Laboratory safety has two goals, one is the prevention of accidents and the other is containment of the consequences of an accident. While the prevention of accidents is a primary goal, they can occur; in such cases, containing and limiting the damage becomes very important. Safety guidelines are intended to reduce the chance of an accident occurring. However, knowledge of these guidelines alone will not prevent all accidents. Rules cannot be written to cover all potentially dangerous situations. Common sense, alertness and a cool head go a long way to ensure that unexpected situations are detected before they become dangerous situations.
Accidents usually create a feeling of panic, if only momentarily. Your reflex action in panic situations was established years ago. For some people, it is a time when their actions are irrational; some will freeze; some will react in a reasonable way to try to contain the accident. If you are aware of the dangers, have taken reasonable precautions and know what to do in the event of an accident, these situations will be much less fearful and the feeling of panic much less severe. You will be more likely to react in a rational way if you are aware of the safety, accident and fire procedures laid out in this manual.
A. GENERAL CONSIDERATIONS ‑ AN OVERVIEW
A‑1 Working Alone
A-2 Safety Glasses
A-3 Fume Hoods
A-4 Vacuum Equipment and Safety Shields
A-5 Carrying Chemicals
A-6 Open Flames
A-7 Refrigerator Storage
A-8 Large Scale Reactions
A-9 Heating Open Vessels
A-10 Heating in a Closed System
A-11 Mixing Concentrated Acids, Bases and Oxidants
A-12 Superheated Liquids
A-14 Chemical Labels
A-15 Replacing Chemicals
A-16 Clothing Protection
A-17 Loose Clothing
A-19 Waste Chemical Disposal
A-20 Safety Equipment
A-21 Know Hazards
A-22 Thermometer Use
In the laboratory the chemist works with many potentially dangerous substances. Yet, with constant alertness, awareness of the potential hazards, and a few common‑sense precautions, laboratory operations can be carried out with a high degree of safety. Although commitment to safety programs must begin at the highest levels of administration, most of the responsibility for the personal safety of the laboratory workers rests on the workers themselves.
A large proportion of reported laboratory accidents are a result of cuts from broken glassware, knives, etc. Chemical hazards in the laboratory may be divided into three main categories: contact of chemicals with the body (toxic and corrosive hazards), fires involving chemicals, and explosions involving chemicals. Many laboratory accidents involve a combination of these hazards. For example, a solvent spill in the presence of a faulty electrical system which is generating sparks might result in a fire (or explosion) or a blockage in equipment might result in an explosion throwing chemicals on a worker. Although gassings and explosions account for less than 2% of accidents, they result in more than a third of fatalities. The evidence for occupationally induced cancer in chemical laboratory workers is weak despite the wide range of potential mutagens and carcinogens found in laboratories. Better studies are required to ascertain if there is an increased risk of certain types of cancers. Allergic responses to chemicals is a very common problem; they are responsible for more than half of the laboratory problems necessitating a change in employment.
Be Alert, Stay Alert
The basic rule of safety in the laboratory is: be alert ‑‑ stay alert; the laboratory is no place for the "absent‑minded professor". Take the trouble to understand what you are doing and to know what the hazards are; take the appropriate precautions, and use the appropriate protective equipment. Some of the more important laboratory rules and precautions are summarized under the following 21 headings.
A-1 Working in the laboratory alone
When carrying out potentially dangerous reactions outside regular hours, it is strongly recommended that someone else be nearby to provide assistance in case of need.
A‑2 Wear eye protection whenever there is a potential hazard.
"Safety glasses" with impact‑ resistant lenses in approved frames, protective goggles, a face shield, or some appropriate combination of these must be worn whenever there is a potential hazard in the laboratory. Safety glasses are approved only for impact resistance; goggles must be used when there is a potential splash hazard. Safety glasses may be obtained either ground to prescription or non‑refracting. Safety glasses and goggles are available from the Science Stores. Side shields of transparent plastic may be clipped on to glasses for additional protection. In the event of an explosion the lenses of ordinary glasses are much more easily shattered and the glass fragments may be driven into the eyeball; in such a case they can be worse than no glasses at all.
