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Laboratory Safety

TOPIC 

General Safety Guidelines 
Aerosol Production 
Animals and Hazardous Materials
Centrifuges 
Compressed Gases 
Cryogenic Liquids 
Electrophoresis 
Glassware 
Heating Systems 
Pressurized Systems 
Refrigerators/Freezers 
Vacuum Systems 

General Safety Guidelines

      Because laboratories involve numerous chemicals, procedures, and operations, they require extensive safety precautions. Laboratory safety involves chemical safety, fire safety, electrical safety, and other safety issues. Follow the guidelines in this chapter for general laboratory safety, but refer to other chapters in this manual for specific information.

      This section discusses the following:


Common Laboratory Hazards

      Examples of common hazards include the following:

          Toxins, corrosives, flammables, and reactives

          Microbes, animals, plants, and genetically modified agents

          Ionizing and nonionizing radiation

          Heating devices, noise, projectiles, fire, cold, etc.

          Fire and shock

          Moving machinery

          Vapours, dust, etc.

          Standing, repetitive motion


Controlling Laboratory Risks

      Administrative and engineering controls can help minimize laboratory risks. However, safety
      conscious workers using good laboratory practices are the most important component of
      laboratory safety. The following factors are important for safe laboratory operations:

          *    Proper ventilation
          *    Nonslip surfaces
          *    Hand washing facilities

          *    Personal protective equipment
          *    Laboratory equipment
          *    Safety devices on laboratory equipment, machines, devices, and instruments

          *    Fire extinguishers
          *    Emergency showers
          *    Eye wash stations

          *    Good housekeeping
          *    Personal hygiene (e.g., washing hands)

          *    Experienced
          *    Trained

      All laboratory doors should be labelled with emergency contact information. If an incident occurs during off-hours, respondents need to know the names and telephone numbers of the people responsible for laboratory operations. Keep this information current and accurate. Emergency contact labels are available from the Health & Safety Department.

      Properly trained and experienced workers have the greatest ability to control laboratory risks. By using good laboratory practices, workers can minimize hazards, exposure, contamination, and workplace accidents.


Safe Laboratory Practices

      To ensure laboratory safety, follow safe laboratory practices, including the following:

                IMPORTANT:
                Never underestimate the hazards associated with a laboratory. If you are unsure about what you are doing, get assistance. Do not use unfamiliar chemicals, equipment, or procedures alone.


Equipment Safety

      There are four fundamental elements of equipment safety: (1) use the correct equipment, (2) know how to operate the equipment, (3) inspect the equipment, and (4) use the equipment properly.

      Use equipment for its intended purpose only. Do not modify or adapt equipment without guidance from the equipment manufacturer or the Health & Safety Department. Do not defeat, remove, or override equipment safety devices.

      Working in a laboratory requires various types of equipment. To ensure equipment safety, you must be familiar with the following:

      Always inspect equipment before using it. Ensure that the equipment meets the following requirements:

               IMPORTANT:
               Disconnect any equipment that is unsafe or does not work properly, and remove it from service. Notify other users of the problem.

      Refer to other sections in this manual for specific information on operating laboratory equipment, such as fume hoods, heating devices, vacuums, etc.


Aerosol Production

      The term "aerosol" refers to the physical state of liquid or solid particles suspended in air. Aerosols containing infectious agents and hazardous materials can pose a serious risk because:


Animals and Hazardous Materials

      Any research or instructional use of hazardous materials in live animals requires the submission of an Animal Use Protocol to the appropriate Animal Care and Use Committee. The Protocol must be fully approved before any researcher may acquire, house, or use animals.

                IMPORTANT:  With the increasing prevalence of animal testing, there comes a greater need to protect researchers. Consider both the direct hazards associated with research animals and the hazardous metabolic by-products produced by research animals.


Animals and Toxic Chemicals

      Animal research or testing with toxic chemicals (including known or suspected carcinogens) may produce aerosols, dusts, or metabolic by-products that contain toxicants. The animal bedding, equipment, and surrounding atmosphere may become contaminated.

      When working with research animals and toxic chemicals, always wear gloves and button your laboratory coat. If aerosol production cannot be controlled, use a respirator. Follow all instructions outlined in the approved Animal Use Protocol for handling these agents.

      A respirator with a HEPA filter will protect you from airborne particulates, but it will not protect you from chemical vapours. Wetting animal bedding before cleanup will help reduce aerosols.


Animals and Infectious Agents

      Personnel performing animal research with infectious agents or working with animals that carry potential zoonoses must utilize isolation procedures. The extent of isolation must be appropriate for the infection risk. All work with these agents and animals that could shed these agents must be approved by the Committee on Infectious Biohazards. Examples of zoonotic diseases that pose a hazard to humans include the following:

      Conduct work with infectious agents according to good laboratory procedures and containment practices. For information on proper disposal methods, refer to the Biological Safety chapter in this manual.


