To investigate the effects of a magnetic field (MF) exposure on mammary tumor growth, melatonin levels, and proliferation capacity of spleenic T lymphocytes in rats.
Mammary tumors were induced by the use of the chemical carcinogen DMBA. The first DMBA application (5mg/rat) at the onset of exposure was followed by three more applications at weekly intervals up to a total of 20 mg DMBA/rat.
A total of 216 animals were used in this study, divided into four groups. Group A) 99 animals, DMBA treated, MF exposed. Group B) 99 animals DMBA treated, sham-exposed. Group C) 9 animals, non DMBA treated, MF exposed. Group D) 9 animals, non DMBA treated, sham-exposed.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Modulation type:
CW
Exposure duration:
continuous, 24 h/day, 7days/week, for 91 days
|
|
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous, 24 h/day, 7days/week, for 91 days |
| Modulation type | CW |
|---|
| Exposure source |
|
|---|---|
| Chamber | exposure chambers, 4 cages 39x55x22cm, 9-10 animals/cage |
| Setup | cages inside the coils |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 50 µT | - | measured | - | - |
8 weeks after DMBA application, significantly more tumors were found in the MF-exposed group than in sham-exposed animals. At time of autopsy, significantly more MF-exposed DMBA-treated animals exhibited macroscopically visible mammary tumors than DMBA-treated controls.
Proliferation of spleenic T lymphocytes was determined at the end of exposure time and revealed a significant suppression in MF exposed non DMBA treated animals compared with MF sham-exposed non DMBA treated rats.
No signifficant difference was seen in nocturnal melatonin levels of DMBA-treated MF exposed and sham-exposed animals. (determination after 9 and 12 weeks after onset of exposure.)
Other findings: No behavioural differences were observed between exposed and sham-exposed animals. Furthermore, no significant differences were found for body weight, spleen, and liver weight were among the four groups.
The results of this study indicates that long-term 50 µT MF exposure of DMBA-treated female rats significantly enhances mammary tumor development and growth.
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