The effect of exposure to radiofrequency fields on cancer risk in the general and working population:

Abstract

The effect of exposure to radiofrequency fields on cancer risk in the general and working population: A systematic review of human observational studies – Part II: Less researched outcomes Karipidis K, Baaken D, Loney T, Blettner M, Mate R, Brzozek C, Elwood M, Narh C, Orsini N, Röösli M, Paulo MS, Lagorio S. The effect of exposure to radiofrequency fields on cancer risk in the general and working population: A systematic review of human observational studies – Part II: Less researched outcomes. Environment International, 2025. doi: 10.1016/j.envint.2025.109274. Abstract Background In the framework of the World Health Organization assessment of health effects of exposure to radiofrequency electromagnetic fields (RF-EMF), we have conducted a systematic review of human observational studies on the association between exposure to RF-EMF and risk of neoplastic diseases. Due to the extremely large number of included exposure types/settings and neoplasm combinations, we decided to present the review findings in two separate papers. In the first one we addressed the most investigated exposure-outcome pairs (e.g. glioma, meningioma, acoustic neuroma in relation to mobile phone use, or risk childhood leukemia in relation to environmental exposure from fixed-site transmitters) (Karipidis et al., 2024). Here, we report on less researched neoplasms, which include lymphohematopoietic system tumours, thyroid cancer and oral cavity/pharynx cancer, in relation to wireless phone use, or occupational RF exposure. Methods Eligibility criteria: We included cohort and case-control studies of neoplasia risks in relation to three types of exposure to RF-EMF: 1. exposure from wireless phone use; 2. environmental exposure from fixed-site transmitters; 3. occupational exposures. In the current paper, we focus on less researched neoplasms including leukaemia, non-Hodgkin’s lymphoma and thyroid cancer in mobile phone users; lymphohematopoietic system tumours and oral cavity/pharynx cancer in exposed workers. We focussed on investigations of specific neoplasms in relation to specific exposure sources (termed exposure- outcome pair, abbreviated E-O pairs), noting that a single article may address multiple E-O pairs. Information sources: Eligible studies were identified by predefined literature searches through Medline, Embase, and EMF-Portal. Risk-of-bias (RoB) assessment: We used a tailored version of the Office of Health Assessment and Translation (OHAT) RoB tool to evaluate each study’s internal validity. Then, the studies were classified into three tiers according to their overall potential for bias (low, moderate and high) in selected, predefined and relevant bias domains. Data synthesis: We synthesized the study results using random effects restricted maximum likelihood (REML) models. Evidence assessment: Confidence in evidence was assessed according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Results We included 26 articles, which were published between 1988 and 2019, with participants from 10 countries, reporting on 143 different E-O pairs, including 65 different types of neoplasms. Of these, 19 E- O pairs satisfied the criteria for inclusion in quantitative syntheses of the evidence regarding the risks of leukaemia, non-Hodgkin’s lymphoma or thyroid cancer in relation to mobile phone use, and the risks of lymphohematopoietic system tumours or oral cavity/pharynx cancer following occupational exposure to RF-EMF. RF-EMF exposure from mobile phones (ever or regular use vs no or non-regular use) was not associated with an increased risk of leukaemia [meta-estimate of the relative risk (mRR) = 0.99, 95 % CI 0.91–1.07, 4 studies), non-Hodgkin’s lymphoma (mRR = 0.99, 95 % CI = 0.92–1.06, 5 studies), or thyroid cancer (mRR = 1.05, 95 % CI = 0.88–1.26, 3 studies). Long-term (10 + years) mobile phone use was also not associated with risk of leukaemia (mRR = 1.03, 95 % CI 0.85–1.24, 3 studies), non-Hodgkin lymphoma (mRR = 0.99, 95 % CI 0.86–1.15, 3 studies), or thyroid cancer (no pooled estimate given the small number of studies). There were not sufficient studies of any specific neoplasms to perform dose– response meta-analyses for either cumulative call time or cumulative number of calls; individual studies did not show statistically significant associations between lifetime intensity of mobile phone use and any specific neoplasm. Occupational RF-EMF exposure (exposed vs unexposed) was not associated with an increased risk of lymphohematopoietic system tumours (mRR = 1.03, 95 % CI = 0.87–1.28, 4 studies) or oral cavity/pharynx cancer (mRR = 0.68, 95 % CI 0.42–1.11, 3 studies). There were not sufficient studies of any specific neoplasms to perform meta-analysis on the intensity or duration of occupational RF-EMF exposure; individual studies did not show statistically significant associations with either of those exposure metrics and any specific neoplasms. The small number of studies, and of exposed cases in some instances, hampered the assessment of the statistical heterogeneity in findings across studies in the meta-analyses. Based on the summary risk of bias, most studies included in the quantitative evidence syntheses were classified at moderate risk of bias. The most critical issue was exposure information bias, especially for occupational studies where the exposure characterization was rated at high risk of bias for all included studies. Outcome information bias was an issue in mortality-based occupational cohort studies investigating non-rapidly fatal neoplasms. Further, the healthy subscriber effect, and (at a lesser extent) the healthy worker effect, were identified as plausible explanations of the decreased risks observed in some studies. The association of RF-EMF exposure from wireless phone use, or workplace equipment/devices, with other important neoplasms was reported by only one or two studies per tumour, so no quantitative evidence syntheses were conducted on these outcomes. It is noted