Medical/biological study (experimental study)

Cell Type-Dependent Induction of DNA Damage by 1800 MHz Radiofrequency Electromagnetic Fields Does Not Result in Significant Cellular Dysfunctions med./bio.

By: Xu S, Chen G, Chen C, Sun C, Zhang D, Murbach M, Kuster N, Zeng Q, Xu Z

Published in: PLoS One 2013; 8 (1): e54906

Aim of study (acc. to author)

The authors systematically investigated the effects of radiofrequency electromagnetic fields on DNA damage by examining and comparing gamma-H2AX foci formation in six cell types after GSM 1800 MHz exposure. Since the gamma-H2AX foci formation is an early marker of DNA damage, it was also investigated whether the exposure-induced gamma-H2AX foci formation resulted in genetic instabilities, aberrant cell cycle progression and other cellular dysfunctions.

Background/further details

Positive controls were performed with 4-nitroquinoline 1-oxide. All experiments were repeated a number of times.

Endpoint

genotoxicity/mutation: DNA damage, DNA double strand breaks

Exposure

- 1,800 MHz
- mobile communications
- mobile phone
- GSM

Exposure	Parameters
Exposure 1: 1,800 MHz Modulation type: pulsed Exposure duration: intermittent for 1 h or 24 h (5 min "on", 10 min "off")	SAR: 3 W/kg mean

Exposure 1

Main characteristics

Frequency	1,800 MHz
Type	electromagnetic field
Exposure duration	intermittent for 1 h or 24 h (5 min "on", 10 min "off")

Modulation

Modulation type	pulsed
Pulse width	576 ms
Repetition frequency	217 Hz
Additional info	GSM-like signal

Exposure setup

Exposure source	waveguide
Setup	two waveguides, one for RF and one for sham exposure; six 35-mm Petri dishes were placed in the H-field maximum of the standing wave
Sham exposure	A sham exposure was conducted.
Additional info	the temperature of the system remained at 37 ± 0.1°C during the whole exposure duration, and the temperature difference between radiofrequency and sham exposed cultures never exceeded 0.1°C.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	3 W/kg	mean	-	-	-

Reference articles

Zeng Q et al. (2006): Effects of global system for mobile communications 1800 MHz radiofrequency electromagnetic fields on gene and protein expression in MCF-7 cells
Schuderer J et al. (2004): High Peak SAR Exposure Unit With Tight Exposure and Environmental Control for In Vitro Experiments at 1800 MHz

Exposed system:

intact cell/cell culture
CHL (Chinese hamster lung) cells, human umbilical vein endothelial cells (HUVEC), primary newborn rat astrocytes, human amniotic epithelial cells, human lens epithelial cells (HLEC), human skin fibroblasts

Methods Endpoint/measurement parameters/methodology

genotoxicity/mutation: DNA damage, double strand breaks: gamma-H2AX foci formation (immunocytochemistry); chromosomal DNA fragmentation (investigated in human skin fibroblasts only): alkaline and neutral comet assay; TUNEL assay
molecular biosynthesis: level of reactive oxygen species (dichlorofluorescein-diacetate stianing; flow cytometry; investigated in human skin fibroblasts only)
cell viability/cell division/proliferation: cell proliferation (cell counting), cell viability (commercial cell counting kit, optical density), cell cycle progression (ethidium bromide staining; flow cytometry) at different times after exposure; all parameters investigated in human skin fibroblasts only

Investigated system:

intact cell/cell culture
cell lysates

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Exposure to radiofrequency electromagnetic fields for 24 h significantly induced gamma-H2AX foci formation in CHL cells and human skin fibroblasts, but not in the other cell types. However, exposure-elevated gamma-H2AX foci formation in human skin fibroblasts did not result in detectable DNA fragmentation, sustainable cell cycle arrest (slightly increased G0 phase/G1 phase arrest at 6 h after exposure but not at 12 h), cell proliferation or cell viability change. Radiofrequency electromagnetic field exposure slightly but not significantly increased the cellular reactive oxygen species level.
In conclusion, the radiofrequency exposure induced a DNA damage in a cell type-dependent manner, but the elevated gamma-H2AX foci formation in human skin fibroblasts did not result in significant cellular dysfunctions. The observed DNA damage might be reversible or compensated by DNA repair pathways or other cellular processes under the current experimental conditions.

Study character:

medical/biological study
experimental study
full/main study
blind study

Study funded by

Fundamental Research Funds for the Central Universities, China
Ministry of Science and Technology (MOST), China
National Natural Science Foundation (NSFC), China
Program of New Century Excellent Talents in University of China
Research Fund for the Doctoral Program of Higher Education, China
Technology Foundation for Excellent Overseas Chinese Scholar, Zhejiang Province Human Resources and Social Security Bureau
Zhejiang Provincial Natural Science Foundation, China
Zhejiang Provincial Program for the Cultivation of High-Level Innovative Health Talents, China

Duan W et al. (2015): Comparison of the genotoxic effects induced by 50 Hz extremely low-frequency electromagnetic fields and 1800 MHz radiofrequency electromagnetic fields in GC-2 cells
Hou Q et al. (2015): Oxidative changes and apoptosis induced by 1800-MHz electromagnetic radiation in NIH/3T3 cells
Perrin A et al. (2010): Evaluation of the co-genotoxic effects of 1800 MHz GSM radiofrequency exposure and a chemical mutagen in cultured human cells
Belyaev IY et al. (2009): Microwaves from UMTS/GSM mobile phones induce long-lasting inhibition of 53BP1/gamma-H2AX DNA repair foci in human lymphocytes
Phillips JL et al. (2009): Electromagnetic fields and DNA damage
Vijayalaxmi et al. (2008): Genetic damage in mammalian somatic cells exposed to radiofrequency radiation: a meta-analysis of data from 63 publications (1990-2005)
Yao K et al. (2008): Electromagnetic noise inhibits radiofrequency radiation-induced DNA damage and reactive oxygen species increase in human lens epithelial cells
Zhang DY et al. (2006): [Effects of GSM 1800 MHz radiofrequency electromagnetic fields on DNA damage in Chinese hamster lung cells]
Markova E et al. (2005): Microwaves from GSM mobile telephones affect 53BP1 and gamma-H2AX foci in human lymphocytes from hypersensitive and healthy persons