Mobile phone users do not have a higher risk of brain tumours

A large international research study, COSMOS, has studied over 250,000 mobile phone users to investigate whether those who use mobile phones extensively and over a long time period have a higher risk of brain tumours than others. The international study, in which Utrecht University’s Institute for Risk Assessment Sciences (IRAS) led the Dutch arm of the study, found no link between mobile phone use and the risk of brain tumours.

Previous studies have had methodological problems that made it difficult to draw firm conclusions. “We obtained information on actual phone usage through providers and were able to reconstruct very detailed phone usage of every individual over a long time”, says professor Roel Vermeulen of Utrecht University’s IRAS.

“For the first time, a prospective cohort study has shown that those who talked the most hours in total on a mobile phone do not have a higher risk of developing a brain tumour than others”, says Maria Feychting, professor at the Institute of Environmental Medicine, Karolinska Institutet, who led the COSMOS study on cancer risk.

Concerns

The widespread use of mobile phones and other wireless communications has led to concerns that the radio frequency electromagnetic radiation from mobile technologies can cause cancer and other diseases. The WHO and the EU have asked for high-quality studies to be able to answer these questions. Against this background, the COSMOS study was initiated almost 20 years ago.

Between 2007 and 2013, a large number of people in Denmark, Finland, the Netherlands, Sweden, and the UK answered detailed questions about their mobile phone use. In addition, call duration information was obtained from phone providers.. The participants were then followed in cancer registries to record any newly developed brain tumours. The occurrence of brain tumours among the ten percent who spent the largest total number of hours talking on a mobile phone during their lifetime did not differ from those who used the mobile phone significantly less. Persons who started using a mobile phone more than 15 years before enrolling in the COSMOS study, did not have a higher risk of contracting the disease than those who used a mobile phone for a shorter time.

Previous studies

Some previous studies have reported an association between mobile phone use and brain tumour occurrence. There, people who had already been diagnosed with a brain tumour and healthy control subjects were contacted. With such an arrangement, there is a risk that the patients overestimate their previous mobile phone use compared to the healthy controls. Such memory errors may affect the results. In COSMOS, the participants answered the questions before someone had fallen ill. Therefore, the disease cannot have had any effect on how participants remembered past mobile phone use.

COSMOS is the only study to date that has been able to combine a prospective cohort design with detailed information on the extent of mobile phone use. Previous cohort studies have only had information on when the participants started using mobile phones. These studies also found no association with brain tumours, but have been criticized for lacking information on how much the participants spoke on their mobile phones. COSMOS has now shown that even those who talk the most on their mobile phones do not have a higher risk of brain tumour than others.

In 2011, the WHO's cancer research institute, IARC, classified radiofrequency fields as "possibly carcinogenic". This assessment was largely based on the so-called case-control studies that asked brain tumour patients and healthy controls retrospectively about their previous mobile phone use. The researchers point out that the results from COSMOS will be an important contribution to the scientific evidence for future health risk assessments. “The timely appearance of these important results from the COSMOS study will make a difference in the health risk assessment of radiofrequency electromagnetic fields the Radiotion and Health department of the World Health Organization is currently undertaking to update their monograph on radiofrequency fields from 1993”, says Professor Hans Kromhout of Utrecht University, who is also member of the WHO Task Group.