Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of more than 10,000 long-lasting, synthetic chemicals that some scientists want banned.

Known as Forever Chemicals, PFAS are some of the most persistent synthetic chemicals ever produced and are predicted to remain in the environment for hundreds of years.

So what are they used for, what damage can they do and should they be more strictly controlled?

Their uses

Due to their ability to repel grease, oil and water, manufacturers use them in a variety of product, such as:

• Non-stick cookware, such as that manufactured by Teflon

• Paper and cardboard food packaging 

• Waterproof outdoor clothing and equipment

• Swimwear

• Mattresses 

• Carpets

• Electronics, such as smartphones

• Cosmetics 

• Fire-fighting foams

According to Dr. Shubhi Sharma, a scientific researcher for charity CHEM Trust, which campaigns to prevent the damage caused by synthetic chemicals: "They're oil repellent, they're grease repellant, but their durability means they're also extremely persistent and stay in the environment for generations."

How persistent are PFAS and how do they spread?

PFAS contain some of the strongest and most stable carbon-fluorine (C-F) bonds in organic chemistry which mean they can persist in nature for decades or even centuries. They naturally resist water degradation, heat breakdown and microbial digestion.

PFAS are extremely mobile in water. Once released in the environment, during manufacturing or after leaching from a consumer product or when thrown into a landfill site, they migrate into the water which means they can be transported over long distances. They have been found as far afield as the Arctic.

The chemicals contaminate soil, groundwater and, by extension, drinking water. Water treatment plants find it very difficult to remove PFAS from water.

Although filtering is sometimes possible, the concentrated waste left behind on the filters themselves presents a problem.

What harm can they do?

Once people drink water with traces of PFAS, multiple studies suggest that the chemicals can enter our liver, blood and reproductive organs. They have been detected in the breast milk of humans and animals.

According to CHEM Trust, two of the most studied chemicals in this family, PFOA and PFOS have been shown to interfere with the hormonal and reproductive systems and foetal development. The charity says they can also "impact the immune system and have been linked to reduced responses to vaccines in children", while promoting the development of kidney and testicular cancer.

Sharma told CGTN: "We have a lot of research on PFAS and PFOS (Perfluorooctane Sulfonate) and solid scientific evidence that these two PFAS can cause a wide variety of diseases ranging from certain types of cancer to immunotoxicity, to reprotoxicity, a negative impact on your liver and high cholesterol. 

"We also know that they tend to pass from mothers to their baby when they're breastfeeding."

In addition, most Forever Chemicals haven't been laboratory tested. She said: "The caveat here is that this doesn't mean that other PFAS are completely harmless. Just because data doesn't exist for these chemicals, it doesn't means that they are fine. No data does not mean no problem."

Research published in the journal The Proceedings of the National Academy of Sciences (PNAS) showed that New Hampshire families living  downstream of groundwater sites known to be contaminated with PFAS saw "a threefold increase in low birth weights and deaths among infants, compared to families upstream of the same sites."

According to Sharma there are similar health impacts on animals.

Ozone chemicals

Even when chemical manufacturers have tried to help the environment, they have sometimes inadvertently caused problems. 

Atmospheric scientists, led by researchers at Lancaster University, recently calculated that CFC replacement chemicals and anaesthetics created to help protect the ozone layer deposited 335,500 tonnes of a PFAS called trifluoroacetic acid (TFA) across the Earth's surface between 2000 and 2022.

What regulation is there?

The European Union this year set legal limits for PFAS in drinking water, which member states must begin enforcing.

Its Industrial Emissions Directive also imposed stricter monitoring of PFAS emissions, with the obligation to report on PFOA and PFHxS from 2028.

Under its Soil Monitoring Law the EU established a list of soil contaminants, including PFAS, which member states must measure in soil samples, "allowing contamination hotspots to be identified."

Among its 2026 set of measures, the Packaging and Packaging Waste Regulation "bans food contact packaging that contains PFAS concentrations above certain limits."

Sharma is full of praise, calling the EU regulation "the gold standard of chemicals regulation." She added: What they have tried to do is quite unprecedented and it's very bold. It's a very comprehensive approach and also a very pragmatic approach."

Elsewhere, the Stockholm Convention on Persistent Organic Pollutants is an international treaty aiming to eliminate or restrict the production and use of the most toxic chemicals of global concern. 

Three sub-groups of PFAS are listed in the convention: 1). PFOS and related substances since 2009 for global restriction; 2). PFOA and related substances since 2019 for global elimination; 3). PFHxS and related substances since 2022 for global elimination without exemptions. 

The US Environmental Protection Agency (EPA) has set regulations on two Forever Chemicals, PFOS and PFOA (perfluorooctanoic acid), limiting them to four parts per trillion in drinking water since 2024. Utilities have until 2031 to comply but since the election of President Donald Trump the agency recently has been trying to roll back this regulation. 

What do manufacturers say?

Chemical firms have long lobbied against regulation, with UK companies currently trying to persuade MPs not to impose a similar ban to that introduced by the EU.

According to The Guardian newspaper, AGC Chemicals Europe, one of the UK's major producers, argued in evidence to the environmental audit committee that "not all Pfas have identical hazards and risk profiles and shouldn't be treated as a single group."

US-based PFAS Consortium acknowledges the issue of PFAS pollution but has warned of the dangers of over-regulation. 

In a 2024 white paper, also reported by The Guardian, it argued that finding safer alternatives was “impossible in some instances” and would require “stepping back decades in technological advancement”.

The PFAS Consortium said the industry was committed to voluntarily reducing pollution “if exemptions [to regulation] are granted”.

CHEM Trust's Dr. Shubhi Sharma accuses opponents of regulation of crying wolf. "Some parts of the industry complain that the regulation of PFAS as an entire group is too big and that industry is going to collapse, but their argument is based on a misconception. 

"What they proposed is that there are some uses of PFAS which are absolutely necessary for society wouldn't be banned tomorrow. They have been given enough time to phase out.

Some medical manufacturers have been given 13-plus years for them to phase out PFAS."

Can new technology help?

There are several technologies in development that aim to break the C-F bonds.

These include:

• Blasting them with ultraviolet radiation

• Using bacterial microbes to eat them

• Vaporizing them with plasma beams

• Supercritical Water Oxidation (SCWO) - degrading them using water's supercritical phase.

• High-frequency sound 

Sharma says the effort to both phase out PFAS use and treat existing chemicals in the environment has to be a global effort. "I think somebody has to start, which is why what the EU is doing is so unprecedented and trailblazing. It's really important that the universal PFAS restriction follows through because PFAS are such mobile chemicals, if it's produced in one country, it's going to end up in another. Ultimately they have to be phased out at a global level."