For decades it served as a landfill for domestic refuse from nearby Coatbridge and industrial waste from the neighbouring Gartsherrie Ironworks.

Now redeveloped as a shared campus for two North Lanarkshire high schools, there are fears the site’s toxic legacy has resurfaced to threaten the health of teachers and pupils.

The facts are concerning. Since the opening of Buchanan High and St Ambrose High in 2012, four former or current teachers have all been treated for cancer, with reports suggesting the cases feature a rare form of bladder cancer.

In addition, the campus has also been the subject of a drinking water scare after the supply turned blue several years ago.

Fears over safety and concerns North Lanarkshire Council has not acted quickly enough to address them came to a head last week at a heated public meeting.

Parents raised concerns about “unexplained symptoms” their children had been suffering, including tiredness, sickness, sore heads and stomach problems.

Afterwards, families were angry at an insistence from officials that all was well and many are now keeping their children at home.

Teachers are also worried. Twelve members of the NASUWT teaching union from Buchanan High have announced seven days of strike action later this month, while members at St Ambrose are also being balloted. Other unions, including the EIS and SSTA, said they were not currently intending to take similar action.

An NASUWT spokesman said: “Whilst we are in dispute over the situation we have taken the unprecedented step of removing our members from the site because of the serious health and safety concerns.”

Denials from the council that there is any safety risk from the former landfill site, which operated between 1945 and 1972, could not be more categoric.

This includes a specific denial of any link between the campus and cases of cancer, with officials arguing the lead-in time to develop bladder cancer is longer than the time the affected school staff spent there.

And while soil over the landfill was assessed as having traces of lead and arsenic before the building of the £44 million campus, the council said it had adhered to strict regulations during the planning and building process and that all testing had shown no risk to the public.

Officials stressed that a layer of clean top soil and building materials had effectively sealed the campus from whatever is buried underneath.

In addition, methane sensors have been fitted in the schools. The alarm has only been set off once since 2012 and officials say this was down to a faulty censor.

A council spokesman said: “Specialist doctors from the public health department of NHS Lanarkshire have confirmed no incidence of cancer is linked to the schools.

“They have also confirmed that no other serious illness is connected to the schools or the site on which they are built. All the facts demonstrate the schools and the site on which they are built is safe.”

This was backed up by Dr David Cromie, a consultant in public health medicine from NHS Lanarkshire, following an investigation.

He said: “The investigation did not find any evidence suggesting a health risk associated with attending Buchanan High School that would have led to the development of cancer.

“The public health assessment is that there is no evidence of arsenic toxicity from the school.”

On the issue of a blue colour in the water, Dr Cromie said it had come from copper pipes and was not dangerous to health.

NASUWT officials now accept it is likely the blue water colouration is down to copper pipes and have welcomed the phased replacement of these with a plastic alternative.

However, the current walk-out centres on recent ground movement in the playground area, which the union fears may cause a future leak of toxic gases.

And while the council argues this is natural settlement, the union wants improved testing to check whether the subsidence could damage the protective barrier between the campus and the landfill beneath.

Families also want children to be tested for signs they have been exposed to toxic metallic elements.

An online petition on the issue launched by parent Lisa McCormick after the public meeting has already reached some 10,000 signatures.

It states: “Parents pleaded for their children and staff to be tested, but this fell on deaf ears and were told this would not be done.

“We need your help, we need to let people in power, Scottish Parliament and council officials know we will be listened to and we will not tolerate anyone playing Russian roulette with our children’s and teachers health and lives.”

There is also now a wider political dimension with local SNP and Labour MSPs calling for a formal inquiry, some who want this to be conducted at a national level.

A Scottish Government spokesman said: “The public health minister has made clear he supports the call for a thorough investigation and for the local health board and council to listen to the concerns.”