see ELF in wikipedia                                                     see ULF in wikipedia

ELF waves are electromagnetic radiation (radio waves) with frequencies from 3 to 300 Hz, ULF is the frequency range of electromagnetic waves between 300Hz and 3kHz. In magnetosphere science and seismology, alternative definitions are usually given, including ranges from from 3 Hz to 3 kHz  and from 1 mHz to 100 Hz, 1 mHz to 1 Hz, 10 mHz to 10 Hz correspondingly. ELF radio waves are naturally generated by lightning and natural disturbances in Earth's magnetic field, thus these phenomena are usually a research subject of atmosphere-focussed physics. Some monitoring stations have reported that a spike in ULF activity sometimes precedes earthquakes [1] [2]. There have been some concerns over the possible ecological impact of ELF signals. Since the late 1970s, questions have been raised whether exposure to ELF electric and magnetic fields (EMF) within this range of frequencies produces adverse health consequences [3]. In October 2005, WHO convened a Task Group of scientific experts to assess any risks to health that might exist from "exposure to ELF electric and magnetic fields in the frequency range >0 to 100,000 Hz (100 kHz) in regards to childhood leukaemia” [3]. There are established biological effects from acute exposure that are explained by recognized biophysical mechanisms. External ELF magnetic fields induce electric fields and currents in the body which, at very high field strengths, cause nerve and muscle stimulation and changes in nerve cell excitability in the central nervous system. Health effects related to short-term, high-level exposure have been established and form the basis of two international exposure limit guidelines (ICNIRP, 1998; IEEE, 2002). The International Agency for Research on Cancer (IARC) has evaluated the scientific data and has classified ELF magnetic fields as being "possibly carcinogenic" to humans. Epidemiological studies suggest a possible association between long term occupational exposure to ELF and Alzheimer's disease [4][5].

The impact of ELF and ULF also studied on animals and plants. In [6] the effect of 120Hz ELF on the healing process of skin in Wistar rats was studied. Some results have shown an improvement of the healing process in animals subjected to ELF. Research has been also devoted to weak sinusoidally varying magnetic fields, generated by high-voltage electric lines, which may introduce a substantial ecological hazard. For instance in [7] NMR analysis reveals alanine production in Duckweed plants exposed to such weak fields. An alternating magnetic field of 10 Hz was shown to have a statistically significant effect on plant growth, which was 20 % higher than control rates [8][9]. In [10] authors present experimental results regarding the cellular division rate and the percentage of chromosomal aberrations induced in the root meristem cells of maize, provided by germinated seeds in the presence of extremely low frequency magnetic field with frequency of 50 Hz and 10 mT magnetic induction. It was shown that the extremely low frequency field could represent the molecular basis of a putative tool in the biotechnology with the advantages of being less toxic and most easy to manipulate in comparison to ionizing radiation. In [11] a meiotic study was performed on Brassica napus exposed to electromagnetic fields. Cytological abnormalities observed are chromosome stickiness, laggards, and micronuclei formation which differed significantly among the genotypes indicating their genetic differences. Generally, there is large number of works devoted to stimulating or inhibiting effects of EM fields, e.g. [12][13].

Substantial research effort is invested in understanding how weak Earth magnetic field (about 50 μT) influence functioning of biological organisms at the cellular, tissue and organ levels. The data presented suggest that prolonged exposures of plants to weak magnetic field may cause different biological effects [14]. In a more general context, several researchers put attentions on influence of Earth geophysical fields on living organisms and appearance of diverse biophysical effects [15]. Issues of environmental geophysics in terms of a combination of ground and airborne radiometric data with related geochemical, geographic, hydrologic and radiation protection results for hazard and risk assessment studies are also studied [16].

References

[1] Fraser-Smith, Antony C.; Bernardi, A.; McGill, P. R.; Ladd, M. E.; Helliwell, R. A.; Villard, Jr., O. G. (August 1990). "Low-Frequency Magnetic Field Measurements Near the Epicenter of the M_s 7.1 Loma Prieta Earthquake" (PDF). Geophysical Research Letters (Washington, D.C.: American Geophysical Union) 17 (9): 1465–1468. 2010. (link to journal) (link to .pdf paper)

[2] KentuckyFC (December 9, 2010). "Spacecraft Saw ULF Radio Emissions over Haiti before January Quake". Physics arXiv Blog. Cambridge, Massachusetts: TechnologyReview.com. 2010. (link to .pdf paper)

