ehs logo

Health & Safety Manual - Biological Safety

2.4 Work Practices

2.4.1 Basic Precautions
2.4.2 Fire Prevention and Biological Safety
2.4.3 Pipetting and Repetitive Stress Injuries

Principal Investigators are responsible for ascertaining that their staff are appropriately trained to carry out their assigned laboratory functions, but ultimately individuals bear primary responsibility for their own safety and health. Never hesitate to inquire of senior lab staff if there is an activity that you are not sure you can perform safely. You may also contact EH&S in such a situation.

2.4.1 Basic Precautions

  • All laboratories must have a door sign that states the name, and phone number of the PI, emergency contact number(s), any entry restrictions, and for labs working at BSL-2 or -3, the universal Biohazards symbol.  These signs are provided by EH&S.
  • Keep laboratory doors closed when working with BSL-2 or BSL-3 organisms.
  • Drinking, chewing gum, applying cosmetics, or handling contact lenses in work areas is strictly prohibited, as is the storage of food or beverages in refrigerators/freezers used for research materials.
  • Cover work surfaces with ‘bench-kote’ or other absorbent; use disinfectant-soaked towels for work with highly infectious material or when splashing/spattering is anticipated.
  • Decontaminate work surfaces at the end of procedures and immediately after a spill.  Limit bench-top items to those in immediate use; cluttered areas are more likely than well-maintained spaces to be the sites of accidents and are harder to clean and disinfect.
  • After use, place reusable sharps such as surgical instruments, in puncture-resistant containers with disinfectant solution and labeled with the biohazard symbol.  Detailed protocols must be developed for handling, cleaning, disinfecting and/or sterilizing reusable sharps.  See:
  • Minimize splashing and aerosol generation.  When pipetting, expel liquids against the side-wall of a tube rather than against the tube bottom.  If aerosols of infectious materials will be generated, work in a BSC.
  • Use secondary containers (trays, specimen transport bags) for the prolonged storage or transport of infectious materials. Whenever possible, replace glass lab ware with plastic; glass Pasteur pipettes are particularly prone to breakage.
  • Never pipette by mouth.
  • Use only mechanical pipetting devices and cotton-plugged pipettes; do not expel air through a pipette to mix suspensions containing infectious or toxic materials. 

Go to Top

2.4.2 Fire Prevention and Biological Safety
Efforts to eliminate contamination, as practiced in some settings, run counter to basic fire prevention principals.  This may occur in two types of activities:

  • Dipping cover slips, cell spreaders and other items for which contamination-free status is required, into alcohol followed by flaming with a Bunsen burner.  This may result in a fire when ignited alcohol drips onto flammable material.
    • Use disposable cell spreaders, which may be collected and re-sterilized by autoclaving for subsequent use.
    • Instead of dipping and flaming cover slips, autoclave batches in a glass petri dish.  If kept covered in a biological safety cabinet, the slips will remain sterile.
  • The use of burners in a biological safety cabinet to flame pipets, bottle and tube necks and inoculating loops needlessly places an ignition source in the work area.  The environment inside the cabinet is microbiologically sterile.  Using wrapped sterile pipets in this environment eliminates the need to flame.  Single use inoculating loops are available and like cell spreaders may be collected and re-sterilized by autoclaving for subsequent use.  Opening and closing of tubes and bottles inside the cabinet eliminates the need for flaming the necks of these containers.

If you must use a flame or heat either purchase a model that comes with a low-flame pilot light or a micro-incinerator that provides a heat source without an open flame.

2.4.3 Pipetting and Repetitive Stress Injuries
Repetitive pipetting, particularly with multi-channel devices may result in harmful stress on the arms, wrists, or shoulders.  Some of this stress can be eliminated by using devices designed with ergonomic considerations.  Ask your supplier about such models or contact EH&S to obtain product information.  To reduce the risk of repetitive stress injuries:

  • Rotate pipetting tasks among several people.
  • Take short pauses of a few seconds when you can’t take a longer break.
  • Choose pipetters requiring the least pressure; use only the force necessary to operate it.
  • Work with arms close to the body to reduce strain on shoulders.
  • Keep head and shoulders in a neutral position (bent forward no more than 30 degrees).
  • Use adjustable chairs or stools; high stools will force you to work with a bent neck.
  • Don’t elevate your arm for lengthy periods without support.

Frequent pipetting requiring thumb action to expel liquids may cause inflammation of the tendon or sheath used for this motion; use pipettes that expel liquids with a "clenching-the-fist" motion.

Go to Top