Download Topic: E

Evaluation of Microwave Field
Absorbed by Human Thyroid Gland
Gh. Gavriloaia, G. Serban, E. Sofron
Electronic, Communications and Computer Department, University of Pitesti, Pitesti, Romania
[email protected]
Topic: E
Presentation: O
Summary: Electromagnetic pollution is spreading more increasingly, and thyroid is one of the
most exposed vital organs at electromagnetic radiation. Production of thyroid hormone is
essential for metabolism, temperature regulation, and many other vital processes in the body.
There are only few published papers reporting the effect of microwave radiation on human
thyroid. The aim of the present study was to assess the microwave field absorbed by human
thyroid gland, and to predict local temperature increase for staff working in the vicinity of
antennas transmitting high microwave power, for example on maritime ships. Thyroid was
modeled using a generic model developed by the authors. The finite element method was used to
solve coupled equations governing the propagation microwave field in different environments
with heat generation and propagation. The results show the specific absorption rates (SAR) that
increases up temperature to 38-45 oC for the frequency range between 1 and 4 GHz. Some
microwave signal power used by ships may lead to increase of 2-4 oC.
Keywords: SAR, thyroid, microwave heating.
Motivation
In the last 20 years, our society has known an exacerbation of environmental pollution by
substances that have a high level of danger, by non-ionising radiations, mainly in the microwave
spectrum, and by a large amount of data leading to an informational intoxication. More then,
there are some places where electromagnetic power density is very high, for instance, near by
transmitter antenna mounted o maritime ship. In this generic framework of the electromagnetic
smog, that becomes less and less friendly, it is necessary to perform theoretical and experimental
studies on the possible field levels that are currently applied to certain body parts.
Electromagnetic fields penetrate the body and act on all the organs, altering the cell membrane
potential and the distribution of ions and dipoles. It has been shown that microwaves produce a
temperature and energy distribution in living tissues. Temperature is an important factor in the
regulation of the release of endocrine hormones and rising only 1 oC can affect hormones
circulation [1]. The thyroid gland is one of the most exposed vital organs and may be a target for
electromagnetic radiation; it is apt to be a region of high SAR at microwave. The thyroid
hormones affect brain function, heart health, and they improve the function of the immune system.
It has been established that even a small change in circulating thyroid hormone levels is sufficient to
alter the brain functions [2, 3]. However, there are only few published papers reporting the effect of
microwave radiation on thyroid. The aim of the present study was to assess the microwave field
absorbed by human thyroid gland, and to predict local temperature increase for staff working in the
vicinity of antennas transmitting high microwave power, for example on maritime ships.
Results
In order to evaluate electromagnetic field incident to thyroid and tissue temperature some
factors have to be considered: geometry of the irradiated organism, the electromagnetic and
thermophysical properties of the tissue, heat production due to absorption of microwaves, heat
production due to metabolic processes, heat flow due to perfusion of blood, thermoregulatory
mechanisms, etc.
Fig. 1: 3D section of human neck containing the
thyroid gland.
Fig. 2: Temperature versus SAR at 2 GHz
In this paper we used a generic model, designed by us. It is composed by two ellipsoids
connected through other ellipsoid simulating the two lobes and isthmus of thyroid, fig. 1. In front
of neck skin a plane wave was applied. Electromagnetic field penetrates the body and act on all
the organs. The neck section was modeled by two regions, inside thyroid - a space filled up with
blood, and outside – o homogeneous space. All regions are characterized by using specific
material parameters. Physical phenomena were simulated by Maxwell and Pennes equations.
Finite element method was used to solve coupled equations governing the propagation
microwave field in different environments with bio-heat generation and propagation. The
temperature does not depend linear versus microwave power density. The amplitude of the input
electric field intensity was raised, and a map of temperature in thyroid gland was evaluated. In
this paper the results for 37-45 oC temperature range were presented. The thyroid response was
investigated for incident signals with frequencies between 1 and 4 GHz. For instance, by
choosing the nearest point from neck skin, the temperature for input signal with 2 GHz versus
incident power is presented on fig. 2. Concerning to some maritime ship antenna, temperature
may rise by 1-2 oC.
References
[1]
[2]
[3]
Koyu A., Gökalp O., Özgüner F., Cesur G., Mollaoğlu H., Özer M,K., Çalışkan S.: The effects of
subchronic 1800 MHz electromagnetic field exposure on the levels of TSH, T3, T4, cortisol and
testosterone hormones. Genel Tip Dergisi 2005, 15, 101-105..
Bauer M, Goetz T, Glenn T, Whybrow PC. The thyroid-brain interaction in thyroid disorders and
mood disorders. J Neuroendocrinol 2008; 20: 1101-14.
Koyu A, Cesur G, Ozguner F, et al. Effects of 900 MHz electromagnetic field on TSH and thyroid
hormones in rats. Toxicol Lett 2005; 157: 257-62.