Looking for Biomarkers Which May Explain Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields (IEI‐EMF): Does RF‐EMF Exposure Influence Salivary Cortisol Response?

In order to understand Idiopathic Environmental Intolerance attributed to Electromagnetic Fields (IEI-EMF), it has been argued that it is crucial to test for effects of radiofrequency electromagnetic fields (RF-EMF) on biomarkers, given that they can be more objective than symptom reports. While no clear evidence links RF-EMF exposure to biomarker changes, research remains limited and largely speculative due to the lack of known bioeffect mechanisms. However, there is in vitro evidence that cortisol is affected by heating, which, as RF-EMF causes heating, raises the possibility that RF-EMF exposure may increase cortisol via thermally mediated processes. If cortisol is affected by RF-EMF exposure, it may form part of a broader aetiology of IEI-EMF, where RF-EMF-induced physiological (cortisol) inputs first generate somatic sensations, which are then fostered by expectancy or learning-based processes to generate symptoms. However, studies investigating whether RF-EMF exposure influences cortisol have reported inconsistent, but mostly null results, and many suffer from methodological issues. The current study was designed with several methodological improvements to determine whether RF-EMF affects cortisol. Seventy-two participants completed a randomized, double-blind, counterbalanced provocation study where they were exposed to both active (2 W/kg peak SAR_10g in head) and sham RF-EMF (0 W/kg peak SAR_10g in head). Despite implementing several methodological improvements, the current study failed to find an effect of RF-EMF exposure on salivary cortisol concentration. This study provides a valuable direction for future research and stresses the importance of establishing and testing theoretically plausible interactions between low-level RF-EMF exposure, the human body, and IEI-EMF symptoms.