Low-Level Radiofrequency Exposure Induces Vasoconstriction in Rats.

Recent studies have revealed that rodents' physiological responses to low-intensity radiofrequency (RF) electromagnetic fields were similar to thermoregulatory responses to cold conditions. The primary autonomic response to cold exposure is peripheral vasoconstriction that allows rodents to reduce heat loss and maintain a relatively constant internal body temperature. In the present study, we investigated the effects of 900 MHz RF at a low level (SAR of 0.35 W/kg) on tail skin temperature (Ttail ) in rats. We showed that rats exposed to RF had lower Ttail than control rats at ambient temperatures between 27 and 28 °C, suggesting that RF could induce a noticeable degree of vasoconstriction under mild-warm ambient temperatures. This difference in Ttail was suppressed after the intraperitoneal injection of a vasodilator, an α-adrenergic antagonist, confirming the hypothesis of the vasoconstriction in exposed rats. Moreover, like a response to cold stimuli, RF exposure led to increased plasma concentrations of important factors: noradrenaline (a neurotransmitter responsible for vasoconstriction and thermogenesis) and fatty acids (markers of activated thermogenesis). Taken together, these findings indicate that low-intensity RF levels triggered some key physiological events usually associated with responses to cold in rats. © 2021 Bioelectromagnetics Society.

Effect of non-thermal radiofrequency on body temperature in mice.

Communication technologies based on radiofrequency (RF) propagation bring great benefits to our daily life. However, their rapid expansion raises concerns about possible impacts on public health. At intensity levels below the threshold to produce thermal effects, RF exposure has also recently been reported to elicit biological effects, resembling reactions to cold. The objective of the present study was to investigate the effects of non-thermal RF on body temperature in mice and the related mechanisms. 3-months-old C57BL/6 J mice were exposed to a continuous RF signal at 900 MHz, 20 ± 5 V.m-1 for 7 consecutive days, twice per day during the light phase, for one hour each time. The SAR was 0.16 ± 0.10 W.kg-1. We showed that body temperature patterns in mice change synchronously with the RF exposure periods. Average body temperature in the light phase in the exposed group was higher than in the control group. The expression of the TRPM8 gene was not affected by RF in trigeminal ganglia. Furthermore, the injection of a TRPM8 antagonist did not induce a temperature decrease in exposed mice, as this was the case for sham-controls. These findings indicate that 900 MHz RF exposure at non-thermal level produce a physiological effect on body temperature in mice. However, the involvement of TRPM8 receptors in the mechanism by which RF induced changes in body temperature of mice which remains to be further explored. It must then be assessed if this effect is extrapolable to man, and if this could lead to consequences on health.