Brits may unknowingly be risking their health by wearing waterproof jackets made with 'forever chemicals'. 

Scientists have for years warned about the dangers of perfluoroalkyl substances, or PFAS.

Dubbed 'forever chemicals' because they can linger in the environment for hundreds of years, they have been linked to everything from cancer and high cholesterol to infertility.

When PFAS enter the body, either through food and water that people eat and drink or by inhaling contaminated air, they can distribute throughout the body in tissues and organs. 

Now, one social media influencer — known for his videos on the outdoors — has claimed PFAS could be lurking in popular Arc'teryx jackets.

This is despite the brand claiming the waterproof jacket tested contains a new PFAS free material — ePE membrane. 

'It’s a breakthrough in sustainability that we’re committed to bringing to our entire line of GORE-TEX jackets by the end of 2025,' the Canadian brand says. 

But the hiking and outdoors influencer Steven Smith, who boasts more than 220,000 followers on his mylifeoutdoors Instagram account, said he found 'five different toxic PFAS chemicals' after 24 hours of testing the jacket.  

In the video, he put the yellow jacket in a self-made machine that recirculated distilled water over the jacket for a full day. 

Tests on the water before the experiment confirmed there were no traces of any PFAS. 

'The five different toxic chemicals shed off the jacket including 21 parts per trillion (ppt) of PFBA' — one type of PFAS, he said.

'This jacket is made from toxic chemicals called PFAS', he added. 

Among the other four chemicals included 0.65 ppt of PFOA — a different type of PFAS, he claimed. 

According to Arc'teryx, this should have been phased out of their clothing in 2016.

MailOnline has approached Arc'teryx for comment. 

The Government said in February that it was considering restricting the use of PFAS in consumer products under the UK’s REACH chemical regulations on the basis that they may be hazardous.

In the UK, other popular outdoor wear brands Páramo and Finisterre say they do not use PFAS in their products, while Fjällräven, Alpkit, Lowe Alpine and Patagonia are mostly PFAS free. 

They and more than a dozen other firms say they will end their PFAS use next year. 

In June, however, research by the Ethical Consumer found over 8 in 10 outdoor clothing brands were still using PFAS to make outdoor clothing. 

The campaigning magazine said of the 27 companies it assessed, 82 per cent had products containing the class of chemicals. 

Nearly half of all companies also had no phase-out date for using PFAS, Ethical Consumer claimed.  

Famed for their durability and stain resistant properties, PFAS have been used in a host of products from nonstick cookware, to clothes, packaging, cosmetics and even children's toys. 

But industries are now moving away from them because of their detrimental impacts. 

PFAS has previously been linked to kidney cancer, prostate cancer and breast cancer, among others. 

While these links are not definitive and research is ongoing, part of the concern is because PFAS are so ubiquitous in modern life and persist so long in the environment they could infiltrate water supplies, further increasing exposure.