Animals and Recombinant Genetic Materials

      Animal research with recombinant DNA (rDNA) must be conducted in accordance with Health guidelines and Company requirements. Because containment and disposition is a critical concern, all experiments involving rDNA or genetically altered animals (including recombinants, transgenics, and mosaics) must receive prior approval from the Institutional Biosafety Committee.


Animals and Radioactive Materials

      A Radiation Safety Officer must approve the use of radioactive materials in animals.  Permits to use radioisotopes must be acquired through the Health & Safety Department.


Mechanical Injury Hazards

      Mechanical injury is the most common hazard associated with animal research. Animals are capable of inflicting extensive injury to humans. Most research animals can bite or scratch. Livestock, large animals, and primates can bite, batter, or crush. Because disease and infection are easily spread by bites and scratches, researchers must take special care when working with animals.


Animal Allergies

      Researchers who work with animals may develop allergic reactions, including rhinitis, conjunctivitis, asthma, and dermatitis. Symptoms of animal allergy may include nasal congestion, sneezing, watery eyes, hives, and eczema.

      Rabbits and rodents are the most common research animals that cause severe allergic reactions. Animal dander, fur, bedding, urine, saliva, and tissues are the primary sources of allergic antigens. Mold spores and proteins in animal feed may also act as antigens.

      To reduce exposure to animal allergens, minimize the generation of aerosols and dust and wear protective equipment. Take special care to wear respiratory protection and gloves when feeding animals, handling animals, changing bedding, or cleaning cages.


Indirect Animal Hazards

      Indirect hazards occur when research animals are intentionally exposed to biological agents, chemicals, and radioactive materials. Because animal bedding, equipment, waste products, and surrounding atmosphere may become contaminated, these items can be hazardous. To protect personnel, manage all animal products and areas according to specific procedures approved by the appropriate oversight committee.

                    NOTE:  See the Agriculture Safety chapter for more information pertaining to the safe handling of livestock.


Centrifuges

      Centrifuging presents the possibility of two serious hazards: mechanical failure and aerosols. The most common hazard associated with centrifuging is a broken tube. To ensure safety when operating a centrifuge, take precautions to ensure the following:

      Follow these guidelines when working with a centrifuge:

      Low-speed and small portable centrifuges that do no have aerosol-tight chambers may allow aerosols to escape. Use a safety bucket to prevent aerosols from escaping.

      High-speed centrifuges pose additional hazards due to the higher stress and force applied to their rotors and tubes. In addition to the safety guidelines outlined above, follow these guidelines for high-speed centrifuges:


Compressed Gases

      Compressed gases in the laboratory present chemical and physical hazards. If compressed gases are accidentally released, they may cause the following:

      Cylinders that are knocked over or dropped can be very dangerous and can cause serious injuries. If a valve is knocked off a compressed gas cylinder, the cylinder can become a lethal projectile. Because disposal of compressed gas cylinders is difficult and expensive, be sure to arrange a return agreement with suppliers prior to purchase.

                IMPORTANT:   Cylinders can travel through walls much like a torpedo travels through water. They can cause structural damage, severe injury, and death.

      Follow these guidelines to ensure safe storage of gas cylinders:

          *    Three 10" x 50" flammable gas and/or oxygen cylinders, and
          *    Two 9" x 30" liquefied flammable gas cylinders, and
          *    Three 4" x 15" cylinders of severely toxic gases (e.g., arsine, chlorine, diborane, fluorine, hydrogen cyanide, methyl bromide, nitric oxide, phosgene).

When working with compressed gas cylinders, remember the following:

          *    Direct the cylinder opening away from people.
          *    Open the valve slowly.


Cryogenic Liquids

      Cryogenic fluids, such as liquid air, liquid nitrogen, or liquid oxygen, are used to obtain extremely cold temperatures. Most cryogenic liquids are odourless, colourless, and tasteless when vaporized. When cryogenic liquids are exposed to the atmosphere, however, they create a highly visible and dense fog. All cryogens other than oxygen can displace breathable air and can cause asphyxiation. Cryogens can also cause frostbite on exposed skin and eye tissue.

      Cryogens pose numerous hazards. For example, cryogenic vapours from liquid oxygen or liquid hydrogen may cause a fire or explosion if ignited. Materials that are normally non-combustible (e.g., carbon steel) may ignite if coated with an oxygen-rich condensate. Liquefied inert gases, such as liquid nitrogen or liquid helium, are capable of condensing atmospheric oxygen and causing oxygen entrapment or enrichment in unsuspected areas. Extremely cold metal surfaces are also capable of entrapping atmospheric oxygen. Additional hazards associated with cryogenic liquids include the following:
 

Cryogenic Hazard Source  Hazard 
Hydrogen, methane, and acetylene  Gases are flammable. 
Oxygen  Increases the flammability of combustibles. 
Liquefied inert gases  Possible oxygen entrapment. 
Extremely cold surfaces  Oxygen atmosphere may condense. 

