RADIATION HAZARDS

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RADIATION HAZARDS
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Important characteristics of radiation

• Wavelength
• Frequency
• Intensity
• Velocity
• Straight line propagation
• Spectrum
• Inverse square law

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Ultraviolet radiation hazards

• Common sources sun, UV lamps (black lights),
  welders 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)

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Types of UV Radiation
Type Wavelength Effect
UV-A Black light Region 315-400 nm Little effect
UV-B 280-315 nm Skin cancer possible
UV-C 100-280 nm Cornea damage
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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

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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

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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

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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

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LASER HAZARDS (contd)

• 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

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Ionizing Radiation Characteristics
Mass Charge Stopped by
Alpha 4 2 4 cm air
Beta 0 -1 6-300 cm air
Lowered 10 by
X-ray 0 0 15-30 cm tissue
Gamma 0 0 50 cm tissue
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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)

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Ionizing radiation damage

• Tissue burns, minor and/or destructive
• DNA breaks leading to cell death or mutation,
  potentially cancer

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Human radiation dose-effect data
DOSE (rems) PROBABLE EFFECT
0-25 No noticeable effect
25-100 Slight blood changes
100-200 Vomiting, fatigue (recovery in weeks)
200-600 Vomiting, severe blood changes, hemmorhage (recovery in 1-12 mo.)
600-1000 Survival unlikely
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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.

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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

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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