Study type: Medical/biological study (observational study)

Effect of long-term occupational exposure to extremely low-frequency electromagnetic fields on proinflammatory cytokine and hematological parameters. med./bio.

Published in: Int J Radiat Biol 2019; 95 (11): 1573-1580

Aim of study (acc. to author)

The effects of long-term occupational exposure to ELF-MF and EF of a power plant on proinflammatory cytokines and hematological parameters in workers should be investigated.

Background/further details

Participants in this study were employees working in different sections of a power plant in Semnan, Iran. A total of 112 employees were included in the study as an exposure group and 138 employees as a control group. The exposure group consisted of technicians (n=33), operators (n=27), mechanics (n=23) and office workers working close to sources of ELF-MF and EF (n=29), while the control group consisted of office workers who were all exposed only to a very low intensity ELF-MF and EF.
Blood samples were taken from all participants before the start of the work shift on the last working day of the week. All participants were male.

Endpoint

Exposure

Exposure Parameters
Exposure 1:
Exposure duration: working for at least 2 years at the power plant in full-time (8-12 hours shifts)
exposure group (total)
Exposure 2:
Exposure duration: working for at least 2 years at the power plant in full-time (8-12 hours shifts)
technicians
Exposure 3:
Exposure duration: working for at least 2 years at the power plant in full-time (8-12 hours shifts)
operators
Exposure 4:
Exposure duration: working for at least 2 years at the power plant in full-time (8-12 hours shifts)
engineers
Exposure 5:
Exposure duration: working for at least 2 years at the power plant in full-time (8-12 hours shifts)
office workers

Exposure 1

Main characteristics
Frequency
Type
Exposure duration working for at least 2 years at the power plant in full-time (8-12 hours shifts)
Additional info exposure group (total)
Exposure setup
Exposure source
Setup participants were exposed to ELF-MF and EF mainly generated by transmission lines, electrical generators, transformers and distribution grids; participants specified their working and non-working workstations (e.g. their places of resting and eating lunch) and the amount of time that they spent in each workstation; spot measurements were taken at these workstations; measuring the magnetic fields was performed by placing the probe device at a height of 1 m; in order to measure the electric fields, the device probe was placed at a 1 m height and 2.5 m distance to the workers’ body, in order to measure the electric fields without disturbance; a particular distance was kept ; in total, about 700 spots in the workstations were measured; the 8 h time-weighted average of exposure to the magnetic fields and electric fields were calculated afterwards
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 172.6 µT maximum measured - -
magnetic flux density 29.5 µT average over time measured and calculated - ± 16.8 µT
electric field strength 82.4 V/m maximum measured - -
electric field strength 25.5 V/m average over time measured and calculated - ± 12.09 V/m

Exposure 2

Main characteristics
Frequency
Type
Exposure duration working for at least 2 years at the power plant in full-time (8-12 hours shifts)
Additional info technicians
Exposure setup
Exposure source
Additional info technicians were mainly responsible for controlling, monitoring, and maintaining equipment throughout the facility
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 172.6 µT maximum measured - -
magnetic flux density 12.6 µT minimum measured - -
magnetic flux density 46.5 µT average over time measured and calculated - ± 19.8 µT
electric field strength 82.4 V/m maximum measured - -
electric field strength 3.2 V/m minimum measured - -
electric field strength 29.1 V/m average over time measured and calculated - ± 14.2 V/m

Exposure 3

Main characteristics
Frequency
Type
Exposure duration working for at least 2 years at the power plant in full-time (8-12 hours shifts)
Additional info operators
Exposure setup
Exposure source
Additional info operators were inspecting power generating equipment and checking the flow of electricity between the generating stations and substations
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 39.7 µT maximum measured - -
magnetic flux density 5.6 µT minimum measured - -
magnetic flux density 25 µT average over time measured and calculated - ± 8 µT
electric field strength 41.6 V/m maximum measured - -
electric field strength 2.3 V/m minimum measured - -
electric field strength 24.3 V/m average over time measured and calculated - ± 8.5 V/m

Exposure 4

Main characteristics
Frequency
Type
Exposure duration working for at least 2 years at the power plant in full-time (8-12 hours shifts)
Additional info engineers
Exposure setup
Exposure source
Additional info duties of the engineers were installation, modification, testing and quality control of the equipment to ensure optimum performance
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 38.2 µT maximum measured - -
magnetic flux density 3.5 µT minimum measured - -
magnetic flux density 22 µT average over time measured and calculated - ± 16.5 µT
electric field strength 49.6 V/m maximum measured - -
electric field strength 2.5 V/m minimum measured - -
electric field strength 23.5 V/m average over time measured and calculated - ± 11.4 V/m

Exposure 5

Main characteristics
Frequency
Type
Exposure duration working for at least 2 years at the power plant in full-time (8-12 hours shifts)
Additional info office workers
Exposure setup
Exposure source
Additional info office workers participated in the planning and scheduling of all plant activities, and the development and improvement of policies, standards and procedures; some were working inside the power plant and in a department which was located close to the turbines and generators and this led to a high level of ELF-MF and EF; in addition, they had to investigate and report the status of the low voltage and medium voltage rooms of the power plant daily and monitor how other job groups do their tasks
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 33.7 µT maximum measured - -
magnetic flux density 7.8 µT minimum measured - -
magnetic flux density 19.4 µT average over time measured and calculated - ± 5.8µT
electric field strength 53.9 V/m maximum measured - -
electric field strength 1.4 V/m minimum measured - -
electric field strength 22.1 V/m average over time measured and calculated - ± 12.9 V/m

Reference articles

  • Cam ST et al. (2011): Occupational exposure to magnetic fields from transformer stations and electric enclosures in Turkey.
  • No authors listed (2010): IEEE C95.3.1-2010 - IEEE Recommended Practice for Measurements and Computations of Electric, Magnetic, and Electromagnetic Fields with Respect to Human Exposure to Such Fields, 0 Hz to 100 kHz.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The mean levels of IL-1β and IL-6, white blood cells and red blood cells, platelets and procalcitonin, lymphocyte percentage as well as mean corpuscular volume were significantly increased in the exposure group compared to the control group.
Moreover, the mean levels of IL-6, IL-1β and the levels of white blood cells, lymphocytes, red blood cells, haematocrit and mean corpuscular volume were significantly higher in technicians, which had the highest level of exposure to magnetic fields of all job groups, compared to the other job groups.
The authors conclude that occupational long-term exposure to extremely low frequency magnetic fields and electric fields of a power plant could have an effect on the production of proinflammatory cytokines and some hematological parameters in workers.

Study character:

Study funded by

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