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RADIATION HAZARDS

RADIATION HAZARDS. Important characteristics of radiation. Wavelength Frequency Intensity Velocity Straight line propagation Spectrum Inverse square law. Ultraviolet radiation hazards. Common sources: sun, UV lamps (‘black lights’), welder’s arc

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RADIATION HAZARDS

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  1. RADIATION HAZARDS

  2. Important characteristics of radiation • Wavelength • Frequency • Intensity • Velocity • Straight line propagation • Spectrum • Inverse square law

  3. Ultraviolet radiation hazards • Common sources: sun, UV lamps (‘black lights’), welder’s arc • Some devices may emit only a small amount of visible light while emitting intense UV radiation • Especially dangerous to the eyes since they do not dilate readily in response to UV -- retinal burns • Photosensitization to UV can occur from certain dermal chemicals and oral drugs (e.g. antibiotics)

  4. Types of UV Radiation

  5. Visible radiation hazards • Common sources: sun, all visible lamps • Major damage likely only if intense beam is focused on the retina • Eye usually registers pain before serious damage occurs

  6. Infrared Hazards • Major effect is burns • Eye is not very sensitive so can be damaged if IR is intense • Skin burns possible but usually avoided due to pain from heat before serious injury occurs

  7. Radio-frequency and Microwave Hazards • Sources include analytical instruments (e.g. NMR), cathode ray tubes (including oscilloscopes, TVs, and computer monitors), microwave ovens, and communications devices (e.g. cell phones) • Biological effects to man uncertain • Suggestion of sterility problems, birth defects and cataracts from microwaves • Pacemakers are effected by microwaves

  8. LASER HAZARDS • LASER = Light Amplified by Stimulated Emission of Radiation • Especially hazardous due to very narrow beam which can be very intense • Lens of eye may concentrate energy onto retina by another 100,000 times

  9. LASER HAZARDS (cont’d) • Use minimum power laser possible for job • Keep laser beam off or blocked when not in use • Post warning signs when lasers are in use • Never look directly at a laser beam or align it by sighting over it • If possible, use laser in lighted room so that pupils will be constricted • Do not depend on sunglasses for shielding. • Make sure any goggles used are for the wavelength of the laser used and are of adequate optical density

  10. Ionizing Radiation Characteristics

  11. Ionizing Radiation Units • Curie (Ci) = 37 billion disintegrations/sec • Roentgen (R) = energy which will produce 1 billion ion pairs/mL air • Rad = 100 ergs absorbed energy/gm • Rem = absorbed dose in rads multiplied by factor related to type of radiation (1 for beta, gamma, X-ray; 20 for alpha)

  12. Ionizing radiation damage • Tissue burns, minor and/or destructive • DNA breaks leading to cell death or mutation, potentially cancer

  13. Human radiation dose-effect data

  14. Regulatory mandateson ionizing radiation • Nuclear Regulatory Commission occupational standard (10 CFR 20) is 5 rems/yr for whole body radiation. [Note that a lifetime exposure to 5 rem total is thought to shorten life by 1-3 weeks.] • Standard for nonwork environment is 170 mrem/yr.

  15. Ionizing radiationGeneral precautions • Confine radioactive chemicals to small areas which are posted • Cover bench tops with plastic-backed absorbent material • Use trays to catch spills • Wear gloves to protect hands and lab coat to catch splatters • Dispose of contaminated clothes appropriately

  16. Radiation monitoring devices • Film badges – after the fact measurement, developed weekly or monthly • Geiger counter – best for high energy beta, gamma • Scintillation counter – used for wipe surveys

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