Study type: Medical/biological study (experimental study)

Life-span exposure to sinusoidal-50 Hz magnetic field and acute low-dose gamma radiation induce carcinogenic effects in Sprague-Dawley rats. med./bio.

Published in: Int J Radiat Biol 2016; 92 (4): 202-214

Aim of study (acc. to author)

The carcinogenic effects of prenatal and postnatal exposure of rats to a 50 Hz magnetic field in combination with gamma radiation should be investigated in a life-span study.

Background/further details

The present study is part of a large EMF animal test project, which has already been described by Soffritti et al. 2010.
A total of 1658 pregnant rats was divided into 3 groups (remark EMF-Portal: number of rats in each group is not stated): exposure to a magnetic field of 20 µT, exposure to a magnetic field of 1000 µT, control group without any exposure. The newborn rats were further exposed and divided into the following groups: 1) exposure to a magnetic field of 20 µT and treatment with gamma radiation (105 male, 107 female rats), 2) exposure to a magnetic field of 1000 µT and gamma radiation (110 male, 112 female rats), 3) only gamma radiation (118 male, 105 female rats), 4) control group without exposure and gamma radiation (500 male, 501 female rats). All the animals were monitored until their natural death.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous for 19 hours/day from the 12th day of pregnancy until death
Exposure 2: 50 Hz
Exposure duration: continuous for 19 hours/day from the 12th day of pregnancy until death

General information

gamma radiation was applied once at an age of 6 weeks (about 0.21 Gy/min, total of 0.1 Gy); exposure was divided into two equal irradiations, performed on the ventral and dorsal side of the animals, respectively; in this way the rats were treated by two opposite irradiation fields, with an almost homogeneous dose distribution

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration continuous for 19 hours/day from the 12th day of pregnancy until death
Exposure setup
Exposure source
  • coil(s)
  • toroidal-shaped device
Chamber polycarbonate cages (41 x 25 x 15 (remark EMF-Portal: cm?)) with covers made of non-magnetic material and a shallow layer of white wood shaving as bedding; cages were placed in exposure system in a room of 60 x 15 x 4 m3
Setup toroid was designed with 24 coils made of three turns of insulated copper cable, mounted on a superstructure of aluminum composed of two insulated parts; mounted inside the toroidal magnet was a wooden support structure for rat cages (5 rats per cage); the field lines were horizontal and parallel to the ground; the field uniformity was better than ± 10%; temperature was 22°C ± 3°C (remark EMF-Portal: or 22°C ± 2°C - contradictory specifications)
Additional info the exposure system was based on independent devices, each serving at least 500 rats; control group stayed in the same room as exposure groups; no noise and vibration were present during exposure
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 20 µT - measured - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration continuous for 19 hours/day from the 12th day of pregnancy until death
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1,000 µT - measured - -

Reference articles

  • Montanari I (2003): Optimal design of a system for large in vivo experiments on the effects of 50-Hz magnetic fields.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

A significantly increased occurence of mammary adenocarcinomas was found in males of group 1 (20 µT + gamma radiation) and in females of group 2 (1000 µT + gamma radiation) compared to the control group. In both groups, the number of animals bearing atypical precursor cells was significantly increased in males in females compared to the control group.
In males of groups 1 and 2, a significantly increased occurence of malignant schwannomas of the heart, and in males of group 2 a significantly increased occurence of lymphomas/leukemias in comparison to the control group was found.
No differences were found in body weight and survial between the exposure groups and the control group.
The authors conclude that exposure of rats to a 50 Hz magnetic field might have cancer promoting effects.

Study character:

Study funded by

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