[3] "Electromagnetic fields and public health". Fact Sheet No. 322, June 2007. World Health Organization, Accessed 7 Feb 2010. (link to the web site)

[4] García AM, Sisternas A, Hoyos SP (April 2008). "Occupational exposure to extremely low frequency electric and magnetic fields and Alzheimer disease: a meta-analysis". International Journal of Epidemiology 37 (2): 329–40. doi:10.1093/ije/dym295. PMID 18245151. (link to the journal) (link to the .pdf paper)

[5] Scientific Committee on Emerging and Newly Identified Health Risks-SCENIHR (January 2009). Health Effects of Exposure to EMF. Brussels: Directorate General for Health&Consumers; European Commission. pp. 4–5. Retrieved 2010-04-27 (link to the .pdf paper)

[6] M. S. Reyes Cadena, L. Sánchez Chapul, Javiér Pérez, M. N. Jiménez García, M. A. Jiménez López, M. E. Sánchez Espíndola, R. Paniagua Perez, N. A. Hernández, G. Paniagua, F. Uribe, J. J. Godina Nava, and M. A. Rodríguez Segura, Ultrastructural Study on Ultra‐Low Frequency Electromagnetic Fields and Transfer Factor Effects on Skin Ulcers, AIP Conf. Proc. 1032, pp. 195-202; doi:http://dx.doi.org/10.1063/1.2979267, 2008 (link to the journal)

[7] Edna Ben-Izhak Monselise, Abraham H Parola, Daniel Kost, Low-frequency electromagnetic fields induce a stress effect upon higher plants, as evident by the universal stress signal, alanine, Biochemical and Biophysical Research Communications, Volume 302, Issue 2, 7 March 2003, Pages 427-434, ISSN 0006-291X, 10.1016/S0006-291X(03)00194-3. (link to the journal)

[8] K. Namba, A. Sasao, S. Shibusawa. "Effect Of Magnetic Field On Germination And Plant Growth", Acta Hort. (ISHS) 399:143-148 (link to the journal)

[9] Yu. I. Novitsky , G. V. Novitskaya, T. K. Kocheshkova1, G. A. Nechiporenko and M. V. Dobrovol'skii, "Growth of Green Onions in a Weak Permanent Magnetic Field", Russian Journal of Plant Physiology. Issue: Volume 48, Number 6. November 2001 (link to journal)

[10] Mihaela RĂCUCIU,  50 Hz Frequency Magnetic Field Effects On Mitotic Activity In The Maize Root, Romanian J. Biophys., Vol. 21, No. 1, P. 53–62, Bucharest, 2011 (link to journal) (link to .pdf paper)

[11] Azita Shabrangi, Masoud Sheidai, Ahmad Majd, Mohammad NabIuni, Davoud Dorranian, Cytogenetic abnormalities caused by extremely low frequency electromagnetic fields in canola, ScienceAsia 36 (2010): 292–296 (link to .pdf paper)

[12] Mihaela Racuciu, Dorina-Emilia Creanga, Biological effects of low frequency electromagnetic field in Curcubita pepo, Proceedings of the Third Moscow International Symposium on Magnetism, p 278-282, 2005 (link to .pdf paper)

[13] Azita Shabrangi, Ahmad Majd, Masoud Sheidai, Mohammad Nabyouni, and Davoud Dorranian, Effects of Extremely Low Frequency Electromagnetic Fields on the Antioxidant Enzymes Activity of C3 and C4 Plants Progress In Electromagnetics Research Symposium Proceedings, Cambridge, USA, p 1083-1087,  2010 (link to .pdf paper)

[14] N.A. Belyavskaya, Biological effects due to weak magnetic field on plants, Advances in Space Research, Volume 34, Issue 7, 2004, Pages 1566-1574, ISSN 0273-1177, 10.1016/j.asr.2004.01.021. (link to journal)

[15] Gak E.Z.1, Gridin V.I., About Nature Influence Geophysics Earth`S Fields Anomalies On The Living Systems, The Sixteenth seminar of BDA, Druskininkai, Lithuania, p 88-91, 2008 (link to .pdf paper)

[16] Henk Coetzee and Peter Wade, Understanding environmental geophysical anomalies – an interdisciplinary case study from the West Rand, doi: 10.2113/​gssajg.109.4.495 South African Journal of Geology December 2006 v. 109 no. 4 p. 495-502 (link to journal)

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