Updated 5/2023

Interim Biosafety Officer: Amy Robison, [email protected] (406) 994-6733

MSU Office of Research Compliance


Autoclaving is an accepted procedure for the decontamination of certain biohazardous waste.  Biological cultures, stocks, contaminated solid waste, and liquid waste can be sterilized through autoclaving.  After sterilization in a validated autoclave, these materials are considered non-biohazardous.  Materials that contain hazardous chemicals, including bleach, must not be autoclaved.

This assurance program applies to all autoclaves used to sterilize waste from Biosafety Level 1 and 2 laboratories.

To ensure that biohazardous waste is properly decontaminated during autoclaving, the following procedures should be followed by laboratory personnel:

  1. Biohazardous waste must be treated in an autoclave for a minimum of 60 minutes at 121oC (250oF); however, the total processing time required to decontaminate biohazardous waste depends on the specific loading factors (container type, water content, quantity, etc.).
    1. Sterilization by autoclaving is accomplished through exposure and penetration of the contaminated material by steam for an adequate amount of time. Because steam will not penetrate a sealed plastic autoclave bag, bags containing dry loads must not be tightly sealed.
    2.  To help ensure proper sterilization water may be added to the load.  Liquid waste may also be autoclaved instead of adding chemical disinfectants and disposed in the sink.
  2. Autoclaved waste must include a steam sterilization indicator strip and/or autoclave tape.
  3. The operating autoclave temperature and time must be verified for each run.  Records of the temperature and time must be maintained for at least one year.
  4. On a monthly basis (at a minimum), confirm that adequate sterilization occurs through the use of Biological Indicators (BIs). Place BIs in the center of autoclave bags (dry loads) or in the liquid (liquid loads) of an autoclave load. There are specific BIs for both dry and liquid loads.
  5. Record monthly BI results in the Autoclave Quality Assurance Form and submit for records.

Monthly Spore Testing Procedure

  1. Place BIs in the center of autoclave bags (dry loads) or in a container with water (liquid load) of an autoclave load. You may tie string to the indicators and tape the string to the outside of the bag/container for easy retrieval.

    Note: The container of water for liquid loads should represent to type of container used and the largest volume of liquid waste to be autoclaved.

  2. Run the autoclave load under normal operating procedures.

  3. Incubate the autoclaved BIs and a non-autoclaved control BI according to the manufacturer’s instructions (normally 55°-60° C for 24 to 48 hours).

  4. If a color change occurs in an autoclaved BI, the sterilization process was unsuccessful.  Discontinue use of the autoclave until it is repaired and passes retesting. Tag the autoclave as “Not Approved for Biohazardous Waste” until the autoclave passes retesting.