Hartikka H, Heinävaara S, Mäntylä R, Kähärä V, Kurttio P, Auvinen A. Mobile phone use and location of glioma: A case-case analysis Bioelectromagnetics Jan 13, 2009 Ahead of print.
Epidemiological studies have not found an increased risk of brain tumors among mobile phone users, but concern remains about the long-term effects on glioma (a type of brain cancer) and acoustic neurinoma (a tumor in the nerves associated with the hearing). Previous studies have been limited by crude measures of radiofrequency electromagnetic field (RF-EMF) exposure. For an accurate assessment of exposure, both the localization of the tumor and information on mobile phone use is needed.
To provide a detailed assessment of the distance between the tumor and presumed location of the mobile phone (source of exposure) in glioma patients in order to determine the local effects of RF-EMF exposure as well as the feasibility of this type of assessment.
Cases were identified from neurosurgery clinics of Helsinki and Tampere University hospitals in Finland between November, 2000 and October, 2002. Subjects were aged between 20 and 60 years, had diagnostically confirmed glioma, and had no prior history of brain tumors. A neurologist at each hospital evaluated the radiological images (from computer tomography and/or magnetic resonance imaging) for each patient and recorded the midpoint of each tumor. Personal interviews regarding mobile phone use were conducted by trained interviewers at the hospitals. Exposure within 1 year preceding the diagnosis was ignored. The site of the source of RF-EMF exposure was considered to be the line from the ear to the corner of the mouth (where a mobile phone would typically be held). The shortest distance from the midpoint of each glioma to this line was measured. Subjects with gliomas within 4.6cm of the source of exposure were compared to those with a distance >4.6cm. Regular users of mobile phones (at least 6 months of weekly use) were compared to never or non-regular users in four different analyses. All analyses were adjusted for age and sex.
Of 144 eligible glioma patients, 99 agreed to participate, had CT/MRI images available, and provided mobile phone use information. A total of 78 participants were regular mobile phone users while 21 were never or non-regular users. The mean distance between tumor midpoint and presumed location of the mobile phone was slightly shorter for regular users than non-users (5.9 versus 6.2 cm). Regular users were 2.58 (95% CI = 0.65 to 10.26) times more likely to have a tumor ≤4.6cm of the exposure source than never or non-regular users. Regular users with a cumulative call time of more than 540 hours were 2.52 (95% CI 0.45 to 13.4) times more likely to have a tumor within 4.6 cm of the exposure source compared to never or non-regular users. Regular mobile phone users who used a mobile phone on the same side of the head as the glioma were 1.43 (95% CI 0.29 to 6.20) times as likely to have a tumor within 4.6 cm of the exposure source compared to never or non-regular users while those who used a mobile phone on the opposite side of the head as the tumor or on both sides of the head were 4.93 times as likely (95% CI 1.13 to 21.5). Regular users with at least 5 years of use were 1.95 (95% CI 0.38-10.2) times as likely to have a tumor within 4.6 cm of the exposure source compared to never or non-regular users.
Implications and Limitations
Regular mobile phone use was not associated with having a tumor close to the likely source of RF-EMF exposure. However, these results are subject to random error due to the small study size and may be subject to recall error by study participants. Nonetheless, the results show that determining the local effects of RF-EMF exposure is possible when tumor localization data are available.
The results do not indicate an association between mobile phone use and the risk of glioma located in the area of the brain likely to receive most of the emitted RF energy.