1.1 Recognition of Non-Ionizing Radiation Hazards
Radiations and fields that form part of the electromagnetic spectrum, having insufficient energy to produce ionization in the medium through which they pass, are termed Non-ionizing Radiation (NIR).
NIRs include: electric and magnetic fields, electromagnetic fields (frequency range 0-300 GHz) defined as Extremely Low Frequency (ELF) fields; optical radiations: ultraviolet (UV), visible light, infrared; Ultrasound (frequencies above 16 kHz). Ultrasound is distinct from electromagnetic radiation in the necessity for the acoustic vibrations to propagate through a physical medium.
| The Electromagnetic Spectrum |
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The electromagnetic spectrum is divided into wavelength or frequency, reflecting the different biological effects.
1.2 Evaluation of Non-Ionizing Radiation Hazards
1.2.1 Sources of Non-Ionizing Radiation
- Ultraviolet (UV) Radiation
Chronic exposure to UV radiation may cause premature skin aging, excessive wrinkling of the skin, skin cancer, and cataracts (opacities in the lens of the eyes). - UV-A (315 - 400 nm)
Effects include tanning (and some burning) of the skin, and fluorescing of ocular media (corneal and lens effects). - UV-B (280 - 315 nm)
Effects include "sunburn" of the skin, inflammation of the cornea of eye, and cataracts. - UV-C (100 - 280 nm) - "Germicidal UV"
Principal effect is inflammation of the cornea of the eye.
1.2.2 Infrared (IR) Radiation
- IR-A (700 nm - 1.4 mm) - "Near IR"
High intensity may cause skin burns and retinal thermal injury. - IR-B (1.4 - 3.0 mm) and IR-C (3.0 mm - 1 mm) - "Far IR"
High intensity may cause skin burns and corneal inflammation.
1.2.3 Radio-frequency (RF) and Microwave (MW) Radiation
- RF (0.3 - 30 MHz) and MW (30 MHz - 300 GHz)
Effects may include formation of cataracts, neurological effects, male sterility and possibly cancer.
1.3 Control Methods for Non-Ionizing Radiation
1.3.1 UV Radiation
Eye protection (goggles, safety glasses, face shields) and protective clothing should be worn when working with high-level UV sources, which should be enclosed or shielded to prevent exposures. When fully enclosed and interlocked UV sources are used, protective eyewear and clothing are not needed.
1.3.2 IR Radiation
Same as UV (eye and skin protection). Measures to avoid hyperthermia (over-heating of the body) may be needed.
1.3.3 Radiofrequency (RF) and Microwave (MW) Radiation
Sources must be properly isolated and shielded.
1.4 Microwave Ovens
Food for human consumption may not be heated in microwave ovens unless the oven is used solely for that purpose.
When melting agar the following precautions must be taken:
- Explosions may occur when melting agar using a microwave oven.
- Caps on screw-cap bottles must be completely loosened before the bottles are heating in the microwave oven.
- A long-sleeve laboratory coat must be worn when heating agar in a microwave oven.
- Heat-resistant gloves must be worn to prevent burns and protect the hands in case of an explosion.
- Face-shields must be used when handling microwave-heated materials.
The following web sites contain a wealth of pertinent information: