What are PFAS?
Per- and poly-fluoroalkyl substances (PFAS), are a large group (more than 12,000 in number) of man-made chemicals characterised by their strong bonds.
These chemicals are exceptionally stable, which means they don't break down easily, even when exposed to high temperatures, and they persist in the environment - hence the name ‘forever chemicals.’
They also have the unique ability to repel both grease and water. To be destroyed, they have to be incinerated at temperatures above 1,100°C which requires specialised processing facilities.
Where are PFAS found?
Since their introduction in the 1940s, PFAS have been used in a wide range of products and applications, such as non-stick coatings (e.g., Teflon), water and stain-resistant treatments for fabrics (e.g., in waterproof jackets), in food packaging and cosmetics (e.g., sunscreen, makeup, and hair products), as coatings on smartphones and solar panels and in cleaning products for floors and cars. They're used in electronics, firefighting foams, aviation, oil production, mining, and even in some pesticides.
Unlike PCBs (polychlorinated biphenyls - used within everyday items such as electronic devices, paints, cements, sealants, adhesives, and pesticide products), which were banned decades ago but still impact the environment today, PFAS are still not outlawed, but are already persistent in our natural world, and their health impacts on marine and human lives are not clear.
How do PFAS make their way into our waters?
PFAS can end up in the environment through two main ways: direct and indirect sources. Direct sources are when they are released into the environment during the entire life cycle of products containing PFAS, during manufacturing, product use, and when these products are disposed of.
One direct pathway for PFAS into the environment is, for example, from firefighting foams used in training exercises and to extinguish liquid (e.g., petroleum) fires. Indirectly, PFAS are also formed as a result of the breakdown of other substances.
The extent of contamination in local areas is often linked to how close they are to industrial sites where PFAS are used (like the paper and textile industry) and the use of PFAS-based firefighting foams at places like airports, military sites, or landfills.
However, not all PFAS contamination can be traced back to industrial activities, waste disposal, or accidental releases. Sometimes, they are found in rivers that aren't near PFAS manufacturing sites, such as the Thames.
PFAS concentrations measured in the Thames have been found to be 10.8 times above what is currently considered to be safe. This suggests that they're coming from sources like everyday consumer products. For example, PFAS can enter the water system when we wash school uniforms treated with PFAS to make them stain resistant or when we rinse off hair conditioners that contain these chemicals.
PFAS are highly mobile in water. Once they get into the environment, whether from manufacturing or seeping out of consumer products, they tend to move around in water and stay intact for a very long time. This enables them to travel over long distances and they have been found in remote and ecologically significant regions like the Arctic and Antarctic.
For more information on the science of PFAS and how they affect cetaceans, see this report by wildlife charity Whale and Dolphin Conservation.