A Caution to Those Wearing Contact Lenses
Contact lenses provide negligible protection, and indeed their use may seriously aggravate hazards from splashed liquids since they will impede washing the eye free of caustic liquids that creep or diffuse under them. It is inadvisable to wear them even under safety glasses, which (it must always be remembered) do not provide good protection from liquid splashes from the top, sides, or bottom; goggles should be worn. Soft contact lenses may absorb and retain vapors (resulting in eye damage due to prolonged contact of the eye with chemicals).
for all operations involving poisonous or offensive gases, fumes or vapours, as well as for operations involving highly flammable or potentially explosive materials. The combination of a fume hood and a safety shield (see below) will provide the maximum readily available protection against minor laboratory explosions. A continuing complaint during inspections is the improper use of fume hoods. Fume hoods must be used properly or they may only give the illusion of protection. Before using a fume hood, one should always check that it is functioning. A simple method of doing this is to tape a small strip of Kleenex or other tissue to the bottom of the sash; this will give an immediate indication of air flow. The exhaust rate is not a single reliable measure of a fume hood's effectiveness; air supply to the room is also important since drafts across the hood face may cause leakage. The ABB fume hoods are not designed to work properly if laboratory doors are left open; these are also fire doors and must be kept closed by law. Although high air flow may cause difficulties when using finely powdered materials and may also cause turbulence resulting in leakage from the hood, normally the hood should be used with the sash as fully closed as possible. Unnecessary materials (reagent bottles, waste bottles, extraneous equipment, etc.) should not be left in the hood since they will cause turbulence that may result in leakage from the hood. This leakage usually occurs where the worker is standing blocking the flow of air into the hood. Equipment should be kept at least 6 inches from the edge of the hood and placed centrally in the hood. Chemicals (including flammable waste solvents) should not be stored in a hood to be used for experimental work because of the added danger in the event of an explosion or fire.
Guard against injury from explosion, implosion, flash fires, and splatter of dangerous liquids by interposing a "safety shield" or other effective barrier between all personnel and any set-up presenting such hazards. This would include vacuum distillations, gas scrubbing trains containing significant amounts of corrosive solutions and all evacuated equipment of any significant size. Additionally, Dewar flasks, vacuum desiccators and other large vessels under vacuum should be well taped with electrical tape in order to contain the glass in the event of implosion.
Only approved safety carriers with well‑fitting covers can be used to transport any dangerous liquids or any solvent in amounts equal to or exceeding 500 mL. Plastic pails are not approved carriers.
A-6 Never heat a flammable solvent in an open vessel over an open flame.
Keep a respectable distance between open vessels containing flammable solvents and any open flames or sources of sparks (e.g. stirring hot plates). Chloroform and methylene chloride will form phosgene in a flame. Except under special circumstances, an open flame should never be used in the laboratory. If necessary, as for glassblowing, open flames are permitted but should be extinguished as soon as they are no longer required. Substances with very low auto-ignition temperatures such as diethyl ether have been ignited by hot plates and carbon disulfide ignited even by steam pipes.
Beakers or unstoppered flasks containing chemicals should not be placed in a refrigerator (even if it is of the "explosion proof" type) or in any other unventilated enclosure. Food or beverages must never be stored in a refrigerator used for storage of chemicals.
Never store volatile toxic materials in a refrigerator or other unventilated enclosure even in a "stoppered" vessel. The first breath a person takes after opening the refrigerator door could be his/her last. Volatile flammable substances must only be stored in approved "explosion proof" refrigerators.
Reactions that work safely with small quantities may not be safe when scaled up (i.e. more than about 100 g).
Always be careful to avoid pointing the mouth of a vessel being heated toward any person, including yourself.
Except for certain operations for which special instruction should be obtained beforehand (reduced‑pressure distillations, reactions in bombs or sealed tubes, etc.) never heat reactants of any kind in a fully closed system; be sure the system is open to the air at some point to prevent pressure build-up due to boiling or gas evolution.