that there were generally no statistically significant exposure-outcome associations for any combinations, independently of the exposure metric and level, with a few studies reporting decreased risks (especially for smoking-related cancers). There was only one study which assessed the effect of RF- EMF exposure from fixed-site transmitters on less researched neoplasms and it reported no statistically significant associations between exposure from base stations and risk of lymphomas overall, lymphoma subtypes, or chronic lymphatic leukaemia in adults. Conclusions For near field RF-EMF exposure to the head from mobile phones, there was low certainty of evidence that it does not increase the risk of leukaemia, non-Hodgkin’s lymphoma or thyroid cancer. For occupational RF-EMF exposure, there was very low certainty of evidence that it does not increase the risk of lymphohematopoietic system tumours or oral cavity/pharynx cancer. There was not sufficient evidence to assess the effect of whole-body far-field RF-EMF exposure from fixed-site transmitters (broadcasting antennas or base stations), or the effect of RF-EMF from any source on any other important neoplasms. Other This project was commissioned and partially funded by the World Health Organization (WHO). Co- financing was provided by the New Zealand Ministry of Health; the Istituto Superiore di Sanità in its capacity as a WHO Collaborating Centre for Radiation and Health; and ARPANSA as a WHO Collaborating Centre for Radiation Protection. Registration: PROSPERO CRD42021236798. Published protocol: [(Lagorio et al., 2021) DOI doi.org]. Excerpts "Our conclusive statements, formulated in accordance with the GRADE guidelines 26 (Santesso et al., 2020), are provided below. • For near field RF-EMF exposure to the head from mobile phones, there was low certainty of evidence that it does not increase the risk of leukaemia, non-Hodgkin’s lymphoma or thyroid cancer. • For occupational RF-EMF exposure, there was very low certainty of evidence that it does not increase the risk of lymphohematopoietic system tumours or risk of oral cavity/pharynx cancer. • There was not sufficient evidence to assess whole-body far-field RF-EMF exposure from fixed- site transmitters (broadcasting antennas or base stations) or the effect of exposure to RF-EMF (from any source) on any other important neoplasms." "The main limitation in this second paper on findings from our systematic review was the small number of studies per tumour type (which in some ways is inherent to this paper, that is dedicated to less researched neoplasms). A formal synthesis of the evidence was only possible for a few types of neoplasms, mainly different types of lymphohematopoietic system tumours, as well as thyroid and oral cavity/pharynx cancers. There were 54 types of neoplasms which were investigated in only one or two studies and did not satisfy the criteria for a quantitative synthesis of the evidence, but none of these showed evidence of an effect of RF EMF." "Looking at specific sources of RF-EMF exposure, the majority of the evidence was on mobile phone use. There was only sufficient evidence to assess the effect of ever (or regular) use vs no (or non-regular) use, as well as of long-term (10 + years) use. There was not sufficient evidence on lifetime intensity of mobile phone use, including cumulative call time and cumulative number of calls, so we could not conduct a dose–response analysis." Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Mark Elwood has given expert advice on topics in electromagnetic fields and health, and on the objective interpretation of epidemiological and other scientific information, over many years to individuals and groups, including government ministries, environmental regulators, community groups, commercial organisations, and formal inquiries by government and professional groups including parliamentary and legal proceedings. Some of this work has been financially supported, by universities, health care organisations, research bodies, or by government, professional or commercial groups. Some work has been reported ‘blind’, with the client being unidentified. Susanna Lagorio was principal investigator (April 2019 – March 2020) of the research project “BRiC 2018/06 − Systematic reviews of exposure to radiofrequency fields and cancer”, supported by the Italian Workers’ Compensation Authority, a public no-profit entity (grant code I85B19000120005). Her employment duties involved provision of advice on health hazards from exposure to RF-EMF to the Italian Ministry of Health and Higher Health Council (she retired on August 1st, 2023). Martin Röösli’s research is entirely funded by public entities or not for profit foundations. He has served as advisor on potential health effects of exposure to non-ionizing radiation to several national and international public advisory and research steering groups, including the World Health Organization, the International Agency for Research on Cancer, the International Commission on Non-Ionizing Radiation Protection, the Swiss Government (member of the working group “Mobile phone and radiation” and chair of the expert group BERENIS), the German Radiation Protection Commission (member of the committee Non-ionizing Radiation (A6) and member of the working group 5G (A630)) and the Independent Expert Group of the Swedish Radiation Safety Authority. From 2011 to 2018, M.R. was an unpaid member of the foundation board of the Swiss Research Foundation for Electricity and Mobile Communication, a non-profit research foundation at ETH Zurich. Neither industry nor nongovernmental organizations are represented on the scientific board of the foundation. Chris Brzozek and Rohan Mate as part of their employment are involved in the provision of advice to the Australian Commonwealth Government, Australian States and Territories and the general public on the risks and health effects of exposure to ionising and non-ionising radiation. The other authors declare that they have no known conflicts of interest. Open access paper: sciencedirect.com

