| Research BackgroundWith the rapid economic development of the Pearl River Delta’s regions, and the degree of modernization improved constantly, there were increasing such devices about electromagnetic radiation and induction equipment as broadcasting and television transmitting system, mobile communication base station, high voltage power transmission and transformation system, electrified railway in urban agglomeration, which led to the electromagnetic radiation rising exponentially. In recent years, we have made the survey which showed that intensity of environmental electromagnetic radiation in the large and medium cities of the Pearl River Delta was manifested increasing obviously. So relative some problems about pollution of electromagnetic radiation have attracted people’s attention vastly. And at the same time, we must take the problems about the disputes of electromagnetic radiation pollution and residents’ complaints seriously, because they are increasing progressively. A lot of research and literature have indicated that after the air pollution, water pollution and noise pollution, electromagnetic radiation pollution has become the fourth largest one in the world today. The electromagnetic radiation as a new form of the environmental pollution and occupational hazards has gotten the widespread attention. With the widespread use of electromagnetic technology, the popularity of communication and radio and television transmitting equipment, and the development of the high voltage transmission lines of power sector, the communication stations, radio and television tower and high voltage power transmission and transformation station and so forth were popular with the people in the city, which closed the distance between people and the electromagnetic radiation, We can see that a variety of large and small power of electromagnetic launch system is surrounded by residential houses. with the rapid development of urban and rural, some sparse regions were also polluted by the electromagnetic radiation. Therefore, The influence of electromagnetic radiation’s pollution on human health has gradually become the focal point for epidemiology and toxicology research. The research of the epidemiological investigation about the influence of electromagnetic radiation’s pollution on human health was the direct evidence for damage of human health from electromagnetic radiation, but because of various reasons, the actual research has faced lots of difficulties, whose main causes include two aspects:On the one hand, it is hard to distinguish the exposure crowd of electromagnetic field and the collaborative factors were complex, so it affects the choice of the sample and quantity. On the other hand it difficult for us to determine the specific parameters about exposed electromagnetic radiation since biological effect mechanism has not been clear yet produced by the electromagnetic fields. At present, a lot of research at home and abroad showed that there are the relative aspects between the electromagnetic radiation and the occurrence of some diseases, such as the electromagnetic radiation and childhood leukemia research etc. Based on the research status of biological effect of electromagnetic field, the world health organization (WHO) believes that there is no sufficient scientific evidence to judge the low intensity electromagnetic radiation whether has exact effect on human health, and as a special group, the children is more sensitive to low intensity electromagnetic radiation environment?Studied in this paper through to monitor the electromagnetic field of general radiation environment and TV tower in Foshan city, the tiejun primary school was selected to be the exposed group whose school was500m far away from TV tower, the nanzhuang jili school as a control group studied which school was12km far away from the tower and no obvious electromagnetic radiation source at the around, which adopts such these kind of ways as questionnaire survey, medical health physical examination (electrocardiogram, blood pressure, height, weight, etc.) to explore the influence of the tower of the radio frequency electromagnetic radiation on children’s health. Similarly, the dongguan normal school affiliated elementary school was selected to be the exposed group It is under the dongguan guan city500kV high-voltage transmission line corridor, and distancing from the power frequency Electromagnetic Radiation Source10km, the the dongguan south sunshine sixth elementary school was to be a control group without any obvious Electromagnetic Radiation Source around it, and it also adopted the questionnaire survey, medical health physical examination (electrocardiogram, blood pressure, height, weight, etc.) to explore the effect of the power frequency electromagnetic field on children’s health.Research Methods1.The research about effect of the radio frequency electromagnetic radiation on pupils’ health1.1The monitoring method of electromagnetic field in general radiation environmentAccording to the relevant standard specification requirements from "radiant environment protect and administrate guideline, electromagnetic radiation monitoring instrument and the method"(HJ/T10.2-1996), the point according to the stationing principle and