(WIREUPDATE) – A United Nations World Health Organization (WHO) put $30 million toward a study involving 50 scientists in 13 countries to provide an answer to the idea that cellphones could cause tumors, however the study was inconclusive.

“An increased risk of brain cancer is not established, but it’s important to note that we can’t establish absence of risk either,” says study leader Elisabeth Cardis of the Centre for Research in Environmental Epidemiology in Barcelona, Spain.

The idea was that if the phones boost the risk of tumors, there would be more phone use in the tumor group compared with the general population, and less phone use in the healthy group. In fact, the team found the opposite.

However, when the team got back in touch with healthy people who had declined to take part in the study, they discovered that these people were less likely to be regular phone users (defined as making more than one call a week for more than six months) than the healthy people who took part.

Despite this bias towards positive results, when the researchers compared the 10 per cent of cellphone users who spent the most time on their phones with non-users and infrequent users (defined as less than one call per week), this level of use did appear to increase the risk of gliomas by 40 percent and meningiomas by 15 percent.

Because the study was retrospective, the researchers relied on participants’ memories – going back up to 10 years – of how much they had used their handsets before being enrolled, and on which side of the head. Yet people who are ill have a tendency – known as “recall bias” – to exaggerate memories of potential risk factors than healthy controls.

Cardis advises caution: “It may not be an unreasonable course of action to limit exposure through the use of text messages, hands-free devices and speaker phones.” Mike Repacholi, who helped set up the study while at the WHO, is more positive: “The study says use of cellphones isn’t associated with tumors.”

Source: http://www.newscientist.com/article/dn18920-dont-hang-up-cellphones-dont-cause-tumours-probably.html