Study type: Medical/biological study (experimental study)

Synergism between sinusoidal-50 Hz magnetic field and formaldehyde in triggering carcinogenic effects in male Sprague-Dawley rats med./bio.

By: Soffritti M, Tibaldi E, Padovani M, Hoel DG, Giuliani L, Bua L, Lauriola M, Falcioni L, Manservigi M, Manservisi F, Belpoggi F
Published in: Am J Ind Med 2016; 59 (7): 509-521
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Aim of study (acc. to author)

The carcinogenic effects of life-span co-exposure of rats to a 50 Hz magnetic field and formaldehyde should be investigated.

Background/further details

The present study is part of a large EMF animal test project, which has already been described in Soffritti et al. 2010.
In previous research, the authors found a slight, non-significantly increased incidence of cancer in rats exposed to 50 mg/l formaldehyde. This concentration was also used in this study, administered from 6 to 104 weeks of age via the drinking water.
Rats were divided into the following groups: 1) exposure to a magnetic field (253 males, 270 females), 2) co-exposure to a magnetic field and formaldehyde (200 males, 203 females), 3) exposure to formaldehyde (200 males, 202 females), 4) unexposed control group (500 males, 501 females). All the animals were exposed and observed until death.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: continuous from 6 weeks of age until death (max. 104 weeks)

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration continuous from 6 weeks of age until death (max. 104 weeks)
Exposure setup
Exposure source
Chamber rats in cages were placed in a large room with a temperature of 22°C ± 3°C and a relative humidity of 40-60%
Setup the field lines were horizontal and parallel to the ground; the field uniformity was better than 10%; there was no noise or vibration from current generator and coils; a maximum variation of 2°C was tolerated near coils; the 24 coils had a toroidal shape and were made of three turns of an insulated copper cable, mounted on a superstructure of aluminum composed of two insulated parts in order to avoid a closed loop subject to total field; the total copper cross-section was 11 mm x 28 mm; mounted inside the toroidal magnet was a wooden support structure for rat cages; each toroidal device was designed for the allocation of 500 rats, 5 per cage, distributed on five levels; the toroidal device had an external diameter of 4.7 m and was 2.1 m high
Additional info control animals stayed in the same room as the exposed animals
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -
Additional parameter details

environmental magnetic flux density was max. 0.1 mT; about 1 m away from the external coil boundary, the magnetic field level was approximately 0.1 mT

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 incidence of malignant tumors, thyroid C-cell carcinomas and lymphomas/leukemias was observed in male rats co-exposed to the magnetic field and formaldehyde (group 2) compared to rats only exposed to the magnetic field (group 1) or the control group (group 4). No statistically significant differences were observed between males of group 2 and group 3 (formaldehyde only) and between female animals of all groups.
The authors conclude that there might be a synergy between life-span exposure of rats to a 50 Hz magnetic field and formaldehyde in terms of carcinogenicity.

Study character:

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