Working with Hazardous
Chemicals
Personal protective equipment
Special conditions
Routes of chemical exposure
Part 1:
• Personal Protective Equipment (PPE)
Standard Lab Dress
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Have as little bare skin as possible
No loose hair, necklaces, neckties
No loose clothing (i.e. sleeves)
No rings, watches
• Key: Easy to remove clothes or wash skin if
chemical contamination or fire occur
Proper use of lab coats
• Always wear lab coats.
– To protect skin and clothes from contamination
– To prevent spread of contamination outside of
lab
• Won’t protect against corrosives
– USE APRON
• Fit: should not be too loose, unbuttoned, or have
rolled sleeves
Should not be laundered at home. Should
not be worn outside of lab.
http://cdn.shopify.com/s/files/1/0041/4632/files/newlab-coat.jpg?1263858434
Appropriate Lab Footwear
•
CLOSED TOE. NOT WOVEN.
– Protect against spills
– Broken glass
•
Lab shoes vs. street shoes
– Disposable shoe covers
http://www.reef-sandalsonline.com/images/reef_convertible_sandal.jpg
http://www.bomir.com/images/zerocharge/a-sc1.jpg
Laboratory Gloves: Purpose
• Gloves serve a wide range of purposes:
– protection against chemicals
– against biologicals
– against punctures
– against temperature extremes
• No single glove can do all this and still be flexible enough to use in
fine manipulations
Choosing Laboratory Gloves
• Consult chemical resistance chart for glove
– degradation rate: tendency of chemical to physically
change properties of glove on contact
– permeation rate: tendency of chemical to penetrate
– breakthrough rate: time required for chemical
spilled on outside of glove to be detected on inside
surface
Proper Glove Use
• Can double glove with
two different glove types
for extra protection
• Choose thickest gloves
which allow dexterity to
perform task
http://www.ansellhealthcare.com/images/ProductImages/undergl
ove_1.jpg
Proper Glove Use (con.)
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Check for holes or tears
Keep cuts bandaged
Keep nails short
Make sure gloves cover wrists
Change regularly and after contact with hazardous materials
Remove gloves so that skin contact does not occur with outside
glove surface
• Wash hands after glove use or if contamination is expected
• Do not touch doorknobs, lights, etc. with gloves on
Eye
Protection
• Safety glasses with side
shields
– small chemical splashes
http://www.cordless-drills.net/images/pictures/ao-safety-seeproplus-safety-glasses.jpg
• Goggles
– large splashes and caustics
• Face shields
– explosion
http://www.dryeyepain.com/Safety-goggle.jpg
• good for UV protection. Wear
eyewear underneath.
http://www.labsafety.com/images/xl/TASCO-9000-Face-ShieldLSS-_i_LBN67630_01S.jpg
Other types of PPE
• Ear protection
– ear plugs or ear muffs
– protect against sonication noise
http://di109.shoppingshadow.com/images/di/32/6a/4f/436437597
• Masks
863504c62796846387041756b6877-149x149-0-0.jpg
– filter dust and aerosols
– protect against minor splashes
– Will not protect against biological
infectious agents
http://www.rosemarydrive.com/renovation/safety/classicdustmask
.jpg
Other PPE (con.)
• Respirators
– protect against toxic
fumes
– must have training to
use
• Self-contained breathing
apparatus
– contains own air supply
– when user must work
in highly toxic fumes
http://images.plant-care.com/respirator-2.jpg
http://www.dalmatianfire.com/Images/Industrial/ProAir%20Evoluti
on.jpg
Part 2:
• Working in special conditions
Working with glass
• Check glassware prior to heating or centrifuging or otherwise
stressing glass
• Place mat in bottom of sink prior to washing glassware
Working with sharps
• Never leave these sitting on benchtops
where someone may accidentally get
hurt
• Always scrape or cut away from body
• Recap needles by placing cap on
benchtop and inserting needle to
prevent punctures
• Dispose of sharps in specially labeled
container
http://sunsetscavenger.com/images/sharps.jpg
Working with gas cylinders
Gases mostly non-toxic and
nonflammable
Danger comes from risk of
explosion or falling
• Wear eye protection
• Attach cylinders to wall
• Transport cylinders one at a time in a cart secured
by a strap
• Keep safety cap on during movement
• Know about hazards of gas prior to use
• Never direct stream of gas at anyone
http://www.med.cornell.edu/ehs/updates/1.4
f
Working with heat
• Bunsen burners
• don’t leave flame unattended
• Don’t leave flame where someone may reach over it
• Keep flame visible
• Hot plates
• Leave note that it is hot after use
• Hot liquids
• Never heat a closed container
• Watch for superheated liquids
• In case of minor burns, flood skin with cold
water for 10 – 15 minutes
Laboratory Fires
Most common source of
fire = ignition of
flammable organic
liquids and vapors
http://pubs.acs.org/cen/img/83/i21/8321gov2_opening.tifcxd.JPG
Preventing Laboratory Fires
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Keep minimum amount of flammables
Keep open solvents away from flame
Store flammables in appropriate cabinets
Use water baths or hot plates instead of Bunsen burners
Limit ignition sources: sparks, static electricity
Never leave flame unattended
Marked heated hot plates
Reduce electrical hazards
Extinguishing Laboratory Fires
• NEED FUEL, HEAT, OXYGEN
TO GET FIRE
– TAKE ONE AWAY AND IT
EXTINGUISHES
http://www.cedars-sinai.edu/Medical-Professionals/Resourcesfor-Physicians/Safety/Images/371590_fire_triangle.gif
Types of Extinguishers
• Class A = paper, cloth, wood
– Use water or multipurpose dry chemical
• Class B = organic solvents, gases, paints
– DO NOT USE WATER
– Carbon dioxide or foam to remove oxygen
• Class C = electrical
– DO NOT USE WATER. May cause electrocution.
