Mobile madness

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: Science and Environmental Epidemiology. This compared the recollections of about 500 Interphone subjects with their actual mobile use according to the records of the network operators. The researchers found a high level of recall errors. Participants underestimated the number of calls they had made by an average of about 20%, and overestimated call duration by 40%. Ominously for the statisticians, the recall errors of those with tumours increased with time.

Suitable (and legitimate) statistical massaging of all the data may be able to offset these biases in a way that could not so easily be done for the smaller data sets from individual countries. Nevertheless Cardis admits the delays in releasing the report have been due to “the difficulty of interpreting the findings due to potential biases” and to the “conducting of additional analyses to try and disentangle the potential impacts of selection and recall errors on the risk estimates”.

The Interphone researchers are split into three camps. One believes any increased incidence of tumours shown in the study is purely the result of the biases. Another thinks it really has found increased risks of certain tumours and wants to call for precautionary measures. A third group is just keeping quiet. One person who knows many of the scientists, but prefers not to be named, describes the relations between members of the three groups as ‘strained’—harsh language in the world of scientific research.

Regardless of what eventually gets published, some people have already decided the findings warrant action. Ronald Herberman, the director of the University of Pittsburgh Cancer Institute, made headlines in July with a memo to 3,000 members of his staff urging them to limit their use of mobile phones, to refrain from keeping their handsets near their bodies at night and to avoid using them when reception is weak as a phone will then boost the strength of its signal in order that the network can hear it. He based his warnings on “early unpublished data”, and is believed to have been referring to Interphone.

Whatever the outcome, though, at least one lesson has been learnt. Follow-up studies now in the planning stage are expected to use prospective as well as retrospective data. In other words they will pick people at random and see what happens to them. That method takes longer to come to a conclusion—but it is more likely to be one you can trust.