A large study of mobile phone users has found no evidence that longer term users are at an increased risk of developing brain tumors.
A Danish study from the Institute of Cancer Epidemiology in Copenhagen looked at over 350,000 people who subscribed to mobile phone contracts before 1996, comparing brain tumor rates in them with non-subscribers. They looked for new diagnoses of brain tumors between 1990 and 2007.
The team concluded: “There was no association between tumors of the central nervous system or brain and long term (10 years or more) use of mobile phones.”
The results are the strongest evidence yet that using a mobile phone does not seem to increase the risk of cancer of the brain or central nervous system in adults.
The Danish study, which built on previous research that has already been published by carrying out a longer follow-up, found there was no significant difference in rates of brain or central nervous system cancers among those who had mobiles and those that did not.
Prof. Anders Ahlbom, from Sweden’s Karolinska Institute, praised the way the study was conducted, adding the findings were ‘reassuring’.
Prof David Spiegelhalter, an expert specializing in the understanding of risk who is based at the University of Cambridge, said: “The mobile phone records only go up to 1995 and so the comparison is mainly between early and late adopters, but the lack of any effect on brain tumors is still very important evidence.”
And Prof Malcolm Sperrin, director of medical physics at Royal Berkshire Hospital, said: “The findings clearly reveal that there is no additional overall risk of developing a cancer in the brain although there does seem to be some minor, and not statistically significant, variations in the type of cancer.”
However, the Danish study, published in the journal BMJ Open, has been criticized as critics beg to disagree in its methods used.
Denis Henshaw, emeritus professor of human radiation effects at Bristol University, said the researchers had wrongly classified the 88 percent of the Danish population who started using a mobile phone since 1996, for whom there is no subscription information for legal reasons as non-users.
They also removed business users from the study, who are likely to have been the heaviest users.
Henshaw concluded that the claims in the study is worthless and seriously flawed because it misleads the public and decision makers about the safety of mobile phone use.
Critics of such studies also point out that brain tumors tend to take decades, not years, to develop.
But the researchers themselves do accept there were some limitations to the study, including the exclusion of ‘corporate subscriptions’, thereby excluding people who used their phones for business purposes, who could be among the heaviest users.