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(HealthDay News) -- Wireless phones have a biological effect on the brain, but it's too early to say whether this poses any health risks, a Swedish medical researcher reports.
Fredrik Soderqvist, of Orebro University, analyzed blood samples from adult wireless phone users and discovered they had elevated levels of a protein called transthyretin, which is found in the blood-cerebrospinal fluid barrier that protects the brain against harmful substances in the blood system.
The findings indicate that the brain is affected by microwaves from cell phones and other wireless telephones, which may cause other as yet unknown effects, said Soderqvist, who conducted the research as part of his doctoral thesis.
He recommended caution in the use of wireless phones, especially among children and teens.
"Children may be more sensitive than adults to radiation from wireless phones," Soderqvist said in a news release from the university.
As part of his thesis, he surveyed wireless phone users about self-reported health problems and found that children and teens who regularly use the devices experienced more health problems and rated their well-being lower than those who didn't regularly use wireless phones.
"The connection was strongest regarding headaches, asthmatic complaints, and impaired concentration," Soderqvist said. "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."
He said the findings are cause for concern, since so many children and teens use wireless phones and "the possible health effects from long-term exposure to microwaves have not been clarified, especially among children and adolescents."
Soderqvist noted that the "threshold [safety] values in place today protect us from warming, a so-called thermal effect. But if there are mechanisms that are independent of warming, it is not certain that today's thresholds provide protection. And it may be that these are effects that will not be perceived until later on in the future."
The U.S. Food and Drug Administration has more about cell phones and health.