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
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
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
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
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
14. Regulatory mandates
on 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 radiation
General 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
