The study presents an exhaustive systematic review and meta-analysis, following the PRISMA protocol and the one published by Lagorio et al. in 2021 specifically for systematic reviews of observational studies in humans of the possible cancer risks of exposure to radiofrequency electromagnetic fields. These types of studies are the strongest scientifically because they are objective and reproducible reviews. In addition, the authors have used risk of bias (RoB) assessment tools to ensure that only the highest quality studies are included. This tool evaluates possible confounding, participant selection and exclusion biases, the degree of confidence in characterising exposure, the confidence in the assessment of results and whether all the results were reported or only part of them (selective reporting), as well as the appropriateness of the statistical methods used.

This methodology relies on a systematic review measuring biases and guaranteeing reproducibility. 63 articles have been included, with participants from 22 countries, covering 119 combinations of exposure-outcome (E-O pairs). The meta-analyses performed show that there is no significant association between exposure to RF-EMF [Radiofrequency Electromagnetic Fields] and an increased risk of the most investigated types of cancer (glioma, meningioma, acoustic neuroma, among others).

Research led by Swedish researcher Lennart Hardell was included in the analysis. However, this work has been criticised in the scientific community for possible problems of bias, which is evident in the study. Their inclusion brings heterogeneity to the results, as Hardell's studies report higher risks associated with cell phone use, hence their inclusion may affect the risk estimates towards an increase. All this has been carefully taken into account.

Thus, the conclusions are robust, supported by quality studies, and indicate that no strong association was found between RF-EMF exposure and increased cancer risk, when considering the totality of the available evidence.

The search and inclusion of papers was performed on May 17, 2024, but at least three later studies could have been included that would provide more evidence to support the conclusions of the study (COSMOS, MOBI-Kids, and UK Biobank studies, among others). It should be noted that the IARC classified radiofrequency electromagnetic fields as “possibly carcinogenic to humans (Group 2B)” based on a review published in 2011. The current review by Karipidis et al. covers a wider time range, including studies from the IARC report; it has used more advanced methodology and has assessed the risks of bias. In addition, the analysis includes other sources --not only mobile phones-- and other cancers such as salivary gland tumors, pituitary tumors and leukaemia. Therefore the evidence provided by the IARC was limited, and this study provides evidence with a higher degree of certainty. In addition, the temporal trend data on brain cancer incidence in recent decades, despite the massive increase in the use of mobile phones, reinforces the lack of an observed causal association.

The authors have been meticulous in assessing and adjusting for potential confounders in the individual studies reviewed. They use advanced statistical models and stratify the analyses to mitigate the impact of known confounders. However, they acknowledge that not all studies included in the review were able to adequately control for these factors, which could introduce biases in some estimates.

The main implications of this study are that, according to the best available evidence to date, exposure to radiofrequency electromagnetic fields, such as those produced by mobile phones or telephone antennas, does not appear to significantly increase the risk of developing cancer. This suggests that current exposure standards, such as those established by ICNIRP [International Commission on Non-Ionizing Radiation Protection] and which are included in some national legislations, as in Spain, are adequate to protect public health.

However, as always in science, the authors recommend continuing with epidemiological surveillance, especially in relation to new technologies such as 5G, as the evidence is still limited and some uncertainties persist, for instance regarding long-term exposures and in more susceptible population subgroups.