October 17, 2024

expert reaction to study on forever chemicals in bottled and tap water

A study published in ACS E&T Water looks at PFAS in drinking water. 

Prof Christer Hogstrand, Professor of Molecular Ecotoxicology, King’s College London, said:

“EFSA’s recent risk assessments of PFAS, based on epideminological studies, concluded that PFAS affects the immune system at exceptionally low levels of exposure. 

 “This has since gained support by mechanistic studies on the immune system response to these forever chemicals. The measurements of UK drinking water in the paper were from the Midlands and the concentrations don’t seem to raise a concern.  

 “It has been reported before that activated carbon removes PFAS from water. I was surprised to see their results suggesting that boiling the water reduced concentrations of some PFAS chemicals, even though it was marginal. It is difficult to explain these results since PFAS are resistant to heat.”

Prof Oliver Jones, Professor of Chemistry, RMIT University, said:

“PFAS are a family of man-made chemicals based on carbon-fluorine bonds.  They are often termed forever chemicals because they are very resistant to degradation. The name is also a little chemistry joke as the F in forever, and C in chemicals can also stand for Fluorine and Carbon, respectively. Unfortunately, the term is misleading as it implies that PFAS never break down and that if they get in your body, they are there forever – neither of which is true.

“This new research about PFAS in drinking water may initially sound scary and raise some concerns with the public. However, the authors do not claim to have assessed risk, and we should remember that the mere presence of something does not mean it will automatically cause harm. Any discussion about toxicity is meaningless without both dose and context. For example, we know you can get skin cancer from exposure to UV light, but that does not mean you will get cancer as soon as you go outside. Similarly, you will have no problem drinking a glass of water, but if you inhale the same amount into your lungs, you’ll have health risks. 

“While PFAS have been linked to a range of health effects, the concentrations of PFAS needed to cause such effects are much higher than the levels reported in this study. In some respects, the work is good news: even the highest total PFAS level reported was just 9.2 ng/L. For reference, one nanogram per litre is 1 part per trillion. This is equivalent to 1 second in 31.5 thousand years. So, yes, 9.2 ng/L is an incredibly small amount, and the risk of PFAS exposure at this level is also very small. Since the researchers only measured ten compounds, it is possible that there was more PFAS present than was reported, but the risk is still very low.

 “The other thing to remember is that PFAS are now ubiquitous in the environment, so if you look hard enough at almost any sample, you will find them. Background contamination from clothes and lab equipment is a problem when assessing PFAS at such low levels, but the authors don’t say how they accounted for this in the main part of the paper.

 “We might say, ‘Why not make the risk zero completely’? But this is impossible to achieve. There is risk in everything we do; for example, if I drive to work, there is a risk I might crash, I go for a swim, I might drown. Both are low risks, but not zero. We could never be sure PFAS concentration was zero, just that it was lower than the minimum amount we could measure. Even the recent US limit of 4ng/L for PFOS and PFOA in drinking water is not based on acceptable risk but just one that can be achieved and reliably measured. 

“So overall, while this paper is interesting it does not mean you need to avoid bottled (or tap) water”.

Dr Ovokeroye Abafe, Lecturer in Environmental Sciences, Brunel University of London, said:

“The study’s conclusions show insights into very simple contaminant reduction methods that can easily be adopted by consumers. The result provides further understanding on the distribution of PFAS in drinking water sources and shows that simple AC filtration and boiling can significantly reduce the concentrations of some PFAS in drinking water, thereby minimising exposure arising from this route.  It is interesting to see very simple and easily adaptable home solutions that can significantly minimise the concentrations of PFAS in drinking water, thereby safeguarding public health.  However, the sample size is relatively small, which is a limitation to be aware of.”

‘Factors Influencing Concentrations of PFAS in Drinking Water: Implications for Human Exposure’ by Chuanzi Gao et al. was published in ACS E&T Water at 13:00 UK time on Thursday 17th October.

Declared interests

Prof Oliver Jones: “I don’t have any conflicts of interest in this case, but I have in the past received funds from the Environment Protection Authority Victoria and various Australian Water utilities for research into environmental pollution, including PFAS.”

Dr Ovokeroye Abafe: No conflicts of interest.

Prof Christer Hogstrand: “I am co-applicant on a research proposal that is looking at PFAS in UK waters. It was submitted a couple of weeks ago. I don’t think that influenced my commentary but could possibly perceived as such.”