Synonym: correlation or relationship. A statistical dependence between two or more events or variables.


Prejudice. Something that may skew the results; having the results appear greater or less than that which is real.

Biological effect

An effect that occurs naturally in the human body. An example: the pupils of the eye will change according to the difference in lighting.

Calculated Fields

Indirect estimate of magnetic fields using current load data and distance to power lines, usually calculated by a software program.


A cancer-causing substance.


The California Department of Health Services, the state agency that managed the California EMF Program. The purpose of the program is to perform EMF research and policy analysis, and provide education and technical help to benefit Californians.

California EMF Program


A factor that can cause the outcome of interest, but is not the factor under investigation.


Close similarity between findings in different samples or populations, or in studies conducted by different methods or investigators.


The California Public Utilities Commission regulates privately owned telecommunications, electric, natural gas, water, railroad, rail transit, and passenger transportation companies. The CPUC is responsible for assuring that California utility customers have safe, reliable utility service at reasonable rates, protecting utility customers from fraud, and promoting the health of California's economy.


The movement of electrons in a conductor.

Electromagnetic Spectrum: The complete range of electromagnetic frequencies is comprised in the electromagnetic spectrum.

Electric power frequencies are found in the ELF (extremely low frequency) band at one end of the spectrum, whereas high-frequency waves (ultraviolet light, X-rays and gamma rays) can be found at the other end. Visible light, including sunlight, occupies the middle region.

Power frequencies

Electromagnetic spectrum


The study of the distribution of health related effects in a specified population.


The rate at which a periodic waveform repeats itself in time at one position in space. Frequency is measured in cycles-per-second or Hertz (Hz). The electric power frequency in North America is 60 Hertz.

Ionizing Radiation

Electromagnetic radiation for which the frequency is high enough so that there is sufficient energy to break the internal bonds in atoms and molecules. Such frequencies typically are in the optical range or higher, more than a trillion times larger than power-line frequencies.

Electromagnetic spectrum


The National Institute of Environmental Health Sciences. This agency managed the federal government's $45-million EMF research program, known as the EMF RAPID Program (for Research And Public Information Dissemination). The final report of this program was submitted to the U.S. Congress on June 15, 1999.

Final report

EMF RAPID program

Non-Ionizing Radiation

Electromagnetic radiation for which the frequency is not high enough so that the bonds in atoms and molecules may be broken. Power-line frequencies, radiowaves, microwaves and other forms at the lower end of the spectrum cannot alter the bonds of molecules or atoms. These forms of electromagnetic energy cannot create ions and thus are known as Non-Ionizing.


The National Radiological Protection Board of the United Kingdom. NRPB is an independent body that has responsibility for advising UK government departments and others on standards of protection for exposure to ionising and non-ionising radiation, which includes electric and magnetic fields.


The federal government's $45-million EMF research program (for Research And Public Information Dissemination) more generally known as the EMF RAPID Program, managed by NIEHS (the National Institute of Environmental Health Sciences).

EMF RAPID program

Scientific Reviews

Multi-disciplinary panels of scientists review all of the research on EMF, in aggregate, to draw conclusions about the significance of the research findings.

Scientific reviews


An examination or analysis of a subject in a particular situation or environment.

Spot Measurements

One-time field measurement of magnetic fields, a so-called “snapshot” or point-in-time measurement.


The electric force that causes current in a conductor.

Wire Codes

A visual classification system that estimates magnetic fields from apparent current carrying capacity of a wire by such things as the diameter of the wire and the distance to the wire.


The World Health Organization. This agency, based in Geneva, Switzerland, operates the International EMF Project, with its objective to assess health and environmental effects of exposure to static and time-varying electric and magnetic fields in the frequency range 0 - 300 GHz.

24-Hour Measures: Round-the-clock measurements of magnetic fields in a selected area.

International EMF project

Additional Information

California Department of Health Services EMF glossary

EMF basics