Medical/biological study (experimental study)

Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields med./bio.

By: Adey WR, Byus CV, Cain CD, Higgins RJ, Jones RA, Kean CJ, Kuster N, MacMurray A, Stagg RB, Zimmerman G

Published in: Cancer Res 2000; 60 (7): 1857-1863

Aim of study (acc. to author)

The study was designed as a 2-year bioassay to test the hypothesis that frequency modulated field exposure might alter either survival or CNS primary tumor incidence.

Background/further details

A life-long exposure was simulated, beginning with exposures of fetal and preweanling rats. A low dose of ENU (ethylnitrosourea, a carcinogen) was selected to give maximum sensitivity for detection of a modification of tumor incidence.

Endpoint

cancer: CNS tumors

Exposure

- microwaves
- mobile communications
- mobile phone

Exposure	Parameters
Exposure 1: 836.55 MHz Modulation type: FM Exposure duration: continuous for about 25 days, see add. information	power density: 2.6 mW/cm² mean (± 0.5 mW/cm²)
Exposure 2: 836.55 MHz Modulation type: FM Exposure duration: repeated daily exposure, 2h/day, 4 days/week, for up to 700 days, see add. information	power: 2.5 W mean (± 0.1 W) SAR: 1.2 W/kg average over mass (brain) (male 450 g) SAR: 0.27 W/kg average over mass (whole body) (male 450 g) SAR: 1 W/kg average over mass (brain) (female 236 g) SAR: 0.42 W/kg average over mass (whole body) (female 236 g)

General information

Rats were assigned to six groups: sham ENU + sham field, sham ENU + field, ENU + sham field, ENU + field, ENU + cage control, sham ENU + cage control. A single dose of ENU was applied on gestation day 18 via the lateral tail vein. Buffer alone was applied to the sham-injected groups. Exposure systems have been described in [Lai et al., 1996].

Exposure 1

Main characteristics

Frequency	836.55 MHz
Type	electromagnetic field
Charakteristic	far field
Polarization	circular
Exposure duration	continuous for about 25 days, see add. information

Modulation

Modulation type	FM
Modulation frequency	12.5 kHz
Additional info	modulation by a recorded 2-min pattern of "balanced speech"

Exposure setup

Exposure source	horn antenna
Chamber	Far field conditions were simulated with an approx. plane wave in a large tapered horn radiator.
Setup	Rat cages were positioned in a vertically oriented 3 x 3 matrix at the square aperture (2 x 2 m²) of the horn. Sham exposures were performed in a square chamber of identical dimensions and materials.
Sham exposure	A sham exposure was conducted.
Additional info	Far field exposure of rats in their home cages began on gestation day 19 and continued until the pups were aged 21 days (about 25 days in total).

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	2.6 mW/cm²	mean	-	-	± 0.5 mW/cm²

Measurement and calculation details

Wavefront circularity (axial ratio) was within 2.3 dB, and power density was within 1.6 dB across the cage exposure area.

Exposure 2

Main characteristics

Frequency	836.55 MHz
Type	electromagnetic field
Charakteristic	near field
Exposure duration	repeated daily exposure, 2h/day, 4 days/week, for up to 700 days, see add. information

Modulation

Modulation type	FM
Modulation frequency	12.5 kHz
Additional info	modulation by a recorded 2-min pattern of "balanced speech"

Exposure setup

Exposure source	half-wave sleeved dipole
Distance between exposed object and exposure source	45 mm
Chamber	Twelve carousel exposure platforms were used each with 10 rats confined in plastic tubular restraints and oriented radially around a central antenna.
Setup	The distance to the antenna from the tip of the nose was 30 mm from weaning to 120 days, and 45 mm thereafter.
Sham exposure	A sham exposure was conducted.
Additional info	Near field exposure began at age 31 days and was performed on 4 consecutive days weekly until termination of the experiment at 731-734 days of age (384 exposures in total).

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power	2.5 W	mean	-	-	± 0.1 W
SAR	1.2 W/kg	average over mass	calculated	brain	male 450 g
SAR	0.27 W/kg	average over mass	calculated	whole body	male 450 g
SAR	1 W/kg	average over mass	calculated	brain	female 236 g
SAR	0.42 W/kg	average over mass	calculated	whole body	female 236 g

Measurement and calculation details

Dosimetric assessments were made by two different techniques, each of which was verified by an independent method: numerical modelling [Burkhardt et al., 1997] verified by electric probe measurement, and thermography verified by thermometric probes. The uncertainty of the numerical dosimetry was estimated to be less than ± 1.5 dB for the brain average and less than ± 1 dB for the whole body average. Uncertainty in thermography is less than ± 3 dB.

