The protracted discussion as to whether mobile phones may cause cancer could be drawing to a close. Results of a study of 10,000 people, conducted by the International Agency for Research on Cancer (IARC), concluded that using a mobile phone does not appear to increase the risk of developing brain tumours. However, the word “appear” left me wondering about the study’s conclusiveness.
Looking at the study in more detail, it cited that the overall rate of brain cancer has not risen in countries with long-term mobile-phone usage. For example, Nordic countries like Sweden and Norway were quick to realise the benefits of wireless communications given the mountainous terrain of those countries. That fact coupled with low population density meant that the cost per person of implementing traditional telephone services was very expensive, leading to the early advent of the mobile phone.
The €20m Interphone study, which happens to be funded in part by the mobile-phone industry, also went on to survey more than 5000 men and women from 13 countries who were diagnosed with one of two types of brain cancer—glioma and meningioma—between 2000 and 2004. These are rare cancers, but are considered to be the most likely to be influenced by phone use.
The cancer patients were asked to record their mobile-phone usage, and then the results were compared with adults of similar age, sex and background who did not have the disease. Some had been using their phones for more than a decade.
It is a fact that most regular users—defined as people who made use of their phone at least once a week—appeared to have a lower risk of brain cancer than those who rarely used a phone. This is consistent with published biological studies, which have not established any effect of exposure to radiation from mobile phones at a cellular level, nor found a mechanism by which cancer could be caused.
Findings dismissed
However, the research dismissed as problematic the findings that at the other extreme end of the spectrum—those using the phone for the longest cumulative periods, more than 1640 hours—appeared to have a higher risk, regardless of the time period. This was as much as 40% higher for glioma, and 15% higher for meningioma. Nearly 50 cancer patients reported using their phone more than five hours every day of the week, with 10 recalling that they had used it for 12 hours each day.
"It's not impossible that people were using their phones for this long, but it is highly unlikely," said Professor Anthony Swerdlow of the Institute of Cancer Research, which carried out one of the two UK arms of the study.
The report says that people with brain tumours were more likely to overestimate the role of a potential risk factor, and that the disease interferes with memory and cognition, undermining the accuracy of the recollections of such extreme use.
Inconclusive evidence
Given that last statement, I wondered how such evidence could be seriously considered as part of a “conclusive” survey. Unlike lung cancer, where the risk rises as more cigarettes are smoked, this report maintains that mobile-phone use shows no increased risk until the very heaviest usage begins.
"This study cannot answer whether there are long-term risks beyond 15 years, nor would it have been able to pick up much, much smaller risks," says Professor Swerdlow. "But if there was a large and immediate risk we would have seen it.
"Whether it is worth doing more research, that is a question for society. These are expensive studies, and there are many other things in the world that should be investigated.
"It is society which has to answer the question of how long you continue to investigate something that does not have a biological basis."
Add those comments to some of the previous statements about this study—plus the fact there were reports of some differences within the research team on the best way to interpret the data—and my confidence in the study’s conclusiveness is waning fast. And I’m not the only one in that camp.
The lobby group Mast was not assuaged by the Interphone findings. It argues that it wanted to see results for other cancers, including salivary gland tumours and acoustic neuromas.
So my conclusive analysis is that we don’t have conclusive, 100% reliable evidence on whether or not mobile phones cause cancer. It is, however, worrying that the study did find some high-usage mobile-phone users who had developed cancer. Expect the protracted discussions to rumble on.