What should schools and parents make of worries about wi-fi safety?
Head teachers say they want to reap the benefits of school wi-fi networks - and want any concerns about health fears to be addressed urgently.
By Sean Coughlan
BBC News education reporter
"Schools can't afford to delay while the scientists make up their minds," says John Dunford of the Association of School and College Leaders.
The BBC programme Panorama is to highlight concerns about a lack of safety research into wi-fi networks.
But the Health Protection Agency says emissions are within safety guidelines.
Wi-fi networks are now in most schools and in many family homes - but once again there have been questions raised about their safety.
Computers have become part of the basic kit for schools
Even if you don't have your own wi-fi network, you could be in range of your neighbour's, or the local cafe's, or the growing trend for whole cities to be switched on to wi-fi.
But are they safe? Last month, a teachers' union voiced concern about the lack of research into the safety of wi-fi networks. And now the BBC programme, Panorama, is questioning whether there has been sufficiently rigorous control over their arrival in the classroom.
Should we be thinking twice about plugging in more wi-fi networks?
The answer from the Health Protection Agency (HPA) is a mixture of reassurance and a recognition that more research needs to be carried out.
The evidence so far does not suggest that wi-fi networks represent a health risk, says the HPA - as the signals are "very low power", typically 0.1 watt.
But the watchdog wants more evidence - such as measuring exposure levels in a range of real-life classroom settings, with different numbers of pupils and connected computers.
Wi-fi is part of everyday life - so schools don't want to be left behind
And it points to the ambiguity surrounding advice on practical issues facing schools - such as whether laptops should be put on pupils' laps. With many modern laptops, putting it on a desk won't make much difference to any emissions, suggests the HPA.
However the HPA emphasises that the levels from wi-fi networks are within the safety guidelines - and that signals are likely to be less intense than for mobile phones.
The HPA also points to the difficulty in isolating any specific impact from wi-fi networks. If pupils are using mobile phones - or are around where they are being used - how can any separate exposure from wi-fi networks be established?
So does this mean that everyone is agreed that wi-fi is safe?
No, there are dissenting voices, who say it's much too early to give wi-fi the all-clear.
Risks and rewards
Dr Andrew Goldsworthy, a biologist now retired after a long career in Imperial College, says that safety guidelines should not be taken as proof that wi-fi networks do not have dangers.
Wireless laptops give students greater flexibility
These guidelines are based on the heating effects of radiation - but Dr Goldsworthy says there are other damaging consequences outside such regulations. These include risks to fertility, genetic defects and cancer, he says.
"The longer the exposure, the greater the risks," he says.
Accepting that he is speaking against the current consensus, he says he expects his warnings to be "fought by vested interests at every stage". But he believes that in the long run, there will be a reassessment.
Mobile phones have health risks, he argues - and that wi-fi networks, using similar technology, will also be found to have long-term implications for users.
In turn, those defending the safety of wi-fi networks draw comparisons with the health scares surrounding the widespread introduction of computer display screens in the 1980s - which later proved to be unfounded
And they argue that it is impossible for scientists to prove or disprove such varied symptoms, attributed to wi-fi networks, as headaches or dizziness.
So how are schools meant to make decisions about installing wi-fi networks?
Head teachers' leader, John Dunford, says if wi-fi networks are considered safe for offices and shops, then schools are not going to want to be left behind.
Dr Dunford, general secretary of the Association of School and College Leaders, says he wants clarification on safety to be carried out as a matter of urgency - because wi-fi networks are proving very popular and beneficial for schools.
Schools, in older buildings, have often found it easier to use wi-fi networks than cabling, he says - and it has been helpful for institutions with more than one site.
"Unless there is evidence that they are damaging, schools will continue to develop them - because they're finding that they're essential," says Dr Dunford.