PFAS have a wide range of different physical and chemical properties. They can be gases, liquids, or solid high-molecular weight polymers. They are sometimes described as long-chain and short-chain as a way to group PFAS that may behave similarly in the environment. PFAS are also grouped into subgroups in various other ways based on their structure. 

PFAS are widely used as they have unique desirable properties. For instance, they are stable under intense heat. Many of them also have surfactant properties and function, e.g., as water and grease repellents. 

Some of the major industry sectors using PFAS include aerospace and defence, automotive, aviation, textiles, leather and apparel, construction and household products, electronics, fire-fighting, food processing, and medical articles. 

Over the past decades, global manufacturers have started to substitute long-chain PFAS with shorter-chain PFAS or with non-fluorinated substances. This trend has been driven by the fact that the undesired effects of long-chain PFAS on human health and the environment were assessed and recognised first by scientists and authorities around the globe. Short-chain PFAS can also have similar or other properties of concern. 

All PFAS are highly persistent in the environment. In fact, they are known to persist in the environment longer than any other man-made substance. As a consequence of this persistence, as long as PFAS continue to be released to the environment, humans and other species will be exposed to ever greater concentrations of PFAS.  Even if all releases of PFAS would cease tomorrow, they would continue to be present in the environment, and humans, for generations to come.

Their release and mobility in water and air causes contamination to groundwater and drinking water, which is difficult and costly to avoid. Certain PFAS are known to accumulate in the bodies of living things and cause toxic effects. Certain PFAS are toxic for reproduction and can harm the development of foetuses. Several PFAS have been demonstrated to cause cancer. Some PFAS are also suspected of interfering with the human endocrine (hormonal) system, but testing in this area is ongoing. 

PFAS are released into the environment from direct and indirect sources, for example, from professional and industrial facilities using PFAS, during use of consumer products (e.g. cosmetics, ski waxes or clothing) and from food contact materials. Humans can be exposed to them every day at home, in their workplace and through the environment, for example, from the food they eat and drinking water.