Never add anything TO a concentrated acid, caustic, or strong oxidant; instead add the acid, caustic, or oxidant slowly and cautiously to the other ingredients, preferably no faster than it is consumed by reaction.
Never add solids (boiling chips, charcoal, etc.) to a hot liquid as this may result in violent boiling if the liquid happens to be superheated. Such additions should be performed when the liquid is still at room temperature.
A‑13 Never pipette by mouth.
Fill a conventional pipette with a rubber bulb or use an automatic pipette.
All chemical containers should be correctly and clearly labelled. Labels for your preparations should contain, besides the name or formula of the contents: your name, the date, and a sample number by which it can be identified in your notebook. Proper labelling is a requirement of the WHMIS legislation.
A‑15 Replacing Chemicals
One should never pour anything back into a reagent bottle.
Protect your self and your clothing by wearing a laboratory apron or a laboratory coat. Lab coats should be washed frequently. Lab coats should not be washed in home laundry equipment. Lab coats could be washed manually in the laboratory sink. Contaminated clothing such as lab coats should not be worn outside the laboratory.
Dangling neckties or scarves, unrestrained long hair, and fluffy or floppy clothing (including over‑large or ragged laboratory coat sleeves) can easily catch fire, dip into chemicals on the laboratory bench, get ensnarled in apparatus and moving machinery, etc. Remove or restrain your long necktie/scarf, put up long hair or at least restrain it with a rubber band. Open‑toed sandals should never be worn in the laboratory. Bare feet are strictly forbidden in the laboratory; be sure to warn your friends who may visit you in the summer. Shorts and T-shirts are also strongly discouraged; they expose large areas of the arms and legs to contaminants and to fire.
The first action to be taken in the event of a chemical spill on the skin is to thoroughly wash the effected part with lots of water. See also Section E-1.
Your hands should be protected with rubber or plastic gloves when handling toxic materials or caustic liquids, or with canvas or other appropriate gloves when handling hot or very cold objects. Gloves made of the proper material should be selected for the chemicals being used; some highly toxic substances will penetrate rubber or vinyl gloves. A list of many chemicals and the most resistant materials to be used with them is available at the back of the Cole-Parmer catalog. One should also be aware that gloves, even when new, may contain holes. Do not hesitate to discard gloves (or aprons, lab coats or even shoes) that become contaminated or have holes in them. Contaminated gloves should be removed before exiting the lab in order to avoid contamination of door knobs, telephones, Departmental instruments, etc.
You should know and observe the approved procedures for disposal of the chemicals and laboratory refuse associated with your experiment (see Section G‑3). No chemical waste should go down the sink. Package hazardous chemical wastes in suitable containers appropriately labelled according to the classifications shown below:
1) Inorganic acids (e.g. hydrochloric and sulfuric acid)
2) Elements and inorganic acidic salts that do not liberate gaseous products when acidified
(eg. solids pH range 7 to 1--sulfate salts, boric acid)
1) Inorganic alkaline chemicals (eg. sodium hydroxide)
2) Organic bases (eg. amines)
3) Elements and inorganic alkaline salts (eg. copper oxide and sodium sulfide)
1) Solid organic compounds (excluding organic bases) (eg. sodium acetate, phenol, carboxylic acids)
1) Non-halogenated organic liquids (excluding bases, resins and paints) (eg. alcohols, ketones, aldehydes, esters, organo-acids)
2) Halogenated organic liquids (eg. carbon tetrachloride, chloroform)
1) Inorganic oxidizing agents (eg. permanganates, nitrates, periodic acid, perchloric acid, chromium trioxide)
1) Inorganic cyanides (eg. sodium cyanide, ferricyanide)
1) Organic pesticides, herbicides and rodenticides
2) Inorganic pesticides, herbicides and rodenticides
1) Potential shock sensitive materials (eg. picric acid, 2,4-DNP)
2) Organic oxidizers (eg. benzoyl peroxide)
3) Moisture sensitive organic compounds (eg. silanes, acid chlorides)
4) Alkyl and aryl metal complexes (e.g. Grignard reagents, triethyl aluminum)
5) Moisture sensitive flammable inorganic materials (eg. sodium)
