Study type: Epidemiological study (observational study)

The Potential Bioeffects of Extremely Low Frequency Electromagnetic Fields on Melatonin Levels & Related Oxidative Stress in Electric Utility Workers Exposed to 132 kV Substation. epidem.

Published in: J Electromagn Anal 2013; 5 (11): 393-403

Aim of study (acc. to author)

A study was conducted in India to investigate the melatonin levels and oxidative stress parameters in electric utility workers with exposure to extremely low frequency magnetic fields.

Further details

Further results on this study population are published in Tiwari et al (2015).
A blood sample for determining melatonin level and other blood parameters was collected in the morning between 9 AM to 10 AM from each study participant.

Endpoint/type of risk estimation

Exposure

Assessment

Exposure groups

Group Description
Reference group 1 occupational exposure to extremely low frequency magnetic fields: no
Group 2 occupational exposure to extremely low frequency magnetic fields: yes
Group 3 duration of occupational exposure to extremely low frequency magnetic fields: 1 - 4 years
Group 4 duration of occupational exposure to extremely low frequency magnetic fields: 5 - 12 years
Group 5 duration of occupational exposure to extremely low frequency magnetic fields: 13 - 28 years
Group 6 daily duration of occupational exposure to extremely low frequency magnetic fields: 1 - 3 hours/day
Group 7 daily duration of occupational exposure to extremely low frequency magnetic fields: 3 - 6 hours/day
Group 8 daily duration of occupational exposure to extremely low frequency magnetic fields: 6 - 9 hours/day
Group 9 exposure based on job titles: low (e.g. administrative workers)
Group 10 exposure based on job titles: medium (e.g. maintenance workers)
Group 11 exposure based on job titles: high (e.g. live-line workers)

Population

Study size

Type Value
Total 142

Conclusion (acc. to author)

The measured mean occupational magnetic field strength in the 132 kV substation at Hyderabad, India was 3.5 µT (SD ± 2.01), while environmental non-occupational exposure was 0.0015 µT (SD ± 0.001). The electric utility workers were exposed for a mean duration of 9.27 (±7.23) years at an average of 9 h per day.
The plasma melatonin level was significantly decreased in high exposed workers (group 11) when compared to the low and medium exposed groups (groups 9 and 10). The lipid peroxidation and nitric oxide levels were significantly increased in all exposed subjects (group 2) in comparison to the control group (group 1). The enzyme activities of antioxidative enzymes of exposed workers (group 2) were significantly lowered when compared to the control group (group 1).

Study funded by

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