Decontamination and Disinfection

Decontamination of work surfaces is essential to prevent researcher exposure and contamination of experiments.  All material taken out of a biological lab should be surface decontaminated before leaving the lab. Decontamination reduces the microbial contamination of materials or surfaces and is accomplished through the use of a chemical disinfectant.  

 

Disinfection refers to the elimination of virtually all pathogenic organisms on inanimate objects and surfaces thereby reducing the level of microbial contamination to an acceptably safe level.  Disinfection is accomplished through use of chemical disinfectants.  In contrast, sterilization refers to the destruction of all microbial life.  At MIT, sterilization is accomplished with heat and steam by autoclaving.

Chemical disinfectants will vary in their effectiveness. Choosing an appropriate disinfectant will depend on a number of factors such as the organism you are handling, the item to be disinfected, and the nature of the disinfectant (cost, ease of use, contact time, residue, odor, etc).

 
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Choosing a disinfectant

 

Choosing an appropriate disinfectant will depend on a number of factors.  First, you will have to determine what disinfectant will inactivate the organism you are using.  Your application will also be important.  Do you need a full decontamination in a spill condition, or are you looking for a product for surface disinfection for general cleanup?  Finally, practical factors such as cost, shelf life, contact time, and Personal Protective Equipment (PPE) requirements can affect your choice.  Please consult the flow chart below for information on selecting an appropriate disinfectant.

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Disinfectant Effectiveness Chart

 

The graph below gives a general overview of the effectiveness of the different classes of disinfectants when used to disinfect different types of biological agents.  Individual products may vary – for example, many of the quaternary ammonium products we recommend have been developed to be effective against Mycobacterium tuberculosis.  Please check the product label for specific efficacy.

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Disinfectant Type and Practical Characteristics

 

     Disinfectant effectiveness will vary depending on the active ingredient in the disinfectant and the nature of the organism.  There are seven broad categories of disinfectants.  Each has benefits and limitations:

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Disinfectants Commonly Used at MIT

 

     The table below shows many disinfectants that are commonly used at MIT and the contact time necessary.  This list is not exhaustive, and other disinfectants are available.  Please contact your biosafety officer if you have questions.

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Disinfectant Cost and Shelf Life

 

Disinfectants vary in cost and how long they last (shelf life).  In generally, concentrated disinfectant will be cheaper than ready-to-use formulations, but the dilutions generally have a shorter shelf life.  Buying disinfectant in bulk quantities can significantly reduce the cost for some disinfectants but storage requirements and shelf life needs to be considered.  The charts below show the disinfectant cost and the shelf life.  Some of these disinfectants are available in the VWR stockroom, and the majority can be ordered through the Atlas eCat system.

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Disinfectants appropriate for use with human material

 

The OSHA Bloodborne Pathogen Standard is designed to protect workers from exposure to Bloodborne Pathogens, including but not limited to HIV, Hepatitis B, and Hepatitis C.  It requires that work surfaces that are contaminated with blood or other potentially infectious material (anything from the human body, including human cell lines) or that have the potential to have become contaminated during the course of work be decontaminated with an appropriate disinfectant. 

Any lab that works with human material must use an appropriate disinfectant to disinfect work surfaces or to decontaminate surfaces and equipment after a spill.  Currently, OSHA recognizes the following as appropriate disinfectants:

  • EPA-registered tuberculocidal disinfectants (EPA-registered list B)
  • EPA-registered disinfectants that are labelled as effect against both HIV and HBV (EPA-registered list D)
  • Diluted bleach solutions (10% or greater dilution of household bleach which equates to 0.5% or greater sodium hypochlorite)
  • Sterilants/High-Level Disinfectants cleared by the FDA (Note: most researchers don’t use these products)
  • Please note that 70% ethanol is NOT recognized as an appropriate surface disinfectant by OSHA.  Evaporation of the alcohol prevents sufficient contact time to inactivate Hepatitis B. 

To check if your product meets the OSHA requirements:

  • Locate the EPA registration number found on the label of your product.
  • Go to the appropriate EPA list using the links above.
  • Search the list using the first two sets of numbers in the EPA registration number.  For example, if your product label lists the EPA registration number as 777-99-675, search the list for 777-99 (omit 675 from your search). 
  • The last number is the distributor identification number.  These will not be included on the EPA lists.  Only the initial formulation submitted to the EPA is listed.

For disinfectants commonly used at MIT that meet these requirements, please see Commonly Used Disinfectants at MIT section above.

For more information about using human material at MIT, please see the Bloodborne Pathogen webpage.

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