| Extension of an international epidemiological study on the association between high-frequency electromagnetic fields and the risk of brain cancer (INTERPHONE) |
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Topic Extension of an international epidemiological study on the association between high-frequency electromagnetic fields and the risk of brain cancer (INTERPHONE) Start 01.07.2001 End 31.12.2004 Project Management INTERPHONE Study Group (Co-ordination: Institute of Medical Biometry, Epidemiology and Informatics, University of Mainz) Objective Previous epidemiological studies have not demonstrated clear evidence for an increased risk of brain tumours as a result of mobile phone use. The significance of these studies, however, was limited as (i) the sample size was not large enough to detect small risks, (ii) latency periods between the start of mobile phone use and tumour diagnosis were quite short and, in addition,(iii) the studies allowed conclusions only on the older, analogue technology. Already in 2000, the WHO therefore initiated an international case control study, which is by now carried out in 13 countries according to a uniform study design. More than 7000 patients with a glioma, meningioma and acoustic neuroma are included in the study, making it possible to detect even small risks. The study region in Germany consisted of the areas around Bielefeld, Heidelberg, Mainz and Mannheim, as a result of the co-operation between the three study centres "Working group Epidemiology and Medical Statistics" at the university of Bielefeld, the Working group "Environmental Epidemiology" of the German Cancer Research Centre in Heidelberg and the Institute for Medical Biometry, Epidemiology and IT of the University of Mainz. Patients between the ages of 30 and 59 who had been newly diagnosed with glioma, meningioma or acoustic neurinoma were contacted directly in neurosurgical wards and ENT clinics and asked to participate in the study. The same computer aided interview was conducted with both, cases and controls. Specific objectives have been defined in the international study design of the INTERPHONE research group. The strategy to analyse the international study was fixed a priori by an "Analysis Task Force", which also included the German research group. The international study’s main hypotheses are: (i) whether the exposure to high frequency electromagnetic radiation from various sources increases the risk of brain tumour and (ii) whether the use of mobile phones increases the risk of developing one of these types of tumour. The German study addendum included an extension of the field phase from 2 years to 3 years as well as the investigation of a second control person per case and the inclusion of 60 to 69-year-olds. In addition, exposure from cordless phones was also included, as cordless telephone base stations working according to the DECT standard emit indoors field intensities in their direct vicinity, which are comparable to fields emitted from external transmitters. Results The findings of the German study show no overall association between the risk of brain tumour and the use of mobile phones for a period of less than ten years. The estimates for the relative risk have in parts been lowered. This could be due to a selection bias (under representation of mobile phone users in the control group). The sample size of long-term users (use of 10 years and more) included in the German study was small: no connection between meningioma and tumour risk was observed here; however the risk of glioma in this group is doubled, but the increased risk is not statistically significant. The increased glioma risk for long-term users has so far not been confirmed by other national INTERPHONE studies; however the sample size is here also very small. Acoustic neurinoma are a rare type of cancer. Different risk factors, which to date have been discussed in relation to this benign auditory nerve tumour, were recorded and assessed. No connection with mobile phone use was found. No associations between the use of cordless telephones and the risk of glioma or meningioma were found. The placement of DECT base stations was considered as well as the use of cordless phones. All information on the German study participants between the ages of 30 and 59 was transferred to the International Agency for Research on Cancer (IARC) in Lyon for further pooled analysis. The complete report is available to download as a PDF file (274 KB). Publications
Conclusions The German INTERPHONE study did not reveal an association between an increased risk of brain tumours (glioma, meningioma and acoustic neuroma) and regular mobile phone use. This applies at least to use up to a 10-year period. The national study does not allow sound conclusions on the risks of long-term use (a period of more than 10 years), as the sample size was relatively small. In addition, it cannot be excluded that mobile phone use, in particular regarding long past mobile phone habits were wrongly classified. Therefore, it is not possible to date to conclusively assess the risk of long-term use based on currently available national data, as epidemiology follows the conditions of real life: Patients included in the German INTERPHONE study were diagnosed with tumours between 2000 and 2003 and those who at this point in time had used a mobile phone for more than 10 years, can be classified as very early users, often having used analogue mobile phone technology not available anymore today. This sample group of long-term users becomes only large enough to draw statistically sound conclusions when data of all 13 INTERPHONE countries are combined, which has been the main reason for such a vast case control study. |