direction-as opposed to the existence-of the biological effect. On the other hand, certain spectral
characteristics-pulse modulation frequency seems to be one of the most important-can fundamentally
modify the biological response.
3. An organism's response to an EMF is determined in part by its physiological history and
genetic predisposition; individual animals, even in an apparently homogeneous population, may exhibit
changes in opposite directions in a dependent biological parameter.
4. Although high-field-strength and long-duration studies are exceptions, EMF-induced
biological effects seem best characterized as adaptive or compensatory; they present the organism with
an environmental factor to which it must accommodate.
If attention were restricted to EMF-related changes in individual body systems such as
intermediary metabolism, the immune-response system, or the adrenal gland, it might be hypothesized
that the action of the field involved certain enzymes, specific antibody regions of certain cells or
particular organs. But the studies clearly showed that EMFs produce a complex interrelated series of
physiological changes (see Figure 8.4). It follows that the consequences of EMF exposure must be
understood in terms of an integrative response of the entire organism. In our view, after the EMF is
detected, information concerning it is communicated to the central nervous system which then activates
the broad array of physiological mechanisms that are available to furnish a compensatory response
(Fig. 9.1). As is generally true of an adaptive response, the particular biological system that is invoked,
and the nature of its response, will depend on numerous factors including the animal's internal
conditioning and its external environment. With one notable exception, the biological processes that
follow detection of an EMF are the same as those associated with the response to any biological
stressor. Thus, for example, the cellular or molecular mechanisms that operate in the adrenal following
a cold stress to produce altered serum corticoid levels will also operate following an electromagnetic
stress, because adrenal activity is initiated by neuronal and hormonal signals, not by the actual presence
of the stressor agent in the tissue. Thus, advances in the understanding of EMF-induced systemic
effects are tied to general progress in physiology. Even so, electromagnetic stress has a characteristic
which sets it apart from other stressors: electromagnetic stress is not consciously perceived. This
suggests that sub-cortical brain centers are the first mediators of the electromagnetic stress response.
The physical processes that occur in this as-yet-unidentified center must, therefore, be different than
those associated with the mediation of other stressors -heat, cold, trauma, for example- all of which are
detected peripherally and are then consciously perceived.
Fig. 9.1. The basic control system that mediates EMF-induced biological effects. The field is detected
and transduced into a biological signal which is received in the CNS. The resulting hormonal and
electrical signals to the various body systems initiate the appropriate adaptive physiological
responses.
ELECTROMAGNETISM & LIFE - 124