Effect of occupational EMF exposure from radar at two different frequency bands on plasma melatonin and serotonin levels
Singh S, Mani KV, Kapoor N. Effect of occupational EMF exposure from radar at two different frequency bands on plasma melatonin and serotonin levels. Int J Radiat Biol. 2015 Jan 7:1-39. [Epub ahead of print].
Objective: The purpose of the present study was to delineate the effect of chronic electromagnetic field (EMF) exposure from radar on plasma melatonin and serotonin levels in occupationally exposed military personnel.
Subjects and Methods: 166 male military personnel participated in the study out of which only 155 joined for blood draw. They were divided into three sets viz control group (n=68), exposure group I (n=40) exposed to 8-12GHz and exposure group II (n=58) working with radar at 12.5-18GHz frequency. All the three groups were further split into two groups according to their years of service (up to 10 years and > 10 years) in order to investigate the effect of years of exposure from radar. Melatonin and serotonin levels were estimated by enzyme immunoassay in fasting blood samples collected during 0600-0700h. EMF measurements were recorded at different locations using Satimo EME Guard 'Personal Exposure Meter' and Narda 'Broad Band Field Meter'.
Results: The group I exposed population registered a minor though not significant decrease in plasma melatonin concentration while the other group II exposed population registered statistically significant decline in melatonin concentration when compared with controls. Highly significant increase in plasma serotonin levels was found in exposure group II when compared to control whereas marginal non-significant rise was also registered in exposure group I in comparison to control. Exposure in terms of length of service up to 10 years did not produce any significant effect in the indoleamine levels in both the exposure groups when they were compared with their respective control groups. Whereas, length of service greater than 10 years was observed to decrease and increase respectively the melatonin and serotonin concentration significantly in exposure group II but not in exposure group I. However, correlation test did not yield any significant association between years of service and melatonin or serotonin levels respectively in both the exposure sets I and II. No significant association was observed between melatonin and serotonin levels as well.
Conclusion: The study shows the EMF ability to influence plasma melatonin and serotonin concentration in radar workers, significantly in 12.5-18GHz range with service period greater than 10 years.
The EMF levels measured in power density (W/m2) were monitored with EME Guard personal exposure meter (frequency range 27MHz to 40GHz with upper and lower detection limit of 200V/m and 5V/m respectively) and Broad Band Field Meter (frequency range 100KHz to 60GHz). Measurements were undertaken inside the radar cabins and outside the radar at different distances of occupational exposures of the personnel. The power density of microwave radiation level inside the radar cabin and outside at various locations around the radar vehicle, where a worker of Group I worked during the course of normal duty ranged from 0.24 – 0.77W/m2. Subjects of Group II were exposed to microwave power density level of 0.1 – 15.6W/m2 inside and outside the radar vehicle.
Despite the measured EMF levels found to be well within the acceptable limits of occupational exposure of 50W/m2 for controlled environments (1.5 to 150GHz) (ICNIRP guidelines, 1998, 2002; Canada Safety Code 6, 2009; NRPB, 2004), changes in pineal indoleamine concentrations with radar exposure in terms of both frequency band and years of service have been observed. The significantly depressed antioxidant level of melatonin in exposure group II signifies the potential of EMF exposure combination at Ku frequency band and mean exposure period of 11.5 years in terms of length of service in inducing stress. At the same time, the slight fall registered in group I may be due to comparatively lower cumulative exposure both in terms of frequency band and length of service (mean 8.3 years) to which the group might have acclimatized as apparent by the non-significant difference when compared with the reference group. Correlation analysis however, did not yield any significant association between years of service and melatonin or serotonin levels in both the exposure sets I and II ...
In light of the observed alterations in melatonin and serotonin found in both the frequency bands of radar and service category though, significant only in the higher frequency band and in greater than 10 years of service duration, our study do imply the EMF potential to alter the plasma indoleamine levels in radar workers. The results need further corroboration; hence, the results should be interpreted with caution. Given the significance of these pineal secretions for organisms, further studies with better EMF characterization and standardization are crucial. In this regard, future studies should target occupational groups with cohort or cross-sectional studies with more time point measurements in order to find the pattern of melatonin and serotonin response with EMF experience. Upcoming studies should also address the effect of EMF on all the components of melatonin biosynthesis in order to concretize the findings in addition to taking into account possible confounders. For the time being, precautionary approach should be adopted and unnecessary exposures should be checked, along with suitable protective measures where such exposures are unavoidable and considerably high.
Joel M. Moskowitz, Ph.D., Director
Center for Family and Community Health
School of Public Health
University of California, Berkeley
Electromagnetic Radiation Safety
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