In epidemiological studies, it is impossible to isolate the possible effects of magnetic fields from those of electric fields. However the controlled conditions of the studies undertaken in the laboratory make it possible to analyse the isolated or compound effects from these two types of fields. The results of cellular and animal studies indicate that the most probable site affected by the action of electric and magnetic fields is the central nervous system.
Studies on volunteers focus on subjective parameters (field perceptions, subjective state evaluations), behavioural effects (reaction time performance, memory and attention tests), and neuro-physiological and psycho-physiological responses (analysis of heart rate and cerebral electrical activity while awake or asleep or during attention tasks). Other aspects are also investigated, such as circadian rhythms, neuro-hormonal, heamatological and immunological systems.
Advantages of human studies
= logical complement of epidemiological studies (e.g., EHS: provocation studies)
- May help in finding an explanation of observed morbidity and mortality data
- May help in a better insight in pathophysiological working mechanisms
- Agents such as antioxidants can be applied to identify potential protective measures against exposure of polluents or mixtures
Limitations of human studies
- Ethical considerations may limit their application (e.g., studies on potential carcinogens)
- Ethical considerations prevent investigations on certain target populations (e.g., children)
- These studies are limited to acute exposures and effects
- These investigations can only be performed on a limited number of subjects
- Usually also quite expensive
- Usually a specific laboratory infrastructure is necessary which is not readily available (only in specialised laboratories)