INTERPHONE study finds no increased tumour risk due to mobile phone use – BfS sees further research needs

Initial results from the INTERPHONE study on the possible long-term effects of mobile phone use were published in 2010 and 2011. According to the evaluation, no evidence was found of an increased risk of brain tumours or tumours of the auditory nerve due to mobile phone use. The study therefore corroborates the results of the German Mobile Telecommunication Research Programme (DMF), which was carried out by the Federal Office for Radiation Protection (BfS). The DMF had shown that there was no evidence of a harmful effect of mobile communications within the applicable limit values.

However, the present study cannot answer all outstanding questions regarding the intensive or long-term use of mobile communications. The BfS therefore concurs with the authors of the INTERPHONE study that further research is needed into intensive and long-term mobile phone use. If you want to reduce individual exposure as a precaution, you have different options.

INTERPHONE study

The INTERPHONE study was launched in the year 2000 by the International Agency for Research on Cancer (IARC) in order to identify potential risks of tumour development due to mobile phone use.

Thirteen countries around the world took part in the INTERPHONE study, which was largely publicly funded. Some 29% of the funding came from the mobile communications industry, although the industry had no influence whatsoever over the study design and results. Germany participated in the study as part of the German Mobile Telecommunication Research Programme, among other initiatives.

Investigated tumours

As the electromagnetic fields from mobile phones primarily affect tissues in the head region, the study focused on the following four types of tumours:

• glioma (a brain tumour that starts in the tissue that supports the central nervous system)
• meningioma (a brain tumour that starts in the meninges)
• acoustic neuroma (a tumour of the auditory nerve)
• tumours of the parotid gland.

Results

No evidence of an increased risk of brain tumours

The INTERPHONE study evaluated data relating to 2,708 patients with a glioma and 2,409 patients with meningiomas as well as corresponding healthy control subjects. The use of mobile phones was surveyed through standardised interviews, and an evaluation of the data did not reveal an increased risk of developing one of the two types of brain tumour due to mobile phone use. Likewise, no increased risk of the two types of brain tumour was identified for long-term users who began using mobile phones more than 10 years ago.

No evidence of an increased risk of acoustic neuromas

The aggregated data from the INTERPHONE study also incorporated 1,105 patients with tumours of the auditory nerve (acoustic neuroma) as well as comparable healthy control subjects. Here, too, mobile phone use was surveyed through standardised interviews, and the evaluation of the full set of data did not reveal an increased risk of developing an acoustic neuroma due to mobile phone use. This finding also applies to long-term users.

No evaluation regarding tumours of the parotid gland

Due to the low numbers of cases in the participating countries, the study had to make do without a summarised evaluation regarding tumours of the parotid gland.

Unclear results for intensive or long-term use

In mobile phone users for whom it was possible to estimate a total usage period of more than 1,640 hours based on the surveys, the researchers calculated a statistically significant increased risk both of gliomas and of acoustic neuromas. However, in the surveys of mobile phone users with the highest total usage period, the scientists obtained implausible answers with regard to usage frequency. This calls the results of this section of the study into question. Some people reported speaking on their mobile phones for over 5 hours a day. As such statements do not seem very realistic, it cannot be ruled out that the observations are due to other underlying causes.

In the case of mobile phone users with particularly high total usage periods, the gliomas and acoustic neuromas tended to appear in the regions close to the ear and on the side of the head reported as the preferred side for making calls. However, subjects with brain tumours generally knew which side of the head their tumour was on and might therefore have overestimated the frequency of mobile phone use on the tumour side when asked about the preferred side of the head for making calls. Various evaluations reinforced this suspicion. Moreover, there is no biological/medical explanation for such observations.

Evaluation by the BfS: further research is needed into intensive or long-term use

The results of the INTERPHONE study corroborate previous evaluations of the possible health risks of mobile communications and the possibilities of preventive exposure reduction listed by the BfS. For example, the final report on the German Mobile Telecommunication Research Programme had already asserted that there has been insufficient research into the possible effects of intensive and prolonged mobile phone use and that further studies are needed in order to reach a final assessment.

Any evaluation of the results must take account of the fact that, although the radiation levels of mobile phones have been falling for years, the extent of mobile phone use is rapidly increasing and the type of use is changing. In other words, new mobile phones are no longer used simply for making calls.

Whereas the INTERPHONE study failed to address a need for research regarding children, the recently completed international MOBI-Kids study looked into a possible impact of mobile phone use on young people between the ages of 10 and 24. The statement by the BfS on the results of the MOBI-Kids study can be found here.

Current research projects: COSMOS

The need for research into intensive and prolonged mobile phone use is currently being addressed as part of the Cohort Study of Mobile Phone Use and Health (COSMOS), a long-term epidemiological study being carried out in the United Kingdom, Denmark, Sweden, Finland, the Netherlands and France. In addition to the tumour types investigated in the INTERPHONE study, COSMOS is also investigating other possible diseases, such as Alzheimer’s and Parkinson’s. The study aims to determine the exposure to high-frequency electromagnetic fields by accurately recording the frequency and duration of phone calls

The BfS's call for further research remains useful and necessary

Although the results of the INTERPHONE study do not, on the whole, show an increased risk of brain tumours or tumours of the auditory nerve due to prolonged use of mobile phones, there remain some uncertainties in relation to intensive or prolonged mobile phone use. For this reason, the BfS is still committed to high-quality research and describes ways of reducing exposure as a precautionary measure.