PFAS and “forever chemicals”: the facts, the myths, and the uncertainties
- PFAS are found in almost 100% of human samples, although the specific molecules and their concentrations vary.
- The toxicity of PFAS does not depend on their quantity and, given the impossibility of assessing their toxicity, the European Chemicals Agency (ECHA) has been tasked with examining a request for a total ban on PFAS submitted by five EU countries.
- On 27th February 2025, France voted to phase out certain products containing PFAS from 1st January 2026.
- Given the bioaccumulation and biomagnification of PFAS through the food chain, humans are likely to be more exposed to them via their diet.
- Certain PFAS (a few dozen) deserve the label “forever chemicals” as no degradation process has been identified in the environment, whilst the majority of the others undergo transformations that make them more stable, potentially rendering them indirectly persistent and, over time, “forever chemicals”.
PFAS, an acronym for per- and polyfluoroalkyl substances, are a family of molecules characterised by the presence of carbon chains and fluorine atoms in their chemical formula, which gives them strength and stability. This property is widely utilised in industry and everyday consumer products (pesticides, non-stick coatings, insulation, clothing, food packaging, etc.). Conversely, once released into the environment, these molecules become dangerous “forever pollutants”. Pierre Labadie, a CNRS researcher in environmental chemistry at the University of Bordeaux, focuses on the presence of PFAS in water and sediments, as well as their transfer to living organisms.
1# We all have PFAS, or “forever chemicals”, in our bodies
TRUE
When testing for PFAS in human samples, they are found almost 100% of the time, while specific molecules and concentration levels vary. We often see hair samples featured in the media, as they are less invasive, but in epidemiological studies, blood and urine samples are preferred as they reflect circulating levels at the time of collection.
UNCERTAIN
Some PFAS are polymers – i.e. macromolecules – that are too large to pass through our cell membranes. They are, for example, used in the medical field (implants, prostheses, etc.). However, recent and preliminary studies show that some of them can degrade or fragment and generate smaller molecules, which are far more toxic! During in vitro tests, Teflon nanoparticles were absorbed by human cells, disrupting their metabolism.
2# PFAS present in small quantities are less toxic
FALSE
Risk assessment is carried out by cross-referencing the concentration and the level of hazard posed by the molecule. Not all PFAS have the same level of toxicity. We only know the toxicity of around ten of them, out of a family made up of thousands of molecules. For the vast majority of PFAS, we simply have no information on their level of hazard. This is, in fact, what prompted European regulators, notably via the European Chemicals Agency (ECHA) 1, to examine a request for a total ban on PFAS submitted by five EU countries, based on the realisation that it is impossible to assess the toxicity of PFAS on an individual basis.
UNCLEAR
There is a lack of toxicological reference values (TRVs), which prevents the implementation of appropriate protective measures. The ANSES has launched a working group to define these TRVs for an extensive list of PFAS, including in particular the compounds most frequently detected in humans 2. Current emissions have changed and are no longer comparable to those of 30 years ago: whilst the compounds are not necessarily less toxic, they are, however, less bioaccumulative in living organisms. But this does not mean that these compounds do not have toxic effects!
3# We know the effects of PFAS on our health and the health of living organisms
This true, false and unclear all at the same time. Our understanding of the effects of PFAS is very limited: as mentioned, it is a very large family. However, a number of toxic effects have been confirmed or are suspected in humans.
The French Agency for Food, Environmental and Occupational Health & Safety (ANSES “L’Agence nationale de sécurité sanitaire”)3 lists on its website the known harmful effects of PFAS on humans: increased cholesterol levels, cancers, effects on fertility and foetal development, and impacts on the liver, kidneys, thyroid system, etc.
The European Food Safety Authority (EFSA) is monitoring four PFAS in particular, considered to pose the greatest potential health risk: PFOS, PFOA, PFNA and PFHxS4. Contamination is thought to occur mainly through food, particularly meat, seafood, fruit and eggs.
The International Agency for Research on Cancer (IARC) has classified the first two of these PFAS as “carcinogenic” (for PFOA5) and “potentially carcinogenic” (for PFOS 6)
On 27 February 2025, France voted to phase out certain products containing PFAS from 1st January 2026, notably: cosmetics, ski coatings and non-professional clothing waterproofing agents7. A ban extended to textiles from 1st January 2030.
UNCLEAR
In the field, correlations can be established between biological effects on living organisms and the level of PFAS contamination in the environment. However, without the controlled conditions of a laboratory, it is more difficult to determine causal links. PFAS are not the only micropollutants present in the environment. Multi-exposure remains a factor, with cocktail effects.
Another important aspect to assess is the bioaccumulation and biomagnification of PFAS through the food web. Humans, considered to be top predators, are likely to be more exposed via their diet, though this depends on what we eat, the drinking water we consume, potential occupational exposure, and so on.
Since January 2026, a European directive has made it mandatory to monitor PFAS in water intended for human consumption. It is estimated that this contamination accounts for around 20% of our exposure to these pollutants, depending on the sampling locations and the method of drinking water production8.
4# PFAS are everywhere and will be there forever
TRUE
Certain PFAS (probably a few dozen) deserve to be called “forever chemicals” because, to date, science has not identified any degradation processes in the environment. Emissions of these types of PFAS are therefore cumulative, over extremely long timescales.
For the majority of remaining PFAS: there are transformation processes that break the molecules down into more stable PFAS, hence our first category. A PFAS can therefore be indirectly persistent, due to the degradation of the reactants of which it is composed. If we wait long enough, they all become eternal pollutants.
Currently, there are already considerable stocks of PFAS in soils, sediments, groundwater, and all environmental compartments… And these constitute secondary sources of emissions of these pollutants. Identifying the kinetics of these transformations is a major research challenge: at what rates, into which compounds, and under what conditions?
UNCLEAR
In reality, it is important to consider the entire life cycle of these molecules. If we take the well-known example of kitchenware: under normal conditions of use, new non-stick pans do not pose a problem.
But upstream, industrial sites that synthesise or use these fluorinated polymers can be major sources of pollution due to poorly controlled emissions.
At the end of their life, these household items are very often incinerated as household waste at insufficient temperatures. In reality, we should be using hazardous waste incinerators that reach 1,300 or 1,400 degrees! Industrial lobbies highlight the lack of alternatives and promise progress on end-of-life management and recycling. As an environmental chemist, I feel like saying, “It’s about time!”