– Use carbon dioxide or dry foam
• Class D = combustible metals
– Need special extinguisher approved for source metal.
Working with extreme cold
• Contact with extreme cold (-78 degrees
Celsius or below) causes skin burns
– Cryogenic liquids can not be used with ordinary lab
glass or plastic. Stored in Dewar vacuum glass
flasks.
• Dry ice = solid
– Use eye protection to chip large blocks
– Do not lean too far into chest for long periods. This
can cause suffocation.
• Liquid nitrogen (-198 degrees Celsius)
– Very hazardous to dispense. Never do this without
training.
Working safely with electricity
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Keep hands dry
Be sure equipment is grounded
Keep area under equipment dry
Check cords to see if in good condition
Working with UV light
UV-B AND UV-C light in labs can damage skin
and eyes
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Always wear approved eye protection
Cover skin
Do not direct UV light at coworkers
Use a face shield if necessary
Use germicidal lamp only when area not in use
Working with autoclaves
Autoclaves are sterilization devices that use
high pressure and very high temperature
• Do not use chipped glassware
• Be sure plastics are autoclavable
• Make sure inside of autoclave is at atmospheric pressure before
opening door
• Wear eye and hand protection
• Stand back when opening door
• Release pressure slowly for liquids to prevent boilover
• Let autoclaved liquids sit 10 minutes prior to removal to prevent
boilover
Part 3:
• Routes of entry for chemical exposure
Routes of entry for toxic chemicals
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Inhalation
Skin and eye contact
Ingestion
Injection
• Most likely in lab = skin contact and inhalation
Measuring chemical toxicity
Chemicals differ in:
– Toxic dose
– Route of toxicity
• LD50 (lethal dose – 50%)
– amount of chemical causing
death in 50% of test animals
– LD50 is recorded in grams
chemical / kilograms body
weight
http://www.chem.duke.edu/~bonk/Chem8304/LD50.GIF
Levels of toxicity
• LD50 depends upon route of exposure
– High toxicity = <500 milligrams / kg by ingestion or injection
– High toxicity = < 1 gram / kg by skin contact
• LC50 (lethal concentration)
– concentration of chemical in air that will kill 50% of exposed
animals.
– Expressed in ppm.
– <2000 ppm inhalation = highly toxic.
Toxicity by inhalation
Reactions range from mild discomfort to
burning to asphyxiation
• For volatile chemicals, can NOT estimate exposure
by odor. Therefore, you should limit your exposure
by working in a fume hood.
ACGIH limits of exposure
•
American Conference of
Governmental Industrial
Hygienists (ACGIH) has
set limits of exposure
– OSHA adopted these
and set as regulated
limits.
•
Threshold Limit Value
(TLV) = airborne
concentration for a
chemical that most
healthy workers can
safely be exposed to for
8 hours per day
repeatedly with no
adverse effects. ( can
be averaged over the
course of the day)
http://www.tsi.com/uploadedImages/Product_Information/Images/
Small/CO-Table1a-new_small.jpg
ACGIH limits of exposure
• TLV-STEL (short term exposure limit) = air
concentration at which only 15 continuous
minutes of exposure is allowed up to 4 times per
8 hour day
• TLC-C (Ceiling exposure limit) = airborne
values must never exceed this value.
Consequences of skin contact with a hazardous
chemical
• No harm
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Rashes, burns, other skin irritations
Penetration of skin = allergic
sensitization
• Penetration of skin and entry into
bloodstream resulting in systemic
toxicity
• Skin is normally a barrier but entry at
hair follicles, sweat glands, cuts and
abrasions can occur
http://www.ansellchemsafe.com/assets/contentImages/irritate2.jp
g
Toxicity by ingestion
• Touching face with
contaminated hands, chewing
on pencils, etc.
http://cdn.womenshealthmag.com/files/images/0909-pencilchewed.preview.jpg
LD lo = lowest dose of chemical
reported to cause a human
death
Use of a fume hood: when is it
required?
Whenever using chemicals that:
• Are volatile
• Have unpleasant smells
• Have TLV lower than 50 ppm in
air
http://www.drs.illinois.edu/images/chempics/factsheets/WorkingIn
AChemicalFumeHood.jpg
Fume hood terminology
Sash: window that is impact-resistant
and can be raised and lowered
Baffles: direct air flow
Airfoils: reduce turbulence in air flow
Face velocity: rate of air flow into
entrance of hood
Types of fume hoods
• Fumes hoods can be
“constant air volume”
(changing sash height
changes the face velocity)
• Can also be variable air
volume which means
relatively constant face
velocity.
http://www.expresspharmaonline.com/20090831/2009083151.jpg
Fume hood use and maintenance
• Testing must occur at least annually.
• Not all parts of a hood are equally good for working in.
• Handle toxic chemicals 5 to 6 inches back from sash.
Fume hood rules of use
• Check hood function
• Put all equipment in at once, check compatibility of chemicals
• Do not overload hood because blocks air flow. Keep equipment
2 inches off of hood surface
• Move sash slowly and keeps hands from making sudden
movements
• Keep face behind hood sash
• Wear face and eye protection
• Do not use infectious agents (need biological safety cabinet)
Fume hood spills
In the event of fire or spill:
1. Close sash completely
2. Leave exhaust fan ON
3. Unplug all equipment in hood (if outlets are
outside sash)
4. Evacuate area