Electric and magnetic fields (EMFs) are invisible areas of energy, often referred to as radiation , that are associated with the use of electrical power and various forms of natural and man-made lighting. EMFs are typically characterized by wavelength or frequency into one of two radioactive categories:
|Radiation Type||Definition||Forms of Radiation||Source Examples|
|Non-Ionizing||Low to mid-frequency radiation which is generally perceived as harmless due to its lack of potency.||
|Ionizing||Mid to high-frequency radiation which can, under certain circumstances, lead to cellular and or DNA damage with prolonged exposure.||
During the 1990s, most EMF research focused on extremely low frequency exposures stemming from conventional
power sources, such as power lines, electrical substations, or home appliances. While some of these studies showed a possible link between EMF field strength and an increased risk for childhood leukemia , their findings indicated that such an association was weak. Now, in the age of cellular telephones, wireless routers, and portable GPS devices (all known sources of EMF radiation), concerns regarding a possible connection between EMFs and adverse health effects still persists, though current research1 continues to point to the same weak association.
Additionally, the few studies that have been conducted on adults show no evidence of a link between EMF exposure and adult cancers, such as leukemia, brain cancer, and breast cancer. Nevertheless, NIEHS recommends continued education on practical ways of reducing exposures to EMFs.
Measured in units called hertz, cell phone emissions, a form of radiofrequency radiation, exist at the lower end of the non-ionizing radiation spectrum at the 900-1900 megahertz range. At present, the weight of the current scientific evidence has not conclusively linked cell phone use with any adverse health problems, though scientists admit that more research is needed. To that end, the National Toxicology Program (NTP), headquartered at NIEHS, is leading the largest laboratory rodent study, to date, on cell phone radiofrequency exposure, the complete findings are expected to be released by the end of 2017. Partial findings from the completed rat studies were released in 2016.
To learn more about these NTP partial findings and the cell phone radiofrequency rodent studies, visit the NIEHS Environmental Health Topics page on cell phones.
It is important to remember that the strength of a magnetic field decreases dramatically with increasing distance from the source. This means that the strength of the field reaching a house or structure will be significantly weaker than it was at its point of origin, as you can see below. For more information, see the NIEHS educational booklet, “EMF: Electric and Magnetic Fields Associated with the Use of Electric Power.”. This booklet, prepared in 2002, contains the most recent NIEHS research on health and powerline electric and magnetic fields. The World Health Organization website has information prepared in 2010. For example, a magnetic field measuring 57.5 milligauss immediately beside a 230 kilovolt transmission line measures just 7.1 milligauss at a distance of 100 feet, and 1.8 milligauss at a distance of 200 feet.
If you are concerned about EMFs emitted by a power line or substation in your area, you can contact your local power company to schedule an on-site reading. You can also measure EMFs yourself with the use of a gaussmeter, which is available for purchase online through a number of retailers.
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