Environmental and Physical Health

By: Kyla Peliquin, Lance Oveson, Erin Hyduke, Aaam Blanchette, Abbie Zank, Micah Samulsen, Peter Storm

Project for Introduction To Environmental Health (ENPH 210), Fall 2003, University Wisconsin Eau Claire

Electromagnetic Fields and Your Health


Electromagnetic Fields in a Transformer

 

 

8.05.5 Undisturbed Electric Field Strength
by High-voltage Overhead Lines (50 Hz) in Vertical Profile

 

 


8.05.6 Influence of Trees
on the Spread of Electric Fields
beneath Overhead Lines (50 Hz)

 

 

 

 

 

 

Electromagnetic Field Strength as a Function of
Distance from Several EMF Sources
[3]

 

 

 

 

 

 

 

 

 

 

 

 

Definition for: electromagnetic field

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.

How much are we exposed?

           The amount of exposure is difficult to determine. Exposure to forces produced by external sources is generally constant, but the structure of a building determines how much of the final field strength can be found inside the building. EMFs produced inside a home can widely vary depending upon the wiring system and appliance usage. These variables cloud efforts to determine the relative importance of local power lines as opposed to the use of appliances or to internal house wiring.

What are the effects of exposure?

          Most of the research--especially research focusing on the relationship between exposure to EMFs and cancer--has focused on public health issues. In most cases, the findings are difficult to trust because of the difficulty in controlling the amount of exposure and other variables, including socioeconomic status, nutrition, lifestyles, genetics, occupation, and exposure to other cancer-causing factors. Many study designs lack validity, which causes further doubt about their value.

          Given these limitations and shortcomings, the research nevertheless does suggest the need for further investigation of the association between EMFs and some cancers. These include childhood brain cancer and female breast cancer. Occupational concerns related to EMFs include adult brain cancer, adult leukemia, and male breast cancer.

          A review of occupational studies examined the occurrence of malignant melanoma, colon cancer, lung cancer, bladder cancer, and non-Hodgkin's lymphoma and found questionable evidence linking those cancers with EMFs or with working in an "electrical" job.

          A number of studies examined the relationship between parental "electrical" occupation and childhood central nervous system cancers and found little to suggest a link. The evidence for adult central nervous system cancers, male breast cancer, and leukemia is also very weak. Many respected scientists critique the studies as being flawed.

          In spite of limited evidence concerning the link between EMFs and cancer, a weak connection between the two appears to exist. Further, valid studies are needed to determine the specific nature of this link.

Are there any measurable negative effects?

         Currently, the only known measurable negative effects of EMFs are related to quality-of-life issues. Local power lines, poles, substations, and high voltage transmission lines are aesthetically displeasing; a possible reduction in property values and a deterioration of community may occur as families choose to relocate to avoid EMFs. Those who live in areas selected for new EMF facilities may be resentful and resistant to them being built..

          In woodlands and farmlands, several rare but easily explained occurrences result from electromagnetic fields. Damaged conifer needles growing close to power lines serve much the same function as a lightning rod in discharging electricity build-up in the air; power lines sometimes create stray voltage effects that cause constant low-level electric shock. Decreased milk production in dairy cows and other minor problems can be avoided by properly grounding equipment and buildings.

          The placement of distribution towers that produce EMFs into recreational areas and natural areas are said to have a negative effect, although no quantifiable data are available and there appears to be no noticeable decrease in the use of those areas.

          Generally, scientists on both sides say they are dealing at most with rare diseases and an increased risk that is almost infinitesimal, especially compared with life's other everyday risks.

What can someone do?

           In spite of the absence of valid evidence based on solid scientific research, the effects of EMFs on the health of individuals and environments may still be of concern to some people. Until research data suggests a need for more extreme action, those who want to do something may wish to consider the following suggestions:

  • Stay away from the EMF sources. The strength of a magnetic field drops quickly just a few feet from the source. Do not sleep or sit for long periods of time near electrical devices, especially those with motors.
  • Stay a minimum of 18 inches away from a video display terminal (VDT). Turn it off when not in use. Don't sit close to the back or sides of the monitor even when it is in another room or behind a partition.
  • Where feasible, turn off or unplug waterbed heaters and electric blankets before going to bed. Unplugging and turning these appliances off removes the electric field.
  • Stay several feet away from all sides of a television including TVs located in another room against a wall.
  • Don't place beds or cribs against wall with major appliances nearby or on the other side of the wall.
  • Move electric clocks, clock radios, and telephone answering machines at least 4 feet away from the head of the bed.
  • Fluorescent bulbs generate stronger fields than incandescent lamps. Estimate 1 foot for incandescent bulbs and 3 feet for fluorescent lamps.
  • Avoid using electric blankets and hair blow dryers.

 

 

 

 

 

 

 

For More Information On Electromagnetic Fields Visit:

www.niehs.nih.gov/emfrapid/booklet/basics.htm      
www.fms-corp/emf-physics.shtml      
www.cancer.gov/newscenter/preerealses/LIBCSPemfQandA

www.who.int/peh-emf/research/risk_assess/en/ 
www.nrpb.org/radiation_topics/emf/