Use of cell phones and brain tumors: a true association?

Abstract

Use of cell phones and brain tumors: a true association? Mortazavi, S.A.R., Mortazavi, G. & Mortazavi, S.M.J. Letter to the Editor: Use of cell phones and brain tumors: a true association? Neurol Sci (2017). doi:10.1007/s10072-017-3055-x. Dear Editor: With great interest, we have read the editorial by Beghi entitled "Use of cell phones and brain tumors: a true association?" that is published in the journal of Neurol Sci 2017 doi: 10.1007/s10072-017-2992-8 [1]. In this article, the author confirms the lack of robust evidence of association between use of cell phones and brain tumors. However, Beghi mentions that absence of evidence does not necessarily mean that there is no any association. The editorial authored by Beghi addresses a very challenging issue. However, this editorial cannot be considered as a good contribution in the field of radiofrequency exposure and cancer. Over the past several years, our team has conducted several studies on the possible association of exposure to radiofrequency electromagnetic fields (RF-EMFs) and adverse health effects. Beghi claims that the findings of case-control studies have not been confirmed by cohort studies "First of all, the positive results of some case-control studies have not been confirmed by cohort studies. Case-control studies, even when methodologically robust, cannot replace cohort studies in confirming or disproving an association between a given exposure and a disease. ....In this context, none of the cohort studies found an increased risk of brain tumors in people exposed to cell phones." Although what he claims about the advantages of cohort studies seems to be right, his conclusion is problematic. Beghi does not mention that the number of cohort studies conducted on this topic so far is drastically low and all of these studies had some basic limitations. Therefore, the absence of cohort-proven findings does not necessarily mean that there is no detrimental effect. In this light, as free radical formation after exposure to RF-EMF is confirmed in many studies, even without firm conclusions from cohort studies, these exposures should be limited. Furthermore, Beghi claims that "Second, the increased risk of brain tumors in case-control studies, if proven, is at best modest and, as brain tumors are rare diseases, the total number of tumors appears only slightly increased." It is worth mentioning that a systematic review and meta-analysis recently published by Yang et al. could not find a link between mobile phone use of any duration and the odds of high-grade glioma. However, there was a 2.22 times greater odds of the occurrence of low-grade glioma for long-term mobile phone use (OR = 2.22, 95% CI = 1.69-2.92) [2]. Beghi also claims that a clear dose-response effect has never been confirmed. Over the past several years, our team has conducted several studies on the possible association of RF-EMFs and adverse health effects. Mortazavi et al. have also recently addressed the shortcoming of some of the papers claiming lack of association between exposure to RF-EMF and cancer. They have provided evidence showing that exposure to RF-EMFs, at least at high levels and long durations, can increase the risk of cancer [3]. Substantial evidence now indicates that the current controversy regarding the carcinogenesis of RF-EMFs might be caused by the lack of accurate information regarding the magnitude of exposure to RF-EMFs which possibly plays a basic role in RF-induced carcinogenesis [4]. We have also provided evidence which shows that, in a similar pattern with ionizing radiation, the carcinogenesis of non-ionizing RF-EMF may have a nonlinear J-shaped dose- response relationship [4]. ncbi.nlm.nih.gov

AI evidence extraction

Main findings

This Letter to the Editor argues that the lack of cohort-study evidence does not rule out an association between mobile phone RF-EMF exposure and brain tumors, citing limitations and low number of cohort studies. It cites a recent systematic review/meta-analysis (Yang et al.) reporting no link for high-grade glioma for any duration of mobile phone use, but higher odds of low-grade glioma with long-term use (OR=2.22, 95% CI=1.69–2.92), and recommends limiting exposures based on evidence of RF-EMF–related free radical formation and potential cancer risk at high levels/long durations.

Outcomes measured

• brain tumors
• high-grade glioma
• low-grade glioma
• cancer
• free radical formation

Limitations

• Letter to the Editor; does not present new primary data in the abstract
• Relies on critique of another editorial and references to other studies without providing methodological details here
• No exposure metrics (frequency, SAR, quantified duration) reported for the claims

{
    "study_type": "other",
    "exposure": {
        "band": "RF",
        "source": "mobile phone",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "brain tumors",
        "high-grade glioma",
        "low-grade glioma",
        "cancer",
        "free radical formation"
    ],
    "main_findings": "This Letter to the Editor argues that the lack of cohort-study evidence does not rule out an association between mobile phone RF-EMF exposure and brain tumors, citing limitations and low number of cohort studies. It cites a recent systematic review/meta-analysis (Yang et al.) reporting no link for high-grade glioma for any duration of mobile phone use, but higher odds of low-grade glioma with long-term use (OR=2.22, 95% CI=1.69–2.92), and recommends limiting exposures based on evidence of RF-EMF–related free radical formation and potential cancer risk at high levels/long durations.",
    "effect_direction": "mixed",
    "limitations": [
        "Letter to the Editor; does not present new primary data in the abstract",
        "Relies on critique of another editorial and references to other studies without providing methodological details here",
        "No exposure metrics (frequency, SAR, quantified duration) reported for the claims"
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.7199999999999999733546474089962430298328399658203125,
    "peer_reviewed_likely": "unknown",
    "keywords": [
        "radiofrequency",
        "RF-EMF",
        "mobile phone",
        "cell phone",
        "brain tumors",
        "glioma",
        "low-grade glioma",
        "high-grade glioma",
        "cancer",
        "dose-response",
        "J-shaped",
        "free radicals"
    ],
    "suggested_hubs": []
}

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