ELF EMF and oxydative stress: an hypothesis (1995-2005)
V.Seutin & A. Boland
Some epidemiological studies reported an association between ELF EMF (1-100 Hz) exposure and neuro-degenerative disorders. In addition, free radical-induced oxidative aggression participates in tissue damage associated with such neuro-degenerative diseases. Once produced in excess, the free radicals can alter many cell constituents and lead to cell death. Our laboratory has performed experiments in order to determine whether ELF EMF might have some effect on cultured brain cells when coupled with free radical-induced cell aggression (oxydative stress).
We have shown (A. Boland, Bioelectromagnetics, 2002, 23:97-105) that, when cultured cerebral cells are exposed to high-intensity (2.5 - 5 mT) intermittent EMF (IEMF) in addition to oxidative stress induced by nitric oxide (NO), a significant increase of cell death, ranging from 11 % to 23 %, occurs. The cause of this augmentation is yet to be identified.
When NO is produced, it can react with another free radical: the superoxide anion (O 2- °), to yield the formation of peroxynitrite (ONOO - ), another oxidative compound able to kill cells. Therefore, in order to know whether EMF is able to modulate peroxynitrite-induced cytotoxicity, we incubated cultured hippocampal cells in the presence of SIN-1, a ONOO - donor, in combination with 50 Hz uninterrupted (UEMF) or IEMFs (0 - 5 mT).
From our data, it appears that, when used alone, EMF are not deleterious to neurons. However, in specific experimental conditions (high intensity interrupted EMF in combination with an oxidative stress), cell mortality may increase. Toxicity can vary according to the type and the intensity of EMF used. It is impossible however, from the data obtained so far on cultured nerve cells, to conclude a potential toxicity of EMFs on human beings and further experiments need to be performed to understand the mechanism of action of ELF EMFs and to determine their effects in vivo.
V.Seutin & A. Boland
Our previous works has shown a twofold increase of a general marker of stress in cells (c-fos) when an intermittent EMF ("1 min. ON + 1 min. OFF, 10 times) was used. Because this marker can induce many responses in cells when activated, we decided both to determine the effect of an intermittent EMF ("1 min. ON + 1 min. OFF, 10 times every 2 hours, 6 times a day during 48 hours) on cultured cerebral cells, and to assess the effect of the same EMF when combined with oxidative stress induced by the free radical nitric oxide (NO).
Results have shown that:
1.The exposure of cultured cerebral cells to different intensities (0 to 5 mT) of intermittent EMF does not produce any modification of cell mortality. Therefore, it seems that, by themselves, such EMF are not deleterious to cultured brain cells.
2. The results obtained when cultured cerebral cells are exposed to intermittent EMF (0 to 5 mT), in addition to oxidative stress induced by NO, have shown that the lowest EMF intensity (0. - 0.45 mT) does not induce any difference in cell mortality. However, for higher intensities (2.5 - 5 mT), we observe a significant increase of cell death ranging from 11 % to 23 %. The cause of this augmentation is yet to be identified.
It seems, therefore, that in our experimental conditions, ELF EMF are not deleterious for cells in vitro unless a stress is already present. It is impossible, however, from the results obtained on cultured nerve cells, to extrapolate on the toxicity of EMF on human beings. Further experiments need to be performed to understand the mechanism of action of ELF EMF and to determine their effects in vivo.
Boland, A., Delapierre, D., Mossay, D., Dresse, A. and Seutin, V. (2002). Effect of intermittent and continuous exposure to electromagnetic fields on cultured hippocampal cells. Bioelectromagnetics 23 , 97-105.