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.
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.
| 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
|
|
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | cylindrical field |
| Modulation type | pulsed |
|---|---|
| Additional info |
Thomas pattern, for further information see Thomas et al. 1997 |
| 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 5 µT | - | measured | - | at the central axis |
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | Helmholtz coils |
| Modulation type | pulsed |
|---|---|
| Additional info |
Thomas pattern, for further information see Thomas et al. 1997 |
| 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 5 µT | - | measured | - | - |
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | attenuated geomagnetic field |
| Modulation type | pulsed |
|---|---|
| Additional info |
Thomas pattern, for further information see Thomas et al. 1997 |
| 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 5 µT | minimum | measured | - | geomagnetic field |
| magnetic flux density | 15 µT | maximum | measured | - | geomagnetic field |
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | low intensity field |
| Modulation type | pulsed |
|---|---|
| Additional info |
Thomas pattern, for further information see Thomas et al. 1997 |
| Exposure source |
|
|---|---|
| Setup | adjacent housing area furthest from the activated coil used |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 1 nT | minimum | measured | - | - |
| magnetic flux density | 5 nT | maximum | measured | - | - |
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | high intensity field |
| Modulation type | pulsed |
|---|---|
| Additional info |
Thomas pattern, for further information see Thomas et al. 1997 |
| Exposure source |
|
|---|---|
| Setup | housing area nearest to the activated coil used |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 2 µT | minimum | measured | - | - |
| magnetic flux density | 5 µT | maximum | measured | - | - |
| Frequency | 25 Hz |
|---|---|
| Type | |
| Exposure duration | 3 hr/day on 38 days |
| Additional info | rotating field |
| 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 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. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 2 µT | minimum | measured | - | - |
| magnetic flux density | 5 µT | maximum | measured | - | - |
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.
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