Can we remove the 'forever' in forever chemicals?

With such a troubling case of substances that seemingly are everywhere, and can cause real harm to ourselves and the ecosystem, is there any way of taking the ‘forever’ out of forever chemicals? Chemistry World’s Phillip Broadwith takes us through some of the ways people are trying to deal with these problematic PFAS.

Phillip - From my point of view, the best thing to do would be to prevent them getting out into the environment in the first place. The most effective way to do that is through regulation. Beyond that, we know there's going to be some emissions. We know there already have been some emissions, so there is PFAS in the environment. We need to start to treat that. The best time to treat it is at its source. There's relatively available filtration technology that companies that produce PFAS could add to their water treatment and the water treatment works could add additionally to the things that they're already doing. Part of the problem with filtration is it's not particularly effective. You'd have to have extra different filters to what you would normally have for other contaminants, which is an extra expense. So people are reluctant to do it unless they have to. And also if you filter out the PFAS from the water, you've still got PFAS there to deal with either on your filtration material or in a separate waste stream. So it still needs to be destroyed in some way. And that's where we get to the difficult part.

Will - There do seem to be quite a few pretty out there looking schemes in order to tackle these particular chemicals as well.

Phillip - Yeah, and the problem with destroying these things is that they're really, really stable. The carbon fluorine bonds are really, really strong. That's one of the things that gives them their really useful chemistry, but it also makes them really difficult to get rid of. There are a few ways where you can destroy certain types of PFAS. You can treat them with light to try and oxidise them, try and break those carbon fluorine bonds. There's people doing electrochemistry, so you have an electrode, then you pass electricity through the molecules to try and break them down. Even people using high energy electron beams from particle accelerators. That gives you an idea of how difficult this is to break these molecules down. Part of the problem is most of these ways will break down some types of PFAS but because PFAS is a big family of compounds, lots of different compounds with slightly different properties, they all break down in slightly different ways. One of the most effective ways is to use what's called supercritical water oxidation. That's when we take water and heat it up to relatively high temperature and high pressure and we lose the distinction between a liquid and a vapour or gas, which is this state called supercritical. And then that makes a highly oxidative environment that can break down quite a lot of different types of PFAS. But that technology is very much in its infancy. It also takes quite a lot of energy and it's expensive and that kind of thing. So it's doable, but it's hard.

Will - From what you are describing, it does seem like, for the moment, we're going to be fairly stuck with these.

Phillip - Yeah, and that's why prevention is going to be the best long-term strategy. But the problem is we already have quite a lot of this stuff out in the environment. It's already contaminating various sites, particularly military and airport type sites where they use a lot of the firefighting foams that have certain types of PFAS in them. And around industrial emissions, historical industrial emissions into rivers and that kind of thing. There's a few court cases going on in the US around those. So we know it's already out in the environment. So how do we treat that? That becomes even more difficult because you then have it in soil, you have it in waterways, you have it in all sorts of different environments. It's very difficult to do a lot of these high energy, expensive techniques. So there are people looking at kind of microbial or biological ways of breaking down PFAS, developing enzymes that will break down the carbon fluorine bonds, which you could then start to maybe apply in the environment and that starts to become a way of clearing up the emissions that are already there. But again, there's a lot of things to kind of work out before you can start putting that kind of thing just out into the environment as well.

Will - Throughout all of these interviews and forays into forever chemicals, the word that keeps cropping up is uncertainty. Uncertainty of the true effect on people and the planet. And it feels justified because the real lack of long-term knowledge of this tiny omnipresent set of chemicals is well to me the most concerning aspect of this. Are you also concerned?

Phillip - Yes. Uncertainty is exactly why. It's probably true that the ecosystems of our bodies and of the environment can handle a certain amount of these without too much of a significant effect. But the problem is that they are so persistent. They stick around for so long and they will therefore accumulate unless we do something to stop them being emitted into the environment. And we don't know what the really long term effects are and we don't know how much we can take. We may already be beyond the level that is acceptable. Certainly in some places we know that we are. So that's the thing that worries me.