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SECTION E5: ELECTROMAGNETIC FIELDS (NONIONIZING RADIATION
SOURCES)
Introduction
Electrical devices and systems produce two different fields: an electric
field like the one produced on the surface of a wool sweater on a dry
winter day, and a magnetic field like the fields produced by a compass
needle, a small magnet or the earth itself. These fields in combination
are referred to as electromagnetic fields or EMF. EMF fields associated
with electrical devices and appliances are produced only when the device
is plugged in and operating. Devices which generate electromagnetic
fields include radio or TV station transmitters, microwave ovens, power
transmission lines, and electrical appliances.
Exposure to the very high intensity electromagnetic fields found
in the immediate vicinity of certain sources such as radar installations
and TV or radio transmitters can produce electrical shock or a variety
of heating effects, which may range from a sensation of warmth to burns
and eventual cataract formation.
The National Research Council recently conducted a review of the
many studies which have examined the effects and risks of exposure
to low intensity EMF. The Council’s conclusion, in a report released
on October 31, 1996, states that "No clear convincing evidence
exists to show that residential exposures to electric and magnetic
fields (EMFs) are a threat to human health." The
nature of most of the exposures to individuals at Princeton University are
comparable to residential exposures, i.e., exposures to common electrical devices
and appliances which do not produce unusually high intensity EMFs.
Standards establishing permissible levels for occupational exposure
to radio frequency radiation (from 300 kiloHertz to 100 gigaHertz)
have been established by the New
Jersey Department of Environmental Protection (NJDEP).
NJDEP has also established regulations requiring that radio frequency
and microwave heaters and sealers and industrial microwave ovens be
registered. The federal government has established emission standards
for the manufacturers of certain equipment, including televisions and
video display terminals to ensure that EMF fields outside the equipment
is limited to levels considered to produce
no adverse effects or harm.
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Scope and Application
This section applies to persons and departments who own or operate
microwave ovens at Princeton University and to any department that
may acquire radio frequency (RF) and microwave heaters and sealers
and industrial microwave ovens. Information about ionizing radiation,
such
as radioisotopes and x-rays, are covered in Section
E1, Radioactive Materials and Section
E2, Radiation-Producing
Equipment.
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Program Description
Registration
Certain devices must be registered with NJDEP, including RF and
microwave heaters and sealers and industrial microwave ovens. A department
notifies
the Office of Environmental Health & Safety (EHS) when such a
device has been acquired. EHS will serve as liaison between the department
and NJDEP and will register any device, as needed. NJDEP charges
an initial and annual registration fee for each machine, the costs
of
which are borne by the department.
NJDEP has specifically exempted from registration microwave ovens
of the type used for heating food in the home.
Microwave Ovens
EHS does not routinely survey most microwave ovens for leakage because
properly operating ovens with intact doors and door seals do not produce
excessive microwave leakage. EHS will survey any microwave oven upon request.
The door seal area of a microwave oven must be kept clean and free
of grease or food buildup to ensure a tight fit between the door
and the oven. Do not clean the door seal area with abrasive cleaners
which can cause scratches or
gouges and can cause microwave leakage.
Monitoring
As described above, EHS performs leakage surveys for microwave ovens
upon request.
The University, through EHS and the University’s Manager
of Electrical Engineering, Engineering and Construction at the MacMillan
Building, also has the capability to monitor the 60 Hertz EMF fields
associated with electrical appliances and the power distribution
system. Requests for 60 Hertz EMF measurements should be directed
through EHS. If EHS does not have the capability to monitor EMF levels
at other frequencies of interest, EHS will assist a department to
obtain the services of an outside consultant.
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Roles and Responsibilities
Department
- Survey departmental facilities to find RF and microwave heaters
and sealers, industrial microwave ovens, or other high
intensity EMF sources.
- Contact EHS when RF or microwave heaters or sealers
or industrial microwave
ovens are purchased.
- Contact EHS when concern is expressed about EMF levels.
- Monitor condition of microwave ovens used within the department
for cleanliness and damage.
- Repair or scrap damaged microwave ovens
or request leakage
surveys.
Supervisor
- Same as department’s responsibilities.
EHS
- Provide technical information about EMF when requested.
- Perform
microwave surveys when requested.
- Perform or arrange for 60 Hz
EMF surveys when requested.
- Provide information about EMF consultants.
- Register devices with
NJDEP when necessary.
- Audit department program periodically.
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For More Information
Contact an EHS Health Physicist at 258-5294.
The following references are available through EHS:
- New
Jersey Administrative Code, Title 7, Chapter 28, Subchapters
42 and 48
- Threshold Limit Values for Chemical Substances and Physical
Agents and Biological Exposure Indices, American Conference
of Industrial Hygienists, published annually.
- Electric and Magnetic Fields from 60 Hertz Electric
Power: What do we know about possible health effects?, Department
of Engineering
and Public Policy, Carnegie Mellon University, 1989.
- Links to other electromagnetic
field-related web sites are available here.
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