Résumé
The possible influence of electromagnetic field (EMF) on the function of neural systems has been widely concerned. In this article, we intend to investigate the effects of long term power frequency EMF exposure on brain cognitive functions and it's mechanism. The Sprague-Dawley (SD) rats were randomly divided into 3 groups: the rats in EMF Ⅰ group were placed in the 2 mT power frequency EMF for 24 days. The rats in EMF Ⅱ group were placed in the 2 mT power frequency EMF for 48 days. The rats in control group were not exposed to the EMF. Then, the 16 channel local field potentials (LFPs) were recorded from rats' prefrontal cortex (PFC) in each group during the working memory (WM) tasks. The causal networks of LFPs were also established by applying the directed transfer function (DTF). Based on that, the differences of behavior and the LFPs network connection patterns between different groups were compared in order to investigate the influence of long term power frequency EMF exposure on working memory. The results showed the rats in the EMF Ⅱ group needed more training to reach the task correction criterion (over 80%). Moreover, the causal network connection strength and the global efficiency of the rats in EMF Ⅰ and EMF Ⅱ groups were significantly lower than the corresponding values of the control group. Meanwhile, significant differences of causal density values were found between EMF Ⅱ group and the other two groups. These results indicate that long term exposure to 2 mT power frequency EMF will reduce the connection strength and the information transfer efficiency of the LFPs causal network in the PFC, as well as the behavior performance of the rats. These results may explain the effect of EMF exposure on working memory from the view of neural network connectivity and provide a support for further studies on the mechanism of the effect of EMF on cognition.
Résumé
OBJECTIVE: To analyze the effects of long term exposure to power frequency electromagnetic fields( PFEMF) on apoptotic rates of peripheral blood T and B lymphocytes in workers of transformer substation. METHODS: A random number table method was used to select 73 workers with long-term exposure to PFEMF as exposure group and 70 non-exposure workers( administrative and logistics staffs) were selected as control group from 10 transformer substations in a province.The peripheral venous blood of workers in these two groups was collected,and the apoptosis of T and B lymphocytes were detected and analyzed by flow cytometry. RESULTS: The apoptosis rates of T and B lymphocyte between the exposure and non-exposure groups showed no statistical difference( median: 1. 555% vs 0. 790%,0. 020% vs 0. 030%,P > 0. 05).The multivariate linear regression analysis showed that both the PFEMF exposure and length of service had no significant effects on the apoptosis rates of T lymphocyte and B lymphocyte after adjusting confounding factors such as gender,age,alcohol drinking,smoking,medication history,medical radiation exposure and stressful events( P > 0. 05). CONCLUSION: Long-term exposure to PFEMF has no effects on apoptosis of peripheral blood T and B lymphocytes in workers of transformer substation.
Résumé
OBJECTIVE: To investigate the effect of the power-frequency electromagnetic field on antioxidant indexes in operation personnel. METHODS: By random sampling method,a total of 58 workers who work in 500 kV transformer substations for at least 5. 0 years were selected as the exposure group,and 60 administrative staffs in the same enterprise were included as the control group. The power frequency electromagnetic fields in the 2 groups were measured. The cumulative exposure dose of individual magnetic field was calculated. Peripheral venous blood was collected in these 2groups and was examined with the superoxide dismutase( SOD) activity,malondialdehyde( MDA) level and the relative gene expression level of manganese superoxide dismutase( MnSOD). RESULTS: There was no statistical significance in the SOD activity,MDA level and the relative gene expression level of MnSOD between the exposure group and the control group( P > 0. 05). The logistic regression analysis results indicated that cumulative exposure dose was not correlated with the SOD activity,MDA level and the relative gene expression level of MnSOD after adjusting confounding factors such as age,smoking,alcohol and tea drinking( P > 0. 05). CONCLUSION: Power-frequency electromagnetic field exposure has no significant effects on the SOD activity,MDA level and the relative gene expression level of MnSOD of operation workers.
Résumé
OBJECTIVE: To explore the effects of long-term exposure to power frequency electromagnetic fields on the humoral immune function in transformer substation workers. METHODS: By simple random sampling method,64 workers with length of service longer than 5. 0 years in 500 k V transformer substation were chosen as exposure group and 57 general administrative staffs without exposure to power frequency electromagnetic field were chosen as control group. Venous blood was collected from subjects of these two groups and the levels of immunoglobulin( Ig) A,Ig G,Ig M,complement( C) 3and C4 in plasma were examined by immunoturbidimetry. RESULTS: Compared with the control group,the levels of both Ig A and Ig G increased( P < 0. 05),while both levels of C3 and C4 decreased( P < 0. 05) in exposure group. Compared with the control,the level of Ig G increased( P < 0. 05),while the levels of both C3 and C4 decreased( P < 0. 05) in exposure subgroup with length of service ≤10. 0 years. The level of C4 decreased( P < 0. 05) in exposure subgroup with length of service > 10. 0 years. CONCLUSION: Long-term exposure to power frequency electromagnetic fields may activate the humoral immune function in transformer substation workers.