What are PFAS used for?

Per- and polyfluoroalkyl substances or PFAS are a group of chemicals that have been used in manufacturing and added to consumer products since the 1950s. They allow grease and dirt to slide off carpets and textiles, protect industrial equipment from heat damage and corrosion, and help to smooth and condition the skin.

They are also used in jet engines, medical devices, refrigeration systems, the construction industry and electrical devices.

However, they can take hundreds or even thousands of years to degrade after the products they have been used in are thrown away. This means that if they leak into the soil or water, which they often do, they could remain there for centuries.

They can also move around, meaning you don’t need to live close to a chemical factory or landfill site to be exposed to them. And they can accumulate in the tissues of living things, including humans, over time. This is concerning because at least some PFAS have been linked to health issues such as high cholesterol, impaired immunity and various cancers.

However, there are thousands of these chemicals, and while the toxicity of some of them is well established, others are potentially less toxic, or they haven’t been studied, so we don’t know if they are harmful.

Do we really need them?

Often there are alternatives. For instance, consumer products such as frying pans or school uniforms don’t need nonstick or stain-resistant coatings to be effective. Cast-iron or stainless-steel pans also work, while a wet sponge quickly removes most stains.

Manufacturers can also develop chemical substitutes, such as PFAS-free firefighting foams that are now being used at many commercial airports, including London’s Heathrow. However, creating them takes time, and there are some chemicals with important industrial applications for which substitutes don’t currently exist.

Transitioning to alternatives too quickly could also create further problems. “There are some things that we will still need to be waterproof or stain-proof, and if we ban PFAS too fast there’s a chance that we could end up using a different product that is also persistent and bioaccumulative,” says Stephanie Metzger, a policy adviser on sustainable chemicals at the UK’s Royal Society of Chemistry. “We need investment and research into alternatives that are both effective and verified as being better for us.”

What are the main ones to look out for?

There are three main types of forever chemicals: fluorosurfactants – soap-like molecules that are widely used in industry and are also added to some paints, varnishes and firefighting foams; fluoropolymers – long, plastic-like chains of carbon and fluorine with wide-ranging consumer applications (the most famous being the nonstick chemical coating Teflon); and fluorocarbons – small-molecule gases or liquids, used in refrigerators and air-conditioning systems.

Neither fluoropolymers nor fluorocarbons have been proven to cause direct harm to consumers, but they may cause problems once their useful lives end and they start breaking down into other PFAS.

The most notorious fluorosurfactants are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). When news articles talk about the toxicity of PFAS, they are often referring to these substances, because there is convincing evidence that they are harmful. One study, which included data from about 69,000 people, concluded that there was a probable link between PFOA exposure and diagnosed high cholesterol, chronic kidney disease, liver disease, ulcerative colitis, thyroid disease, testicular and kidney cancer, and pregnancy-induced hypertension (high blood pressure).

Because of this, the use of PFOA and PFOS is banned or severely restricted under a global treaty called the Stockholm convention. However, this has led to their replacement with different chemicals, some of which may also be harmful.

Do I need to worry about exposure from everyday items?

PFAS are everywhere, from rainwater and Arctic ice to the sewage sludge farmers spread on their fields. They have also been detected in the blood of up to 99% of Americans. While many scientists are concerned about these chemicals, they stress that the direct risk posed by many of the PFAS-containing products in our homes is likely to be low.

“The biggest risk is not from household products,” says Metzger. “The bigger potential route for harm is through drinking contaminated water and potentially through food; there are movements to phase out the use of PFAS in food packaging because that comes into contact with what we eat. It is a more direct link to our bodies than, say, a carpet that’s been treated to be stain-resistant.”

The environmental charity Fidra found PFAS in food packaging collected from eight out of nine major UK supermarkets and 100% of the takeaways that it tested – with significant levels detected in cookie and bakery bags, microwave popcorn packaging, pizza boxes, takeaway bags and compostable moulded fibre takeaway boxes.

In theory, PFAS could also get into your body through cosmetics or personal care products, particularly those applied to the eyes or lips.

Despite these concerns, the strongest predictor of having high levels of PFAS in your body appears to be living in an area with a heavily contaminated water supply. PFAS can get into drinking water through discharge from manufacturing plants, the use of certain firefighting foams at, for example, airports or military bases near water sources, or runoff from landfill sites. Last year, the Guardian reported on the legal discharge of large amounts of PFAS into the River Wyre by a chemical plant in Lancashire.

Since July 2022, the Drinking Water Inspectorate (DWI), which oversees the safe supply of drinking water in England and Wales, has required water companies to monitor levels of 47 individual PFAS in drinking water and notify consumers if they breach certain levels. If they do, they must also treat the water – for example by diluting it with water from other sources.

Some scientists and campaigners would like to see the introduction of stricter limits. The Royal Society of Chemistry has suggested a maximum acceptable concentration of 10ng/L (0.01 micrograms a litre) for individual PFAS – 10 times lower than the current guidelines.

Research is also urgently needed into new ways of removing PFAS from the environment and breaking them down into harmless molecules.

Can we rid our lives of PFAS?

Tempting as it may be to strip your house of all PFAS-containing items and take them to the dump, experts agree that, from an environmental perspective, this is probably the worst thing that you could do.

Metzger recommends considering the lifecycle of the products we buy: “Your nonstick pan might not hurt you today, as long as you use it properly. But if it goes into landfill and contaminates the environment, the PFAS in it could be around for tens or hundreds of years, polluting the soil and water systems for you and your children or grandchildren.”