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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.