eliminating principle by2km*2km grid points method have arranged, namely each center of grid was selected as a metrical point, In the process of measurement,you should avoid tall buildings and trees as much as possible and the center location measurers can’t reach, trying to select the recent sensitive points (communities, schools or hospitals) as measuring points. And requiring the errors of measuring points must not exceed1/4of the grid, otherwise the measuring points were eliminated. Foshan city center could be divided into40points by the method of grid points, and the36points were monitored on the field. The SRM-3000radiofrequency radiation analyzer to measure each point, required to stabilize after every15s read a number and measuring1.7meters in height. Measured intensity of electric field, magnetic field and power density of each point, measured3times for each point and record the measured values, the average represents the level of intensity.1.2The monitoring methor of electromagnetic field of Foshan TV towerAccording to the relevant standard specification requirements from "radiant environment protect and administrate guideline, electromagnetic radiation monitoring instrument and the method"(HJ/T10.2-1996), Tower was as centered by meter font stationing. These points were recorded in every50m layout a spot within500m, per100m layout a point within500m to lkm, every200m layout a point within lkm to2km, a total of20points were measured in the east, west, south, north, southeast, northeast, southwest, northwest eight direction measurement line respectively. Adopting the the spectrum analyzer analysis model of SRM-3000radiofrequency radiation to let the range of frequency fix into the range of frequency47-856MHz in our country’s tower. The measurers were required to stabilize them after every15s and reads the number, and measuring1.7meters in height. Measuring intensity of electric field, magnetic field and power density of each point respectively, and each point should be measured5times and then you recorded their measured values, finally taking the average value as the level of intensity.1.3Research field and research objectsAccording to the monitoring results about the electromagnetic field of general radiation environment and TV tower in Foshan city, the429pupils were selected to be the observation group whose school was500m far away from TV tower. And the256pupils in the control group studied at a school which was12km far away from the tower. The radio frequency electromagnetic radiation intensity of the two primary schools was monitoredon the spot, and through the questionnaire survey, medical health physical examination to explore the tower of the radio frequency electromagnetic radiation on children’s health effects.2.The research about effect of the power frequency electromagnetic field on pupils’ health2.1literature reviewAccording to a report of WHO, there was a close relation between residential power frequency magnetic field intensity and the distance of the high tension line, and suggested the residential areas, schools, kindergartens and hospitals should not be build from the high tension line within50m. The international agency for research on cancer (IARC) indicated that if children were exposed so long in power frequency magnetic field which outweighed0.3to0.4μT, the leukemia risk was would increase2times.2.2Measure of guan city500kV high-voltage transmission lineAccording to investigation on site, we select guan city500kv substation3set of overhead lines as the metrical targets, they were high line18m,25m and30m respectively, with the lowest point of edge wire of two base tower HuChui to ground zero as the starting point, from the vertical projection line Om,5m,10m,15m,20m five point measurement.2.3Research field and research objects Based on literature review and measurement results of guan city500kV high-voltage transmission line, the456pupils were selected to be the exposed group whose school was under the guan city500kV high-voltage transmission line corridor. And similarly we chose another272pupils in a primary school around which there was not obvious radiation source, and the control group,whose had similar situation with the exposed group. The power frequency electromagnetic field intensity of the two primary schools was monitored. And according to such ways as the healthy questionnaire survey and medical health physical examination,the researchers can analyze the effect of exposed power frequency electromagnetic field on pupils’health.Research Results1.The research about effect of the radio frequency electromagnetic radiation on pupils’ health1.1The monitoring results of electromagnetic field in general radiation environment in Foshan city centerIn Foshan city center, the average of electric field strength is between179.67to802.03mV/m and the total average is340.09mV/m. The average of magnetic field strength is between460.3to2069.67μA/m and the total average is903.68μA/m. The average of power density is between8.498to159.57nW/cm2and the total average is36.13nW/cm2, far less than the standard limit of "electromagnetic radiation protection regulations"(electric field:12V/m, magnetic field:32mA/m, power density:4*104nW/cm2).1.2The monitoring results of electromagnetic