Moreover, the EMFinduced effects were relatively independent of the type of applied field- whether
electric or magnetic. For example, DC electric and magnetic fields each produced desychronization in
the EEG (2), and low-frequency electric and magnetic fields each altered human reaction time (41, 42).
Despite the observed nonspecificity of the biological effects with regard to the frequency or type of
applied field, other characteristics of the applied EMFs did have a significant effect on the biological
response. Pulse width and modulation frequency, for example, were important parameters in
bloodbrain barrier penetration, interresponse times, and the self-stimulation response. Sometimes,
pulsed EMFs produced biological effects at much lower average incident energy levels than was
obtained with continuouswave EMFs, and in some cases only the pulsed EMF elicited an effect.
Exposure duration also was an important factor in the elaboration of some effects. Thus, in general, the
bioeffects were relatively independent of frequency and field type, but other signal characteristics were
important in the development of the observed responses.
Dose:effect relationships were not manifested within or between studies. For example, in one
instance a ten-factor increase in the strength of the applied field did not produce a corresponding
increase in the brain enzyme level (24), and in a second case it produced a change opposite to that
found at the lower field strength (23). The general absence of dose:effect relationships suggests that the
EMFs had a trigger effect which was relatively independent of their magnitude. The field-induced
effects, moreover, were time-dependent phenomena and for this reason, from a dose:effect viewpoint, it
is not possible to compare the results of studies which used different exposure periods (36, 37).
The physical characteristics of the applied EMFs partially determined the biological effects.
Another important - perhaps, in some cases, principal - factor in the production of such effects was the
physiological state of the subject. About half the rabbits in Kholodov's study, for example, exhibited
the sustained delta pattern: in the remaining animals it did not appear or it appeared only briefly.
Bychkov found elevated and depressed EEG activity, or no effect at all, depending on the particular
animal. The behavioral studies involving reaction time and motor activity clearly suggest that the
subject's state of arousal was an important element in determining the direction, and perhaps the
existence, of a field-induced effect. In all such cases, some factor, or combination of factors, peculiar to
each animal was crucial in the elaboration of the effect. Sometimes - the zoonosis in the Friedman
study, for example - such an operative factor was apparent. More frequently, however, they were
simply uncontrolled variables (see chapter 8).
The overall pattern of the nervous system studies was one of detection and adaptation to the
applied EMFs; an electrically diverse range of fields produced similar kinds of electrical, metabolic,
and behavioral changes in the nervous system. At first glance it seems difficult to understand how
different stimuli could produce similar responses, but this was exactly the situation which led Hans
Selye, in 1936 (69), to propose his now established theory of biological stress (70): diverse stimuli -
heat, cold, trauma, crowding, and many others - elicit a common physiological adaptive response in the
organism. The response syndrome consists of measurable changes in the biochemistry, physiology, and
histopathology of the neuroendocrine system, and in the organs and functions that are responsive to it.
Any stimulus which elicits the syndrome is, by definition, a stressor.The idea that the electromagnetic
field is a stressor is developed further in the succeeding chapters.
References
1. Becker, R.O. 1963. Relationship of geomagnetic environment to human biology.
N. Y. State J. Med.
63:2215.
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