5. How may static fields affect cells or animals?
- 5.1 What have studies on cells revealed about the effect of static magnetic fields?
- 5.2 How can laboratory animals be affected by static electric or magnetic fields?
5.1 What have studies on cells revealed about the effect of static magnetic fields?
Studies on cells or cellular components are useful for understanding interaction mechanisms of static magnetic fields. They are not sufficient to identify health effects, but can give an indication of the sorts of effects that might be investigated in animals and humans. Static electric fields generate a surface electric charge and are not appropriately studied in vitro.
A number of different biological effects of static magnetic fields have been explored, by studying cells or their components and processes. These include changes in cellular processes, gene expression, cell growth and genetic material. The findings have been contradictory. Several effects have been observed at field strengths lower than 1000 mT, but most results were not replicated by other researchers. Overall, the experiments on cells conducted so far do not present a clear picture of specific effects of static magnetic fields and do not indicate possible adverse health effects. More...
5.2 How can laboratory animals be affected by static electric or magnetic fields?
5.2.1 Few studies have been carried out on the effects of static electric fields on animals. The only effects observed in these were linked to the perception of the surface electric charge because of its interaction with body hair and other effects such as spark discharges. No evidence of adverse health effects has been reported.
In contrast, a large number of studies have been carried out in order to investigate possible effects of static magnetic fields on animals. The studies which are the most relevant for human health are those that have examined the acute effects of field strengths considerably higher than that of the natural geomagnetic field, and equivalent to those used in industrial processes (in the mT range) or in magnetic resonance imaging (exceeding 1000 mT).
Few studies, however, have examined possible chronic effects of exposure, particularly in relation to cancer. More...
5.2.2 Studies focussing on the nervous system consistently indicate that laboratory rodents feel discomfort when moving in static magnetic fields of 4000 mT or more and thus try to avoid them. This is thought to be linked to effects of magnetic fields on the system in the inner ear which controls balance and body orientation.
Certain animal species appear to be able to use the Earth’s magnetic fields for orientation. Such effects are not present in humans, and therefore this has no implications on human health. More...
5.2.3 There is good evidence that exposure to static magnetic fields can induce electric charges around the heart and major blood vessels. This has been observed in smaller animals when fields exceed about 1000 mT (and in larger animals 100 mT), but possible health consequences are unclear. In pigs, several hours of exposure to very high fields (up to 8000 mT) did not result in any such effects. However, in rabbits, short– and long–term exposures to much lower fields have been reported to have a slight influence on the heart rhythm and the circulation of the blood, although the evidence for this is not strong.
It is difficult to reach any firm conclusions until more of these results have been replicated by other researchers. More...
5.2.4 Few studies have looked at the possible effect of static magnetic fields on blood cells, on the endocrine system, or on reproduction and development. Most of the results are not consistent and have not been replicated, so further studies are needed in order to assess the health risk. More...
In general, so few animal studies have been carried out with regard to harmful effects on genetic material and cancer that it is not possible to draw any firm conclusions from them.