That intense use of mobile phones over many years may promote the growth of malignant brain tumors is a result of a recently published study entitled (Mobile phone use and risk of glioma in 5 North European countries, Anna Lahkola et al., International Journal of Cancer, DOI 10.1002/ijc.22503).

Anna Lahkola of the Finnish Radiation and Nuclear Safety Authority together with colleagues from Sweden, Denmark, Norway and the UK had interviewed some 1500 patients suffering from glioma, a malignant tumor of the connective tissue of the brain, the southern German daily Süddeutsche Zeitung citing information provided by the study reports. Thus after more than 10 years of use there was a 39 percent increase, according to the study, in the risk of developing a glioma on that side of the head to which a person normally held his or her mobile handset.

However there is still an intense debate about whether or not the electromagnetic radiation emitted by mobile handsets represents a health hazard. Thus Danish researchers at the end of last year had concluded from the results of a large-scale epidemiological study that mobile phone use, even if continued for decades, did not increase cancer risk. Earlier studies, on the other hand, have, like the present one, detected an increased cancer risk on that side of the head to which a user commonly holds his or her handset.

Such studies have multiple sources of error, however. Thus the researchers, for example, need to rely on the memory of all participants, patients and controls alike, being equally good as to their telephone behavior over a period of many years. Furthermore, infrequent users tended to underestimate the time they held their handset to their ear, whereas heavy users tended to overestimate the time they spent talking on their mobiles, the Süddeutsche Zeitung quoting a number of other studies writes. In addition patients suffering from a brain tumor were disposed to believe that the side where the tumor was located was the one to which they had invariably held their mobile phone while talking on it, the newspaper observes. At any rate, the study now published by Anna Lahkola and her colleagues has a less than 5 percent probability for the results being entirely random.

Several factors not taken into account in this study (such as the use of DECT telephones), as well as a number of contradictory results (for participants of the study who remembered their telephone behavior very well the results are not sound; plus a number of figures even appear to point to a reduction of glioma risk due to mobile phone use), have led to the researchers again expressing a need for further research. No clear connection between the use of mobile phones and cancer had yet been established; only the results for users who had been using mobile handsets for more than 10 years appeared to point to a connection, the paper quoting the scientists states. But it is these results in particular that scientists such as the epidemiologist Eberhard Greiser consider plausible. The former head of the Bremen Institute for Prevention Research and Social Medicine (BIPS) told the Süddeutsche Zeitung: "From a biological point of view it would make sense for the effects of mobile phone use to remain hidden for 10 years. It takes long for tumors to develop." (Robert W. Smith) / (jk/c't)

http://www.heise.de/english/newsticker/news/84594