9. What is known about environmental effects of electromagnetic fields?
- 9.1 What species might be sensitive to electromagnetic fields?
- 9.2 What possible environmental effects have been studied?
- 9.3 Conclusion on Environmental effects?
9.1 What species might be sensitive to electromagnetic fields?
Migratory birds rely on magnetic fields for orientation
Credit: Michael Hatherly
- Animals, such as migratory birds, bats, and certain fish and insects, that are strongly dependent on magnetic fields for orientation or migration.
- Animals, such as sharks and rays, that possess electric sense organs.
- Animals with weak defence mechanisms. For instance, those with a limited ability to regulate their body temperature may be more vulnerable to the effects of high frequency EMF
Apart from some minor local effects no significant effects of EMF on environmental species have been identified.
Studies occasionally published on the effects of EMF on species in the environment have generally been scattered in focus and uneven in quality. The available data is thus insufficient to assess the risk of EMF for the environment. More...
9.2 What possible environmental effects have been studied?
The few recent studies on environmental effects of electromagnetic fields (EMF) have mostly focused on extremely low frequency (ELF) fields, such as those generated by overhead power cables. They mostly considered plants and not species that would be expected to be among the most sensitive to EMF.
Previously, studies mainly focused on the presence or absence of visible symptoms (endpoints), for instance a decrease in pollen fertility. Such results are relatively easy to interpret but may not reveal more subtle effects at low levels of exposure.
These have measured, for instance:
- the amount of antioxidants in the blood;
- substances that indicate stress such as alanine (in plants) and heat shock proteins (in animals);
- changes in the growth of certain plant cells;
- DNA changes.
Such tests seemed to detect changes at low field strengths which are much closer to those generally found in the environment. However, their interpretation in terms of species and ecosystem health is more challenging. Unfortunately these techniques have not particularly targeted species that would be expected to be among the most sensitive to EMF.
In duck weed, exposed in the laboratory to low intensity magnetic fields that vary in time at extremely low frequency (ELF), an accumulation of alanine occurred. Alanine accumulation is found as a stress signal following many other kinds of stress and might be explained by the generation of free radicals by the magnetic field.
Effects of low frequency electromagnetic fields on snails were observed both in the laboratory and under overhead power cables.
The authors attribute the effects to the generation of free radicals by the low frequency electromagnetic fields. The authors also observed effects on cell components and on DNA. However, no physical damage to the snails was reported.
Several studies on plants have examined the combined impact of EMF and other environmental conditions, for instance the impact of exposure to EMF from a GSM telephone combined with calcium deprivation on flax seedling growth, or the impact of EMF combined with UV-B radiation on cucumber seedling growth. These studies raise the question whether the impact of EMF may add itself to the effects of other environmental factors and what practical consequences this might have for individual plants and ecosystems.
The data presently available are inadequate to assess this. More...
9.3 Conclusion on Environmental effects?
There continues to be a lack of good quality data for species that would be expected to be among the most sensitive to electromagnetic fields (EMF). This is why it is not possible to determine whether a single exposure standard is appropriate to protect all environmental species from EMF.
Similarly the data are totally inadequate to judge whether the environmental standard(s) should be the same or significantly different from those appropriate to protect human health.
Whether the impact of EMF may be additive with some other environmental stressors, at least in plants, needs further examination.
At present it is not possible to draw any conclusions regarding human health from this data base. Nonetheless, long-term monitoring of carefully selected species and/or ecosystems may be valuable to asses the potential effect of EMF on human health. More...