Appendix B – Decontamination and Disinfection

Appendix B:  Decontamination and Disinfection

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7 Comments

  1. Yolanda Arriaga Stringer's Gravatar Yolanda Arriaga Stringer
    May 20, 2016    

    It would be helpful if Appendix B – Decontamination and Disinfection described more than basic strategies, specifically recommending consulting the Public Health Agency of Canada “Pathogen Safety Data Sheets”, Section IV, subsection “Susceptibility to Disinfectants” (http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/index-eng.php) for specific organisms and researching susceptibility in scientific literature rather than relying on general classifications of disinfectants. It would be helpful if similar information is included in the Agency Summary Statements. Referencing the EPA Lists of Disinfectants (https://www.epa.gov/pesticide-registration/selected-epa-registered-disinfectants) is also highly recommended as a resource. Appendix Tables 1 and 2 are great. Table 2 is very helpful for the product concentrations to use; the activity level not so much for me. Some biosafety and training programs (i.e., UC-San Diego, etc.) have revised the disinfectant tables (pp. 104-105) from the 1979 “Laboratory Safety Monograph; A Supplement to the NIH Guidelines for Recombinant DNA Research” and have produced some very useful tables that would be great to see in BMBL6.

  2. ABSA Member's Gravatar ABSA Member
    May 20, 2016    

    Appendix B : Decontamination and Disinfection

    Environmentally Mediated Infection Transmission
    Labs do not usually use chemical sterilants to clean surfaces. What is used are disinfectants or decontaminants. Sterilization is generally only done for wastes.

    Principles of Sterilization and Disinfection
    This section defines disinfection and sterilization but not cleaning, germicide, or sanitization.

    Sterilization

    Regarding “sterility assurance level”, This could be interpreted that only 1 in 1 million is a sterility assurance level which would be inaccurate. It would be best to add that “the sterility assurance level of a sterilizing process is the degree of assurance with which the process renders a population of items sterile.” Quoted from Disinfection, Sterilization, and Preservation. 5th Ed. Seymour Block editor. Chap. 70 pg. 1361.

    Disinfection

    The statement is made, “Disinfection is a procedure that reduces the level of microbial contamination, but there is a broad range of activity that extends from sterility at one extreme to a minimal reduction in the number of microbial contaminants at the other.”

    Comment: Disinfection is a procedure that reduces the level of pathogenic contamination. Decontamination is the procedure that reduces the level of microbial contamination.

    The statement is made,” Some germicides rapidly kill only the ordinary vegetative forms of
    bacteria such as staphylococci and streptococci, some forms of fungi, and lipid containing
    viruses, whereas others are effective against such relatively resistant organisms as Mycobacterium tuberculosis var. bovis, non-lipid viruses, and most forms of fungi.”

    Comment: The term, “germicide” is never defined in this appendix. In this case the author is using germicide to be synonymous with disinfectant or decontaminant.

    High-Level Disinfection

    The statement is made, “These chemical germicides are potent sporicides and, in the United States, are classified by the FDA as sterilant/disinfectants. They are formulated for use on medical devices, but not on environmental surfaces such as laboratory benches or floors.”

    Comment: The FDA registers those disinfectants intended for use on medical devices only.
    High level disinfectants are used on environmental surfaces routinely in the biotechnology and pharmaceutical industries.

    Decontamination and Cleaning

    The statement is made, “If dangerous and highly infectious agents are present in the laboratory, the methods for decontamination of spills, laboratory equipment, BSC, or infectious waste are very significant and may included prolonged autoclave cycles, incineration or gaseous treatment of surfaces (see below).”

    Comment: Decontamination is always very significant. Does the author mean that in this case it is significantly different then when working with Risk Group 2 organisms? Even with Risk Group 2 organisms, surfaces are generally treated with disinfectants and not gaseous (except for pre-maintenance or general shut-down). If this is in reference to Risk Group 4 organisms only, then that should be made clear.

    Table I: Descending Order of Resistance to Germicidal Chemicals

    This table should be updated to note the following descending order: prions>bacterial spores>coccidia>mycobacteria, and then the rest of the table remains the same.

    Decontamination of Large Spaces

    The statement is made, “Thus, in the BSL-3 laboratory, surface decontamination, not fumigation, is the primary means of decontaminating space.”

    Comment: It should be made clear here that in many BSL-3 facilities, fumigation is done on a periodic basis, such as when certain maintenance activities are conducted or sometimes when the infectious agent in use in the laboratory changes.

    The statement is made, “Verification of seals is usually not required for most BSL-3 laboratories.”

    Comment: This step is required for ABSL-3 facilities. Also, in the National Institutes of Health Design Criteria for BSL-3: “D.8.2.8 Penetrations and Joints: All penetrations in walls, floors, and ceilings shall be sealed with a smooth finish to facilitate decontamination and cleaning. All joints between fixed cabinetry and equipment (e.g., shelves, cabinets, plumbing fixtures, etc.) and the floor or wall shall be smooth covered and sealed to ensure maximum cleanability. Supply and exhaust ducts shall be gasketed or sealed at the point of penetration into the laboratory to ensure containment and the capability of gas decontamination. Light fixtures in BSL-3 laboratories shall be surface or pendent mounted.”

    Most BSL-3 labs designed today are capable of being pressure tested, which means verification of the seals as part of the facility certification process. This is particularly the case in NIH funded laboratories (RBLS). Since these labs are generally subjected to gaseous decontaminations, verification of seals must be in place prior to fumigation.

    Formaldehyde-paraformaldehyde

    The statement is made, “Formaldehyde gas at a concentration of 0.3 grams/cubic foot for four hours is often used for space decontamination.

