Medical/biological study (experimental study)

Long term and excessive use of 900 MHz radiofrequency radiation alter microRNA expression in brain med./bio.

By: Dasdag S, Akdag MZ, Erdal ME, Erdal N, Ay OI, Ay ME, Yilmaz SG, Tasdelen B, Yegin K

Published in: Int J Radiat Biol 2015; 91 (4): 306-311

Aim of study (acc. to author)

The effects of a chronic exposure of rats to a 900 MHz electromagnetic field on the expression of some microRNAs in the brain should be investigated.

Background/further details

MicroRNAs are small, non-coding RNA molecules, which play a critical role in gene regulation and could be related to the development of cancer and neurodegenerative diseases.
14 rats were divided into two groups (n=7 each): exposure and sham exposure.

Endpoint

molecular biosynthesis: microRNA expression in the brain

Exposure

- 900 MHz
- mobile communications
- GSM

Exposure	Parameters
Exposure 1: 900 MHz Exposure duration: continuous for 3 h/day on 7 days/week for 12 months	SAR: 0.198 W/kg peak value (in brain) SAR: 0.143 W/kg mean (1 g) (in brain) SAR: 0.114 W/kg mean (10 g) (in brain) SAR: 0.0369 W/kg effective value (whole body) SAR: 2.023 W/kg maximum (whole body) (± 0.121 W/kg)

Exposure 1

Main characteristics

Frequency	900 MHz
Type	electromagnetic field
Exposure duration	continuous for 3 h/day on 7 days/week for 12 months

Exposure setup

Exposure source	GSM generator + mobile phone antenna equivalent
Distance between exposed object and exposure source	1 cm
Chamber	rats were confined in a Plexiglas carousel with the antenna in the center; carousel was surrounded by electromagnetic absorber material backed by metal for isolation from environmental electromagnetic fields
Setup	distance from the antenna to the head of the rats was 1 cm; signal was emitted omnidirectional on the plane perpendicular to the antenna axis; temperature was maintained at 22°C and the relative humidity was maintained at 45%
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	0.198 W/kg	peak value	measured and calculated	-	in brain
SAR	0.143 W/kg	mean	measured and calculated	1 g	in brain
SAR	0.114 W/kg	mean	measured and calculated	10 g	in brain
SAR	0.0369 W/kg	effective value	measured and calculated	whole body	-
SAR	2.023 W/kg	maximum	measured and calculated	whole body	± 0.121 W/kg

Exposed system:

animal
rat/ Wistar albino
partial body: head

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: microRNA expression-rates in the brain (quantitative RT-PCR of microRNAs rno-miR-26b-5p, rno-miR-9-5p, rno-miR-29a-3p, rno-miR-106b-5p, rno-miR-107 and rno-miR-125a-3p)
effects on the neurological system: see "molecular biosynthesis"

Investigated system:

DNA/RNA

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The expression rate of rno-miR-107 was significantly reduced in the exposure group compared to sham exposure. The expression rates of the other investigated microRNAs were not significantly different in the two groups.
The authors conclude that a chronic exposure of rats to a 900 MHz electromagnetic field could influence the expression of some microRNAs in the brain.

Study character:

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

Study funded by

not stated/no funding

Dasdag S et al. (2015): Effects of 2.4 GHz radiofrequency radiation emitted from Wi-Fi equipment on microRNA expression in brain tissue
Yang XS et al. (2012): Exposure to 2.45 GHz electromagnetic fields elicits an HSP-related stress response in rat hippocampus
Paparini A et al. (2008): No evidence of major transcriptional changes in the brain of mice exposed to 1800 MHz GSM signal
Nittby H et al. (2008): Exposure to radiation from global system for mobile communications at 1,800 MHz significantly changes gene expression in rat hippocampus and cortex
Zhao R et al. (2007): Studying gene expression profile of rat neuron exposed to 1800 MHz radiofrequency electromagnetic fields with cDNA microassay
Belyaev IY et al. (2006): Exposure of rat brain to 915 MHz GSM microwaves induces changes in gene expression but not double stranded DNA breaks or effects on chromatin conformation