Toxicological risk assessment for PFAS

The material class per-and polyfluoroalkyl substances (PFAS) consists of several thousand industrial chemicals that can be used in many processes and products. The reason these substances are used so widely is that their very stable carbon-fluorine bonds result in products with special physical and chemical properties.

For example, using large quantities of PFAS in polymers ensures high chemical and thermal stability, significantly reduced wettability and excellent tribological properties. However, fluorinated compounds are also used as ingredients in many important pharmaceutical products and agrochemicals. In public discourse, PFAS are mainly associated with a wide variety of everyday products, from leisurewear and outdoor fabrics to coatings for pans and packaging, right through to paints, varnishes, fire-extinguishing agents and cosmetics. PFAS are also used in a diverse range of high-tech processes and products in the areas of medical technology, energy technology, photonics and semiconductor technology, and much more besides.

The various technical benefits of PFAS are countered by their serious impact on nature, the environment and human health. There are many risks associated with the release of these chemicals during production or after products reach the end of their service life. A range of PFAS have been clearly shown to have toxic effects on humans and the environment.

It has been proven beyond doubt that PFAS compounds accumulate and remain in drinking water, soil, foods and organisms for the long term. The high stability of these compounds is a disadvantage in this context, as it means they do not easily degrade. The term “forever chemicals” has become established in public discourse.

At Fraunhofer ITEM, we are investigating how PFAS impact people’s health. Our main objective here is to separate the PFAS family into subclasses according to their structures and physical and chemical properties, and use this as a basis for determining limits for safe amounts of ingestion for each subclass, i.e., how much can be ingested without causing health risks.

The toxicological data currently available for PFAS was mainly collected in the past through animal testing. In our projects, we are currently using a NAM-based approach (new approach methodologies); NAMs are new methods in the field of toxicology that are based on the 3R concept and include modeling techniques. For PFAS, we are developing a suitable PBK model (physiologically based kinetic model) to simulate the absorption, distribution, metabolism and excretion of these substances in the bodies of humans and animals. The simulations will allow us to predict the health risks as precisely as possible.