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Medical/biological study (experimental study)

Results of lifespan exposure to continuous and intermittent extremely low frequency electromagnetic fields (ELFEMF) administered alone to Sprague Dawley rats.

Published in: Environ Res 2018; 164: 271-279

Aim of study (acc. to author)

To evaluate the possible carcinogenic effects of livelong exposure to 50 Hz magnetic fields in rats.
Background/further details: The present study is part of a large EMF animal test project, which has already been described by Soffriti et al. 2010. In former studies, cocarcinogenic effects of 50 Hz magnetic fields with formaldehyde (Soffritti et al. 2016a) and gamma radiation (Soffritti et al. 2016b) were examined.
Six groups of rats were examined: 1) control group (male n=500, female n=501), 2) continuous exposure to 2 µT (male n=500, female n=502), 3) continuous exposure to 20 µT (male n=501, female n=502), 4) continuous exposure to 100 µT (male n=500, female n=500), 5) continuous exposure to 1000 µT (male n=250, female n=250) and 6) intermittent exposure to 1000 µT (male n=253, female n=270).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: during whole life span for 19 h/day (starting in utero until death)
Exposure 2: 50 Hz
Exposure duration: during whole life span for 19 h/day (starting in utero until death)
Exposure 3: 50 Hz
Exposure duration: during whole life span for 19 h/day (starting in utero until death)
Exposure 4: 50 Hz
Exposure duration: during whole life span for 19 h/day (starting in utero until death)
Exposure 5: 50 Hz
Exposure duration: intermittent (30 minutes on/30 minutes off) during whole life span for 19 h/day (starting in utero until death)
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration during whole life span for 19 h/day (starting in utero until death)
Exposure setup
Exposure source
Chamber rats (5 rats per cage) in polycarbonate cages (41 cm x 25 cm x 15 cm, white wood shavings as bedding) were placed in a toroidal exposure apparatus in a large room with a temperature of 22°C ± 3°C and a relative humidity of 40-60% with 12 h/daylight/dark; control and exposure groups were all in the same room in several independent toroids (ca. 500 rats per toroid possible)
Setup a toroidal exposure apparatus was designed with 24 coils made of three turns of insulated copper cable, mounted on a superstructure of aluminum composed of two insulated parts; total copper cross section was 11 x 28 mm2; the large amount of a good thermal-conducting insulation prevented heating (ensuring room temperature); vibrations and noise were proved to be absent; a wooden structure was mounted inside the toroidal magnet for rat cages; the field lines were horizontal and parallel to the ground; the field uniformity was better than 10%; the current supply had a maximum harmonic distortion of 3%; the field rise time at power-up was at least 200 ms
Sham exposure A sham exposure was conducted.
Additional info the natural field level was no more than 0.1 μT
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 µT - measured - -
Exposure 2
Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration during whole life span for 19 h/day (starting in utero until death)
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 20 µT - measured - -
Exposure 3
Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration during whole life span for 19 h/day (starting in utero until death)
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 100 µT - measured - -
Exposure 4
Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration during whole life span for 19 h/day (starting in utero until death)
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1,000 µT - measured - -
Exposure 5
Main characteristics
Frequency 50 Hz
Type
Waveform
Polarization
Exposure duration intermittent (30 minutes on/30 minutes off) during whole life span for 19 h/day (starting in utero until death)
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1,000 µT - measured - -
Reference articles
  • Soffritti M et al. (2016): Synergism between sinusoidal-50 Hz magnetic field and formaldehyde in triggering carcinogenic effects in male Sprague-Dawley rats.
  • Soffritti M et al. (2016): Life-span exposure to sinusoidal-50 Hz magnetic field and acute low-dose gamma radiation induce carcinogenic effects in Sprague-Dawley rats.
  • 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 material:
Investigated organ system:
  • investigation of dead rats
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

No significant differences were found between exposed rats (groups 2-6) and those from the control group (group 1).
However, in previous studies, when 50 Hz magnetic fields were combined with formaldehyde or gamma radiation, the 50 Hz magnetic fields seemed to enhance their carcinogenic power in the examined rat model (Soffritti et al. 2016a, Soffritti et al. 2016b). The authors conclude that these findings are relevant in terms of public health because 50 Hz magnetic field exposure is always combined with concurrent exposures to other chemical or physical agents in every day life.
Study character:

Study funded by

  • Fondazione del Monte di Bologna e Ravenna, Italy
  • CHILDREN with CANCER UK
  • Istituto Nazionale Per L'Assicurazione Contro Gli Infortuni Sul Lavoro (INAIL; Italian Workers' Compensation Authority), Italy
  • Environmental Health Trust
  • Istituto Ramazzini, Italy
  • Regional Agency for the Prevention and the Environment of the Emilia-Romagna Region (Agenzia Regionale per la Prevenzione e l'Ambiente dell'Emilia-Romagna, ARPA), Italy
  • Fondazione Cassa di Risparmio in Bologna, Italy

Related articles

  • Soffritti M et al. (2016): Synergism between sinusoidal-50 Hz magnetic field and formaldehyde in triggering carcinogenic effects in male Sprague-Dawley rats.
  • Soffritti M et al. (2016): Life-span exposure to sinusoidal-50 Hz magnetic field and acute low-dose gamma radiation induce carcinogenic effects in Sprague-Dawley rats.
  • Qi G et al. (2015): Effects of extremely low-frequency electromagnetic fields (ELF-EMF) exposure on B6C3F1 mice.
  • Chung MK et al. (2008): Lack of a co-promotion effect of 60 Hz rotating magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in F344 rats.
  • Fedrowitz M et al. (2008): Exposure of Fischer 344 rats to a weak power frequency magnetic field facilitates mammary tumorigenesis in the DMBA model of breast cancer.
  • Negishi T et al. (2008): Lack of promotion effects of 50 Hz magnetic fields on 7,12-dimethylbenz(a)anthracene-induced malignant lymphoma/lymphatic leukemia in mice.
  • Sommer AM et al. (2006): 50 Hz magnetic fields of 1 mT do not promote lymphoma development in AKR/J mice.
  • Otaka Y et al. (2002): Carcinogenicity test in B6C3F1 mice after parental and prenatal exposure to 50 Hz magnetic fields.
  • Mandeville R et al. (2000): Evaluation of the potential promoting effect of 60 Hz magnetic fields on N-ethyl-N-nitrosourea induced neurogenic tumors in female F344 rats.
  • Boorman GA et al. (1999): Chronic toxicity/oncogenicity evaluation of 60 Hz (power frequency) magnetic fields in F344/N rats.
  • McCormick DL et al. (1999): Chronic toxicity/oncogenicity evaluation of 60 Hz (power frequency) magnetic fields in B6C3F1 mice.