Study type: Medical/biological study (experimental study, observational study)

Absence of chronic effect of exposure to short-wave radio broadcast signal on salivary melatonin concentrations in dairy cattle. med./bio.

Published in: J Pineal Res 1997; 22 (4): 171-176

Aim of study (acc. to author)

To study the influence of electromagnetic fields in the short-wave range (3-30 MHz) radio transmitter signals on salivary melatonin concentration in dairy cattle.

Background/further details

Two dairy herds at two farms were compared, one located at a distance of 500 m (exposed), the other at a distance of 4,000 m (unexposed) from the transmitter.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 3–30 MHz
Exposure duration: continuous for 2 days, then 3 days transmitter off, continuous for another 5 days

Exposure 1

Main characteristics
Frequency 3–30 MHz
Type
Exposure duration continuous for 2 days, then 3 days transmitter off, continuous for another 5 days
Exposure setup
Exposure source
Distance between exposed object and exposure source 500 m
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic field strength 1.59 mA/m - - - -

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

The mean values of the two initial nights did not show a statistically significant difference between exposed and unexposed animals. A chronic melatonin reduction effect seemed unlikely.
However, on the first night of re-exposure after the transmitter had been off for three days, the difference in salivary melatonin concentration between the two herds was statistically significant, indicating a two- to seven-fold increase of melatonin concentration.
Thus, a delayed acute effect of electromagnetic field on melatonin concentration cannot completely be excluded. However, findings should be interpreted with caution and further trials are required.

Study character:

Study funded by

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