Electric and magnetic fields
Electric and magnetic fields (EMF) are part of our everyday lives. Everyone is exposed to them in varying degrees. Electric currents flowing deep within the earth's core produce the earth's strong magnetic field. And, all power lines and electrical devices - appliances, computers and household wiring - produce electric and magnetic fields.
SRP recognizes that some customers have concerns about whether exposure to EMF may contribute to human health problems. Therefore, SRP is providing this summary of available information regarding EMF research, exposure levels, and guidelines.
EMF and health effects
The major research on health effects of low frequency (60-Hz) EMF has been performed in the following areas:
- Epidemiological studies attempt to establish patterns, links or association between environmental agents and diseases in human populations, such as cancer or leukemia.
- Animal studies have been performed on animals over several generations at exposures that are thousands of times higher than the EMF in a typical residential setting.
- Biological studies look for EMF responses on individual cells or DNA.
- Clinical studies have been performed on human volunteers in residential or work environments.
The overall scientific consensus about EMF and health effects is summarized by information currently posted on the World Health Organization (WHO) website. "Based on a recent in-depth review of the scientific literature, the WHO concluded that current evidence does not confirm the existence of any health consequences from exposure to low level electromagnetic fields."
Several thousand scientific papers have been published and over two dozen expert panels have reviewed this research. For most diseases, the epidemiology has been inconclusive and inconsistent, although some childhood leukemia studies have found an increased risk with magnetic field exposures. Epidemiological studies do not provide a conclusive cause and effect between EMF exposure and disease, and the animal, biological and clinical studies which have been done do not support a hypothesis that EMFs are harmful. Additionally, no plausible bio-mechanism is known by which 60 Hz magnetic fields would be harmful.
Strength of typical magnetic fields
Because electric and magnetic fields exist all around us, managing only the fields near power facilities does not control exposures. Studies show that primary sources of EMF exposure for most people are inside the home and workplace. This is largely because people are typically in closer proximity to those EMF sources than they are to power facilities.
|Electrical device||1 inch away (mG)||1 foot away (mG)||3 feet away (mG)|
|Hair dryer||60 – 20,000||0.1 – 70||0.1 – 0.3|
|Vacuum cleaner||2,000 – 8,000||20 – 200||1.3 – 20|
|Microwave oven||730 – 2,000||40 – 80||2.5 – 6|
|Iron||80 – 300||1.2 – 3||0.1 – 0.3|
|Television||25 – 500||0.4 – 20||0.1 – 1.5|
Typical magnetic field levels near power lines
|Location||Directly under overhead transmission line||100 feet away from overhead transmission line||Directly over underground distribution line||20 feet away from underground distribution line|
|Field strength||5 to 100 mG||1 to 20 mG||6 to 30 mG||2 to 10 mG|
Governmental reviews of the research have concluded that there is not sufficient evidence to establish an "unsafe exposure level," and, as a result, there are no federal or State of Arizona standards that limit exposure to 60-Hz EMF. Some guidelines established by other entities include:
- International Commission on Non-Ionizing Radiation Protection: 2,000 mG for the public and 10,000 mG for workers
- American Conference of Governmental Industrial Hygienists: 10,000 mG for workers
What SRP is doing
SRP is a leader in providing safe, reliable and environmentally appropriate service to its customers and ensuring the safety of its employees. We follow industry best practices in designing and locating our transmission, distribution and substation facilities. SRP electric facilities are designed and operated in compliance with applicable federal, state and local regulations, clearance requirements (National Electrical Safety Code) and health standards.
Primarily through the Electric Power Research Institute (EPRI), SRP has supported and funded EMF-related medical and scientific research and will continue to pursue answers to EMF questions. SRP is committed to research and communication about exposure to EMF for the benefit of its customers.
SRP is committed to sharing and communicating information about EMF so its customers are well informed and have easy access to EMF research findings.
Other sources of information about EMF are available on the Internet. Some informative websites are:
- World Health Organization EMF Home page
- WHO information on typical exposure levels (multiply results given in microTesla by 10 to convert to milliGauss)
- The National Institute of Environmental Health Sciences (NIEHS) - see the section, What if I live near a power line?
- 60 Hz magnetic field exposure guidelines of 2,000 mG for the general public and 10,000 mG for occupational settings, International Commission on Non-Ionizing Radiation Protection, updated 2010, see Tables 3 and 4.
SRP encourages you to learn more about EMF in order to understand this field of study. If you have questions regarding EMF, please write to us at firstname.lastname@example.org or call SRP Consumer Affairs at (602) 236-2196.