Title: RADIATION HAZARDS
1RADIATION HAZARDS
2Important characteristics of radiation
- Wavelength
- Frequency
- Intensity
- Velocity
- Straight line propagation
- Spectrum
- Inverse square law
3Ultraviolet 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)
4Types 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
5Visible 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
6Infrared 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
7Radio-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
8LASER 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
9LASER 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
10Ionizing 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
11Ionizing 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)
12Ionizing radiation damage
- Tissue burns, minor and/or destructive
- DNA breaks leading to cell death or mutation,
potentially cancer
13Human 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
14Regulatory 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.
15Ionizing 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
16Radiation 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