WHO mobile-phone health study proves inconclusive
Research that studied almost 13,000 mobile phone users for 10 years to find out whether mobiles cause brain cancer has not produced a definitive answer.
The Interphone study by the World Health Organisation's International Agency for Research on Cancer (IARC), the largest yet to look at possible links between mobile phones and brain cancer, gave inconclusive results.
Researchers said that the topic demanded deeper examination, especially in light of changing usage patterns.
"An increased risk of brain cancer is not established from the data from Interphone," said Dr Christopher Wild, director of the International Agency for Research on Cancer (IARC). "However, observations at the highest level of cumulative call time and the changing patterns of mobile phone use since the period studied by Interphone, particularly in young people, mean that further investigation of mobile-phone use and brain cancer risk is merited."
The results have been keenly awaited by mobile phone companies and by campaign groups that have raised concerns about whether mobile phones cause brain tumours.
Years of research have failed to establish a connection.
The UK-based GSM Association, which represents mobile phone firms, said IARC's findings echoed “the large body of existing research and many expert reviews that consistently conclude that there is no established health risk”.
The Australia-based Mobile Manufacturers Forum also welcomed the study and backed “the need for ongoing research”.
Wild said part of the problem with the study, which was launched in 2000, was that rates of mobile phone usage in the period it covered were relatively low compared to those of today.
It was also based on people trying to remember how much time they spent on their mobiles, which can lead to inaccuracies.
European scientists last month launched what will now become the biggest ever study into the effects of mobile phone use on long-term health. It aims to track at least a quarter of a million of people in five European countries for up to 30 years. This kind of study is considered more accurate because it does not require people to remember their mobile phone use, but tracks it for them.
Data from the IARC study showed that overall, mobile phone users had a lower risk of brain cancer than people who had never used one, but the 21 scientists who conducted the study said this finding suggested problems with the method, or inaccurate information from those who took part.
Other results showed high cumulative call time may slightly raise the risk, but again the finding was not reliable.
“We can't just conclude that there is no effect,” said Elisabeth Cardis of the Centre for Research in Environmental Epidemiology in Barcelona, Spain, who led the study.
“There are indications of a possible increase. We're not sure that it is correct. It could be due to bias, but the indications are sufficiently strong... to be concerned.”
Because of this, and because mobile phone use is still rising, more research was needed, the scientists said.
The Interphone International Study Group was part-funded by money from mobile phone companies. The study was published in the International Journal of Epidemiology.
Mobile phone use has increased dramatically since the devices were introduced in the early 1980s. About five billion mobile phones are currently in use worldwide.
The researchers said the majority of people covered in their study “were not heavy mobile phone users by today's standards”. The average lifetime cumulative call time for those who took part was around 100 hours, with an average of two to two and half hours of reported use a month. Yet the 10 per cent of users who made the most frequent use of mobile phones clocked up an average of 1,640 hours of use over 10 years, or about half an hour a day.
“Today, mobile phone use has become much more prevalent and it is not unusual for young people to use mobile phones for an hour or more a day,” the researchers wrote. But they added that increasing use is tempered by generally lower radiation emissions from modern phones, greater use of texting, and hands-free sets that keep the phone away from the head.
The study received €19.2 million in funding, around €5.5 million of which came from industry sources. It analysed data from interviews with 2,708 people with a type of brain cancer called glioma and 2,409 with another type called meningioma, plus around 7,500 people without cancer.
Participants came from Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden and Britain.