field of Foshan TV towerFrom the monitoring results of electromagnetic field of Foshan TV tower, although all points were less than the standard limit of "electromagnetic radiation protection regulations"(electric field:12V/m, magnetic field:32mA/m, power density:4*104nW/cm2), but compared to the average of general radiation environment of foshan city (340.09mV/m,903.68A/m,36.13nW/cm2), the average level of tower electromagnetic field intensity within500m tower was greater, and the500m was less than average.1.3Two groups of primary field monitoring resultsThere were56points measured in electromagnetic radiation of exposed group, including45points in the classroom,11points outside classroom. And the range of electric field strength was from147.3to1077mV/m in the classroom, magnetic field intensity was from391.0to2857A/m, and power density was from57.5to3078μW/m. Outside the classroom, the range of field electric intensity was from161.1to922.7mV/m, magnetic field intensity was from427.2to2448A/m, and power density was from150.8to2259μW/m2. And there were49points measured in electromagnetic radiation of control group, including35points in the classroom and14points after class, and the range of electric field strength within the classroom was from136.2to645.1mV/m, magnetic field intensity was from235.0to1104μA/m, and power density was from49.2to459.3p,W/m2u. Outside the classroom, the range of field electric intensity was from150.8to416.1mV/m, magnetic field intensity was from235.4to1104μA/m, and power density was from60.3to459.3μW/m2. Through the Wilcoxon’s text, whether in the classroom or outside the classroom, the electromagnetic radiation exposure levels in exposed group were significantly higher than control group, and the difference was statistically significant (P<0.05).1.4The results of health survey on pupils from Radiofrequency electromagnetic radiation of TV tower.It suggested that the TV tower radio frequency electromagnetic radiation had no harmful influence on the pupils’ the neuropsychiatric system symptoms. Part of the blood system routine blood index was statistically significant, compared with the control group, the number of platelets, percentage of neutrophils and percentage of monocytes were low, and basophils and huge number of immature cells, percentage of basophils and percentage of eosinophils and percentage of huge immature granulocytes was high on exposed group (P<0.05). By the multiple linear regression analysis also found that there are certain the blood routine indexes and exposure of TV tower radiofrequency radiation have significant correlation (P<0.05). The serum electrolyte of K+and Na+had statistical significance, but the multiple linear regression analysis found that the serum electrolyte of K+and Na+had not significant correlation (P=0.380and0.114). The blood pressure and heart rate difference was statistically significant, and the multiple linear regression analysis and the tower radiofrequency radiation exposure had significant positive correlation (P<0.05).2.The research about effect of the power frequency electromagnetic field on pupils’ health2.1Measure results of guan city500kV high-voltage transmission lineIn the height of line of18m,the maximum of electric field strength can be up to1076V/m when it appears in the vertical projection distance from ground0m. Similarly,the maximum of magnetic induction intensity can be up to1880nT when it appears in the vertical projection distance from ground5m. In the height of line of25m, electric field intensity and magnetic induction intensity maximum can be up to224.9V/m and1880nT when it appears in the vertical projection distance from ground Om. When the line is30m highthe, the maximum of electric field strength can be up to116.4V/m when it appears in the vertical projection distance from ground10m, and the maximum of magnetic induction intensity can be up to343.0nT when it appears in the vertical projection distance from ground0m. They all are less than the evaluation standard4kV/m and100μT from HJ/T10.3-1998of power frequency electromagnetic field (The technical specification of electromagnetic radiation environmental impact assessment of500kV ultra-high pressure electricity transmission project).2.2Two groups of primary field monitoring results21points were distributed in exposed group, the range of electric field strength within the classroom was from522to3930mV/m, and magnetic field intensity was from171.5to357.8nT.In the control group, they distributed30points, the range of electric field strength within the classroom was from16to2919mV/m, and magnetic field intensity was from9.95to372.08nT. Through the Wilcoxon’s text, two groups of primary electric field intensity and difference of magnetic induction intensity were statistically significant (P<0.05).2.3The results of health survey on pupils from Extra High Voltage Transmission Power Line of Power frequency electromagnetic fieldThe survey suggested that the Extra High Voltage Transmission Power Line Power frequency electromagnetic field had no harmful influence on the pupils’ neuropsychiatric system symptoms. Part of the blood system routine blood index were statistically significant, compared with the control group, the mononuclear cells, the width of red