The Government has admitted for the first time that Sellafield 'is a source of plutonium contamination' across the country. Public Health Minister Melanie Johnson has revealed that a study funded by the Department of Health discovered that the closer a child lived to Sellafield, the higher the levels of plutonium found in their teeth.

Johnson said: 'Analysis indicated that concentrations of plutonium... decreased with increasing distance from the west Cumbrian coast and its Sellafield nuclear fuel reprocessing plant - suggesting this plant is a source of plutonium contamination in the wider population.'

Johnson claimed the levels of plutonium are so minute that there is no health risk to the public. But this is disputed by scientists, MPs and environmental campaigners who have called for an immediate inquiry into how one of the world's most dangerous materials has been allowed to continue to contaminate children's teeth. There have long been claims of clusters of childhood leukaemia around Sellafield.

In the late 1990s researchers collected more than 3,000 molars extracted from young teenagers across the country during dental treatment and analysed them. To their surprise they found traces of plutonium in all the teeth including those from children in Scotland and Northern Ireland. Alarmingly, they discovered that those living closer to Sellafield had more than twice the amount of those living 140 miles away.

Plutonium is a man-made radioactive material and the only source of it in Britain is from Sellafield. The plant, which reprocesses nuclear fuel from reactors, still discharges plutonium into the Irish Sea.

The original research was carried out in 1997 by Professor Nick Priest who was working for the UK Atomic Energy Authority. At the time the conclusions of the research received little attention because the study concluded that the contamination levels were so minuscule they were thought to pose an 'insignificant' health risk.

But earlier this year the Committee Examining Radiation Risks from Internal Emitters, looking at health risks posed by radioactive materials, examined Priest's study. Some of the committee's members have now cast doubt on the conclusions that plutonium in children's teeth posed no health risk.

Professor Eric Wright, of Dundee University Medical School, is one of the country's leading experts on blood disorders and a member of the committee. He believes that the tiny specks of plutonium in children's teeth caused by Sellafield radioactive pollution might lead to some people falling ill with cancer.

He said: 'There are genuine concerns that the risks from internal emitters of radiation are more hazardous [than previously thought]. The real question is by how much. Is it two or three times more risky... or more than a hundred?'

Wright believes that, while the plutonium contamination is unlikely to pose a health risk to much of the British population, it might be a problem for some individuals.

He said: 'If somebody has a bad collection of genes which means their body cannot deal with small levels of internal radioactive material, then there could be an issue.'

Wright's comments, coming on top of the admission from the Health Minister, have led to calls for an independent inquiry. Liberal Democrat environment spokesman Norman Baker said: '[This] stinks of a cover-up. They have known for six years that Sellafield has contaminated the population with plutonium but done nothing. Yet the plant continues to discharge plutonium into the Irish Sea. It shows the wanton disregard the nuclear industry has for public health and there needs to be an independent inquiry.'

Janine Allis-Smith of the campaign group Cumbrians Opposed to a Radioactive Environment said: 'There is no safe amount of plutonium. The plant must be closed down immediately.'

However, Priest, who is now professor of environmental toxicology at Middlesex University stands by his original conclusions. He said: '[The plutonium in teeth] was at such low levels that it was toxicologically insignificant. There really is nothing to worry about.'

A spokesman for BNFL, which runs Sellafield, said: 'What is not clear is whether the plutonium recorded in this study originated [from Sellafield] or from nuclear weapons testing fall-out.'