by one is time-consuming, expensive, and likely inefficient.
New research suggests that even lesser-known PFAS may reflect biological disruptions caused by well-studied and already banned compounds.
This strengthens the argument for a unified regulatory approach, especially since PFAS persist in the environment for decades and accumulate across ecosystems.
Threats from the first moments of life
The study highlights growing concerns among environmental scientists. PFAS risks are not limited to long-term accumulation and can begin at the earliest stages of an outbreak.
With evidence that PFAS can alter gene expression in embryos, the chemicals could have health effects long before birds encounter the outside world.
As policymakers consider a wide range of restrictions, researchers emphasize the importance of further research that mimics natural conditions.
Given the tenacity and global reach of PFAS, the stakes are much more than a duck egg. These permanent chemicals can impact wildlife populations from the animal’s first heartbeat, long before it takes its first breath.
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