Analysis On Biological Effects After Exposure To Extremely Low Frequency Electromagnetic Fields

Living beings are exposed daily to extremely low frequency electromagnetic fields(ELF-EMFs)in everywhere.With the pervasive application of power energy,there are more chance for humans to get close to extremely low frequency electromagnetic fields,especially for workers with occupational exposure.More recent investigations have focused on obtaining data to assess potential carcinogenic risks.The first study of ELF electric and magnetic fields and childhood cancer was conducted in Denver,CO,USA(Wertheimer&Leeper,1979).Since then,epidemiological investigations and experimental studies for relationship between extremely low frequency electromagnetic fields and human health have been developed for many years.Many scholars have found that the emergence of the peak in incidence of carcinomas may be due to exposure to extremely low frequency electromagnetic fields,such as acute lymphoblastic leukaemia in children,breast cancer and brain tumor.The quantum energy caused by extremely low frequency electromagnetic fields is week and easy to accumulated in human bodies.In principle,meaningful physiological changes can result only if the 'signal'produced by the field exceeds the threshold present in the relevant biological system.In order to detect the exposure dose of exposed population,block the occurrence and development of certain diseases,it is important to search for biomarkers of extremely low frequency electromagnetic fields.Proteins and microRNAs are found to be stable in serum,and might be ideal novel non-invasive biomarkers in the early diagnosis of diseases and risk assessment.BALB/c mice were randomly assigned to control group and three experimental groups of O.1mT,0.5mT and 2.5mT under the exposure to 50Hz extremely low frequency electromagnetic fields.Nutritional conditions of mice were observed every day and boby weights were measured every few days.Serum was collected after exposure for 0,1,10,30,90 days.A part of the serum samples were used for measuring concentrations of chemokines by Luminex technology.The results of chemokines were verified by ELISA.Another part of the serum samples were used to analyze microRNA expression by high-throughput sequencing.Differently expressed microRNAs were filtrated by microRNA targets prediction combined with KEGG pathway analysis.The results of microRNA expression were verified by qPCR.There were significant differences between experimental groups and control group in weight growth only in the first exposure month,the weight growth rate in every experimental group was significantly lower than that of the control group(P value lower than 0.05).There was no significant differences in weight growth in the last two exposure month(P value higher than 0.05).The results of chemokines revealed that the concentration of MCP-1 was significantly increased after exposure to 0.5mT extremely low frequency electromagnetic fields at early stage.The level of MCP-1 of 0.5mT group was always higher than that of control group during the whole exposure period(P value lower than 0.05).The levels of EOTAXIN-1 in three experimental groups were significantly increased after exposure for 1 day(P value lower than 0.05).The level of EOTAXIN-1 of 0.5mT group was always higher than that of control group during the whole exposure period(P value lower than 0.05),while the level of EOTAXIN-1 of 2.5mT group was only significantly different after exposure for 1 day(P value lower than 0.05).The level of GRO-a might be affected by the dose of extremely low frequency electromagnetic fields,but irrelevant to exposure length.There was no signidicant difference in other chemokines.Difference analysis for exosome-derived microRNAs revealed that the expression of miR-128-3p in 0.1 mT group was increased,the expression of miR-133a-3p in 0.5mT group was decreased,the expression of miR-142a-5p in 2.5mT group was decreased.Through literature researches combined with results as above,we summarized two conclusions:1.MCP-1 and EOTAXIN-1 may be involved in the immune responses caused by extremely low frequency electromagnetic fields,resulting in inflammatory responses and other diseases.EOTAXIN-1 may act as an indicator in immune system for exposure to 0.5mT extremely low frequency electromagnetic fields.2.Serum exosome-derived miR-128-3p,miR-133a-3p and miR-142a-5p may act as an indicator reflecting the physiological changes under the exposure to 0.1 mT,0.5mT and 2.5mT extremely low frequency electromagnetic fields respectively.They may play important roles in acute leukemia,cardiovascular diseases and so on,providing evidences for early detection of diseases.