A field of force, produced by electric charges and currents, which has both an electric and a magnetic component and contains electromagnetic energy. The properties of electromagnetic fields were outlined by Scottish physicist James Clerk Maxwell in 1865.
Are Electromagnetic Fields Hazardous To Your Health?
EMF fields are known to interact with tissues by inducing electric fields and currents in them. This is the only established mechanism of action of these fields. However, the electric currents induced by EMF fields commonly found in our environment are normally much lower than the strongest electric currents naturally occurring in the body such as those that control the beating of the heart.
Many studies show that sources that emit electromagnetic fields, give off radiation at low frequencies well below the safe level. There have been no instances in which people have been directly affected by cell phones, alarm clocks, pagers, etc, with the exception of tanning beds that emit ultraviolet radiation. People have very little risk (if any at all) of developing cancer from these sources.
How are humans exposed?
Pinpointing a single source of exposure is difficult because humans may be exposed to a multitude of possible sources. Electromagnetic fields are found naturally in the environment, such as in lightning and in the Earth's magnetic field, which causes a compass needle to point north. The natural electromagnetic fields in the human body allow messages to flow through the nervous system.
Electric and magnetic fields are produced by distribution or power lines, the electrical wires inside the walls of homes, and a wide assortment of electrical appliances. While electric fields do not pass through building materials, magnetic field do. Magnetic fields can also be found near buried electric lines.
Electromagnetic fields are commonly found around:
- high voltage power lines
- neighborhood transmission lines
- grounding systems that protect residents from lightning
- grounding systems that protect residents from electric shock that can result from faulty appliances
- the operation of common electrical appliances, including microwave ovens
- ovens, electric ranges, aquariums, table fans, electric space heaters
- computer monitors, electric clocks, clock radios, heated waterbeds
- electric blankets, hair dryers, cellular phones
Electromagnetic fields are divided into several categories:
- appliances and power lines--extremely low frequencies (ELF)
- AM radio transmission--high and low frequencies (HF and LF)
- TVs and video display terminals--very low frequencies (VLF)
- TV and FM radio transmissions--very high frequencies (VHF)
- microwaves--super high frequencies (SHF)
Recommended safety levels range from 0.5 mG to 2.5 mG as the maximum exposure -
with 1.0 mG as a preferred standard. Adverse biological effects have been found at 2.5 mG.