Dr. H.Khouja
2nd Year MT Skill
Lab Safety
Chemical Safety
General considerations
1- The medical technologist working in the clinical lab is always in contact with various
types of chemicals.
2- He experiences a long-term contact with such chemicals as he works in the lab.
3- Such chemical substances fall into a number of categories from safety point of view;
they can be corrosive, harmful, flammable, toxic, carcinogenic, explosive ... etc.
4- Therefore, practice extreme care and caution when dealing with or handling
chemicals.
5- Always learn and apply safety procedures regardless of the concentration or types of
chemical being used.
6- Acquire complete information and knowledge of the properties of the chemicals used
in your lab (including the ones in storage).
7- Never play or miss about with chemicals.
8- Always wear gloves, masks, shoes and lab coat when handling, transporting or storing
chemicals.
9- When adding or pouring chemicals, direct the beaker or the tube away from your face
or any body’s face.
10- Carry out addition and use of concentrated acids or alkalis, volatile and flammable
chemicals, toxic materials and organic solvents in a well-ventilated and operating fume
cupboard.
11 - Carry out prolonged incubations of reaction mixtures
(especially if fumes or gasses are liberated) in well-ventilated and operating fume
cupboards.
12- Never leave concentrated acids or alkalis, toxic materials, volatile and flammable
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Dr. H.Khouja
2nd Year MT Skill
Lab Safety
chemicals, fuming and explosive chemicals on benches on routine lab.
13- Never add water straight on concentrated acids or alkalis.
14- Add concentrated acids or alkalis drop by drop to flasks with water.
15- Store strong acids and alkalis in steel cupboards or in sand buckets.
16- Never store large quantities of chemicals in the same routine lab.
17- flammable liquids should be stored tightly capped in steel cupboards or in sand
buckets.
18- Never allow incompatible chemicals to be stored by each other.
19- Toxic chemicals should be locked away in safety deposits, and a record or log book
of the users is used.
20- Never use cracked or chipped glass or plastic ware for chemicals
21- DON'T store strong alkalis in ordinary glass bottles.
22-Always label chemical reagents which you prepared or poured from other bottles
clearly.
23-such labeling must include the following information:
NAME OF CHEMICAL
Hydrochloric acid
CHEMICAL FORMULA
HCl
CONCENTRATION
4.3M
SAFETY PRECAUTIONS
corrosive & fuming
DATE OF PREPARATION
:23-10-1998
STORAGE INSTRUCTIONS : tightly capped in steel cupboards
ANY ADD. RELEVANT. INFO. : use fume cupboard for addition
YOUR INITIALS & SIGNATURE : H.I.K
24- When following or writing a procedure manual, follow or include safety precautions
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Dr. H.Khouja
2nd Year MT Skill
regarding the reagents used.
e.g.: H2S04 - corrosive.
Lab Safety
Na Azide - toxic
25- After using corrosive or toxic materials, all glassware must be thoroughly rinsed
with water or ethanol as appropriate before leaving them for the normal wash.
26- NEVER use the common drain to dispose of chemical liquid waste, especially
harmful substances.
27- Avoid spilling chemicals on benches or floor.
28- If spillage occurs, then use commercially available spill removal kits.
29-Generally, NaHCO3 powder is used for acid spills and 2% Acetic acid for alkali
spills.
30-Use eye-wash and call doctor if splash is on the eyes.
31-Use emergency shower if splash is on the skin.
32-Remember that most chemical substances are toxic in excess
33-Exposure to chemicals can be through:
a) direct skin contact.
b) inhalation (breathing).
c) injection I inoculation ( by needle stick or sharps).
d) ingestion into the alimentary canal by mouth.
34- Effect of chemicals on the body (local or systemic) can be acute or chronic
depending on:
1 - Type of chemical.
2- It's concentration.
3- Duration of exposure.
BUT generally:
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2nd Year MT Skill
Dr. H.Khouja
Lab Safety
ACUTE = short or single contact with high concentration of harmful chemicals.
CHRONIC = long-term, repeated contact with smaller concentrations of harmful
chemicals.
Types (categories) of Chemicals: According to safety [hazard] encountered in the clinical lab
A) Corrosive:
Acids Sulfuric, Hydrochloric Nitric, ... etc.
Alkalis: KOH, NaOH, NH4OH, .. etc.
Causes severe burn (especially at HIGH concentrations) to skin and eyes by direct contact
Causes severe injury to the respiratory tract if inhaledCauses severe injury to gastrointestinal tract if ingested or swallowed
B) Toxic Cause death even at low concentrations or doses by various routes
-Direct skin contact
-Injection I Inoculation
-Ingestion
Examples:
- KCN Very toxic, death occurs in minutes by all routes.
-Mercury and its vapors and compounds : extremely volatile and are rapidly absorbed by skin and
respiratory tract.
—Na azide skin contact, injection, inhalation, ingestion.
—Selenium vapor toxic by inhalation.
-Many substances are toxic at High concentrations
-Many gasses and vapors coming off from reactions
a) Less explicit sensations
-CO (carbon monoxide) or silent killer
- Chlorform
CCl4
-Methanol — Acetone
b) Explicit sensory irritations:
-Bromide
-Ammonia
-Formaldehyde
C) Carcinogenic chemicals
These cause cancer of one or more of the organs of the body. e.g.
— benzidines
-NaNO2
-aspestos fibres
With more and more studies the list of such chemicals is increasing, so updated lists should be
consulted frequently.
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2nd Year MT Skill
Dr. H.Khouja
Lab Safety
D- Flammable / Combustible:
Flash point (FP): the temperature at which sufficient vapor is given off to form an ignitable mixture
with air.
Flammable liquids; FP BELOW 37.8 oC
Combustible liquids; FP AT or ABOVE 37.8 oC
They are mainly used in lab, for dissolving, extracting, fixing, developing, cleaning and other purposes
Liquids: Acetone. benzene, methanol, ethanol iso-propanol,petroleum ether, toluene, xylene .. etc.
Gasses: methane, propane
Solids: paraffin.
E- Reactive chemicals
These are chemicals which under certain conditions can spontaneously explode, ignite, evolve heat,
evolve flammable or explosive gasses.
Examples;
-Na or K elements when mixed with water H gas is liberated & ignite
-CaO and conc acids (H2S04, HC1, HNO3) when mixed with water are extremely exothermic
-peroxides (and other strong oxidizing agents) when mixed with strong reducing agents violent
reactions with possible explosion or ignition may occur
-explosive on contact with air; picric acid, nitroglycerides, perchlorates
F- Incompatible chemicals
These are chemicals that when they come in contact with certain other chemicals toxic, flammable, or
explosive compounds.
Examples:
—acetic acid with chromic acid —acetic acid with nitric acid
-azides & copper
-azides & iron —CC14 & Na
-methanol & H2O2
-methanol & HNO3
-ethanol & H2O2
-ethanol & HNO3
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