Radiofrequency exposure and the risk for brain tumors.

Abstract

To the Editor: Morgan and co-workers reported recently on mortality, including malignant diseases of the brain and lymphatic/hematopoetic systems, in a cohort of U.S. Motorola employees with potential radiofrequency (RF) exposure. 1 The results did not support an association between such exposure and these or other malignancies. The authors created job-exposure matrix to categorize each of 9,724 job titles into one of four RF exposure groups (background, low, moderate, and high). RF exposure from a cellular telephone was not assessed since such use was variable, extended across different job titles, and was not well documented. Thus, subjects in their unexposed group might in fact have been exposed to RF from cellular telephones, biasing the study results. The paper is not clear on the types of brain tumors that were included. Since it was a mortality study, the brain tumors were likely to be mostly malignant. Thus, information on brain tumors with a better prognosis, such as meningioma, would be lacking. Meningioma has been reported to be the most common brain tumor associated with ionizing radiation. 2 Depending on the antenna, use of a mobile telephone gives the highest RF exposure in the anatomical areas closest to the handset, that is the temporal, temporoparietal, and occipital lobes on the same side. 3 Hence, in a study on cell phone use and brain tumors, it is important to assess which ear has been used during telephone calls as well as the anatomical localization of the tumor. In our own case-control study on brain tumors we assessed, among other exposures, use of mobile telephones and the ear most often used during such phone calls. The tumor localization in the brain was determined as obtained from CT-scans or MR investigations. Our main finding was in the multivariate analysis an increased risk for brain tumor in the area with RF exposure from ipsilateral use of a cellular telephone (OR = 2.62; 95% CI = 1.02–6.71 after adjusting for exposure to laboratory work and diagnostic medical x-ray of the head and neck.). 4,5 Contralateral use did not increase the risk (OR = 0.97; 95% CI = 0.36–2.59). We did not find an increased risk in other parts of the brain considered to be unexposed. Further studies should monitor in detail the target areas for RF exposure of the human body. We think that the Motorola study is of value primarily to understand better the potential health effects from whole body RF exposure. Lennart Hardell Kjell Hansson Mild Arne Hallquist