Radiofrequency radiation-induced gene expression.

Gene expression (the process by which genetic information is converted into a functional product) changes in response to environmental changes to restore cellular homeostasis. This is an adaptive mechanism. The nature of these changes reflects how cells are affected by disruptive factors. In their narrative review, the authors summarize the extensive scientific literature on the effects of radiofrequency electromagnetic fields (RF-EMF) on gene expression.

In their narrative review, the authors evaluated over 500 primary studies that examined the genetic effects of RF radiation. The authors focused on studies examining frequencies between 800 and 2500 MHz – a spectrum typical of mobile devices. The included studies used in vitro and in vivo models, as well as acute and chronic exposure. The model organisms included a wide variety, ranging from cell cultures of various origins to rodents, insects, and plants. The 6 categories of gene expression covered were: 1) repair and removal of damaged proteins, 2) DNA damage, 3) oxidative processes, 4) stress responses, 5) apoptosis, and 6) brain functions. Exposure parameters varied considerably, with specific absorption rates (SAR) ranging from a few µW/kg to 20 W/kg.

Given the wide variation in study design among the primary studies, it is not surprising that they present an inconsistent picture of altered gene expression. However, one consistent finding is that RF radiation alters the expression of genes involved in key cellular processes. For example, heat shock proteins (Hsp70 and Hsp90) are consistently overexpressed. (Despite their name, these proteins respond to various cellular stress factors helping, among others, to protect DNA and break down damaged cellular components; editor's note.) Changes have also been observed in genes associated with DNA damage and repair, such as p53 and p21. Other areas in which adaptive gene expression has been repeatedly observed include oxidative processes (e.g. antioxidant and protective enzymes, Hsp70), programmed cell death (both pro- and anti-apoptotic), and genes associated with brain function. These include neurotransmitter genes, NMDA receptor genes, and cancer-related microRNA (miRNA). At a SAR value of less than 0.4 W/kg, 40 different effects of RF radiation on gene expression were detected.

The authors argue that changes in gene expression provide strong evidence that RF radiation affects cellular functions. This is a direct response to external stress, through which normal conditions are restored. The function or association of the altered genes reveals the effects of RF radiation on cells. For example, it would be illogical to assume that genes associated with DNA repair would be upregulated in the absence of DNA damage. Due to the complex interaction between RF radiation and cells, a non-linear dose–response relationship is to be expected, as are studies in which no biological effect of RF radiation on gene expression can be detected. The frequency of effects at low intensities (SAR < 0.4 W/kg) calls into question the appropriateness of current exposure guidelines. Lai and Levitt call for more in-depth research on altered gene expression due to RF radiation, focusing on two areas in particular: (1) the involvement of cellular stress responses in the hypothalamic–pituitary–adrenal (HPA) axis and its effects on the limbic system and (2) cellular oxidation processes, particularly the induction of free radicals.

Editor's note:

As a narrative review, this study does not claim to provide a complete statistical evaluation of all relevant primary studies. However, it identifies recurring patterns by using a wide range of primary studies with different designs, endpoints, and results. (RH)