Study type: Medical/biological study (experimental study)

Nonthermal GSM RF and ELF EMF effects upon rat BBB permeability med./bio.

By: Nittby H, Brun A, Strömblad S, Moghadam MK, Sun W, Malmgren L, Eberhardt J, Persson BR, Salford LG
Published in: Environmentalist 2011; 31 (2): 140-148
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Aim of study (acc. to author)

To study whether the extremely low frequency magnetic fields from the external fan (50 Hz, 0.3-1.5 T) used in previous studies for ventilation of the TEM cell might add to the radiofrequency effect on blood brain barrier permeability in rats (see "related articles" of Salford et al., Nittby et al. and Eberhardt et al.).

Background/further details

64 rats were divided into four groups (each group n=16): 1) radiofrequency exposure only, 2) extremely low frequency exposure only, 3) radiofrequency + extremely low frequency exposure, 4) sham exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 900 MHz
Exposure duration: continuous for 2 h
RF exposure only
  • power: 10 mW peak value (per TEM cell)
  • SAR: 0.37 mW/kg average over mass (whole body) (male rats)
  • SAR: 0.44 mW/kg average over mass (whole body) (female rats)
Exposure 2: 50 Hz
Exposure duration: continuous for 2 h
ELF exposure only
Exposure 3: 900 MHz
Exposure duration: continuous for 2 h
combination of RF and ELF exposure
-

General information

rats were treated in four groups: i) sham exposure ii) RF exposure iii) ELF exposure iv) RF exposure + ELF exposure

Exposure 1

Main characteristics
Frequency 900 MHz
Type
Waveform
Exposure duration continuous for 2 h
Additional info RF exposure only
Exposure setup
Exposure source
Chamber TEM cells as exposure chambers
Setup mobile phone connected via a coaxial cable to the TEM cells; through power splitter the mobile phone's output power was divided into equal parts fed into the two TEM cells used; TEM cell enclosed in a 15 cm x 15 cm x 15 cm (inner dimensions) wooden box that supported the outer conductor, made of brass net and a central conducting plate which separated the top and bottom of the outer conductor symmetrically; each TEM cell contained two 14 cm x 14 cm x 7 cm plastic trays with a rat each; fan placed besides the TEM cell with the air flow directed 90° away from the cell; fan turned off
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power 10 mW peak value - - per TEM cell
SAR 0.37 mW/kg average over mass - whole body male rats
SAR 0.44 mW/kg average over mass - whole body female rats

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Exposure duration continuous for 2 h
Additional info ELF exposure only
Exposure setup
Exposure source
Setup mobile phone turned off: fan turned on
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1.7 µT minimum - - in the TEM cell closest to the fan
magnetic flux density 1.9 µT maximum - - in the TEM cell closest to the fan
magnetic flux density 0.5 µT minimum - - in the middle of the TEM
magnetic flux density 0.8 µT maximum - - in the middle of the TEM
magnetic flux density 0.1 µT minimum - - at the TEM cell wall opposing the fan
magnetic flux density 0.3 µT maximum - - at the TEM cell wall opposing the fan

Exposure 3

Main characteristics
Frequency 900 MHz
Type
Exposure duration continuous for 2 h
Additional info combination of RF and ELF exposure
Additional info + 50 Hz from the fan
Exposure setup
Exposure source
Setup mobile phone turned on: fan turned on
Sham exposure A sham exposure was conducted.
Parameters

No parameters are specified for this exposure.

Additional parameter details

exposure parameters are a combination of the exposure parameters from exposure 1 and exposure 2

Reference articles

  • Nittby H et al. (2009): Increased blood-brain barrier permeability in mammalian brain 7 days after exposure to the radiation from a GSM-900 mobile phone
  • Nittby H et al. (2008): Cognitive impairment in rats after long-term exposure to GSM-900 mobile phone radiation
  • Grafstrom G et al. (2008): Histopathological examinations of rat brains after long-term exposure to GSM-900 mobile phone radiation
  • Eberhardt JL et al. (2008): Blood-brain barrier permeability and nerve cell damage in rat brain 14 and 28 days after exposure to microwaves from GSM mobile phones
  • Salford LG et al. (2003): Nerve cell damage in mammalian brain after exposure to microwaves from GSM mobile phones
  • Persson BRR et al. (1997): Blood-brain barrier permeability in rats exposed to electromagnetic fields used in wireless communication
  • Salford LG et al. (1994): Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50, and 200 Hz
  • Salford LG et al. (1993): Permeability of the blood-brain barrier induced by 915 MHz electromagnetic radiation, continuous wave and modulated at 8, 16, 50 and 200 Hz
  • Martens L et al. (1993): Electromagnetic field calculations used for exposure experiments on small animals in TEM-cells
  • van Hese J et al. (1992): Simulation of the effect of inhomogeneities in TEM transmission cells using the FDTD method

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

In none of the sham exposed animals, there was a pathological albumin leakage in the brain. In the radiofrequency exposed rats, there was a somewhat increased leakage (in 25% of the animals), while the "extremely low frequency" and "radiofrequency + extremely low frequency" exposed groups were not significantly different from the control group.
The authors conclude that the use of external fans has not had any major influence upon the results they have accumulated during the past 20 years. The findings are in line with their previous work of increased blood-brain barrier permeability after nonthermal radiofrequency exposure especially at very low SAR levels, in this case more than 1,000 times lower than the recommended limit value of 2 W/kg.

Study character:

Study funded by

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