Medical/biological study (experimental study)

Exposure of cultured astroglial and microglial brain cells to 900 MHz microwave radiation med./bio.

By: Thorlin T, Rouquette JM, Hamnerius Y, Hansson E, Persson M, Bjorklund U, Rosengren L, Ronnback L, Persson M

Published in: Radiat Res 2006; 166 (2): 409-421

Aim of study (acc. to author)

To assess whether 900 MHz irradiation could affect rat astroglial and the microglial cells in culture by studying markers for damage-related processes in the cells.

Background/further details

Astroglial (astrocytes) and microglial cells, two types of glial cells in the brain are interesting in the context of biological effects from microwave exposure.
The release of the two pro-inflammatory cytokines interleukin 6 and tumor necrosis factor-alpha was investigated. Levels of the astroglial cell-specific reactive marker glial fibrillary acidic protein and the microglial reactivity marker ED-1 (a macrophage activation antigen) were also measured.
Positive controls were performed in increased temperatures.

Endpoint

cell function: cell reactivity/cell damage

Exposure

- microwaves
- mobile communications
- digital mobile phone
- GSM

Exposure	Parameters
Exposure 1: 906.6 MHz Modulation type: pulsed Exposure duration: continuous for 4, 8, and 24 h	power: 2.8 W average over time power: 23 W peak value SAR: 3.1 W/kg average over time (± 0.2 W/kg) SAR: 25 W/kg peak value
Exposure 2: 906.6 MHz Modulation type: CW Exposure duration: continuous for 4 or 24 h	SAR: 27 W/kg mean (± 2 W/kg) SAR: 54 W/kg mean (± 3 W/kg)

Exposure 1

Main characteristics

Frequency	906.6 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 4, 8, and 24 h

Modulation

Modulation type	pulsed
Duty cycle	12.5 %
Repetition frequency	217 Hz
Additional info	GSM modulated, one slot

Exposure setup

Exposure source	cellular phone cavity resonator software-controlled, amplifier
Chamber	short-circuited aluminium waveguide cavity with adjustable end plate operating in TE₁₀₃ mode
Setup	Cells in seven 35-mm Petri dishes were positioned in a ring which was placed in a Plexiglas box located inside the cavity. An extra center dish containing medium but no cells was added to obtain a more homogeneous SAR distribution. Petri dishes were located in the H-field maximum of the standing wave.
Sham exposure	A sham exposure was conducted.
Additional info	The temperature in the cell culture dishes was maintained at 37 ± 0.2°C by thermostat-controlled cooling water flowing between two glass plates below the dishes. To prevent evaporation of the culture medium, the bottom of the tissue dish holder was filled with a thin layer of deionised water with tensides added which was found not to affect the characteristics of the chamber and also improved the thermal contact between the dishes and the bottom glass plate of the cooling system.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	2.8 W	average over time	measured	-	-
power	23 W	peak value	measured	-	-
SAR	3.1 W/kg	average over time	measured and calculated	-	± 0.2 W/kg
SAR	25 W/kg	peak value	-	-	-

Additional parameter details

Positive control cells were exposed for 24 h to 38°C or 42°C.

Measurement and calculation details

The fields inside the cavity, the S11 parameter and the SAR distribution were calculated using a modified FDTD method. The S11 calculations were verified experimentally using a network analyzer. The SAR calculations were verified by measuring the initial temperature rises for 1 min in all seven culture dishes (19 measurements per dish repeated five times).

Exposure 2

Main characteristics

Frequency	906.6 MHz
Type	electromagnetic field
Charakteristic	guided field
Exposure duration	continuous for 4 or 24 h

Modulation

Modulation type	CW

Exposure setup

Exposure source	same setup as exposure 1
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
SAR	27 W/kg	mean	measured and calculated	-	± 2 W/kg
SAR	54 W/kg	mean	measured and calculated	-	± 3 W/kg

Exposed system:

intact cell/cell culture

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: release of interleukin 6 and tumor necrosis factor-alpha (ELISA); levels of glial fibrillary acidic protein (ELISA) and microglial reactivity marker ED-1 (Western blot); cellular protein content
cell function: cell reactivity/cell damage (investigation of cell injury markers; see "molecular biosynthesis")
morphol./histopathol. changes: cell morphology (light microscopy; phase-contrast microscopy)

Investigated system:

isolated bio./chem. substance
intact cell/cell culture
culture medium; cell lysates

Time of investigation:

before exposure
after exposure

Main outcome of study (acc. to author)

No significant differences could be found for any of the parameters studied at any time and for any of the exposure characteristics. Thus the data do not provide evidence for any effect of the microwave irradiation used on damage-related factors in glial cells in vitro.

Study character:

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

Study funded by

Ahlén-Foundation, Sweden
Edith Jacobssons Foundation for Neurological Research, Sweden
Fredrik and Ingrid Thurings Foundation, Sweden
Gun and Bertil Stohnes Foundation, Sweden
Swedish Council for Working Life and Social Research (FAS)
Swedish Medical Research Council (SMRC), Sweden

Lu Y et al. (2014): Differential Pro-Inflammatory Responses of Astrocytes and Microglia Involve STAT3 Activation in Response to 1800 MHz Radiofrequency Fields
Zeni O et al. (2012): Radiofrequency radiation at 1950 MHz (UMTS) does not affect key cellular endpoints in neuron-like PC12 cells
Karaca E et al. (2012): The genotoxic effect of radiofrequency waves on mouse brain
Liu YX et al. (2012): Exposure to 1950-MHz TD-SCDMA Electromagnetic Fields Affects the Apoptosis of Astrocytes via Caspase-3-Dependent Pathway
Campisi A et al. (2010): Reactive oxygen species levels and DNA fragmentation on astrocytes in primary culture after acute exposure to low intensity microwave electromagnetic field
Hirose H et al. (2010): 1950 MHz IMT-2000 field does not activate microglial cells in vitro
Ammari M et al. (2010): GFAP expression in the rat brain following sub-chronic exposure to a 900 MHz electromagnetic field signal
Ait-Aissa S et al. (2010): In situ detection of gliosis and apoptosis in the brains of young rats exposed in utero to a Wi-Fi signal
Ammari M et al. (2008): Effect of a chronic GSM 900 MHz exposure on glia in the rat brain
Kim TH et al. (2008): Local exposure of 849 MHz and 1763 MHz radiofrequency radiation to mouse heads does not induce cell death or cell proliferation in brain
Brillaud E et al. (2007): Effect of an acute 900MHz GSM exposure on glia in the rat brain: a time-dependent study
Mausset-Bonnefont AL et al. (2004): Acute exposure to GSM 900-MHz electromagnetic fields induces glial reactivity and biochemical modifications in the rat brain
Fritze K et al. (1997): Effect of global system for mobile communication microwave exposure on the genomic response of the rat brain

Exposure of cultured astroglial and microglial brain cells to 900 MHz microwave radiation med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Additional parameter details

Measurement and calculation details

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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