Effects Of Occupational Exposure To Electromagnetic Field From High Voltage Power Transmission Line On Nervous System Function

Background:Electromagnetic field can induce two kinds of biological effects.One is thermal effect.In fact,there exists endogenous electromagnetic field in organism or cells. Generally,the organism or cells can suit the endogenous electromagnetic field and earth magnetic field.However,when organism receives high-frequency electromagnetic radiation,polarization and oriented relaxation effect will occur and molecular vibration and friction will cause temperature rise in the organism.The temperature increasing is associated with radiation power absorbed by unit volume and exposure time.When organism can not balance the temperature rise at certain parts,some kinds of damage will occur.The other is non-thermal effect.Electromagnetic field may also cause some physiological effect without significant temperature rise.This is because electromagnetic fields can induce axial displacement of molecule rotation or abnormal molecular chain arrangement in the organism,and finally results in disorder of physiological function and diseases.Following the rapid development of electrical power industries in our country,electromagnetic field pollution from super-high voltage power transmission lines will become one of major factors which limit the development of super voltage power transmission lines in our country.Based on present conditions, studying the effects of electromagnetic field from super-high voltage power transmission lines upon occupational workers has an important scientific and actual significance.In order to investigate the occupational exposure of electromagnetic field from high voltage power transmission line for long periods on the operating ability,efficiency and nervous system function of occupational workers,an epidemiological study, nervous system function and behavior analysis has been taken among the more than 400 occupational workers in the present research.Purposes:1,To study the effects of occupational exposure to electromagnetic fields produced by high voltage power transmission lines for long period on nervous system function of workers.2,Providing scientific database for developing power-frequency magnetic field exposure limits.3,Providing scientific database for personal protection and forming a protective system for occupational works who exposed to electromagnetic field from high voltage power transmission lines.Methods:In the present research,400 occupational workers who have engaged in the works of high voltage power transmission lines for long period from a thermal power construction company were selected and served as an exposure group.These workers who had a history of nerve system disease,visual or hearing disorder,hand dyskinesia and drunkard were excluded.The exposure group was composed of 200 male workers and 200 female works age range from 28 to 40 years,and was further divided into short-term exposure group and long-term exposure group according to their length of service time,The healthy employees who have not been engaging in the work of high voltage power transmission lines in the same company were selected and served as a control group(63 male and 37 female employees aging 28±2 years).Behavior index measurement was performed according to emotion status characteristics,digital decoding,target tracking and other three indices in the neurobehavioural core test batteries(NCTB) recommended by WHO.Data were presented as means±S in the study,and were analyzed by SPSS11.0 statistical software followed by Kruskal-WallisH test and x~2 test.A difference at p＜0.05 was considered statistically significant.Results:Results of emotion status testing showed that compared with the control group,the differences in item A,D and F of the exposure group were statistically significant(P＜0. 01).It is suggested that the workers who exposed occupationally to high voltage electromagnetic fields trended to an agitated and tired status.Compared with short-term exposure group,the difference in item F in long-term exposure group was statistically significant(P＜0.05).In the nervous behavior testing,results of the digital decoding test,backward recite number test and visual sense response showed that there were no statistically significant difference in score between short-time exposure group, long-term exposure group and control group(P＞0.05).However,results of target tracking test showed that the dot numbers of short-time exposure group and long-term exposure group were significantly decrease compared with that of the control group(P＜0.05),and results of the portable rotary speed test showed that the short-time exposure group and long-term exposure group were significantly smaller than the control group (P＜0.01).In the relativity analysis between age and education degree factors with testing,results indicated that the scores of intension,melancholy and anger in emotion status testing increased following ages and presented positive correlation(r= 0.206～0.262,P＜0.05).Yet,the scores of intension,melancholy,anger and exhaustion presented a negative correlation with the education degree(r=-0.203～-0.238,P＜0.05).The correct dot number of backward recite test,digital decoding and target tracking presented positive correlation with the education degree(r=0.205～0.288,P＜0.05).Conclusion:Based on the present study,results indicated that exposure to electromagnetic fields from high voltage power transmission lines could cause workers tired status and significant decrease of immediate ability of memory,attentiveness,velocity and accuracy of hand movement.It is suggested that power-frequency electromagnetic fields could result in adverse effects on occupational works in mental state,hand operating ability and operating efficiency.