There are concerns over the use of wi-fi technology in classrooms
A County Tyrone teacher has called for wireless products, known as wi-fi, to be taken out of classrooms because of health concerns.
Colin Kenney, of Cookstown High School, said there has not been enough research into its long-term effects.
Wi-fi technology uses radio waves, in the same way mobile phones. Many schools now use it to teach lessons.
"We just simply don't want another asbestos-type disaster, in another 20 years time," said Mr Kenney.
He raised the issue at the Association of Teachers and Lecturers annual conference.
"We welcome new technology to deliver the curriculum, but when there's an element of doubt that there may be biological effects on children, I don't think we can take the risk," said Mr Kenney.
His concerns have been supported by Dr Grahame Blackwell, who has carried out several studies on wireless and mobile communications technology and has supported groups who have opposed its installation.
He said there was "clear evidence in government reports that there could be biological effects below levels that we regard as our safety thresholds".
"If this was lipstick it would not be allowed on the market until they tested that out and checked there was not a problem," he said.
Professor Paddy Regan of the University of Surrey, however, said there was no proven link.
"I don't think there is any quantifiable, sensible risk in using wi-fi in schools.
"On the Health Protection Agency website, their overall conclusion is that there is no proven link of any biological effects."
Dr Blackwell said that there was sufficient research to suggest wi-fi was a health risk, and that action should be taken now.
"There is substantial evidence that there could be a problem.
"If you are going to wait until you can actually identify the causal link, then you could find yourself a few years down the line with major problems."