Biological Exposure or Spills: Reponse, Decontamination & Clean-up

(this information has been adopted and modified from the University of Minnesota’s website)


Specific instructions on what to do following an accidental splash or splatter to facial mucous membranes, punctures with contaminated sharps, and exposure to biohazardous aerosols must be provided/listed in in the Standard Operating Procedures, and must be available in the laboratory for continuous access.

If an incident results in a bloodborne or other biohazards exposure (infectious agents, rDNA, biological toxins, etc), by a needle-stick or other exposure (i.e. face and/or eye splash, cut or puncture with sharps, contact with non-intact skin, animal bites or scratches):

  • Clean It:  For skin exposure, immediately remove contaminated clothing and wash area with soap and water for 15 minutes; encourage needle sticks and cuts to bleed.  For eye exposure, flush the eye with water for 15 minutes at an eyewash station or sink.
  • Treat It:  For Risk Group (RG) 1 infectious agents it is necessary to seek medical attention (Northfield Hospital; Allina Clinic) within 1-2 hours so that treatment is instituted within a timeframe that increases effectiveness.  If overtly exposed to recombinant or synthetic nucleic acid molecules or Risk Group (RG) 2 infectious agents seek immediate medical attention.
  • Report It:  Report all exposures to the Chemical Hygiene Officer.

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.


All workers handling biohazards must know what to do in an emergency/spill before they begin work.

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.

Decontamination: Definitions

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.

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.

Chart: 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


Common Types of Disinfectants: Their Advantages & Disadvantages

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
– Non-corrosive
– Effective with detergent
– Can have reduced effectiveness in organic material, does not penetrate organic material
– Flammable
– 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
– Corrosive
– 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
– Non-corrosive
– Effective over wide pH range
– Easily inactivated by organic materials, anionic detergents, and salts of metals in water (hard water)
– Skin irritant


Disinfectant Selection

This Table 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.
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
  • Materials to keep on hand for spill cleanup
    • Written spill procedure including emergency phone numbers
    • Disinfectant suitable for biological materials and surfaces being used
    • Paper towels, gloves, shoe covers, and safety goggles
    • Forceps to pick up sharps, including broken glass
    • Squeegee (or other appropriate device) and dustpan to clean up shards of broken glass in contaminated liquid, should be autoclavable or otherwise capable of being decontaminated
    • Biohazard bags (red bags for pick-up or autoclave clear bags for 60 minutes at 121°C)
  • General Spill Cleanup Procedures
    • If the spill may involve an infectious aerosol, instruct all occupants to leave the room for 30 minutes to allow aerosols to settle.  Aerosols can form if material is dropped.  Place a sign on the door warning staff not to enter the room due to a spill.
    • Remove contaminated lab coat or clothing and wash exposed skin.
    • Put on clean gloves and lab coat.
    • Prepare enough volume of a 1:10 dilution of chlorine bleach or other approved disinfectant to saturate the contaminated area.
    • Contain the spill with paper towels or other absorbent material such as bench liners.
    • Flood the spill area with disinfectant.
    • Allow 30 minutes of contact time.
    • Push the absorbent material at the edge of the spill into the spill’s center.  Add more paper towels as needed.
    • If broken glass or sharps are present, use tongs or forceps and a dustpan to remove pieces and place into a sharps container.
    • Discard the contaminated paper towels into the proper waste container.
    • Using clean paper towels and a disinfectant, wipe all surfaces that may have come in contact with the spilled material.
    • Discard contaminated gloves into the proper waste container.
    • Wash hands thoroughly.
    • Autoclave overtly contaminated lab coats prior to placing into laboratory laundry bag.