The Causal Relationship Between Radiofrequency-Electromagnetic Radiation from Wireless Phones and Brain Tumor, Part 1: A Systematic Review for Possible Biases and Confounding

Abstract

Introduction: The hypothesis of this study is that RF-EMR exposure from wireless phones causes brain tumors and that this causal relationship can be accurately validated only when accurate exposure assessment methods are applied. As a starting point of this series article, a systematic review of published literature for possible biases and confounding in previous studies will be conducted in the first part. Methods: The medical librarian searched MEDLINE: PubMed, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library (until 24 December 2020). Results and Discussion: Of the total of 13 studies included, 8 studies concluded that the risk estimates in original studies were underestimated. The other 2 studies concluded that the risk estimates in original studies were underestimated in most scenarios except for a limited number of low possibility scenarios. The other 2 studies concluded the risk estimates might be under- or over-estimated equivocally, and another 1 study concluded the risk estimates might be fair. One study insisted the accurate assessment of RF-EMR exposure should be based on (ⅰ) site-specific, (ⅱ) time integral of (ⅲ) specific absorption rate (SAR). As for the ‘site specific’ component, the fact that the widespread Bluetooth technology is making the distance between the head and wireless phones farther than before should be considered. As for the ‘time-integral’ component, almost all people in modern society are using their mobile phones every day, every minute, even when they are sleeping (as a morning-alarm device), for various purposes other than mere calling. As for the ‘SAR’ component, the fluctuating output power range according to various conditions should be considered in the exposure assessment. Conclusion: Overall, the risk estimates were underestimated in previous literature. However, a more important point is that accurate exposure assessment is required for valid epidemiologic studies.