Forever Chemicals?

Sean Moran 06/11/2025

480 3 minutes read

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I see a lot of stuff about “forever chemicals” in the news. Perhaps the general public are unaware of the fact that “forever chemicals”, or more accurately “persistent organic pollutants” are something we dealt with back in 2001, with the Stockholm convention.

The headlines are however not about chemicals which meet the definition of persistent organic pollutants set out in the convention. The headlines are about perfluoroalkyl and polyfluoroalkyl substances (PFAS), a broad class of perhaps 7 million different chemicals, just two of which have been shown to have potential harmful effects. PFOA is classed by the International Agency for Research on Cancer as “carcinogenic to humans”, and PFOS is classed as “possibly carcinogenic to humans”, which means that just one of these 5000+ chemicals has been shown to cause human disease.

Because of this classification, both PFOA and PFOS are controlled in the UK under REACH regulations, and they are addressed by the Stockholm Convention as well, PFOS (Perfluorooctane sulfonic acid) and its derivatives since 2009, PFOA (Perfluorooctanoic acid) and its related compounds since 2019. PFHxS (Perfluorohexane sulfonic acid) and its related compounds were also listed in 2022, even though evidence for harmful effects in humans is entirely lacking.

The Stockholm Convention set rational criteria for classifying something as a persistent organic pollutant, which a very small number of PFAS meet. These are:

Bioaccumulation- some PFAS compounds are capable of bioaccumulation, many are not

Toxicity- only one PFAS compound has been shown to cause human disease (though of course, even this is dose dependent)

Long-range environmental transport- some PFAS compounds are capable of this, many are not.

So PFAS as a class fail to meet the Stockholm Convention criteria for rational concern. You’d never know from the media that this is the case, or even that the Stockholm convention exists at all.

This is hysteria, whipped up by NGOs and scientifically illiterate press. PFAS as a class include PTFE (Teflon, the stuff used on non-stick pans). Even though no-one has shown any harmful effects from PTFE, manufacturers are being pressured by consumers to remove PTFE from airfryers and other cooking equipment.

It is all rather reminiscent of the Greenpeace campaign against all compounds containing halogens some years ago. They started with campaigning for a total ban on chlorine and chlorinated organics. Now they have got round to a subclass of fluorine containing compounds.

A previous environmental issue with a class of halogenated organic compounds, chlorofluorocarbons (CFCs) was dealt with in 1989 by the Montreal Convention, and many of the chemicals which prompted the Stockholm convention were also chlorinated organics. There are lots of halogenated organics which are useful to us. There is a subset which damage the ozone layer, and a subset which are persistent organic pollutants. There’s no rational reason to ban all of the useful ones.

DDT, PCBs and other specific compounds tick all three of the Stockholm Convention’s boxes, and need to be phased out. These boxes matter because the potential for bioaccumulation means that compounds can concentrate up through the food chain.

Contamination of the environment with low levels of persistent, toxic, bioaccumulative compounds leads to toxic effects in apex predators like the raptors in Rachel Carson’s Silent Spring, or even humans. The compounds which have these three characteristics, such as DDT have low water solubility, and high fat solubility. Low concentrations in the fat of prey animals are concentrated in the fat of animals which eat them. The animals which eat those animals have higher concentrations still.

It almost doesn’t matter what the level of environmental pollution was. For everything else, it does. Without bioaccumulation, whether something is harmful or not depends on the dose an organism is exposed to. Longer chain PFAS are more likely to demonstrate bioaccumulation, those with 6 carbon atoms or less are less likely to bioaccumulate.

Setting aside the junk science used by hired gun experts in US courts, a reasoned attitude to PFAS is that further research is necessary. Reasoned attitudes are however really unfashionable. Chemophobia is the fashion, and anti-PFAS hysteria is just one strand of it. This might be something to do with how profitable it is for ambulance-chasing US lawyers, and profiteering NGOs.

The graphic is what ChatGPT served me up as a suitable illustration for the article. I know it’s wrong, but I couldn’t get Chat GPT to understand that. There may be seven million different PFAS compounds, but none of them look like those structures.