Article review date
October 2024
Article publication date
August 2024
Summary
This systematic review and meta-analyses examined the scientific evidence of the effect of radiofrequency electromagnetic fields (RF-EMF) on biomarkers for oxidative stress as reported in experimental animal (in vivo) and cell (in vitro) studies. A literature search found 12409 studies and of these, 56 met the inclusion criteria for further analysis. Results were analysed by individual biomarkers for oxidative stress and were further subdivided by the biological system the marker was recorded from. Results were reported as the standardised mean difference (SMD) with a 95% confidence interval (CI). Certainty of evidence and risk of bias for each result was assessed according to OHAT-GRADE.
For many outcomes, calculating a pooled effect size was not possible as the results of the included studies were too inconsistent to make a meaningful synthesis, ranging from large decreases to large increases compared to a control. Where a pooled effect size was calculated, most outcomes reported a statistically non-significant result however, some of the analyses showed significant effects ranging from small to large. These effects were reported for oxidised DNA bases in rodent cells (SMD 2.49; 95% CI [1.30, 3.67]), plasma (SMD 2.25; 95% CI [1.27, 3.24]) and testis (SMD 1.60; 95% CI [0.62, 2.59]) as well as modified proteins in the thymus (SMD 6.16; 95% CI [3.55, 8.76]) and liver (SMD 0.55; 95% CI [0.06, 1.05]) of rodents. However, all outcomes, regardless of whether they showed an effect or not, were assessed as very-low certainty evidence. This was primarily due to high risk of bias ratings across the included studies and the large degree of inconsistency and imprecision in the measured effects. In some cases, the analysis was based on results from single studies with very small sample sizes. Although a full dose response analysis was not possible, the authors identify several counter-intuitive trends across the studies where the study with the lowest RF-EMF exposure level reported the largest effect or the study with middling exposure reported the largest effect.
The study concludes that, due to the very low certainty in the evidence, the current scientific literature does not have any implications for policy related to RF-EMF but does highlight the need for drastic improvements in future studies.
Published in
Environmental International
Link to study
Commentary by ARPANSA
The present study represents the most comprehensive and latest review of the scientific literature related to the effect of RF-EMF exposure on oxidative stress. The review also identifies several challenges in this field of assessment. Evaluating the generation of reactive oxygen species or biomarkers of oxidative stress is challenging because these umbrella terms represent a broad class of molecules that participate in an extremely wide range of chemical transformations, both positive and negative. One of the challenges for biomarkers of oxidative stress is that they can also be formed through other mechanisms, giving results that may lack enough specificity. As such, it is recommended that multiple biomarkers are used to assess oxidative stress (Frijhoff et al., 2015; Murphy et al., 2022). However, singular biomarkers are overwhelmingly over-represented in many of the meta-analyses in this review, reflecting the low overall quality of the scientific evidence. Further to the challenges of measurement, the connection between oxidative stress and various diseases is also complex. While oxidative stress is frequently associated with the pathology of certain diseases, it is comparatively infrequently identified as a part of the cause and onset of a disease (Forman & Zhang, 2021).
The counter-intuitive negative correlation between effect size and RF-EMF level has also been shown in a previous analysis conducted by ARPANSA of in vivo and in vitro studies investigating the bioeffects of RF fields used by 5G telecommunications (Wood et al, 2021). The ARPANSA review also reported a negative correlation between effect size and study quality, meaning that poor quality studies showed RF bioeffects whereas good quality studies did not.
These challenges are reflected in the current body of evidence and consequently the very low certainty ratings given to all meta-analyses in this review. The most important outcomes from the review are the flaws identified in the body of evidence and the recommendations made for improvements. Further experimental studies that follow these recommendations are required before more robust conclusions about the relationship between RF-EMF and biomarkers of oxidative stress can be made.
This review is part of the World Health Organisation’s ongoing project assessing the health effects of RF-EMF (SR9 – Effect of exposure to RF on biomarkers of oxidative stress). ARPANSA is supporting this WHO review process.
