Electric & Magnetic Fields
Electric and magnetic fields (EMFs) are invisible areas of energy, often referred to as radiationDictionary of Environmental Health, 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:
- Non-ionizing: low-level radiation which is generally perceived as harmless to humans
- Ionizing: high-level radiation which has the potential for cellular and DNA damage
|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 leukemiaDictionary of Environmental Health, 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 research 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.
Does my cell phone emit EMF radiation?
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 findings of which are expected sometime in 2015.
To learn more about cell phone radiofrequency or the NTP rodent study, visit the NIEHS Environmental Health Topics page on cell phones.
What if I live near a power line?
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, a concept which is illustrated on page 37 of the NIEHS educational booklet, “EMF: Electric and Magnetic Fields Associated with the Use of Electric Power.”. 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.
How can I find out if I’m being exposed to EMFs?
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.
Where can I learn more?
- British Journal of Cancer
- Centers for Disease Control and Prevention
- Federal Communications Commission
- International Agency for Research on Cancer
- National Cancer Institute
- NIEHS Report on Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields(751KB)
- Occupational Safety and Health Administration
- U.S. Environmental Protection Agency
- U.S. Food and Drug Administration
- World Health Organization