Brillouin Precursors, a theoretical oddity or a real concern for 5G millimetre-wave bands to be used in future high-speed telecommunications?

Excerpts

“… With a millimeter wavelength of 0.65 mm at 42 GHz. The waves can penetrate into the human skin deep enough to affect most skin structures located in the epidermis and dermis.1 However, these types of waves present other challenges. The first is that when most of the energy is focused in a small area, such as 5G antenna beam-forming, the risk of human tissue heating for anyone in the path of the beam will be increased.

The second challenge is that signals such as radar that are made of sharp pulses behave differently when they enter body tissue containing moving charges (such as potassium ions). Each incoming pulse generates a force that accelerates these moving charges, thereby causing them to become emitters of electromagnetic radiation (EMR). This additional radiation adds large spikes onto the leading and trailing edges of the original EMR pulse. The sharp transients, called “Brillouin Precursors” increase the strength of the original signal and reradiate EMR waves deeper into the body than predicted by conventional thermal models. 2

The creation of Brillouin Precursors within the body by very short pulsed signals in the frequency of 10 GHz or more (millimeter wave bands) was described by Albanese et al in 1994. These authors predicted that the interaction of these signals with human tissue would cause disruption of large molecules, and damage cell membranes leading to blood-brain barrier leakage. 3 ….

It must be pointed out that little research has been carried out on the possibility of adverse biological effects from the creation of Brillouin precursors with 5G phased array antennas (let alone on 6G communications). Considering the high download speeds, which may have unintended adverse biological effects, this should be a priority.

Other damaging effects have been predicted in a paper published in Health Physics in December 2018 by Esra Neufeld and Niels Kuster. The paper suggests that permanent skin damage from tissue heating may occur even after short exposures to 5G millimetre wave pulse trains (where repetitive short, intense pulses can cause rapid, localised heating of skin). The authors stated that there is an urgent need for new thermal safety standards to address the kind of health risks possible with 5G technology….

It is possible that this advice was in response to the ICNIRP draft guidelines (2019) as some changes were made to the final published guidelines. However, the changes did not conform to those suggested and it is not clear that the possibility of excessive heat absorption from these higher frequencies, which may result in pain, has been addressed in ICNIRP’s current guidelines.

The necessity for more reliable research into possible damaging effects of pulsed millimetre waves used for 5G communications is also seen in an August 2021 paper by Foster and Vijayalaxmi….

Concerns over the lack of scientific data regarding possible biological effects of millimeter waves proposed for use in modern telecommunications have been raised by Nicholas Lawler et al. in Biomedical Optics Express (May 2022). The authors found that the studies cited indicate a strong power and dose dependence of millimeter wave induced effects at biologically relevant exposure levels such as those recommended by the International Commission on Non-Ionizing Radiation Protection (ICNIRP)….

The “take-home” message from the above mentioned papers is that we still do not have adequate research on 5G millimetre waves to be able to assure the public that the many thousands of 5G antennas, in many instances placed in close proximity to homes and workplaces, are without a possible health risk because the necessary research has not yet been conducted.”