      Because the low temperatures of cryogenic liquids may affect material properties, take care to select equipment materials accordingly.

      Follow these guidelines when working with cryogenic liquids:

                    IMPORTANT:    Be aware of the tremendous expansion and threat of asphyxiation when a cryogenic liquid vaporizes at room temperature.


Electrophoresis

      Electrophoresis equipment may be a major source of electrical hazard in the laboratory. The presence of high voltage and conductive fluid in this apparatus presents a potentially lethal combination.

      Many people are unaware of the hazards associated with this apparatus; even a standard electrophoresis operating at 100 volts can deliver a lethal shock at 25 milliamps. In addition, even a slight leak in the device tank can result in a serious shock.

      Protect yourself from the hazards of electrophoresis and electrical shock by taking these precautions:


Glassware

      Accidents involving glassware are the leading cause of laboratory injuries. To reduce the chance of cuts or punctures, use common sense when working with glassware. In addition, follow special safety precautions for tasks that involve unusual risks.

      Follow these practices for using laboratory glassware safely:


Heating Systems

      Devices that supply heat for reactions or separations include the following:

      Some laboratory heating procedures involve an open flame. Common hazards associated with laboratory heating devices include electrical hazards, fire hazards, and hot surfaces.

      Follow these guidelines when using heating devices:

           •Ensure that heating units have an automatic shutoff to protect against overheating.
           •Ensure that heating devices and all connecting components are in good working condition.

           RULE OF THUMB:  Reaction rates double for each 10 C increase in temperature.

          IMPORTANT:    Never leave an open flame unattended.


Pressurized Systems

      Do not conduct a reaction in, or apply heat to, a closed system apparatus unless the equipment is designed and tested to withstand pressure.

      Pressurized systems should have an appropriate relief valve.

      Pressurized systems must be fully shielded and should not be conducted in an occupied space until safe operation has been assured. Until safe operation is assured, remote operation is mandatory.

      Safety points to remember:

  1. Minimize risk and exposure.
  2. Identify and assess all hazards and consequences.
  3. Use remote manipulations whenever possible.
  4. Minimize pressure, volume, and temperature.
  5. Design conservatively.
  6. Use material with a predictably safe failure mode.
  7. Ensure that the components of the pressurized system will maintain structural integrity at the maximum allowable working pressure. Avoid material that may become brittle.
  8. Operate within the original design parameters.
  9. Provide backup protection (e.g., pressure relief valves, fail-safe devices).
  10. Use quality hardware.
  11. Use protective shield or enclosures.
  12. Use tie-downs to secure tubing and other equipment.
  13. Do not leave a pressurized system unattended.

    IMPORTANT:  Normally pressurized systems should not include glass components unless they are specially designed and intended for that purpose.


Refrigerators/Freezers

      Using a household refrigerator to store laboratory chemicals is extremely hazardous for several reasons. Many flammables solvents are still volatile at refrigerator temperatures. Refrigerator temperatures are typically higher than the flashpoint of most flammable liquids. In addition, the storage compartment of a household refrigerator contains numerous ignition sources including thermostats, light switches, and heater strips. Furthermore, the compressor and electrical circuits, located at the bottom of the unit where chemical vapours are likely to accumulate, are not sealed.

      Laboratory-safe and explosion-proof refrigerators typically provide adequate protection for chemical storage in the laboratory. Laboratory-safe refrigerators, for example, are specifically designed for use with flammables since the sparking components are located on the exterior of the refrigerator. Explosion-proof refrigerators are required in areas that may contain high levels of flammable vapours (e.g., chemical storage rooms with large quantities of flammables).

      Follow these rules for using refrigerators in the laboratory:

          *    Laboratory-safe and explosion-proof refrigerators should be identified by a manufacturer label.
          *    "Not Safe for Flammable Storage" labels are available from the Health & Safety Department.
          *    Refrigerators used to hold food should be labelled "For Food Only".


Vacuum Systems 

      Vacuum systems pose severe implosion hazards. Follow these guidelines and requirements to ensure system safety:

          IMPORTANT:    All vacuum equipment is subject to possible implosion. Conduct all vacuum operations behind a table shield or in a fume hood.

          CAUTION:  Do not underestimate the pressure differential across the walls of glassware that can be created by a water aspirator.

      The glassware used with vacuum operations must meet the following requirements:

      Glass desiccators often have a slight vacuum due to contents cooling. When using desiccators, follow these guidelines:


Cold Trap

      A cold trap is a condensing device to prevent moisture contamination in a vacuum line. Guidelines for using a cold trap include:


Disinfectant Trap

      A disinfectant trap should be used in-line when a vacuum is used with hazardous biological materials. The diagram below illustrates a suitable disinfectant trap assembly.