Hazard Category - Radiation Energy - Defense Centers for Public Health

Radiation Energy

Coordinate with the Health Hazard Assessment (HHA) Program early in the acquisition process to eliminate or control ionizing and nonionizing radiation exposures associated with materiel. Subject matter experts from the Nonionizing Radiation Division and Health Physics Division provide input for HHAs related to radiation energy. Most systems require a Nonionizing Radiation Protection Study (NRPS) in conjunction with an HHA.

Exposure to nonionizing radiation may cause eye and skin injuries, with the eye being the most sensitive. Higher-powered systems requiring high voltage may result in shock or burn hazards. For most sources, the effects of exposure are determined by the wavelength and dose received by the Soldier. Exposure to ionizing radiation resulting in an absorbed dose may cause acute tissue reactions or an increased risk of cancer. The nature of these effects depends on the amount of radiation absorbed, the rate at which it is absorbed, and the biological tissues affected. Keeping exposures as low as reasonably achievable (ALARA), requiring proper engineering controls and safety features (e.g., interlocks, laser beam attenuators), and implementing a safe standoff distance (SSD) are examples of risk mitigations recommended to protect Soldier health.

Laser and Optical Radiation

Nonionizing, electromagnetic radiation at wavelengths in the ranges from 100 nanometers to 1 millimeter representing ultraviolet radiation, visible light, and infrared radiation (i.e., wavelengths that affect the eye and skin). Potential sources of optical radiation include lasers and high-intensity optical sources (HIOS) (e.g., spotlights).

Data Requirements

Request an NRPS for all applicable laser and optical radiation sources. The NRPS documents the laser system's classification (i.e., Class 1, 1M, 2, 2M, 3R, 3B, or 4) and appropriate control measures^1,2,3,4,5. Provide all available system information such as the name and model, serial number, wavelength, average and/or maximum power or energy, divergence, initial beam diameter, and pulse information (e.g., pulse width, frequency). Identify details about the system's normal use (e.g., how it's used, Soldier locations, mounting platform) and safety features.

Health Protection Criteria

Army systems comply to the greatest extent possible with the U.S. Food and Drug Administration (FDA) requirements and with the accessible emission limits (AELs) and maximum permissible exposure (MPE) limits^1,2,3,4. Some laser products are declared military-exempt, meaning they are specifically exempted from one or more FDA requirements due to military mission need⁶. Military-exempt systems must still include alternate controls to eliminate or control hazards⁵^,7.

Radio Frequency Radiation

Nonionizing, electromagnetic radiation with a wavelength from about 1 millimeter (about 300 gigahertz (GHz)) to static fields (0 hertz).

Data Requirements

Request an NRPS for all applicable radio frequency radiation (RFR) sources. In lieu of an NRPS, provide adequate data that supports an assessment. Provide all available radio frequency emitter information such as the emitter name and model, serial number, frequency, average output power, antenna gain, duty factor, beam width, and aperture area. Emitter information can be obtained from DD Form 1494, the manufacturers' technical manuals, or the FCC⁸. Identify details about the system's normal use (e.g., how it's used, Soldier locations, antenna height, elevation angle) and safety features.

Health Protection Criteria

Guidance for protection of personnel to RFR includes information such as MPE limits, warning sign formats, and recommended practices for safety programs^9,10. There are no expectations that any adverse health effects result from exposures that are below the MPE limits, even under repeated or long-term exposure conditions. A minimum safety factor of 10 is incorporated into these standards. These MPEs are also assessed with reference to spatial and temporal averaging.

Ionizing Radiation

Charged, subatomic particles and ionized atoms with kinetic energies greater than 12.4 electronvolts (eV), electromagnetic radiation with photon energies greater than 12.4 eV, and all free neutrons and other uncharged subatomic particles (except neutrinos and antineutrinos). When ionizing radiation passes through material, it can deposit enough energy to produce ions by breaking molecular bonds and displacing (or removing) electrons from atoms or molecules.

Data Requirements

Provide detailed information about all sources of ionizing radiation prior to purchase and use by the Army. Identify details about the system's normal use (e.g., Soldier locations, exposure duration and frequency, expected radiation dose rates) and controls implemented to keep exposures ALARA. Identify the types, quantities, and radiological characteristics of all radioactive material (RAM) and ionizing radiation-generating devices.

Health Protection Criteria

Army life cycle management implements ionizing radiation safety requirements and exposure limit criteria for personnel potentially exposed to ionizing radiation^2,^11,12,13. The primary limit is an effective whole-body dose not exceeding 50 millisievert (5000 millirem) per year¹¹. A U.S. Nuclear Regulatory Commission (NRC) license or Army Radiation Authorization (ARA) must be in place to support acquisition for most RAM.

For more information and guidelines for assessing radiation energy health hazards, see Technical Guide 351B, Health Hazard Assessor's Guide, Volume 2: Radiation Energy.