Reference articles

Burkhardt M et al. (1997): Exposure setup to test effects of wireless communications systems on the CNS
Lai H et al. (1996): Single- and double-strand DNA breaks in rat brain cells after acute exposure to radiofrequency electromagnetic radiation

Exposed system:

animal
rat/Fischer 344
whole body
partial body: head

Methods Endpoint/measurement parameters/methodology

cancer: incidence, numbers, and types of CNS tumors; ENU-induced tumor incidence
effects on the neurological system: CNS tumor
body weight; survival

Investigated system:

tissue slices
spinal cord sections
investigation on living organism

Investigated organ system:

brain/CNS

Time of investigation:

after exposure

Main outcome of study (acc. to author)

There were no effects on incidence of either spontaneous or ENU-induced primary tumors of the CNS associated with lifetime exposure of rats to frequency modulated microwave fields simulating electrical characteristics of hand-held mobile telephone transmissions at the head of the user.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

Motorola

Paulraj R et al. (2011): Effects of low level microwave radiation on carcinogenesis in Swiss Albino mice
Saran A et al. (2007): Effects of exposure of newborn patched1 heterozygous mice to GSM, 900 MHz
Smith P et al. (2007): GSM and DCS Wireless Communication Signals: Combined Chronic Toxicity/Carcinogenicity Study in the Wistar Rat
Oberto G et al. (2007): Carcinogenicity Study of 217 Hz Pulsed 900 MHz Electromagnetic Fields in Pim1 Transgenic Mice
Sommer AM et al. (2007): Lymphoma Development in Mice Chronically Exposed to UMTS-Modulated Radiofrequency Electromagnetic Fields
Shirai T et al. (2007): Lack of promoting effects of chronic exposure to 1.95-GHz W-CDMA signals for IMT-2000 cellular system on development of N-ethylnitrosourea-induced central nervous system tumors in F344 rats
Tillmann T et al. (2007): Carcinogenicity study of GSM and DCS wireless communication signals in B6C3F1 mice
Heikkinen P et al. (2006): No effects of radiofrequency radiation on 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone-induced tumorigenesis in female Wistar rats
Zook BC et al. (2006): The effects of pulsed 860 MHz radiofrequency radiation on the promotion of neurogenic tumors in rats
Huang TQ et al. (2005): Effect of radiofrequency radiation exposure on mouse skin tumorigenesis initiated by 7,12-dimethybenz[alpha]anthracene
Shirai T et al. (2005): Chronic exposure to a 1.439 GHz electromagnetic field used for cellular phones does not promote N-ethylnitrosourea induced central nervous system tumors in F344 rats
Sommer AM et al. (2004): No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice
LaRegina MC et al. (2003): The Effect of Chronic Exposure to 835.62 MHz FDMA or 847.74 MHz CDMA Radiofrequency Radiation on the Incidence of Spontaneous Tumors in Rats
Heikkinen P et al. (2003): Effects of mobile phone radiation on UV-induced skin tumourigenesis in ornithine decarboxylase transgenic and non-transgenic mice
Bartsch H et al. (2002): Chronic exposure to a GSM-like signal (mobile phone) does not stimulate the development of DMBA-induced mammary tumors in rats: results of three consecutive studies
Heikkinen P et al. (2001): Effects of mobile phone radiation on X-ray-induced tumorigenesis in mice
Imaida K et al. (2001): Lack of promotion of 7,12-dimethylbenz[a]anthracene-initiated mouse skin carcinogenesis by 1.5 GHz electromagnetic near fields
Zook BC et al. (2001): The effects of 860 MHz radiofrequency radiation on the induction or promotion of brain tumors and other neoplasms in rats
Adey WR et al. (1999): Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats chronically exposed to 836 MHz modulated microwaves
Higashikubo R et al. (1999): Radiofrequency electromagnetic fields have no effect on the in vivo proliferation of the 9L brain tumor
Imaida K et al. (1998): The 1.5 GHz electromagnetic near-field used for cellular phones does not promote rat liver carcinogenesis in a medium-term liver bioassay
Repacholi MH et al. (1997): Lymphomas in Eµ-Pim1 transgenic mice exposed to pulsed 900 MHz electromagnetic fields
Salford L et al. (1997): Brain tumour development in rats exposed to electromagnetic fields used in wireless cellular communication
Toler JC et al. (1997): Long-term, low-level exposure of mice prone to mammary tumors to 435 MHz radiofrequency radiation
Wu RY et al. (1994): Effects of 2.45-GHz microwave radiation and phorbol ester 12-O-tetradecanoylphorbol-13-acetate on dimethylhydrazine-induced colon cancer in mice

Spontaneous and nitrosourea-induced primary tumors of the central nervous system in Fischer 344 rats exposed to frequency-modulated microwave fields med./bio.

Aim of study (acc. to author)

Background/further details

Endpoint

Exposure

General information

Exposure 1

Main characteristics

Modulation

Exposure setup

Parameters

Measurement and calculation details

Exposure 2

Main characteristics

Modulation

Exposure setup

Parameters

Measurement and calculation details

Reference articles

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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