Mobile phones are not good for children, we have already been told. But now UK experts are warning against laptops with wireless internet too.
Professor Lawrie Challis, head of the government's committee on mobile phone safety research, said children should keep a safe distance from the embedded antennas.
Challis, a retired professor of physics at the University of Nottingham, said: "With a desktop computer, the transmitter will be in the tower.
"This might be perhaps 20cms from your leg and the exposure would then be around one per cent of that from a mobile phone.
"However, if you put a laptop straight on your lap and are using wi-fi, you could be around two centimetres from the transmitter, and receiving comparable exposure to that from a mobile phone."
He added that children are much more sensitive than adults to dangers such as pollutants like lead and UV radiation.
"So if there should be a problem with mobiles, then it may be a bigger problem for children.
"Since we advise that children should be discouraged from using mobile phones, we should also discourage children from placing their laptop on their lap when they are using wi-fi."
Meanwhile, teachers have called for an investigation into whether there are any health risks from wireless computer networks in schools.
The Professional Association of Teachers union is writing to the education secretary for a clarification on wi-fi safety.
Many primary and secondary schools use wi-fi networks - but the PAT believes there is insufficient long-term evidence to demonstrate whether such networks are safe.