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

Abstract

Overview

In the context of the World Health Organization’s evaluation of health impacts from radiofrequency electromagnetic fields (RF-EMF), this systematic review focused on human observational studies investigating the association between RF-EMF exposure and less researched neoplastic outcomes in both the general and occupationally exposed populations. Unlike its companion paper that addressed widely examined cancers, this review centers on neoplasms such as those of the lymphohematopoietic system, thyroid cancer, and oral cavity/pharynx cancer as related to wireless phone use or occupational RF exposure.

Methods

• Eligibility Criteria: Inclusion of cohort and case-control studies examining neoplasia risk from: (1) wireless phone use, (2) environmental exposure via fixed-site transmitters, and (3) occupational RF-EMF exposure.
• Screening: Systematic literature searches in Medline, Embase, and EMF-Portal databases.
• Risk of Bias: Assessment via the OHAT tool; studies categorized into low, moderate, or high bias tiers.
• Data Synthesis: Random effects REML models applied; GRADE criteria used for evidence confidence.

Findings

• Included 26 articles from 1988 to 2019, encompassing 143 exposure-outcome pairs and 65 neoplasm types.
• For mobile phone RF-EMF exposure, meta-analyses indicated no statistically significant increase in risk for leukaemia, non-Hodgkin's lymphoma, or thyroid cancer (various studies, mRRs near 1.0).
• Long-term phone use also did not yield increased neoplasia risk; individual studies were unable to assess dose-response effects due to limited data.
• Occupational RF-EMF exposure was not associated with increased risk for lymphohematopoietic or oral cavity/pharynx cancers.
• Risk of bias was generally moderate, with major concerns over exposure assessment—especially in occupational contexts.
• Insufficient studies precluded dose-response or intensity/duration meta-analyses for either occupational or environmental exposures.
• Only one study examined exposure from fixed-site transmitters, showing no statistically significant associations with lymphoma or chronic lymphatic leukaemia.

Conclusion

• There is low certainty that mobile phone-related RF-EMF exposure does not increase risk of leukaemia, non-Hodgkin's lymphoma, or thyroid cancer.
• For occupational exposure, very low certainty exists that RF-EMF does not increase risks for lymphohematopoietic or oral cavity/pharynx cancers.
• Limited evidence and studies make it impossible to draw conclusions about whole-body far-field RF-EMF from transmitters, or the effect of RF-EMF on other neoplasms.
• The link between RF-EMF exposure and cancer cannot be ruled out, especially given the low certainty and risk of biases in existing studies. This underlines the need for continued caution and further research regarding the potential health risks associated with EMF exposure, particularly for less studied cancer types.