The effects of exposure of calves to a 50 Hz magnetic field in two different seasons (summer and winter) on the salivary melatonin levels should be investigated.
Two sessions were conducted: one session in the summer and the other one in the winter. For each session, 8 calves were divided into an exposure group and a control group (n=4 each) with equal numbers of male and females in each group (remark EMF-Portal: it is not clear how many animals of each breed were used and how the control groups were treated). Different animals were used for each session.
During each session, samples were taken on days 0, 10, 20, 30 and 35. Every sampling day involved four samples from each calf, collected at 12.00 noon, 10.30 p.m., 02.00 a.m. and 04.30 a.m..
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Exposure duration:
continuous (?) for 35 days
summer exposure
|
|
|
Exposure 2:
50 Hz
Exposure duration:
continuous (?) for 35 days
winter exposure
|
|
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous (?) for 35 days |
| Additional info | summer exposure |
| Exposure source |
|
|---|---|
| Chamber | wooden boxes (closed to 3 sides, access to an open enclosure through the fourth) in a stable |
| Setup | the wooden boxes (one calve per box) were oriented with the longer axis along 17°/197° and this was also the main direction of the oscillation of the artificial magnetic field; the coils consisted of 6 turns of coaxial cable (shielded to prevent the generation of electrical fields) wrapped around a box (remark EMF-Portal: it is not clear if animals had free access to the open enclosure in front of their boxes); the average ambient temperature (in the enclosure outside the boxes) was 26.2°C during the summer session |
| Additional info | at 12.00 h, about 85 lx were measured in the enclosure and up to 20 lx were measured inside the boxes; at night, the light intensity was always below the detection threshold |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 0.39 µT | minimum | measured | - | measurement on sampling days only; location of measurement not stated |
| magnetic flux density | 0.41 µT | maximum | measured | - | measurement on sampling days only; location of measurement not stated |
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | continuous (?) for 35 days |
| Additional info | winter exposure |
| Exposure source |
|
|---|---|
| Setup | the average ambient temperature (in the enclosure outside the boxes) was 2.7°C during the winter |
| Additional info | light intensity in winter during the day (12.00 h) was around 30 lx in the open enclosure in front of the boxes and 0 lx inside the boxes; at night, the light intensity was always below the detection threshold |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 0.39 µT | minimum | measured | - | measurement on sampling days only; location of measurement not stated |
| magnetic flux density | 0.41 µT | maximum | measured | - | measurement on sampling days only; location of measurement not stated |
The average melatonin level in the exposure group was significantly higher in the summer and significantly lower in winter compared to the respective control group. Moreover, females showed significantly higher melatonin levels than males in both seasons and in both groups.
The authors conclude that exposure of calves to a 50 Hz magnetic field might influence the melatonin level as a function of the season. They recommend to consider seasonal factors (photoperiod and temperature) in future studies.
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