Blood test call for people potentially impacted by cancer-causing chemicals in the ground

She argued there were too many “unknowns” about the impacts of concentrations of PCBs on the body and no treatment for those found to have elevated levels in their blood.

“All we could do is give [people] a number that we can’t really interpret and then we can’t make right.”

She felt this could “create even more worry and that is a health harm in itself”.

“There is nothing that blood testing can do that would magically take those worries away – it would only potentially magnify them,” Jones said.

Asked whether the cost of implementing a blood testing regime was also a factor, she said: “No… this is not about money.”

Rather than blood testing, Jones argued public authorities should focus on taking “whatever steps need to be taken to make these [suspected dumpsites] as safe as possible”.

Dr Will Mackintosh, from the Royal College of GPs Cymru, said it may be that “additional support” would be required for GPs in future, in communities where concerns had been raised about alleged contamination.

“It’s clearly something which obviously large numbers of people are concerned about, and general practice has a role in responding to that as best as we can,” he said.

The Welsh government said “addressing the issue of contaminated land is a key priority for this government”.

“We will develop a Wales-wide strategy to progressively restore post-industrial land so that communities are no longer exposed to potential risks,” it said.

“This will include strengthening the ‘polluter pays principle’ while we continue to press for environmental justice by raising the importance of seeking UK Government funding direct with the UK Treasury.”

Monsanto does not exist any more and Eastman Chemical Company, responsible for the firm’s legacy production in the UK, has not responded to BBC Wales’ requests for comment.