Special Topics

Electromagnetic Force (EMF) occurs whenever there is an electrical current and associated with an electric field is also a magnetic field.  During the past two decades there have been reports suggesting that high voltage electric transmission lines may cause leukemia in children and other biological effects.

Lasers are devices that modify light to form a powerful beam of energy capable of causing biological damage.  Lasers are classified by their wavelength and energy, which provides a reference to judge their potential danger.  Lasers have applications in industry, medicine, communications, entertainment and research.  Improper use of a laser may cause blindness.  Lasers used in surgery also create a hazard to health care personnel from the vaporization of biological material if the area is not well ventilated.

Magnetic Resonance Imaging (MRI): uses a very strong magnet and a RF coil to transmit a signal that flips the protons in the hydrogen atoms to become all aligned in the same direction.  The RF coil then becomes a radio receiver to detect how many hydrogen atoms return to their original spin direction.  The concentration of hydrogen atoms in this medical imaging technique assists physicians to identify certain medical conditions.  There are no known ill health effects from strong magnetic fields; however, there is a missile hazard.  Patients with metal implants may experience some localized heating from the RF coils.  Loose metal objects can be drawn to the magnet at high velocities.  Also magnetic storage devices may become damaged, such as credit and bank cards with magnetic strips.

  • In partnership with the Society of Magnetic Resonance Technologists (SMRT), FDA has created an educational resource poster intended to increase the safety of patients undergoing Magnetic Resonance Imaging exams. The poster provides tips for increasing patient safety and preventing thermal injuries during MRI exams. You may download three different sizes of the poster from FDA’s website for use at your own facility. We hope you find this educational resource helpful for increasing patient safety! [Posted November 18, 2015]
  • Link to the MRI Burn Prevention poster: MRI Burn Poster.
  • All three sizes are available from the MRI homepage: FDA MRI Home Page

Microwaves and radar are high frequency RF waves and have applications in telephone communications, satellite communications, navigation, law enforcement, and aeronautics.  The FCC also regulates this spectrum of the RF as well.   Again the RF levels used in these applications are safe for the general public, there are some precautions that occupational workers need to observe, particularly while working near transmitting antennas, or the waveguides.  There are other applications not related to communications and therefore not regulated by the FCC.  For example there are RF sealers that are used to seal plastic wrappers in packaging, or medical devices used to heat portions of the body.

Non-Ionizing Radiation: Most people think of ionizing radiation when they hear the word “radiation.”  Radiation is one of several ways energy is transferred.  If the energy is great enough to create ions, then the radiation is capable of causing damage to biological material and causing other health effects, such as radiation sickness, genetic defects, and cancer.  If the radiant energy transferred is not enough to cause ionization, then this radiation is called non-ionizing radiation.  Non-ionizing radiation can also cause damage to living material, primarily by heating effects. Examples of non-ionizing radiation are listed below along with web addresses of organizations that may have useful information:

  • OSHA Non-ionizing radiation Regulations: 29 CFR Part 1926
  • Occupational Safety and Health Administration webpage: OSHA

Radiofrequency (RF) waves are in the upper spectrum of the electromagnetic waves.  They are used primarily for communications, such as radio, television, cell phones and other services.  The Federal Communications Commission (FCC) regulates the use of RF by assigning frequencies and power limitations to their licensees.  RF radiation levels used in these applications are safe for the general public; there are some precautions that occupational workers need to observe, particularly while working near transmitting antennas.

Ultrasound is a high frequency sound wave transmitted in water or biological tissue. Low energy ultrasound has application in medicine as a diagnostic imaging technique, particularly in obstetrics, and cardiology.  There are no known ill health effects from diagnostic ultrasound; however, all medical procedures incur a risk.  High power ultrasound waves are used to break up kidney stones instead of surgically removing the stones.

Ultraviolet light (UV) in tanning may damage the skin and prematurely age the skin.  UV may also cause skin cancer.  The US Food and Drug Administration regulates the manufacture of tanning lamps and medical tanning lamps.


Office of Radiological Health | 109 Governor Street, 7th Floor | Richmond, VA 23219

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