Study type: Therapeutical study (experimental study)

Growth of injected melanoma cells is suppressed by whole body exposure to specific spatial-temporal configurations of weak intensity magnetic fields. med./bio.

Published in: Int J Radiat Biol 2010; 86 (2): 79-88

Aim of study (acc. to author)

To measure the effect of exposure to a specific spatial-temporal electromagnetic field presented using different geometric configurations on the growth of experimental tumors in mice.

Background/further details

A total of 65 male mice were used. The experiment was performed in two separate blocks separated by six months to control for potential effects of the endogenous geomagnetic field: Block 1 contained 32 mice and block 2 contained 33 mice. Beginning on the day of cancer cell injection, the mice were exposed to two control (sham exposure and cage control) and six different magnetic field configurations (six groups of four mice) between 21 h and midnight (3 h) every day for 38 days.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
cylindrical field
Exposure 2: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
Exposure 3: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
attenuated geomagnetic field
Exposure 4: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
low intensity field
Exposure 5: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
high intensity field
Exposure 6: 25 Hz
Modulation type: pulsed
Exposure duration: 3 hr/day on 38 days
rotating field

Exposure 1

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info cylindrical field
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997

Exposure setup
Exposure source
Setup two 25 cm x 1 cm solenoids created by 1050 turns of insulated wire wound around an iron nail; solenoids separated by 20 cm: mice placed in 20 cm x 30 cm x 20 cm plastic cages in the heterogenous field between the solenoids
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 5 µT - measured - at the central axis

Exposure 2

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info Helmholtz coils
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997

Exposure setup
Exposure source
Setup two Helmholtz coils 30 cm apart; each constructed by wrapping a 39 cm x 39 cm box with 305 m of 3 American Wire Gauge in a single layer, 18 cm wide ; mice placed in 20 cm x 30 cm x 20 cm plastic cages in the homogenous field between the coils
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 5 µT - measured - -

Exposure 3

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info attenuated geomagnetic field
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997

Exposure setup
Exposure source
Setup two opposing double Helmholtz coils created by wrapping two 112 cm x 125 cm plastic boxes with 72 turns of 30 AWG wire in a single layer, 13 cm wide; coils placed 2 cm apart; two stainless steel shelfs for shielding of the geomagnetic field
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 5 µT minimum measured - geomagnetic field
magnetic flux density 15 µT maximum measured - geomagnetic field

Exposure 4

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info low intensity field
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997

Exposure setup
Exposure source
  • same as E3
Setup adjacent housing area furthest from the activated coil used
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 nT minimum measured - -
magnetic flux density 5 nT maximum measured - -

Exposure 5

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info high intensity field
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997

Exposure setup
Exposure source
  • same as E3
Setup housing area nearest to the activated coil used
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 µT minimum measured - -
magnetic flux density 5 µT maximum measured - -

Exposure 6

Main characteristics
Frequency 25 Hz
Type
Exposure duration 3 hr/day on 38 days
Additional info rotating field
Modulation
Modulation type pulsed
Additional info

Thomas pattern, for further information see Thomas et al. 1997 field for 0.5 s in each opposing solenoid within the X-, Y-, Z-plane, then for 0.5 s in all planes simultaneously

Exposure setup
Exposure source
Setup three pairs of solenoids; each solenoid placed in the center of each face of a 30 cm x 30 cm x 30 cm cube;
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 2 µT minimum measured - -
magnetic flux density 5 µT maximum measured - -

Reference articles

  • Persinger MA et al. (2005): Sudden death in epileptic rats exposed to nocturnal magnetic fields that simulate the shape and the intensity of sudden changes in geomagnetic activity: an experiment in response to Schnabel, Beblo and May.
  • Martin LJ et al. (2004): Thermal analgesic effects from weak, complex magnetic fields and pharmacological interactions.
  • Martin LJ et al. (2003): Spatial heterogeneity not homogeneity of the magnetic field during exposures to complex frequency-modulated patterns facilitates analgesia.
  • McKay BE et al. (2000): Exposure to a theta-burst patterned magnetic field impairs memory acquisition and consolidation for contextual but not discrete conditioned fear in rats.
  • Persinger MA et al. (1999): Facilitation of seizures in limbic epileptic rats by complex 1 microTesla magnetic fields.
  • St-Pierre LS et al. (1998): Experimental induction of intermale aggressive behavior in limbic epileptic rats by weak, complex magnetic fields: implications for geomagnetic activity and the modern habitat?.
  • Thomas AW et al. (1997): Antinociceptive effects of a pulsed magnetic field in the land snail, Cepaea nemoralis.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

Mice exposed to the field that was rotated through the three spatial dimensions and through all three planes every two seconds (see field 6) did not grow tumors after 38 days. However, the animals in the sham exposed field and cage controls showed massive tumors after 38 days. Tumor growth was also affected by the intensity of the field, with mice exposed to a weak intensity field (1-5 nT, field 4) forming smaller tumors than animals exposed to sham exposure or high intensity (2-5 µT) fields. The mice exposed to the cylindrical field, Helmholtz field, attenuated geomagnetic field, high intensity field, or the sham exposure conditions formed large tumours that were not different from the non-handled cage controls.
Immunohistochemistry of tumors from those mice exposed to the different intensity fields suggested that alterations in leukocyte infiltration or vascularization could contribute to the differences in tumor growth.
The authors conclude that exposure to specific spatial-temporal regulated electromagnetic field configurations had potent effects on the growth of experimental tumors in mice. These effects were also dependent on the intensity and special complexity of the field pattern.

Study character:

Study funded by

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