blood cell volume distribution, average blood platelet volume and The width of platelet volume distribution were lower (P<0.05) in exposed group. However, the hemoglobin,the average amount of hemoglobin and hemoglobin average concentration of hemoglobin were higher than the control group (P<0.01). By the multiple linear regression analysis,it can be found that mononuclear cells, platelet volume distribution,red blood cell volume distribution width, average blood platelet volume and the width of and power frequency electromagnetic field exposure existed obviously negative correlation, while the average amount of hemoglobin and concentration of hemoglobin existed obviously positive correlation (P<0.05). In the exposed group, the content of copper and iron and zinc in serum were higher than the control group (P<0.05), and the differences between two groups were associated with the exposure of the power frequency electromagnetic field statistically by the multivariate linear regression analysis. The systolic blood pressure and heart rate level of exposed group were higher than the control group, and diastolic blood pressure level was lower than the control group by analysis of single factor and multiple factors. Between rate of abnormal electrocardiogram and exposure levels, there was no clear correlation between two groups, whether the single factor or two classification logistic analysis we analyzed.Conclusion1. The results about monitoring general radiation environment and the TV tower showed that every metrical point of electromagnetic field intensity was much lower than the standard limit of GB8702-22"electromagnetic radiation Protection regulations" and electromagnetic field intensity of the TV tower within500m was greater than the average of general radiation environment. This suggested that TV tower was the main source of electromagnetic radiation, which can be provided the basis for choosing the research field and research objects of low intensity radio frequency electromagnetic radiation on children’s health.2. The results showed that electromagnetic field intensity of every measurement point were much lower than the standard limit of GB8702-22"electromagnetic radiation Protection regulations" and electromagnetic field intensity of the TV tower within500m was greater than the average of general radiation environment from the monitor of general radiation environment and the TV tower. This suggested that TV tower was the main source of electromagnetic radiation, which provided the basis for us to choose the research field and research objects about the effect of low intensity radio frequency electromagnetic radiation on children’s health.3. After analyzing about logistic regression analysis of orderly classification and then excluding the effect of confounding factors, we still haven’t found that the radiofrequency electromagnetic radiation of TV tower had adverse impact on the neuropsychiatry of pupils there. And through analysis of the single factor and multiple factors,we found that part of the routine blood indicators and exposure to low intensity radiofrequency electromagnetic radiation had significant correlation. From the analysis of single factor, we found that the difference of the content of pupil’s K+and Na+between the two groups is statistically significant,while we haven’t found yet that the content of pupil’s K+and Na+in the two groups is to do with exposure by analysis of multiple factors, Whether the radio frequency electromagnetic radiation can influence on serum electrolyte of pupils or not still need further study. and on the two groups of pupils of blood pressure and heart rate of single factor and multiple linear regression analysis results showed that the systolic pressure, diastolic blood pressure and heart rate of pupils of exposed group was positively correlated with radiofrequency electromagnetic radiation of TV tower, illustrated the radiofrequency electromagnetic radiation of TV tower may had a certain influence on the cardiovascular system for the pupils.4. After analyzing about logistic regression analysis of orderly classification and then excluding the effect of confounding factors, we still haven’t found that the power frequency electromagnetic field have adverse impact on the neuropsychiatric of pupils by the analysis of health questionnaire.Through analysis of single factor and multiple factors,we found that part of the routine blood indicators and serum electrolyte and exposure to low intensity radiofrequency electromagnetic radiation have significant correlation, which illustrated that the low intensity power frequency electromagnetic field maybe had influenced on pupil’s blood system. The result about analyzing single factor and multiple linear regression of blood pressure of pupils and heart rate showed that the exposed group of pupils’ heart rate is positively correlated with power frequency electromagnetic field exposure, and diastolic blood pressure there is negative correlation, but the abnormal rate electrocardiogram not found that differences between two groups of pupils, illustrated the power frequency electromagnetic field may had a certain influence on the cardiovascular system for the pupils. |
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