EMFs and ELFs
PROBLEM: Too Many Gadgets
Many of the conveniences of modern life—everything from lamps to hairdryers—emit dangerous electromagnetic fields that interfere with the functions of cells in your body.
What are Electromagnetic Fields?
Electric fields are generated by an electric potential, and magnetic fields are created by a flow of electric current. Together they comprise what is commonly known as electromagnetic radiation, or an electromagnetic field (EMF).
Electric fields exist whenever an electrical charge is present, even if no current is flowing. For example, a lamp plugged into a wall circuit will have an electric field surrounding it even though the lamp may be turned off. The higher the voltage, the stronger the electric field of an appliance. The strength of an electric field diminishes rapidly as you move away from the source.
In contrast, a magnetic field is created only when an appliance is turned on and exists together with the electric field. The larger the current or amperage, the stronger the magnetic field. Like an electric field, magnetic field strength diminishes rapidly as you move away from the source; however, unlike an electric field, the only other way of diminishing the strength of a magnetic field is to enclose the appliance in a metal box that serves to redirect the magnetic field internally (such as those found in microwave ovens).
The home environment is subject to a variety of EMF sources, ranging from Extremely Low Frequency (ELF) sources to radiofrequency sources, depending on wiring configurations and the number of modern electronic devices employed. Learn more about Radiofrequency sources here.
The electromagnetic fields created by power lines and household appliances, such as toasters, lights, and electric heaters, are examples of ELF fields with frequencies up to 300 cycles per second or 300 Hertz (Hz). Other technologies, such as computer screens, security alarms, and anti-theft devices, create Intermediate Frequency (IF) fields ranging from 300 Hz to 10 million Hz (MHz). Depending on their strength and proximity, ELF and IF fields can induce currents in the human body that produce a range of biological effects.
Extremely Low Frequency Fields
Several studies have revealed an association between ELF exposure and childhood cancer.1 A 2005 review of the epidemiological evidence on EMF exposure reports a consistent pattern of increased risk for childhood leukemia associated with ELF fields.2 Cancer was first associated with exposure to electromagnetic fields in 1979 when investigators reported that children dying from cancer resided in homes believed to be exposed to higher ELF frequencies than those of healthy children.3 These findings have been corroborated in recent studies.4 Other research has implicated ELF exposure to a host of adverse effects, ranging from adult melanoma5 to neurodegenerative disease6,7 and miscarriage.8,9,10
Proximity to high voltage power lines, electrical wiring, and household appliances accounts for the background level of ELF fields found in the home environment. Studies show that homes not located near high voltage overhead lines generally have background EMFs below 0.2 micro Tesla (μT), well within presently established exposure limits for the general public. However, directly beneath high voltage power lines the field strength can be quite high. In 2001, researchers noted a doubling in the incidence of childhood leukemia for EMF fields greater than 0.4 μT.11 This finding was later corroborated when scientists found a 70% increase in childhood leukemia rates for those living within 200 meters of a high voltage overhead power line.12
1 David A. Savitz, “Health Effects of Electric and Magnetic Fields: Overview of Research Recommendations,” Environmental Health Perspectives Supplements 101, no. 4, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1519698/pdf/envhper00381-0064.pdf (accessed November 19, 2010).
2 M. Feychting, A. Ahlbom, L. Kheifets, “EMF and health,” Annu Rev Public Health 2005, no. 26, p. 165-89.
3 N. Wertheimer, E. Leeper, “Electrical wiring configurations and childhood cancer,” Am J Epidemiol 109, no. 3, p. 273-84.
4 G. Theriault, “Electromagnetic fields and cancer risks,” Rev Epidemiol Sante Publique 40, no. 1.
5 T. Tynes, L. Klaeboe, T. Haldorsen, “Residential and occupational exposure to 50 Hz magnetic fields and malignant melanoma: a population based study,” Occup Environ Med 60, no. 5, p. 343-7.
6 M. Feychting, F. Jonsson, N.L. Pedersen, A. Ahlbom, “Occupational magnetic field exposure and neurodegenerative disease,” Epidemiology 14, no. 4, p. 413-9.
7 N. Hakansson, P. Gustavsson, C. Johansen, B. Floderus, “Neurodegenerative diseases in welders and other workers exposed to high levels of magnetic fields,” Epidemiology 14, no. 4, p. 420-6.
8 G.M. Lee, R. R. Neutra, L. Hristova, M. Yost, R.A. Hiatt, “A nested case-control study of residential and personal magnetic field measures and miscarriages,” Epidemiology 13, no. 1, p. 21-31.
9 D.K. Li, R. R. Neutra “Magnetic fields and miscarriage,” Epidemiology 13, no. 2, p. 237-8.
10 Y.N. Cao, Y. Zhang, Y. Liu, “[Effects of exposure to extremely low frequency electromagnetic fields on reproduction of female mice and development of offsprings],” Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi 24, no. 8, p. 468-70.
11 International Commission for Non-Ionizing Radiation Protection, “Review of the Epidemiologic Literature on EMF and Health,” Environmental Health Perspectives 109, no. 6, http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240626/pdf/ehp109s-000911.pdf (accessed November 19, 2010).
12 Gerald Draper, Tim Vincent, Mary E Kroll, John Swanson, “Childhood cancer in relation to distance from high voltage power lines in England and Wales: a case-control study,” BMJ 330, http://www.bmj.com/content/330/7503/1290.full.pdf+html (accessed November 19, 2010).
13 WHO Regional Office for Europe, “What are electromagnetic fields?” World Health Organization, http://www.who.int/peh-emf/about/WhatisEMF/en/ (accessed November 19, 2010).