Doctors conducting an investigation into why five children living within two miles of each other in Coventry contracted a rare form of cancer have ruled out any link.
The inquiry, by the Health Protection Agency and Coventry Teaching Primary Care Trust, was launched in January when it emerged that three children in one school and a fourth living close by, all contracted neuroblastoma.
Yesterday the doctors conducting the probe presented their findings to the national board meeting of the HPA, being held in Birmingham, concluding that the cluster of incidences was probably down to chance.
The disease usually only affects 100 children in the UK per year - or just two cases every three years in Coventry.
The parents of five-year-olds Bethany Keenan, Dylan Williams and Jordan Accardi and seven-year-old Charlotte Moore, demanded an investigation to see if there were links between the cases, because of their proximity to each other.
Three of the children affected lived a few streets from each other in Tile Hill, while the fourth lives nearby in Cannon Park.
"If you get in excess of two you would count it as a cluster," said Dr Mamoona Tahir, consultant in Communicable Disease Control with Coventry and Warwickshire HPA. "Our job was to carry out a systematic investigation into whether there were any factors linking the children and whether there was an accepted biological pathway which would make them significant."
Scientists estimate 20 per cent of childhood cancers are genetic, but exposures to pesticides, electro-magnetic fields and medicines during pregnancy have been studied as potential triggers.
The scientists went to the families and identified what the children had been exposed to, while in the womb and growing up.
They also drove around looking for other potential risks nearby, such as fume-releasing factories incinerators and electricity pylons.
Dr Tahir: "There are certain factors that have been studied relating to neuroblastoma, but evidence has not been conclusive. For example parental exposure to hair dyes, types of medication, hair dyes, pesticides.
"The parents had concerns about the nearby Canley Crematorium and being in the Birmingham International Airport flight path," said Dr Tahir.
"Anything that caused concern we looked at very seriously, but we did not find anything significant."