High voltage DC is used to transmit electrical energy over long distances, including under the sea, and to interconnect different frequency networks. Moreover, in Belgium for example, trains, excluding high speed train, also operate in DC.
Let us see how static electric and magnetic fields can ineract with the human body.
The particularity of static EF is to exert forces on charged particles (positive or negative electric charges).
Static EF does not enter our body; it induces movements of electric charges at the body surface. These movements will be perceived for example at the level of hair. They are also involved in electrostatic discharges.
At high intensity, we can feel static EF in hair.
(Source: Maison de la Science, Université de Liège)
Static MF exerts forces on metals (cf. magnet) and on moving electric charges.
By interacting with metals, high magnetic fields can interfere with implanted medical devices, such as pacemakers, comprising a metallic material. Furthermore, hemoglobin, a protein present in our red blood cells useful in the transport of oxygen in the body, contains iron, as well as ferritin, another protein that stores iron in the body (ferritin screening is used to follow iron deficiency or overdose). These proteins may be sensitive to static magnetic fields, but their very small size makes unlikely the possibility of an effect. Similarly, magnetite (iron oxide Fe3O4) has been assayed in some animals. It is involved in the migratory behaviour of several of them. Its presence in humans is not confirmed to date (see insert below).
Magnetic sensitivity
Our body has always been submitted to Earth’s geomagnetic field. Are we sensitive?
Ability to detect geomagnetic field is one of the elements that explain the migration of certain animals (birds, fishes …). This magneto-reception is due on one hand to the presence of magnetite crystals and on the other hand to proteins called cryptochrome, present in the retina for example.
Magnetite crystals have been detected in many animals, migrants or residents, but their presence is not confirmed in humans. They react like a compass needle and can follow the direction of the geomagnetic field.
Many experiments have shown that magnetite was not the only one involved in the migratory behaviour. In fact, the retina contains a protein (cryptochrome) susceptible to light and which is in some animals a magneto receiver. This protein is also present in humans. It is involved in the regulation of biorhythms and would not or no longer have a function related to geomagnetic field.
Some animals are sensitive to geomagnetic field without being migratory. Magnetic sense might therefore also contribute more generally to spatial recognition (J Vanderstraeten, 2013).
Let us look at the second characteristic of static MF, ie their action on moving electric charges. Two situations have been well studied:
These effects only occur in the presence of particularly high static MF, above a few teslas, and they are temporary, ie they disappear with increasing distance from the source.
Relatively few studies have been conducted on exposure to static fields. They generally conclude to the absence of health effects.
The only effects retained are perceptions of hair movements and electrostatic discharges in the presence of high fields. These effects are associated with acute exposure. To date, no study has been conducted on the long-term effects of static EF.
Researchers studied many potential health effects, such as effects on fertility, growth and development, on cancer, on cardiovascular systems, on cognitive functions … (Health Protection Agency 2008). They worked on cells and animals and also conducted experimental or epidemiological studies in humans.
Apart from temporary effects such as dizziness or nausea, transient decreases in performance… reported by people moving in high static MF, studies do not put in advance any effects on health. These temporary effects are pursued because they can cause anxiety in people who are the victims.
There is no evidence of long term effects such as cancer.
Further studies are needed to determine the effects of high static MF and long-term exposure.
Current guidelines do not recommend limiting static EF levels.
The following limits are recommended by ICNIRP (2009):
For implanted electronic medical devices, the limit is set to 0.5 mT.
The 2013/35/EU European Directive for the protection of workers advocates the same values as ICNIRP. Moreover, in occupational environments, exposure up to 8 T is tolerated for the entire body, if the environment is controlled and work practices are adapted to reduce the speed of execution and movements in such fields.
Contessa GM, Falsaperla R, Brugaletta V, Rossi P. Exposure to magnetic fields of railway engine drivers: a case study in Italy. Radiat Prot Dosimetry. 2010 Dec;142(2-4):160-7. doi: 10.1093/rpd/ncq270. Epub 2010 Nov 11.
https://pubmed.ncbi.nlm.nih.gov/21071462/
Health Protection Agency (2008). Static magnetic fields, Report of the independant Advisory Group on Non-ionising Radiation. Documents of the Health Protection Agency – Radiation, Chemical and Environmental Hazards.
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/335120/RCE-6_for_Web_16-05-08.pdf
Directive 2013/35/UE du parlement européen et du conseil du 26 juin 2013
http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2013:179:0001:0021:FR:PDF
International Commission On Non‐Ionizing Radiation Protection. ICNIRP guidelines on limits of exposure to static magnetic fields. Health Physics 96(4):504‐514; 2009.
http://www.icnirp.org/cms/upload/publications/ICNIRPstatgdl.pdf
Leitgeb N. Limiting electric fields of HVDC overhead power lines. Radiat Environ Biophys. 2014 May;53(2):461-8. doi: 10.1007/s00411-014-0520-2. Epub 2014 Feb 27.
Perrin A, Souques M (2010). Champs électromagnétiques, environnement et santé. Paris, France : Springer Paris.
http://books.google.be/books/about/Champs_%C3%A9lectromagn%C3%A9tiques_environnemen.html?id=VuhxH24C2GEC&redir_esc=y
Ptitsyna NG1, Kopytenko YA, Villoresi G, Pfluger DH, Ismaguilov V, Iucci N, Kopytenko EA, Zaitzev DB, Voronov PM, Tyasto MI. Waveform magnetic field survey in Russian DC and Swiss AC powered trains: a basis for biologically relevant exposure assessment. Bioelectromagnetics. 2003 Dec;24(8):546-56.
Vanderstraeten J. (2013). Analyse de l’hypothèse de la perturbation des biorythmes par les champs magnétiques d’extrêmement basse fréquence Mécanismes possibles, impact en santé publique, protocoles de mise à l’épreuve. Thèse présentée en vue de l’obtention du titre de Docteur en Sciences de la Santé Publique
https://difusion.ulb.ac.be/vufind/Record/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209445/Holdings
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