AI evidence extraction

Main findings

This systematic review of cohort and case-control studies (26 articles, 1988–2019) reported no statistically significant associations between mobile phone use (ever/regular or long-term 10+ years) and risks of leukaemia, non-Hodgkin’s lymphoma, or thyroid cancer in pooled analyses. Occupational RF-EMF exposure (exposed vs unexposed) was also not associated with increased risk of lymphohematopoietic system tumours or oral cavity/pharynx cancer in pooled analyses. Evidence for fixed-site transmitters and for other less-researched neoplasms was insufficient for quantitative synthesis; one study on base stations reported no statistically significant associations with lymphoma outcomes or chronic lymphatic leukaemia in adults.

Outcomes measured

• Leukaemia
• Non-Hodgkin’s lymphoma
• Thyroid cancer
• Lymphohematopoietic system tumours
• Oral cavity/pharynx cancer
• Lymphomas (overall and subtypes)
• Chronic lymphatic leukaemia (adults)

Limitations

• Small number of studies per tumour type, limiting quantitative synthesis for many outcomes
• Limited ability to assess statistical heterogeneity due to small numbers of studies and exposed cases
• Most studies in quantitative syntheses classified as moderate risk of bias
• Exposure information bias noted as a critical issue, especially for occupational studies (exposure characterization rated high risk of bias for all included occupational studies)
• Outcome information bias in mortality-based occupational cohort studies for non-rapidly fatal neoplasms
• Potential healthy subscriber effect and (to a lesser extent) healthy worker effect as explanations for decreased risks in some studies
• Insufficient studies to conduct dose–response meta-analyses for cumulative call time or cumulative number of calls
• Insufficient evidence to assess far-field exposure from fixed-site transmitters for less-researched neoplasms

Suggested hubs

• who-icnirp (0.86)
  Conducted within the WHO assessment framework and commissioned/partially funded by WHO.
• cell-phones (0.84)
  Quantitative syntheses focused on mobile phone use and multiple cancer outcomes.
• occupational-exposure (0.72)
  Includes pooled analyses of occupational RF-EMF exposure and cancer risks.

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    "main_findings": "This systematic review of cohort and case-control studies (26 articles, 1988–2019) reported no statistically significant associations between mobile phone use (ever/regular or long-term 10+ years) and risks of leukaemia, non-Hodgkin’s lymphoma, or thyroid cancer in pooled analyses. Occupational RF-EMF exposure (exposed vs unexposed) was also not associated with increased risk of lymphohematopoietic system tumours or oral cavity/pharynx cancer in pooled analyses. Evidence for fixed-site transmitters and for other less-researched neoplasms was insufficient for quantitative synthesis; one study on base stations reported no statistically significant associations with lymphoma outcomes or chronic lymphatic leukaemia in adults.",
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        "Pooled analyses found no association between ever/regular mobile phone use and leukaemia, non-Hodgkin’s lymphoma, or thyroid cancer.",
        "Long-term (10+ years) mobile phone use was also not associated with leukaemia or non-Hodgkin’s lymphoma, and thyroid cancer could not be pooled due to few studies.",
        "No dose–response meta-analyses were possible for cumulative call time or number of calls due to insufficient studies, and individual studies did not show statistically significant associations for lifetime intensity metrics.",
        "Occupational RF-EMF exposure (exposed vs unexposed) was not associated with lymphohematopoietic tumours or oral cavity/pharynx cancer in pooled analyses.",
        "Exposure characterization was identified as a major limitation, especially in occupational studies where exposure assessment was rated high risk of bias.",
        "Evidence for fixed-site transmitters and for many other neoplasms was insufficient; one base-station study reported no statistically significant associations with lymphoma outcomes or chronic lymphatic leukaemia in adults."
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        "tweet": "Systematic review (WHO-commissioned) of 26 human observational studies found no increased risk of leukaemia, non-Hodgkin’s lymphoma, or thyroid cancer with mobile phone use, and no increased risk of lymphohematopoietic or oral cavity/pharynx cancers with occupational RF exposure; certainty was low to very low due to limited studies and exposure assessment bias.",
        "facebook": "A WHO-commissioned systematic review of human observational studies (26 articles) examined radiofrequency EMF exposure from mobile phones, occupational sources, and fixed-site transmitters in relation to less-researched cancers. Meta-analyses reported no increased risks for leukaemia, non-Hodgkin’s lymphoma, or thyroid cancer with mobile phone use, and no increased risks for lymphohematopoietic tumours or oral cavity/pharynx cancer with occupational exposure. The authors rated certainty as low (mobile phones) and very low (occupational), mainly due to limited studies and exposure assessment limitations.",
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