PFAS is a collective term for a wide range of chemicals whose properties are similar in some ways but different in others. Yet they are seen as a group because they share one key problematic property and that is that they hardly biodegrade at all. They persist in the environment. Forever chemicals. This means that their other properties can also lead to increasing problems. The following sections outline the key practical, harmful and chemical properties. 

Practical properties

PFAS are extremely strong compounds and it is in part due to this that they offer unique combinations of properties, such as abrasion resistance, heat resistance and resistance to moisture, grease, dirt and chemicals. These properties or combinations offer scope for thousands and thousands of applications.

Key applications of PFAS:

  1. Use as an ingredient or auxiliary material in industrial applications: for example in coolants, air condition systems and heat pumps. PFAS are also used in spray cans, insulation materials, medicines and pesticides.
  2. Use as a protective coating to repel water and grease: for example in textiles, pans, fast food packaging, mobile phones, solar panels, wind turbines, components of engines and planes, medical devices and implants, as well as munitions, guitar strings, dental floss, contact lenses and laboratory equipment.
  3. Use as a surfactant (providing a soap-like effect): for example in extinguishing agents, dyes, personal care products and also in floor, car and ski wax. In inks and dishwashing detergents.

The list of applications is practically endless. This wide range of applications means that PFAS are found in various waste streams and in sewage water. PFAS have also been detected in recycled products such as paper and compost.

Harmful properties

The immense strength of PFAS compounds means they are very resistant to degradation and difficult to handle in waste incineration. Measurements have shown that these substances occur widely in our environment. Among PFAS compounds, there are also many that are difficult to eliminate from the environment.

Non-biodegradability is the overarching property shared by all PFAS, including the many PFAS that are currently still poorly understood. Other properties vary from PFAS to PFAS. 

  • Disperse quickly and easily (mobile)
  • Accumulate in the human body, animals and plants (bioaccumulative)
  • Produce harmful effects in humans and the environment (toxic)

Harmful effects include impacts on the immune system, reproduction and the development of unborn children. PFAS may also adversely affect the blood and liver, and can cause cancer. In nature, PFAS can impact birds, mammals and other animals at the top of the food chain.

Chemical properties

PFAS is short for per- or poly-fluorinated alkyl substances. In principle, this covers all substances that include at least 1 perfluorinated methyl (-CF3) or methylene (-CF2-) group. Chemists can use these groups to create variants. Quite a lot of variants in fact. The Organisation for Economic Co-operation and Development (OECD) devised a definition for PFAS in 2021. There are currently 10,000 different compounds that meet this definition.

Definition of PFAS (OECD, 2021)

PFASs are defined as fluorinated substances that contain at least one fully fluorinated methyl or methylene carbon atom without any H/Cl/Br/I atom attached to it), i.e. with a few noted  exceptions, any chemical with at least a perfluorinated methyl group (–CF3) or a perfluorinated  methylene group (–CF2–) is a PFAS.