Exposure to High-Powered Microwave Frequencies May Cause Brain Injuries

Summary: Exposure to extremely high microwave and radio frequencies may result in high stresses within the brain, researchers say.

Source: Texas A&M

Contrary to what was once popular belief, microwaves don’t cause cancer. It’s a decades-old concern that may evoke an image of a child standing in front of a microwave, peering through the dimly-lit door, only to be told to take a few steps back or they could be sickened by an inexplicable illness or worse—radiation poisoning.

Thanks to advancements in science, engineering and technology, we now know that microwaves are safe, effective and efficient.

However, recent research from Texas A&M University reveals that exposure to certain extremely high-powered microwave and radio frequencies may result in high stresses within the brain.

Justin Wilkerson, assistant professor in the J. Mike Walker ’66 Department of Mechanical Engineering, in collaboration with researchers at the U.S. Army Research Laboratory and the Air Force Research Laboratory, began investigating the effects of high-powered pulsed microwaves on the human body.

Most commonly used for rapid cooking, microwaves are a type of electromagnetic radiation that fall between radio and infrared light on the electromagnetic spectrum.

Using computational modeling, the team’s two-simulation approach first calculates the specific absorption rate (SAR) of planar electromagnetic waves on a 3D model of a human body. The SAR values are then used to calculate changes in temperature throughout the head and brain. Those temperature changes are then used to determine how the brain tissue physically alters in response to the high-intensity microwaves.

“The microwave heating causes spatially varying, rapid thermal expansion, which then induces mechanical waves that propagate through the brain, like ripples in a pond,” Wilkerson said.

“We found that if those waves interact in just the right way at the center of the brain, the conditions are ideal to induce a traumatic brain injury.”

Published in Science Advances, Wilkerson’s research revealed that when applying a small temperature increase over a very short amount of time (microseconds), potentially injurious stress waves are created. Imagine all of the microwave energy needed to pop a bag of popcorn condensed into one-millionth of a second and then directed at the brain.

However, there’s no need to worry about every day exposure to microwaves or radiofrequency levels. Wilkerson’s study included magnitudes of power far greater than anything the average human will be exposed to.

This shows a diagram from the study
Flow chart of the computational approach. First, a simulation of full-body irradiation with microwaves (A and B) is used to find the normalized SAR (SAR*) within tissues. The SAR* values are used to compute temperature changes (C) and registered as initial conditions to a 3D FEM. At the end of the pulse duration (e.g., τd = 5 μs), the temperatures are maintained constant in the FEM simulations because of the slow time scales of thermal conduction, as shown by the idealized approximation of cooling at the surface from a single pulse in (D). The FEM (E) is prescribed as temperature initial conditions for computation of the early time (<500 ms) mechanical response (F). Credit: The researchers

“Although the required power densities at work here are orders of magnitude larger than most real-world exposure conditions, they can be achieved with devices meant to emit high-power electromagnetic pulses in military and research applications,” Wilkerson said.

Wilkerson and the team used finite element simulations as part of their computational modeling—the same models that have been used to predict traumatic brain injury in car crashes, football impacts and even explosive blasts on the battlefield.

By applying it to a new energy deposition, the microwave, Wilkerson has opened the door for more research to be conducted on the interactions between the biological body and electromagnetic fields and its applications.

About this neuroscience research news

Author: Laura Simmons
Source: Texas A&M
Contact: Laura Simmons – Texas A&M
Image: The image is credited to the researchers

Original Research: Open access.
Computational modeling investigation of pulsed high peak power microwaves and the potential for traumatic brain injury” by Amy M. Dagro et al. Science Advances


Abstract

Computational modeling investigation of pulsed high peak power microwaves and the potential for traumatic brain injury

When considering safety standards for human exposure to radiofrequency (RF) and microwave energy, the dominant concerns pertain to a thermal effect.

However, in the case of high-power pulsed RF/microwave energy, a rapid thermal expansion can lead to stress waves within the body. In this study, a computational model is used to estimate the temperature profile in the human brain resulting from exposure to various RF/microwave incident field parameters. The temperatures are subsequently used to simulate the resulting mechanical response of the brain.

Our simulations show that, for certain extremely high-power microwave exposures (permissible by current safety standards), very high stresses may occur within the brain that may have implications for neuropathological effects.

Although the required power densities are orders of magnitude larger than most real-world exposure conditions, they can be achieved with devices meant to emit high-power electromagnetic pulses in military and research applications.

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