Forever chemicals are a sticky issue

Chemists are currently at loggerheads about the definition of per- and polyfluoroalkyl substances (PFAS), also known as forever chemicals. The International Union of Pure and Applied Chemistry, the world authority on chemical terminology, is currently attempting to standardise PFAS’s definition. But some chemists are pushing back over concerns that a standardised definition will exclude certain groups of harmful chemicals, with knock-on effects to environmental protection. So what are forever chemicals and should we be worried about them?

A strong bond

PFAS are a huge group of compounds (depending how you count, there are between 4700 and 7 million), which are all artificial. They all have fluorine atoms attached to an alkyl group, creating a very strong fluorine–carbon bond that makes them tough and resilient.

There are also subgroups with specific traits. For instance, fluorosurfactants have parts that are hydrophilic and hydrophobic, meaning they can repel both water and oil. This makes them perfect for applications that need to be non-stick, water resistant and stain resistant. Scientists use them to create firefighting foams for use on oil fires at airports and at major incidents – these foams work by forming a buffer layer that starves the fire of oxygen from the atmosphere.

The dark side to PFAS

There are two major problems with PFAS. The first is thanks to the very reason that we use them: that hard-to-destroy fluorine–carbon bond. While they aren’t really ‘forever’ chemicals, they can linger in the environment for decades and accumulate in animals and soil.

PFAS are a great example of the two-sided coin of chemistry: it can be both useful and problematic

Which brings us to the second problem: the reason for the limits. As PFAS begin to accumulate, they start to pose a danger to human health. Scientists have linked them to a host of issues, including thyroid disease, certain types of cancer, liver damage, high cholesterol, fertility problems and dangers to unborn children.

There is already an international effort to begin to phase out PFAS and clean up our environment. Such initiatives have worked before with different chemicals. We have pulled together globally to stop chlorofluorocarbons damaging the ozone layer, and to stop using leaded petrol in cars as it was causing lead poisoning around the world.

But limiting the use of PFAS is going to require a lot of effort. Currently, the most common way to combat PFAS pollution in water is adsorption, using a solid such as activated charcoal. The chemicals attach to the solid’s surface and remove it from the water (this is also how cat litter works). Other options include filtering PFAS out with membranes that act like a sieve or even blasting them apart with bolts of plasma.

Ultimately, we might need all of these options. PFAS are a great example of the two-sided coin of chemistry: it can be both useful and problematic, and we must always consider all aspects, from manufacture to disposal, when we make a new scientific breakthrough.