No causal link between mobile phone usage, brain tumour Premium

There were no statistically significant associations with talking for at least 20 minutes per week or with at least 10 years use

The researchers found that recent generations of wireless technologies emit lower output power. | Photo Credit: Getty Images

The latest U.K. Million Women Study on cellular telephone use and the risk of brain tumours published online on March 29, 2021 in Journal of the National Institute of Cancer confirms the accumulating evidence that cellular telephone use under usual conditions does not increase brain tumour incidence. The topic has added interest now because phone companies plan to launch 5G technologies soon.

Cellular telephone usage

During 1996-2001, U.K. Million Women Study recruited 1.3 million women born in the 15-year period between 1935-1950 into the study. Researchers asked questions on their cellular telephone use first in median year 2001 and again in median year 2011. They followed all study participants via record linkage to National Health Services databases on deaths and cancer registrations (including nonmalignant brain tumours).

The researchers linked the independent electronic health records of each participant with his/her behaviour, in this instance, the personal usage of cellular phones.

During 14 years of follow-up of 7,76,156 women who completed the 2001 questionnaire, the study registered 3,268 brain tumours in total. Adjusted relative risks forever vs never cellular telephone use were 0.97 for all brain tumours, 0.89 for glioma, and not statistically significantly different to 1.0 for meningioma, pituitary tumours, and acoustic neuroma.

Compared with never-users, researchers did not find statistically significant associations overall or by tumour subtype, for daily cellular telephone use or for having used cellular telephones for at least 10 years.

Taking use in 2011 as a baseline, the researchers found that there were no statistically significant associations with talking for at least 20 minutes per week or with at least 10 years use. For gliomas occurring in the temporal and parietal lobes, the parts of the brain most likely to be exposed to radio frequency electromagnetic fields from cellular telephones, relative risks were slightly below 1.0.

In a press release from the Science Media Centre, London, Prof Malcolm Sperrin, Oxford University Hospitals noted that this study from Oxford is a welcome addition to the body of knowledge looking at the risk from mobile phones, and specifically in relation to certain types of tumour genesis.

Need for research

“It is a well-designed, prospective study that identifies no causal link but does recognise that there may have been false correlations arising from previous studies that are retrospective in design. There is always a need for further research work especially as phones, wireless etc become ubiquitous but this study should allay many existing concerns.” he cautioned.

Researchers investigated the associations of cellular telephone use and brain tumours in many studies, as the brain was the most exposed organ. When we keep cell phones very close to our head, the RF-EMF emitted by cell phones penetrate several centimetres into our head; the energy gets absorbed in the tissues in the temporal and parietal lobes of the brain. The well-established biological effect of RF-EMF on tissue is heating. When researchers developed limits for human exposure to RF-EMF for cellular telephones, the prime consideration was to prevent any substantial heating that could lead to adverse health effects.

Effects of RF-EMF

There were legitimate concerns that there may be adverse biological effects from RF-EMF exposure below those limits, possibly caused through mechanisms other than heat. Researchers added a safety factor of fifty to take care of such unknown mechanisms. In any case, long-term epidemiological studies are defendable.

In an earlier analysis in 2013 after seven-year follow up, the researchers have shown that mobile phone use was not associated with increased incidence of glioma, meningioma or non-CNS cancers. The present study after a 14-year follow up, a 60% increase in numbers of brain tumours, and new analyses by tumour laterality and location within the brain, again confirmed that cellular telephone use under usual conditions does not increase brain tumour incidence.

Low output power

The researchers found that the more recent generations of wireless technologies emit substantially lower output power, so that on balance a very heavy user of today is unlikely to accumulate the same RF-EMF exposure as a modest user of the first two wireless generations.

We need not lose sleep worrying over brain tumours and cell phone use. 

(K.S. Parthasarathy is a former Secretary of the Atomic Energy Regulatory Board. ksparth@yahoo.co.uk)    

• The latest U.K. Million Women Study on cellular telephone use and the risk of brain tumours published online on March 29, 2021 in Journal of the National Institute of Cancer confirms the accumulating evidence that cellular telephone use under usual conditions does not increase brain tumour incidence
• The researchers linked the independent electronic health records of each participant with his/her behaviour, in this instance, the personal usage of cellular phones
• Researchers investigated the associations of cellular telephone use and brain tumours in many studies, as the brain was the most exposed organ
• The researchers found that the more recent generations of wireless technologies emit substantially lower output power, so that on balance a very heavy user of today is unlikely to accumulate the same RF-EMF exposure as a modest user of the first two wireless generations