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Back to Bleach Basics
Due to many EPA registered disinfectants being in high demand, common laboratory disinfectants are unavailable or backordered with long lead times. An effective alternative that kills a wide range of organisms and inactivates viruses that is inexpensive and already readily available in most labs is bleach.
A basic 10% solution of bleach can be made by diluting 1 part bleach with 9 parts water. To be effective, bleach solutions should remain wet on surfaces for at least 10 minutes or follow the contact time recommended by the manufacturer.
When handling bleach, be mindful that:
- Bleach is corrosive on metal surfaces, such as biosafety cabinet work surfaces. To prevent damage, after a sufficient contact time, rinse surfaces with sterile water or ethanol.
- Bleach is irritating to mucous membranes, eyes, and skin. Use appropriate PPE.
- Bleach may damage or discolor clothing and surfaces. Protect clothing and use caution around sensitive equipment.
The available chlorine in bleach rapidly degrades over time, with increased temperatures, and in light; therefore, solutions should be prepared at least weekly and preferably daily. Store bleach solutions in a closed, opaque container at room temperature. Never mix bleach with other chemicals, such as acids or ammonia, which can create hazardous gases.
Disinfection
Consult manufacturer directions to determine the efficacy of the disinfectant against the biohazards in your lab and be sure to allow for sufficient contact time. Some disinfectants appropriate for lab use include: household bleach (5-10% solution), quaternary ammonium compounds, and phenolic compounds.
When choosing a disinfectant consider the following:
- The microorganisms present
- The item to be disinfected or surface(s)
- Corrosivity or hazards associated with the chemicals in the disinfectant
- Ease of use
The Hospital Storeroom stocks a variety of approved disinfectants including bleach, "Cavicide"-a ready to use spray (quaternary ammonium with alcohol) and "Beaucoup"- a concentrated Phenolic.
70% Ethanol
Aqueous alcohol solutions are not appropriate for surface decontamination because of the evaporative nature of the solution; a contact time of ten minutes or more is necessary and not achievable using a 70% (v/v) aqueous solution of ethanol. 70% ethanol can be used to soak small pieces of surgical instruments and for wipe downs following a disinfectant (e.g., 10% bleach) that might leave a corrosive residue.
Difficult organisms
Some agents such as Cryptosporidium, Bacillus spores and prions are very resistant to the usual disinfectants. EHS Biosafety is available to assist you in determining the appropriate disinfectant and provides guidance on use of appropriate disinfection techniques and materials for researchers.
Summary and Comparison of Liquid Disinfectants
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| 70% Isopropyl Alcohol solution | -Cleaning some instruments -Cleaning skin | -Changes protein structure of microorganism -Presence of water assists with killing action | -Fairly inexpensive | - < 50% Solution not very effective -Not active when organic matter present -Not active against certain types of viruses -Evaporates quickly -Contact time not sufficient for killing | -Flammable -Eye Irritant -Toxic | |
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| Chlorine Compounds | -Spills of human body fluids Bactericidal - Good | -Free available chlorine combines with contents within microorganism, reaction byproducts cause its death -Need 500 to 5000 ppm -Produce chemical combination with cell substances -Depends upon release of hypochlorous acid | -Kills hardy viruses (e.g. hepatitis) -Kills a wide range of organisms -Inexpensive -Penetrates well -Relatively quick microbial kill -May be used on food prep surfaces | -Corrodes metals such as stainless, aluminum -Organics may reduce activity -Increase in alkalinity decreases bactericidal property -Unpleasant taste and odor -Tuberculocidal, with extended contact time | -Follow spill procedure and dilution instructions -Make fresh solutions before use -Eye, skin and respiratory irritant -Corrosive -Toxic | -Bleach solutions (sodium hypochlorite) -Clorox -Cyosan -Purex |
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| Glutaraldehyde | Bactericidal - Good Fungicidal - Good Tuberculocidal - Excellent Virucidal - Good Sporicidal - Good | -Coagulates cellular proteins | -Non-staining, relatively noncorrosive -Useable as a sterilant on plastics, rubber, lenses, stainless steel and other items that can't be autoclaved | -Not stable in solution -Has to be in alkaline solution -Inactivated by organic material | -Eye, skin and respiratory irritant -Sensitizer -Toxic | -Calgocide 14 -Cidex -Vespore |
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| Iodophors (Iodine with carrier) | -Disinfecting some semicritical medical equipment Bactericidal - Very Good | -Free iodine enters microorganism and binds with cellular components -Carrier helps penetrate soil/fat -Need 30 to 50 ppm -Probably by disorder of protein synthesis due to hindrance and/or blocking of hydrogen bonding | -Kills broad range of organisms -Highly reactive -Low tissue toxicity -Kills immediately rather than by prolonged period of stasis -Not affected by hard water -May be used on food prep surfaces | -May stain plastics or corrode metal -May stain skin/laundry -Stains most materials -Odor -Some organic and inorganic substances neutralize effect -Tuberculocidal, with extended contact time -Sporicidal, some | -Dilution critical -Follow directions! -Use only EPA registered hard surface iodophor disinfectants -Don't confuse skin antiseptic iodophors for disinfectants -Skin and eye irritant -Corrosive -Toxic | -Bactergent -Hy-Sine -Ioprep -Providone (iodine/betadine) -Wescodyne |
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| Phenolic Compounds | Bactericidal - Excellent Fungicidal - Excellent Tuberculodial - Excellent Virucidal - Excellent | -Gross protoplasmic poison -Disrupts cell walls -Precipitates cell proteins -Low concentrations inactivate essential enzyme systems | -Nonspecific concerning bactericidal and fungicidal action -When boiling water would cause rusting, the presence of phenolic substances produces an antirusting effect | -Unpleasant odor -Some areas have disposal restrictions -Effectiveness reduced by alkaline pH, natural soap or organic material -Sporicidal, no | -Skin and eye irritant -Sensitizer -Corrosive -Toxic | -Hil-Phene -Lph -Metar -Vesphene |
| Class | Recommended Use | How They Work | Advantages | Disadvantages | Comments & Hazards | Examples |
| Quaternary Ammonium compounds (QUATS) | -Ordinary housekeeping (e.g. floors, furniture, walls) Bactericidal - Excellent | -Affects proteins and cell membrane of microorganism -Releases nitrogen and phosphorous from cells | -Contains a detergent to help loosen soil -Rapid action -Colorless, odorless -Non-toxic, less corrosive -Highly stable -May be used on food prep surfaces | -Does not eliminate spores, TB bacteria, some viruses -Effectiveness influenced by hard water -Layer of soap interferes with action | -Select from EPA list of hospital disinfectants -Skin and eye irritant -Toxic | -Coverage 258 -End-Bac -Hi Tor |
This information was provided to the University of Virginia by:
Barbara Fox NellisJohnson & Johnson
Clinical Diagnostics
1999 Lake Avenue
Bldg. 83, KRL
Rochester, NY 14650-2209
phone: (716) 453-5697
fax: (716) 453-5696