    Comment: This concentration is less time than the National Sanitation Foundation recommends for a BSC. It is recommended changing this statement to read: “…0.3 grams/cubic foot for a minimum of six hours…..”

    The web link, http://www.epa.gov/pesticides is referenced in this section. It is recommended that guidance be given by the following alternative web link:” http://www.epa.gov/pesticides/factsheets/paraformaldehyde_factsheet.htm”, which will allow direct access to the paraformaldehyde fact sheet.

    Hydrogen Peroxide Vapor

    The statement is made, “Hydrogen peroxide can be vaporized and used for the decontamination of glove boxes as well as small room areas. Vapor phase hydrogen peroxide has been shown to be an effective sporicide at concentrations ranging from 0.5 mg/L to <10 mg/L.”

    Comment: Vaporized hydrogen peroxide has also been for decontamination of large spaces.

    Chlorine Dioxide Gas

    The statement is made, “Chlorine dioxide possesses the bactericidal, virucidal and sporicidal properties of chlorine, but unlike chlorine, does not lead to the formation of trihalomethanes or
    combine with ammonia to form chlorinated organic products (chloramines).

    Comment: It is unclear if the author is referencing chlorine gas or if they mean to reference sodium hypochlorite. While trihalomethane generation poses health hazards which should be avoided, the generation of chloramines does not pose comparable health hazards. Chloramines are used in sanitizers and disinfectants.

    The statement is made, “Because chlorine dioxide gas exits the generator at a modest positive pressure and flow rate, the enclosure also need not be evacuated and could be a sterility-testing isolator, a glove box or sealed BSC, or even a small room that could be sealed to prevent gas egress. Chlorine dioxide gas is rapidly broken down by light; care must be taken to eliminate light sources in spaces to be decontaminated.”

    Comment: Since chlorine dioxide was used to decontaminate very large government buildings, I would remove the words, "even a small room".

    Table II: Activity Levels of Select Liquid Germicides

    The table notes that the aqueous concentrations of glutaraldehyde, chlorine dioxide, and peracetic acid acid are “variable” when used as sterilizing agents and disinfectants.

    Comment: The EPA registered high level/sterilants are in a narrow band of 2.0-3.4% for glutaraldehyde. This level is 2% for chlorine dioxide. There are no strictly peracetic acid agents registered – only mixtures.

    The table notes that the aqueous concentrations of iodophors are “30-50 mg/L free iodine up to
    10,000 mg/L available iodine and 0.1-0.2%) variable” when used as disinfectants.

    Comment: The concentration noted (0.1-0.2%) should be moved one line as this is the concentration for quaternary ammonium compounds not iodophors.

    Footnote “c” of this table states, “Although the indicated concentrations are rapid
    acting and broad-spectrum (tuberculocidal, bactericidal, fungicidal, and virucidal), no
    proprietary hypochlorite formulations are formally registered with EPA or cleared by
    FDA.”

    Comment: The EPA has over 3 dozen sodium hypochlorite disinfectants registered in their various lists.

    Comment: It should be noted that Table 2 is a direct copy of Table 43.4 from ref. 6.

    Special Infectious Agent Issues

    Transmissible Spongiform Encephalopathy Agents (Prions)

    The first paragraph in this section reads, “ The major exception to the rule is the previous discussion of microbial inactivation and decontamination is the causative agent of CJD or other prion agents responsible for transmissible spongiform encephaplopathies of the central nervous system in humans or animals. Studies show that prions are resistant to conventional uses of heat and/or chemcil germicides for the sterilization of instruments and devices. (See Chapter 9).

    Comment: There is no Chapter 9 in the 5th edition of the BMBL; “Prion Diseases” are covered in section VIII-H of the 5th Edition of the BMBL.

    References
    7. Centers for Disease Control and Prevention [www.cdc.gov]. Atlanta: The Centers
    for Disease Control and Prevention; [updated 2006 Sept 21]. Guidelines for
    Environmental Infection Control in Health-Care Facilities, 2003; [about 2
    screens]. Available from: http://www.cdc.gov/ncidod/hip/enviro/guide.htm

    Comment: This web site reference is out of date. Currently, it is http://www.cdc.gov/ncidod/dhqp/gl_environinfection.html

  3. Sandia National Laboratories International Biological and Chemical Threat Reduction's Gravatar Sandia National Laboratories International Biological and Chemical Threat Reduction
    May 12, 2016    

    Consider addressing specific risks regarding waste handling.

  4. Sonia Godoy-Tundidor, PhD's Gravatar Sonia Godoy-Tundidor, PhD
    May 11, 2016    

    * Table 1, page 330: Please include prions in the table.

  5. CSHEMA Biosafety Community of Practice's Gravatar CSHEMA Biosafety Community of Practice
    May 9, 2016    

    Page 332: Can a recommendation be made for how often bleach mixtures should be made (everyday, weekly, monthly)?
    Page 332: They give submersion/contact time for alcohol. Can we get recommended contact times for all chemical disinfectants?

  6. Julie Johnson's Gravatar Julie Johnson
    May 4, 2016    

    I agree with this comment. More guidance needs to be provided as to what is acceptable criteria for validating decontamination methods.

  7. Brian O'Shea's Gravatar Brian O'Shea
    April 29, 2016    

    With the recent discussions regarding inactivation of pathogens and improper or incomplete inactivation of pathogens, Appendix B should include detailed processes and procedures for researchers to follow in order to validate their own decontamination, inactivation, and sterilization processes. This should not only include standardized methodology for conducting process validations, but also government acceptance criteria for these processes.