Saracci S, Samet J. (2010). Commentary: Call me on my mobile phone...or better not?—a look at the INTERPHONE study results. International Journal of Epidemiology. 39(3):695-698.
The authors comment on the results of the INTERPHONE study, the international multicenter case-control study on mobile phone use and brain tumors. They point out that the conclusion reached by the INTERPHONE investigators “tolerates diametrically opposite readings.” The first sentence of the conclusion (“There were suggestions of an increased risk…at the highest exposure levels…) implies an increased risk from intensive mobile phone use, while the second sentence (…biases and errors limit the strength of the conclusion we can draw from these analyses and prevent a causal interpretation”) allows to dismiss the observed elevated risks as not real.
The authors of the commentary discuss reasons why the question of potential brain tumor risk from mobile phone use remains unanswered after publication of the INTERPHONE study results. They outline strengths and limitations of the INTERPHONE study.
Results and Interpretation
The INTERPHONE investigators rigorously followed the protocol and carefully explored potential sources of bias in their study. The multi-centric nature of the study offers an advantage of simultaneous replication and checking the results for consistency among centers. At the same time, the INTERPHONE study could not address “the risk of main interest”, i.e. brain tumor risk from life-long mobile phone use. In high income countries, mobile phones have been in use since 1980’s, but only in the mid-1990’s the prevalence of mobile phones became wide. Therefore, the INTERPHONE study could only answer the question as to whether or not mobile phones increase the risk within the first 10-15 years of use. Scientific evidence indicates that none of the established carcinogens increases the risk in the first 10 years after first exposure.
A consistent pattern of reduced brain tumor risk was observed for all participating countries and for different metrics of mobile phone exposure, which is most likely explained by bias. The authors of the commentary discuss potential sources of bias, some of which were explored by the INTERPHONE investigators and others were only briefly mentioned. One source of bias is lower participation rates among controls than among cases. The other is that “people with prodromal manifestations of neurological disease make less use of mobile phones”.
The authors conclude their commentary with recommendations for further research, indicating possible methodological approaches.