Cellphones and other cordless telephones have a biological effect on the brain, according to research from Sweden's Örebro University.
It's still too early to say if any health risks are involved, but those cautious Swedes are recommending that people, especially children, should use headsets.
"Children may be more sensitive than adults to radiation from wireless phones," says Örebro researcher Fredrik Söderqvist.
Söderqvist examined the use of wireless telephones among children and adolescents, and asked adolescents themselves whether they thought it was giving them health problems.
He then went on to study blood samples from adults, looking at a protein that exists in the blood-cerebrospinal-fluid barrier, which is part of the brain's protection against outside influences.
The study revealed an association between use of wireless telephony and increased content of the protein transthyretin in the blood.
Söderqvist stresses that the increase needn't in itself be a cause of concern. But since it indicates that the brain is in fact affected by microwaves from wireless telephones, he says, there may be other - as yet unknown - effects that may impact our health.
"We should all follow the recommendations of the Radiation Safety Authority when it comes to using headsets and avoiding mobile phone use when the coverage is poor," he says.
Children and adolescents who regularly use wireless telephones reported more health symptoms and graded their well-being lower than those who do not use them regularly.
"The connection was strongest regarding headaches, asthmatic complaints, and impaired concentration," says Söderqvist. "But more research is needed to exclude the effects of other factors and sources of error, even though it is difficult to see how this connection could be fully explained by such factors."