Interview on PFAS substitutes: ‘None of the identified materials proved to be technically feasible.’

Mr Kühne, how did the Thinktank IRS approach its AI-supported study on PFAS substitutes?

Christian Kühne: Together with the companies Carl Zeiss, Karl Storz, Mercedes-Benz, Novaliq and Richard Wolf, we analysed the functionality, i.e. the benefit dimension of the PFAS used in selected products for the sectors particularly affected by the PFAS ban, i.e. automotive manufacturers and suppliers, medical technology and pharmaceuticals. For the six benefit functions of long-term stability, chemical stability, thermal stability, light resistance, high sliding properties and biological compatibility, we have compiled the required benefit functions for each of the products analysed. PFAS are characterised by the fact that they fulfil not just one, but several important benefit functions with high quality at the same time. This is particularly important in the search for alternatives.

In a second step, we trained the CumulusAI AI system developed by TIM Consulting with over 2,000 data sets on the question of which substances could potentially replace the technical functionalities of PFAS for the selected products. CumulusAI is an analysis tool for large amounts of data and uses transformer-based language models for efficient data handling and deeper insights.

The AI analysed more than 35,000 publications worldwide and independently expanded the research framework. It focussed on the benefit function and not on the chemical structure of the PFAS. This made it possible to search not only for chemically analogue compounds, but also for any type of chemical substance that can fulfil this utility function. This also includes, for example, nanomaterials or ceramic materials. A total of 420 substances were identified and structured in 32 clusters. This initially sounded very promising.

Together with the Institute for Industrial Ecology at Pforzheim University, we then created material-specific functional profiles for the companies and assessed the substitution potential of the identified materials.

What are the main results of the research in relation to medical technology?

Christian Kühne: Using the example of a resectoscope, a medical instrument with a wire loop that ablates tissue using high-frequency current, we analysed the required use of PFAS. Fluoropolymer components are used in five different functions in resectoscopes. One of these is the use of sleeves made of the PFAS PTFE for electrical insulation of the electrodes. They guarantee a very high dielectric strength of 20 kV/mm and must be thermally stable, chemically resistant, non-stick, relatively flexible and also biocompatible - in other words, they must fulfil six useful functions at the same time.

After filtering the overall results according to the required utility dimensions, the first of the two participating medical technology companies produced a list of 36 materials and the second company a list of 20 materials. However, after analysing and studying the original sources in more detail, none of the identified materials proved to be technically feasible. All promising, accessible research approaches have already been taken into account.

PFAS are used in endoscopic devices.  ©Envato Elements

That doesn't sound very encouraging, although the media often report on research projects to develop PFAS substitutes. Are they coming too late?

Christian Kühne: The problem is not that they are coming too late. PFAS are an extensive class of compounds with very unusual but also different properties. For example, the PFAS used in medical technology are biocompatible, i.e. well tolerated by humans and harmless. At the same time, they are chemically stable. However, this chemical stability is not desirable for the environment, as they do not degrade or degrade very slowly if they are released into the environment. This conflict of objectives, this balancing act between desired and undesired properties, must also be resolved by the alternatives. At best, however, the current solutions only manage to fulfil one or more properties or functions less well. In other areas, such as technical textiles, it may be possible to do without simultaneous water and oil impermeability, but in medical technology this would be fatal.

What conclusions does the Thinktank IRS draw from the study results? What do you want to do next?

Christian Kühne: The most important realisation is that there is no equivalent substitute in certain technical areas of application. Nor do the existing research approaches show a reliable, time-definable way of developing adequate alternatives, producing them industrially and securing the corresponding certifications and authorisations. Conversely, the question arises as to what is to be achieved and whether there are alternatives. We have therefore proposed a scientifically sound risk-benefit analysis of PFAS for technical applications. 

In the medical sector, the vast majority of PFAS are released into the environment via gases. The coatings of endoscopes are not affected by this. Taking into account the health risks for the people affected, regulations on the handling and disposal of these devices would be sufficient to ensure that the PFAS used are not released into the environment. It is also common practice in other industrial sectors to handle highly toxic and ecologically risky substances with appropriate regulations and protective measures. In addition, fluoropolymers play an important role in medical technology, which in turn are considered to be much less harmful to the environment than other PFAS and should therefore be considered separately. In areas such as consumer products, I believe it is easier to dispense with the use of PFAS, especially as monitoring is much more difficult here.

In the Thinktank, we want to work together with industry, science and politics to develop a proposal or methodology for such a detailed risk-benefit analysis and ultimately an assessment.

Are the results of your project suitable for guiding upcoming EU decisions in a practical direction?

Christian Kühne: Even if we have only looked at a small section of the use of PFAS in technical products, we believe that we have made an important contribution to the discussion on PFAS alternatives. Our approach has attempted to include all alternatives that have not yet been considered. The ultimately sobering result of our study should be clear to decision-makers, at least in terms of its consequences.

The use of PFAS in areas where they pose a health risk, are easily released into the environment and, in particular, where their properties can be described as ‘nice to have’, could quickly be banned. PFAS substance classes and technical areas with no or very low risks, for example closed industrial systems with pipework coated on the inside with PFAS, medical technology or others, could be excluded. This can be done with the proposed risk-benefit analysis and assessment. At the same time, research into PFAS alternatives should be strongly promoted and expanded throughout Europe.

About the person

Dr rer. nat. Christian Kühne has many years of experience in environmental administration. He was responsible for environmental technology and resource efficiency at the Baden-Württemberg Ministry of the Environment, most recently as Deputy Head of Division. Kühne managed and coordinated R/E projects for the Federal Environment Agency and the Federal Environment Ministry, advised the administrations of Eastern European countries, Thailand and Israel in EU projects and is or was active in committees up to UN level. Since 2019, Christian Kühne has headed the Thinktank Industrial Resource Strategies, which advises policymakers and industry on key issues relating to resource efficiency, utilisation and policy. The core task of the Thinktank, which is based at the Karlsruhe Institute of Technology (KIT), is to provide scientifically sound information for decision-makers.