Medical/biological study (observational study)

Effects of dietary green tea polyphenol supplementation on the health of workers exposed to high-voltage power lines med./bio.

By: Zhang Y, Zhang D, Zhu B, Zhang H, Sun Y, Sun C

Published in: Environ Toxicol Pharmacol 2016; 46: 183-187

Aim of study (acc. to author)

The effects of occupational exposure to high-voltage power lines (50/60 Hz) on oxidative stress and oxidative DNA damage in workers urine and the protective effect of green tea polyphenols should be investigated.

Background/further details

Several studies have found a protective effect of green tea polyphenols against oxidative damage, what should now be tested in electro-magnetic field exposure.
Participants consisted of substation workers with occupational exposure to 110-420 kV lines as exposed subjects and subjects who work in administration as non-exposed subjects. Both groups were randomly divided into two subgroups: placebo and green tea polyphenol supplementation (GTPS) for 12 months. The capsules were orally administered twice daily and contained 250 mg of green tea extract without caffeine. The following groups were used in the study: 1) occupational exposure and placebo (n=67), 2) no exposure and placebo (n=54), 3) occupational exposure and GTPS (n=123), 4) no exposure and GTPS (n=77).

Endpoint

urinary oxidative stress and oxidative DNA damage

Exposure

- power transmission line
- electrical substation
- occupational
- co-exposure

Exposure	Parameters
Exposure 1: LF (< 10 MHz) Exposure duration: approximately 8 hours/day	-

Exposure 1

Main characteristics

Frequency	LF (< 10 MHz)
Type	electric field magnetic field
Exposure duration	approximately 8 hours/day

Exposure setup

Exposure source	power lines
Setup	working in a 110-420 kV substation

Parameters

No parameters are specified for this exposure.

Exposed system:

human

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: urinary oxidative DNA damage (amount of 8-OHdG in 24 h urine samples; ELISA)
urinary oxidative stress (amount of 8-isoprostane in 24 h urine samples; ELISA)

Investigated system:

isolated bio./chem. substance
DNA/RNA
urine
investigation on living organism

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Prior to the GTPS treatment, subjects from the exposure groups (groups 1 and 3) showed significantly higher levels of oxidative stress and oxidative DNA damage compared to the control groups (groups 2 and 4). After 12 months of GTPS treatment (group 3), the values were significantly reduced compared to the initial value, while there were no significant changes observed in the placebo group (group 1).
3 months after the end of GTPS treatment, oxidative stress and DNA damage were again increased to the initial levels before GTPS treatment in group 3, which revealed the reversible effect of GTPS.
The authors conclude that occupational exposure to high-voltage power lines (50/60 Hz) might induce oxidative stress and oxidative DNA damage and that green tea polyphenol supplementation might protect against these effects.

Study character:

medical/biological study
observational study
full/main study
interventional study

Study funded by

not stated/no funding

Comments on this article

Eslami J et al. (2019): Effects of Dietary Green Tea Polyphenol Supplementation on the Health of Workers Exposed to High-voltage Power Lines

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