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Abstract

Содержание

Introduction

The use of microwave waves in medicine is most often associated with a positive effect, which gives local heating of certain parts of the human body. This is the most studied side of electromagnetic radiation, used in medical practice. At the same time, electromagnetic radiation also has a negative character associated with the influence of the microwave field on the neural connections of the intercellular structure, as well as DNA. This effect, as well as other aspects of the medical and psychological effects of microwave waves on humans, are now in the field of experimental studies [1].

The widespread use of cellular communications has caused concern about possible harmfulness from the electromagnetic field emitted by the phone.

An analysis of this problem revealed that the effect of radiation from a cellular phone has a negative impact on human health, which cause various functional abnormalities that lead to the development of pathological changes.

1. Theme urgency

Modern commercial programs of electrodynamic modeling of microwave structures significantly expanded the range of physical problems that can be successfully solved and thus changed many concepts about the surrounding world [2].

Medical problems associated with microwave radiation [3] is the modeling of phenomena that have both a positive and negative impact on the vital activity of living organisms and plants. In connection with the wide spread of cellular communication, the problem of the influence of the mobile phone's electromagnetic field (EMF) on the human body is currently relevant [4,5]. It is thanks to the modeling that it is possible to clearly demonstrate and prove the negative influence of the radiation of the cell phone of the phone. The given problem for today is that on is actual.

2. Goal and tasks of the research

The aim of the research is to build three models of interaction between the microwave radiation of a mobile phone and the head of a child user (1-year-old, 5-year-old and 10-year-old).

The main objectives of the study:

1. Study of special literature to identify the physical parameters of the layers of the head of a child of different ages.

2. Building a child's head model based on averaged anatomical data, modeling a mobile phone.

3. Calculation of the specific absorption coefficient of electromagnetic energy (SAR) in the layers of the child's head model with the choice of radiation frequencies corresponding to the most common standards of cellular communication.

4. Modeling the effect of local tissue heating on the microwave radiation of a mobile phone.

5. Comparison of the results of modeling the software product with the results of other researchers and making a general verdict.

3. Influence of mobile phone radiation on a child (literature review)

    

In recent years, the use of mobile phones by adults, young people, children and the elderly has increased significantly. In parallel, the scientific community, authorities and the public raised increased concern about the safety of these phones. The most numerous group of mobile phone users are children and adolescents, whose organism is most sensitive to various unfavorable environmental factors [6].
Studies of scientists from France showed that the maximum SAR10g, which was estimated in the head models of adults and children, is approximately the same, since the differences are small compared to standard deviations. Analysis of the results obtained also showed that the maximum SAR1g of peripheral brain tissue models of children aged 8 to 15 years is comparable to the maximum SAR1g peripheral brain tissue of adult models. While this indicator is about twice higher for models of children aged 5 to 8 years, which is associated, in turn, with smaller thicknesses of the auricle, skin and skull [7].
    Some studies by several scientists from around the world have used the FDTD method to simulate a certain absorption coefficient (SAR) in the head of a cell phone user. At present, this is the most suitable method, when highly inhomogeneous structures are involved, for which the boundary methods have fundamental limitations. The results of the SAR assessment showed exposure levels that significantly exceed the limits of acceptable guidelines [8].

For a full analysis, the results of the study of the effect on the child's head model with different criteria and parameters of the model under study were used.

The first model of the child's head was based on a scalable adult head model, and a SAR was obtained with respect to the adult head model of about 120% [9].

The second model of the child's head was constructed using magnetic resonance imaging using similar electromagnetic parameters, such as for adults, and no significant differences between the results of SAR were observed for adults and children [10] .

The third model of the head is based on approximation by spheres with allowance for a certain change in the electromagnetic parameters and showed an increase of about 20% in the calculated SAR [11].

The fourth child's head model, described in the study [12], is also based on a scaled model with initial electromagnetic parameters for the adult's head. In this study, no significant changes were noted for the mean SAR in the entire head, and a 35% increase in SAR was recorded only when considering the effects on brain tissue.

Some studies have been conducted to evaluate the absorption of power in models of women and children. The 10-year-old and 5-year-old child was modeled, scaling the adult model of the human body. It should be noted that the scaling of the adult model of the human body to child sizes does not give an accurate model, since different organs are scaled differently; However, the general functions in terms of height and weight are satisfied when taking into account the power absorption. Thus, resonant frequencies of 104 MHz for an isolated model and 65 MHz for a grounded 10 year old child were obtained, while for a 5-year-old child they were equal to 126 and 73 MHz, respectively [2]. In several papers, scalable versions of the adult human model representing 10-, 5-, and 1-year-old children were studied, and a simulation of both a grounded and isolated model was performed [13]. In Fig. 1 shows the frequency dependence of SARWB obtained for the models of three children in isolated conditions and a falling power density of 1 mW / cm2. The shift in resonance frequency is related to the height of the model - the higher the model, the lower the resonance frequency [13].

Frequency dependence of SAR averaged over the whole body, for various

Fig. 1 – Frequency dependence of SAR averaged over the whole body, for various
models of children: 10, 5, and 1 year (Power of influence 1 mW / cm2)

So, the available data on the power absorption in the models of the human body, when exposed to the fields of a plane wave, show that the choice of the model of the human body affects the results obtained. Differences among published data are usually stronger in local SARs than in SAR averaged over the whole body. Body height, weight, tissue distribution and composition, including fat and muscle, are important factors in the absorption of power and can explain some differences among published data. Another fundamental aspect is the value of the permittivity of various tissues or organs in the body model. In the case of children, a change in the properties of biological tissue can also affect the results of the calculation [14,15].

References

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