6) Moisture sensitive corrosive inorganic compounds (eg. titanium tetrachloride)
Note: The above must be shippable under the Transportation of Dangerous Goods Act
1) Pressurized, compressed or liquified gases in lecture bottles or other cylinders (eg. hydrogen sulfide, carbon dioxide)
1) Paints, varnishes and thinners
1) Resins and non-reactive activators (eg. isocyanates, polymers)
2) Glues and adhesives
Exceptions: (the following materials are not disposed of with the normal chemical waste)
1) Radioactive materials of any type
2) PCB's of any type
3) Bio-hazardous materials
Beyond these general classifications, one should be aware of potential specific chemical incompatibilities. One of these, which is avoided by segregating halogenated solvents, is the potential reaction between acetone and chloroform. These will react to produce "chloretone" in an exothermic reaction catalysed by bases. In a tightly closed bottle, a violent explosion can take place.
Label Waste Bottles Clearly
Labels for waste bottles may be obtained from Science Stores and must be placed on waste containers when they are first set out for use. Unlabelled waste will not be accepted. Any unusual wastes should be labelled with a description so that the waste can be sorted later according to its chemical compatibilities with other substances. It is important that such information be provided. Unknown chemicals will not be accepted for waste disposal; wastes must be accurately identified.
Waste should not be allowed to accumulate in the labs. Please follow this link to download the new procedures for disposing of hazardous waste and the on-line submission form:
A-20 Safety Equipment
Know the location of exits, fire extinguishers, fire blankets, sand pails, safety showers and eyewash fountains. Supervisors are legally responsible for ensuring that their students/employees are trained in the proper use of safety devices. Familiarize yourself with the purposes of these devices and with the procedures for their use.
Fire blankets are to be found in ABB just outside the chemistry wing on the most floors (outside ABB 474, 367, 266A, B113) and half way down the wing on the first floor (outside ABB 115). If clothing is on fire, get the victim to the floor, roll them over and over, and smother the flames with the fire blanket or a lab coat.
Chemicals In The Eyes
In case of eye contact with chemicals, immediately bathe the eyes in cool running water: subject the eyes to a copious (but not forceful) flow of water from the eyewash fountain located by the exit door; hold the eyelids thoroughly open to bathe the eyeballs and undersides of eyelids.
Summon medical help immediately (call 88). If alkali is involved, follow the washing by water with application of a 3% solution of boric acid. Time is of the essence; caustic alkali can destroy the cornea in as little as five minutes. CAUTION: Boric acid should be used externally for the eyes only. Boric acid is very toxic if taken internally, thus never take boric acid by mouth as an antidote for a base or for any other reason.
Eye wash fountains should be flushed for several minutes each week to minimize the build-up of microorganisms.
Before beginning any procedure with which you have not had adequate previous experience and/or don't have a thorough knowledge of the hazards, you should find out what the hazards and appropriate precautions are by reading the literature and/or conferring with someone having such knowledge and experience. Supervisors are legally responsible for ensuring that their students/employees are properly trained to handle hazardous materials and procedures. (See list of references, Section K).
When inserting a glass thermometer into a rubber adapter or stopper, use lubrication and protect the hands in case of breakage by using wadded up paper towels or other protection. Grasp the thermometer near the insertion point and try to apply force directly down the axis of the thermometer.
This list of twenty‑one safety guidelines and precautions has been chosen somewhat arbitrarily and is by no means complete. However, it represents in our view a selection that contains the most important precautions. This list should be reread periodically until observance of these precautions has become second nature. These same precautions and some additional ones will be treated in specific contexts in the following sections which should be read in advance of performing the corresponding laboratory operations and should be reviewed from time to time.