Medical/biological Study (experimental study)

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. med./biol.

PubMed Entry

Journal web site

Aim of study (according to author)
To study the effects of a two year exposure to an electromagnetic near field equivalent to that generated by cellular phones on tumor development in the central nervous system of rats.
Background/further details:
Pregnant rats were given a single administration of N-ethylnitrosourea on gestational day 18. A total of 500 pups were divided into five groups (each composed of 50 males and 50 females): Group 1, untreated control group; Group 2, N-ethylnitrosourea administration alone; Groups 3 to 5, N-ethylnitrosourea + electromagnetic field exposure (two levels) or sham exposure.

Endpoint

• cancer: tumor development in the central nervous system

Exposure
General category: mobile communication system, digital mobile phone, CDMA

Field characteristics	Parameters
1.95 GHz exposure duration: repeated daily exposure, 90 min/day, 5 days/week, for 104 weeks, starting at 5 weeks of age	SAR: 0.67 W/kg average over mass (brain) SAR: 3.1 W/kg peak value SAR: 2 W/kg average over mass (brain) SAR: 7.6 W/kg peak value SAR: 0.464 W/kg max value (whole body) (over 2 years)

Exposed system:
animal (species/strain): rat/Fischer 344
partial body exposure: nose/head

Methods
Endpoint/Measurement parameters/Methodology

• cancer: tumor development in the central nervous system (incidences and numbers of tumors in brain and spinal cord); leukemia; histological examination of brain lesions including tumors
• morphological/histopathological changes: histological examination of all observable organ lesions (hematoxylin-eosin stain)
• endocrine changes: melatonin, corticosterone and ACTH level
• others: body weight; organ weights; food consumption; mortality

Main outcome of study (according to author)
The incidence and numbers of brain tumors in female rats exposed to the electromagnetic fields showed tendencies to increase but without statistical significance. Overall, no significant increase in incidences or numbers of CNS tumors, either in the male or female rats, was detected in the electromagnetic field exposed groups. In addition, no clear changes in tumor types in the brain were evident.
In conclusion, under these experimental conditions the data showed that exposure of heads of rats to 1.95 GHz W-CDMA signals for a two year period did not accelerate or otherwise affect N-ethylnitrosourea-initiated brain tumorigenesis.

(Study character: medical/biological study, experimental study, full/main study, blind study)

Study funded by

• Ministry of Internal Affairs and Communications, Japan

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