Study type: Medical/biological study (experimental study)

Study on pineal function and DMBA-induced breast cancer formation in rats during exposure to a 100-mG, 50 Hz magnetic field. med./bio.

Published in: J Toxicol Environ Health 1996; 48 (2): 169-185
Journal partially peer-reviewed/unclear

Aim of study (acc. to author)

To investigate a possible association between melatonin depression by magnetic field (MF) exposure and DMBA-induced breast cancer growth in femal rats.

Background/further details

A total of 216 rats were used in this study, divided into four groups: Group A) 99 animals, DMBA treated, MF exposed. Group B) 99 animals, DMBA treated, MF sham-exposed. Group C) 9 animals, non-DMBA-treated, MF exposed. D) 9 animals, non-DMBA-treated, MF-sham-exposed.
The first DMBA (5 mg/rat) application occured prior exposure and was followed by three more applications in a weekly interval up to a total doses of 20 mg/rat.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 24 h/day, 7 days/week for 91 days

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 24 h/day, 7 days/week for 91 days
Exposure setup
Exposure source
Setup 4 Merritt coils, 26 and 11 turns on outer and inner coils, copper wire gauge 1.5 m²
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
electric field strength 29 V/m minimum measured unspecified -
electric field strength 69 V/m maximum measured unspecified -
magnetic flux density 10 µT effective value measured - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

A non statistically significant tendency to an enhanced tumor incidence in MF-exposed rats could be observed. Tumor size was similar in MF-exposed and sham-exposed groups. DMBA-treated animals had a significantly lower nocturnal pineal melatonin level as compared with non-DMBA-treated animals. Also MF-exposed animals had significantly lower nocturnal melatonin serum levels as compared with sham exposed animals. The data demonstrate that significantly decreased melatonin levels, caused by MF exposure, are not associated with a significant effect on the development and growth of DMBA-induced mammary tumors.

Study character:

Study funded by

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