Health – Blood-Brain-Barrier
The Blood-Brain-Barrier is an organic barrier between circulating blood and the central nervous system. It regulates, in part actively and in part passively, the exchange of substances between blood and the brain. At the same time it acts as a protective shield by preventing the penetration of harmful substances into the brain fluid. Few pathogens can overcome the blood-brain-barrier. The filter is primarily made up of (see illustration) so-called endothelial cells which surround the blood capillaries and from the ends of astrocytes which have, among others, important structural and metabolic functions
Disorders of the blood-brain-barrier, i.e. changes to its permeability, can lead to pathogens and toxic substances penetrating into the brain more easily, causing cerebral edema (swelling of the tissues by a collection of fluid) which depending on the size can increase cerebral pressure resulting in circulatory disorders. In medicine one uses the knowledge about the development of barrier disorders to ease the transport of medication from the blood into the brain. Appropriate medication can be tailor-made in order that they can overcome the blood-brain-barrier.
The influence of electromagnetic radiation on the function of the blood-brain-barrier has been investigated since the 1970s. In addition tests on animals (so-called in vivo studies) as well as laboratory experiments with cell cultures (so-called in vitro studies) have been carried out. Amongst other things, it could be shown that very strong EMFs (field strength above the applicable limit values) make the blood-brain-barrier more permeable as a result of the thermic effects (warming of the brain tissue) and that they could be problematic from a health perspective. It was also investigated whether weak fields lead to health-relevant blood-brain-barrier disorders. Until now this could not be scientifically proven.
Scientific investigations made until now show no indication of a health-relevant disorder of the blood-brain-barrier attributable to the influence of EMFs permissible within the limit values. Individual studies that came to different results, have in part considerable methodoloigcal deficiencies and/or the results could not be confirmed in confirmatory investigations.
BioInitiative Working Group (2012). Health effects from radiofrequency electromagnetic fields. BioInitiative Report, www.bioinitiative.org. Section 10.
Hossmann, K.-A., Hermann, D.M. (2003). Effects of electromagnetic radiation of mobile phones on the central nervous system. Bioelectromagnetics, 24, 49-62.
Hossmann, K.-A., Stögbauer, F. (2005). Gutachten zur Blut-Hirn-Schranke. In: P.M. Wiedemann, H. Schütz. A. Spangenberg (Hrsg.). Risikobewertung Mobilfunk. Ergebnisse eines wissenschaftlichen Dialogs. Schriften des Forschungszentrum Jülich. Band 54, H1-H15. Jülich: Forschungszentrum Jülich.
Independent Advisory Group on Non-Ionising Radiation (AGNIR) (2012). Health effects from radiofrequency electromagnetic fields. U.K. Health Protection Agency, Oxfordshire. Chapter 4.1.4, 130-133.
International Commission on Non-Ionizing Radiation Protection ICNIRP (2009). Exposure to high frequency electromagnetic fields, bilogical effects and health consequences (100 kHz-300 GHz). Chapter II.4.4.2, 182-186.
Perrin, A., Cretallaz. C., Collin, A., Amourette, C., Yardin, C. (2010). Effects of radiofrequency field on the blood-brain barrier: A systematic review from 2005 to 2009. C. R. Physique, 11, 602-612.
SCENIHR (Scientific Committee on Emerging and Newly Identified Health Risks) (2015). Opinion on Potential Health Effects of Exposure to Electromagnetic Fields (EMF). European Commission, Brussels. Section 188.8.131.52.
Stam, R. (2010). Electromagnetic fields and the blood-brain barrier. Brain Research Reviews, 65, 80-97.
Stögbauer, F. (2003). Beeinflussung der Blut-Hirn-Schranke durch elektromagnetische Felder. Forschungsgemeinschaft Funk e.V. Edition Wissenschaft, 15, 3-15.