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Bio Basics Fact Sheet:
Biohazards Decontamination & Spill Clean-up


Decontamination is any process that reduces biohazardous material (infectious agents, rDNA material, human material, biological toxins, etc) to an acceptable level, one that is below the level necessary to cause disease. Acceptable levels will depend on the biohazardous material in question and the type of work being done.

This Fact Sheet deals with liquid chemicals used for routine decontamination and spill cleanup. In order to select the proper decontamination procedure one must consider many factors including; the biohazard's concentration and resistance to disinfectants, chemical compatibility with other materials present, surface being decontaminated, and hazards to humans and the environment associated with the disinfectant. Ineffective decontamination can provide a false sense of security and spread disease.

Acceptable levels of decontamination, along with methods used to decontaminate, should be determined before work is begun and should be included in the lab's Standard Operating Procedures (SOPs).

Note: All rDNA containing waste, including Biosafety Level 1 material, must be decontaminated prior to disposal or disposed of as biohazard waste before being released from the laboratory.

See attached Decontamination and Spill Clean-up template. It can be used in writing lab specific SOPs. This template must be customized for each lab.


Sanitizing - reduces the number of microbes to a safe level.
Antiseptics - destroy microorganisms on living tissue.
Disinfectants - destroy microorganisms on inanimate objects.
Sterilization - kills all microbes.

Microbial Resistance to Chemical Disinfectants:

More Resistant Microorganisms Examples
Prions BSE, vCJD, Scrapie
Bacterial Spores Bacillus, Geobacillus, Clostridium sp.
Protozoan Oocytes Cryptosporidium
Helminth Eggs Ascaris, Enterobius
Mycobacteria M. tuberculosis
Small non-enveloped viruses
Poliovirus, Parvoviruses, Papillomaviruses
Protozoan Cysts Giardia, Acathomoeba
Fungal Spores Aspergillus, Penicillium
Gram-negative Bacteria E. coli, Salmonella spp.
Vegetative Fungi & Algae Candida, Chlamydomonas
Vegetative Helminths & Protozoa Ascaris, Cryptosporidium, Giardia
Large non-enveloped viruses Adenoviruses, Rotaviruses
  Gram-positive Bacteria Staphylococcus, Streptococcus, Enterococcus
Less Resistant Enveloped viruses HIV, Hepatitis B, Herpes Simplex Virus

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Common Types of Disinfectants:

The following two tables provide general information only. Phenolics and quats are available in many formulations with different properties. Follow the manufacturer's recommendations for use.

Type Tips for Use Advantages Disadvantages
Chlorine Compounds -Dilute household bleach 1:9 (v/v) solution of household bleach (10% bleach solution); make fresh monthly
-Store diluted solutions in sealed container that is protected from light.
-For spill cleanup and to wipe down work surfaces
-FINAL concentration of 10% bleach used for liquid infectious waste
-Fisher Scientific supplies Fisherbrand* Bleach Solution Dispenser. It is a unique, two-bottle design and fixed-ratio trigger sprayer automatically mixes concentrated bleach with tap water. Cat. No. 23-640-127
-Relatively nontoxic
-Low cost
-Effective with detergents
-Fast acting
-Broad spectrum effectiveness
-Inactivated by organic material such as blood
-Do not use at less than 1:9 (v/v) dilution
-Strong oxidizer; corrosive
-Irritates mucus membranes, eyes, skin
-No residual activity on surfaces
-Can damage clothing
-Incompatible with quats
-Produces toxic chlorine gas if mixed with acids or ammonia compounds
-Can't be used to disinfect radioactive iodine.
Alcohols -Dilute to 70% in water, (loses effectiveness at concentrations above 90%)
-Use to clean instruments and wipe down interior of Biological Safety Cabinets
-Use as topical antiseptic on intact skin
-Effective with detergent
-Can have reduced effectiveness in organic material, does not penetrate organic material
-No residual activity and limited effective exposure time due to high rate of evaporation
Phenolics -Dilute according to manufacturer's instructions
-Commonly used to clean walls, floors, etc
-Useful in areas where organic matter cannot always be removed, such as animal areas
-Good effectiveness in organic material
-Effective with detergent
-Has some residual effectiveness
-Toxicity varies with specific compound, can be absorbed through skin
-Some formulations may have unpleasant odor
-Skin irritant
-Not effective against spores
QUATS Quaternary Ammonium Compounds (cationic detergents) -Dilute according to manufacturer's instructions
-Surfaces must be rinsed free of anionic soap or detergents before use
-Commonly used to clean walls, floors, etc
-Strong surface activity
-Low toxicity
-Effective over wide pH range
-Easily inactivated by organic materials, anionic detergents, and salts of metals in water (hard water)
-Skin irritant

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Disinfectant Selection:

Chlorine Compounds
Bacteria Very good Good Good Good for gram positive
Very good Good Good Good
Very good Fair** Fair** Not effective
Fungi Good Fair Good Fair
Good with high concentration Not
Moderate with high concentration and long contact time (hours) Not
Fair (some quats at high concentration)
* hydrogen peroxide most effective
** check disinfectant susceptibility for individual virus

Decontamination Procedures:

For any spills of agents that are transmitted by inhalation, such as Mycobacterium tuberculosis, evacuate the lab immediately, close the door, do not allow any one to enter the lab, remove any contaminated clothing, wash exposed skin with soap and water, called the Biosafety Officer for assistance (612-626-6002). Report all spills to P.I. or lab supervisor.

Toxin Decontamination

Materials to keep on hand for spill cleanup

Small and moderate spills outside the biological safety cabinet

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Large spills (greater than 100ml) within or without of the biological safety cabinet

For small spills in a biological safety cabinet

For moderate spills in a biological safety cabinet follow general spill procedures plus

For major spills in a biological safety cabinet

Accidental Exposure Response:

If incident results in a hazard exposure (i.e. face and/or eye splash, cut or puncture with sharps, contact with non-intact skin, animal bites or scratches):

Note: It is important to fill out all of the appropriate documents to be eligible to collect workers compensation should any complications from the hazardous exposure arise in the future.

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Disinfection, Sterilization, and Preservation edited by Seymour S. Block, Lippincott Williams & Wilkins, Philadelphia, 2001

For EPA registered antimicrobial products effective against certain blood borne/body fluid pathogens, Mycobacteria spp (tubercle bacteria), human HIV-1 virus, Hepatitis B or Hepatitis C virus as well as products classified as sterilizers and products used for medical wastes see

APIC (Association for Professionals in Infection Control and Epidemiology) "Guidelines for Selection and Use of Disinfectants" reprint from American Journal of Infection Control see

For information on "FDA-Cleared Sterilants and High Level Disinfectants with General Claims for Processing Reusable Medical and Dental Devices" published in November 2003 see

Biological Safety Principles and Practices edited by Diane Fleming & Debra Hunt, ASM Press, Washington DC, 2000.

CDC/NIH Biosafety in Microbiological and Biomedical Laboratories, 5th edition

NIH Guidelines for Research Involving Recombinant DNA Molecules,

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