Scientists from the World Health Organisation have concluded that MBT, which is used in rubber manufacturing, should be added to its "encyclopaedia of carcinogens".

The long list of products the substance is in also includes, soft playground surfaces made of `rubber crumb`, medical catheters, car tyres, rubber insoles for shoes, air beds, elastic bands, swimming caps and goggles.

At a meeting in Lyon, France, 24 experts from eight countries concluded that the substance `probably causes cancer`, putting it alongside red meat and only one rung below cigarettes, asbestos and other definite causes of cancer .

Professor Hans Kromhout, a member of the committee which reviewed the chemical, said MBT had been identified "in gloves and baby bottle teats and soothers" and more recently in "inhalable road dust with the wearing of rubber tyres the most likely source of this contamination."

Data on the substance has been reviewed by the WHO`s International Agency for Research on Cancer which also looked at a study of workers at a Welsh chemical factory.

But because the workers were also exposed to other chemicals, it was hard to be certain MBT was to blame, according to the report.

The research, by professor Tom Sorahan, of Birmingham University, linked MBT to bladder cancer, bowel cancer and a type of blood cancer.

The news comes after a former NHS chief claimed that 3G football pitches may have caused his son`s cancer.

Nigel Maguire quit as the chief executive of NHS Cumbria when his son Lewis, who had a trial at Leeds United, was diagnosed with the disease.

Since then Maguire has been calling for a ban on 3G pitches, which he believes are the root of the problem.

Many of the pitches are covered in small rubber pellets, which are made out of old rubber tyres and can contain toxic chemicals such as mercury and arsenic.

Campaigners believe that the pellets can cause cancer if players accidentally swallow them or get them in cuts.

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Maguire says his goalkeeper son was exposed to these harmful chemicals while diving around on the pitches.

He said: "Goalkeepers like Lewis dive dozens of times in training so they breathe it in or swallow it and it gets in their grazes.

"He used to come home with his kit covered in the stuff. We`d have to scrape it off.

"The more I look into it, the more horrified I am. Anyone who thinks swallowing half a teaspoon a week of that stuff is a good idea is barking mad."

He added: "I suspect if people knew where the black rubber pellets came from and were made of; many would think twice. I certainly would. If your son/daughter is training on this stuff you might want to think twice."

It wasn`t the first time such a claim has been made by the parents of a cancer sufferer.

Austen Everett, a goalkeeper for the University of Miami, died aged 25 in 2012 and her mother, Jean Leahy, is concerned the pitches could have been a contributory factor to her death.

"I have no doubt Austen`s illness was linked to her love for football," Jean said. "It`s horrific to think the sport she loved could have killed her.

"I`d urge the authorities in the UK to stop using the pitches until a definitive answer can be found on whether they are safe or not."

University of Washington coach Amy Griffin, a former World Cup-winning goalkeeper for the US women`s national team, said she had found over 158 cases of footballers developing cancer while doing her research and she believes artificial pitches could be a contributory factor.

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