November 5, 2014

Malignant Brain Tumors Associated With Mobile and Cordless Phone Use

Study warns of the dangers of wireless technology
Will a recent study finding a significant association between mobile and cordless phone use and malignant brain tumors cause us to reconsider our addiction to wireless technology?


Hardell L, Carlberg M, Söderqvist F, Mild KH. Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use. Int J Oncol. 2013;43(6):1833-1845.


Case-control study


Data collected from patients in the Department of Oncology, University Hospital, Orebro, Sweden


There were 593 participants, of whom 350 were male. Participants were aged 18 to 75 years and were diagnosed with various grades of malignant brain tumors between 2007 and 2009. Additionally, there were 1,368 matched controls.

Study Method

Exposure was assessed by a self-administered questionnaire. Unconditional logistic regression analysis was used, adjusting for age, gender, year of diagnosis, and socioeconomic index using the whole control sample. 

Outcome Measures 

Odds ratio (OR) was calculated by phone use type and time of exposure (defined as “latency”). Cumulative use of 39 hours or less in total among the controls was used as cut-off for the referent group of “no exposure” among cases and controls. Latency was analyzed using 6 time periods: less than 1 to 5 years, 5 to 10 years, 10 to 15 years, 15 to 20 years, 20 to 25 years, and over 25 years. To further determine any dose-response relationship, cumulative use of the phone types was divided into quartiles based on use of wireless phones in total among the controls: first quartile was 39 hours to 405 hours, second quartile 406 hours to 1,091 hours, third quartile 1,092 to 2,376 hours, and fourth quartile over 2,376 hours.

Key Findings 

This study demonstrated an association between mobile and cordless phone use and malignant brain tumors and increased risk with ipsilateral use and latency (time since first exposure). 
Overall, there was a statistically significant increased risk for malignant brain tumors associated with wireless phones: OR:1.7; confidence interval (CI):1.04-2.8. The trend was for increased risk in the less than 1 to 5–year group with a drop off for the 5 to 10–year group and the 10 to 15–year group. The highest risk was in those with 25 years or more of exposure: OR:3.0; CI:1.5-6.0. Risk increased with increased usage when stratified by 100-hour increments and a stronger association with ipsilateral vs contralateral use.
Phone type and time of latency were stratified further. Mobile use with analog-type phones increased risk: OR:1.8; CI:1.04-1.33. This increased with increasing latency, reaching OR:3.3; CI:1.6-6.9 for those with a latency greater than 25 years. Digital 2G mobile phone use yielded OR:1.6; CI:0.996-2.7, and those with latency of 15 to 20 years increased to OR:2.1; CI:1.2-3.6. Cordless phone use had OR:1.7; CI:1.1-2.9, and this increased to OR:2.1; CI:1.2-3.8 for those participants between 15 and 20 years of latency. There was insufficient data to reliably analyze 3G wireless. 

Practice Implications

Wireless phone technology was initially adopted widely in the Nordic countries, resulting in key data with regards to latency studies. This Swedish study uses entirely new data from both mobile and cordless desktop phone use for longer than 10 years and specifically assesses malignant brain tumors. The new data can be contrasted with the large 2010 Interphone Study, a major international collaboration that was inconclusive regarding an association with brain tumors and exposure to radiofrequency electromagnetic fields (RF-EMFs) from wireless phone use for 10 years or less.1 The new study reports an association between mobile and cordless phone use and malignant brain tumors, demonstrating higher risk with increased latency of 15 to 25 years. In this publication, the authors noted a number of animal cell studies that demonstrate free radical activity in cells induced by RF-EMF exposure that resulted in DNA damage.2-4 They emphasize that their study further supports the hypothesis that RF-EMFs contribute to the initiation and development of carcinogenesis over time.
Decades after the introduction of wireless telecommunications, cell phone safety has yet to be addressed in a meaningful way.
How do we as clinicians acknowledge and utilize the mounting data? The Swedish study brings new focus to the risks associated with cumulative use of cell phones. Pandora’s box has been undeniably opened with the consequences unfolding before us. We would be hard pressed as a culture to stop using mobile phones, cordless phones, and the myriad wireless technology available to combat our insatiable desire for data retrieval and accessibility. But the evidence is hard to turn away from: Our brains are being affected by the radiofrequencies emitted by the ubiquitous devices woven securely into our cultural fabric. 
RF-EMFs are emitted not only from cordless and mobile phones, but also from WiFi routers, Bluetooth headsets, and even baby monitors. Two of the most vulnerable populations are grade-school children and adolescents. Recent surveys report that 78% of adolescents own cell phones and that 56% of children between the ages of 8 and 12 have cell phones.5,6 A recently published pilot study reported that the majority of adolescents take their phones to bed, implying continuous RF exposure throughout the night.7 Decades after the introduction of wireless telecommunications, cell phone safety has yet to be addressed in a meaningful way, perhaps because it is obscured by the perceived benefits and conveniences the technology offers. More data need to be collected and assessed, especially with the knowledge that the risks are cumulative. An analysis published in Electromagnetic Biology and Medicine describes the mobile phone safety certification process, which significantly underestimates the specific absorption rate for most users, especially children.8 In the analysis, the authors plead with the US Federal Communications Committee to use more accurate and appropriate methods to determine safety standards—standards that are currently in place in other countries.  
Reducing our overall use, turning off devices—including routers—when they’re not in use, and keeping a safe distance between wireless technology and the brain are some of the safety measures that can be taken. Wired headphones or air-tube technology are available and can broaden the distance between the user’s brain and the cell phone. Texting can be utilized instead of phoning. Reinstating vintage corded landlines at home can further reduce exposure. It is important to sleep away from cell phones, especially for children and adolescents. Exerting parental prerogative and personal self-restraint may be necessary in a culture that promotes wholesale adoption of wireless technology. Knowing the risks and implementing basic protective measures will potentially benefit current and future generations.

Categorized Under


  1. The INTERPHONE Study Group. Brain tumour risk in relation to mobile telephone use: results of the INTERPHONE international case-control study. Int J Epidemiol. 2010;39(3):675-694.
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  4. Liu C, Duan W, Xu S, et al. Exposure to 1800 MHz radiofrequency electromagnetic radiation induces oxidative DNA base damage in a mouse spermatocyte-derived cell line. Toxicol Lett. 2013;218(1):2-9.
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