Edition No. 17/E August 2002
EFFECTS OF HIGH- AND LOW-FREQUENCY ELECTROMAGNETIC FIELDS ON EMBRYONIC DEVELOPMENT
AN INVENTORY OF TERATOLOGIC STUDIES
Dr. Hans-Peter Thalau
Institute of Zoology, University of Frankfurt / Germany
Owing to the increasing use of low and high frequency electromagnetic fields (EMF), a considerable number of studies have been done to investigate the effects of EMF-exposure on embryonic development in a number of species. Teratology is a subdivision of embryology and deals with the incidence of malformations during embryogenesis. Congenital malformations (present at birth) have their origins in genetic defects and/or in external environmental factors (e.g. chemical agents, pathogens, X-rays).
In this report almost 200 articles are presented, each with a short summary of the exposure conditions, the organisms which were investigated, the parameters and the results. The articles also include laboratory work (in vitro & in vivo), reviews and epidemiological studies. In several chapters investigations on mammals, birds, non-mammalian vertebrates and invertebrates exposed to electric and magnetic fields, microwaves, fields emitted by magnetic resonance imaging (MRI) and video display terminals were described, evaluated and (in part) discussed. In addition to the teratological articles, a short survey on a number of selected toxicological and genetical investigations is included in this report.
Investigations on the effects of low frequency electric and magnetic fields (including MRI and emissions from video display terminals) revealed inhomogeneous and often contradictory results, this was even the case in related studies with the same or a similar design. Most studies which reported significant detrimental effects on embryogenesis were carried out on chicken embryos. However, in the majority of these studies only the early stages of embryonic development were investigated. Thus, in these cases no unequivocal conclusions could be drawn concerning the effects of EMF exposure on the entire embryonic development of chickens (birds). With regard to the studies investigating small mammals (e.g. rats, mice), in most cases, no detrimental effects of exposure could be observed. In the few studies where low frequency EMF was used to determine what embryolethal and/or teratogenic effects occurred, it was impossible to reproduce and confirm the results.
With regard to microwave exposure, most of the teratogenic and embryolethal effects observed were caused by hyperthermia; whereas athermal effects, if observed and unequivocal, were mostly restricted to special races, strains or populations. Investigations with 1.8 GHz fields (E-net) are missing completely.
Due to ethical reasons no "in vivo" experiments on humans were carried out. Thus, only epidemiological investigations (very few with microwave exposure) supply some, but often questionable, data.
The evaluation of the data reported on so far has proven that the teratogenic
and embryolethal effects of athermal EMF-exposure are considerably weak
and the extent of their occurrence depends on the genetic disposition
of the exposed organisms and also on the environmental parameters during
exposure (e.g. interaction of EMF with chemical agents, drugs, medication).
Some important questions (e.g. the interaction between EMF exposure and
drugs, medication or chemical agents) remain to a large extent unanswered.
Therefore, we can conclude that further investigations are indispensable
in the near future.