“Forever chemicals” have scientists worried for some time now. Named so because of their near indestructibility, this group of per- and polyfluoroalkyl substances (PFAS) is used to make almost everything—from packaging boxes to cookware. Some 14,000 chemicals have been classified as PFAS so far. Being near immortal, they keep moving around the environment and have been found in human blood. PFAS are endocrine disrupters and linked to cancer. A paper in Nature Geoscience in April 2024 looks at global presence of PFAS and finds that 31 per cent of the groundwater samples tested, which were not near any obvious source of PFAS contamination, had the chemical present in levels considered harmful to human health.
In an interview with Down To Earth, one of the authors of the paper, Denis O’Carroll, who is a professor of civil and environmental engineering at Australia’s University of New South Wales, tells why the presence of PFAS could still be an underestimation. Excerpts:
Why are PFAS a big concern?
PFAS do not break down readily when they get into the environment. They move around in our waters and in the atmosphere and sometimes stick to soils. But they also desorb [get released after being absorbed] from soils. This way, PFAS travel around the world. That is why we are concerned about them.
We wanted to see how pervasive PFAS are in source waters, internationally. We already know that they are in our waters in Australia [which has no manufacturing site]. Doing a global study would help us compare and look at levels around the world.
PFAS were recently listed under Stockholm Convention that aims to protect human health and the environment from persistent organic pollutants that remain intact in the environment for long periods. Has this affected their prevalence?
Countries that have signed the Stockholm Convention would not make PFAS, like perfluorooctane sulfonic acid and perfluorohexane sulfonic acid. We are also seeing PFAS levels in our blood decline, which is good. The concern is if we are making other types of PFAS that are not regulated yet.
What makes regulation of PFAS challenging?
Manufacturers slightly modify the molecule. These are not regulated. And there is the issue of potential accumulation of other PFAS molecules that we probably do not know about, or which conceptually could exist, but may not have been studied for their transport, fate in the environment or toxicity. We need to figure out which PFAS chemicals are out there, which ones are being made, where do they go, how pervasive they are and their impacts.
Your study finds that Australia, China, Europe and North America are hotspots for PFAS in surface water and groundwater. Do you expect developing countries to also emerge as hotspots if testing is done there?
Absolutely. If these chemicals were made, used, or brought in as consumer products, they would be present. I think, we need to do more testing and measure PFAS in a wider range of our waters. Test if they are in our drinking waters. We need to do more work to identify what types of PFAS are out there as well.
Your study says that the PFAS definition continues to evolve, and the extent of underestimation would be a function of its definition. Could you elaborate on that?
Different organisations define PFAS. Depending on the definition, they would incorporate more (or less) chemicals into the PFAS class. For example, perfluorooctanoic acid has a lot of fluorine atoms in it. But if you just have one, would that still fall into the PFAS class?
If a compound has one fluorine atom, does it still come with some health impacts?
That is the question. So, some pharmaceuticals use PFAS with limited fluorine atoms in them. They would use it for beneficial purposes in the body. So, certainly, a limited number of PFAS can have an impact, but the ones that are regulated are more fluorinated (they have more fluorine atoms). And we do not know the toxicity of the different ranges of PFAS. Only a limited number have been studied so far.
Does this mean that all the 14,000 chemicals classified as PFAS have not been studied for their health impacts?
No. PFAS receives attention, but it takes a lot of time to look at that many chemicals. More funding certainly could be useful to look at the health impacts and the environment impacts.
This was first published in the 16-31 December, 2024 print edition of Down To Earth