Biological effects of technical electric and electromagnetic VLF fields.

Abstract

The biological effects of electric and electromagnetic fields have again and again been the subject of observations and investigations by natural and medical scientists (Barnothy, 1969; Presman, 1970; Reiter, 1960). Inthe past few years it was mainly biometeorology that dealt with the subject. The findings on natural fields, their changes and effects on living nature gave rise to numerous scientific research projects (Kouwenhoven et al. 1967; Skumza, 1970). Investigations have been conducted in the most different frequency ranges. Our interest is focussed on the frequency range below 100 Hz. According to the literature currently available biological effects on the human organism are to be expected in the following fields: motor activities, heart, brain currents, blood parameters, immunity phenomena, enzymatic activity, and ir~termediary metabolism. The frequency range below 100 Hz covers not only the natural fields but also the technical electric fields of 50 or 60 Hz and 16-2/3 Hz. This leads to the question which is increasingly being discussed nowadays whether and to what extent the health and lives of persons who are exposed to such electric fields in their professional and everyday life can be jeopardized. In order to gather scientifically reliable experience in this field the Institut f11r Hoehspannungs- und Anlage~teehnik of the Munich Technical University in cooperation with the Forsehungsstelle ftir Elektropathologie of Freiburg embarked on a research programme. In a completely isolated climatic chamber a high-voltage plant capable of producing in the man-occupied zone undisturbed electrical fields of up to and including 25 kV/m within the frequency range from 0 to 100 Hz, was erected (Fig.l) To obtain uniform test conditions, the temperature was mair~tained at 22°C and the relative humidity at 50%. The test subject did not notice the switching on and off of the transformer, because of music providing a background noise and an atmosphere of relaxation. The test subject was earthed and si~ting at a table. To begin with, 10 test persons were exposed to 50 Hz ae fields of 1 kV/m and 15 kV/m. In the morning the test period was divided into three periods of 45 mill each, a field-free period alternating with a field period. In the morning ECG, EEG, and pulse were measured at intervals of 5 min and blood pressure was measured every 15 rain. In the afternoon the reaction time was tested every 5 mill. For the measurement of the ECG and EEG, the field was switched off every 5 see. For comparison, the tests were conducted under the same conditions without field effects. Under the conditions specified above the tests showed no significant changes for electrocardiogra m, electroencephalo gram, pulse and blood pressure.