Disinfectant

This article is about antimicrobial agents. For the Macintosh anti-virus software, see Disinfectant (software).

Disinfection of a floor using disinfectant liquid applied using a mop

Disinfectants are substances that are applied to non-living objects to destroy microorganisms that are living on the objects.^[1] Disinfection does not necessarily kill all microorganisms, especially nonresistant bacterial spores; it is less effective than sterilisation, which is an extreme physical and/or chemical process that kills all types of life.^[1] Disinfectants are different from other antimicrobial agents such as antibiotics, which destroy microorganisms within the body, and antiseptics, which destroy microorganisms on living tissue. Disinfectants are also different from biocides — the latter are intended to destroy all forms of life, not just microorganisms.

Sanitisers are substances that simultaneously clean and disinfect.^[2]

Bacterial endospores are most resistant to disinfectants, but some viruses and bacteria also possess some tolerance.

Disinfectants are frequently used in hospitals, dental surgeries, kitchens, and bathrooms to kill infectious organisms.

Properties

A perfect disinfectant would also offer complete and full microbiological sterilisation, without harming humans and useful forms of life, be inexpensive, and non-corrosive. However, ideal disinfectants do not exist. Most disinfectants are also, by nature, potentially harmful (even toxic) to humans or animals. Most modern household disinfectants contain Bitrex, an exceptionally bitter substance added to discourage ingestion, as a safety measure. Those that are used indoors should never be mixed with other cleaning products as chemical reactions can occur.

The choice of disinfectant to be used depends on the particular situation. Some disinfectants have a wide spectrum (kill many different types of microorganisms), while others kill a smaller range of disease-causing organisms but are preferred for other properties (they may be non-corrosive, non-toxic, or inexpensive).

There are arguments for creating or maintaining conditions that are not conducive to bacterial survival and multiplication, rather than attempting to kill them with chemicals. Bacteria can increase in number very quickly, which enables them to evolve rapidly. Should some bacteria survive a chemical attack, they give rise to new generations composed completely of bacteria that have resistance to the particular chemical used. Under a sustained chemical attack, the surviving bacteria in successive generations are increasingly resistant to the chemical used, and ultimately the chemical is rendered ineffective. For this reason, some question the wisdom of impregnating cloths, cutting boards and worktops in the home with bactericidal chemicals.

Types

Air disinfectants

Air disinfectants are typically chemical substances capable of disinfecting microorganisms suspended in the air. Disinfectants are generally assumed to be limited to use on surfaces, but that is not the case. In 1928, a study found that airborne microorganisms could be killed using mists of dilute bleach.^[3] An air disinfectant must be dispersed either as an aerosol or vapour at a sufficient concentration in the air to cause the number of viable infectious microorganisms to be significantly reduced.

In the 1940s and early 1950s, further studies showed inactivation of diverse bacteria, influenza virus, and Penicillium chrysogenum (previously P. notatum) mold fungus using various glycols, principally propylene glycol and triethylene glycol.^[4] In principle, these chemical substances are ideal air disinfectants because they have both high lethality to microorganisms and low mammalian toxicity.^[5][6]

Although glycols are effective air disinfectants in controlled laboratory environments, it is more difficult to use them effectively in real-world environments because the disinfection of air is sensitive to continuous action. Continuous action in real-world environments with outside air exchanges at door, HVAC, and window interfaces, and in the presence of materials that adsorb and remove glycols from the air, poses engineering challenges that are not critical for surface disinfection. The engineering challenge associated with creating a sufficient concentration of the glycol vapours in the air have not to date been sufficiently addressed.^[7][8]

Alcohols

Alcohols, usually ethanol or isopropanol, are sometimes used as a disinfectant, but more often as an antiseptic (the distinction being that alcohol tends to be used on living tissue rather than nonliving surfaces). They are non-corrosive, but can be a fire hazard. They also have limited residual activity due to evaporation, which results in brief contact times unless the surface is submerged, and have a limited activity in the presence of organic material. Alcohols are most effective when combined with purified water to facilitate diffusion through the cell membrane; 100% alcohol typically denatures only external membrane proteins.^[9] A mixture of 70% ethanol or isopropanol diluted in water is effective against a wide spectrum of bacteria, though higher concentrations are often needed to disinfect wet surfaces.^[10] Additionally, high-concentration mixtures (such as 80% ethanol + 5% isopropanol) are required to effectively inactivate lipid-enveloped viruses (such as HIV, hepatitis B, and hepatitis C).^[10][11][12] Alcohol is, at best, only partly effective against most non-enveloped viruses (such as hepatitis A), and is not effective against fungal and bacterial spores.^[9][11] The efficacy of alcohol is enhanced when in solution with the wetting agent dodecanoic acid (coconut soap). The synergistic effect of 29.4% ethanol with dodecanoic acid is effective against a broad spectrum of bacteria, fungi, and viruses. Further testing is being performed against Clostridium difficile (C.Diff) spores with higher concentrations of ethanol and dodecanoic acid, which proved effective with a contact time of ten minutes.^[13][14]

Aldehydes

Aldehydes, such as formaldehyde and glutaraldehyde, have a wide microbiocidal activity and are sporocidal and fungicidal. They are partly inactivated by organic matter and have slight residual activity.

Some bacteria have developed resistance to glutaraldehyde, and it has been found that glutaraldehyde can cause asthma and other health hazards, hence ortho-phthalaldehyde is replacing glutaraldehyde.^{[citation needed]}

Oxidizing agents

Oxidizing agents act by oxidizing the cell membrane of microorganisms, which results in a loss of structure and leads to cell lysis and death. A large number of disinfectants operate in this way. Chlorine and oxygen are strong oxidizers, so their compounds figure heavily here.

• Sodium hypochlorite is very commonly used. Common household bleach is a sodium hypochlorite solution and is used in the home to disinfect drains, toilets, and other surfaces. In more dilute form, it is used in swimming pools, and in still more dilute form, it is used in drinking water. When pools and drinking water are said to be chlorinated, it is actually sodium hypochlorite or a related compound—not pure chlorine—that is being used. Chlorine partly reacts with proteinaceous liquids such as blood to form non-oxidizing N-chloro compounds, and thus higher concentrations must be used if disinfecting surfaces after blood spills.^[15] Commercial solutions with higher concentrations contain substantial amounts of sodium hydroxide for stabilization of the concentrated hypochlorite, which would otherwise decompose to chlorine, but the solutions are strongly basic as a result.
• Other hypochlorites such as calcium hypochlorite are also used, especially as a swimming pool additive. Hypochlorites yield an aqueous solution of hypochlorous acid that is the true disinfectant. Hypobromite solutions are also sometimes used.
• Electrolyzed water or "Anolyte" is an oxidizing, acidic hypochlorite solution made by electrolysis of sodium chloride into sodium hypochlorite and hypochlorous acid. Anolyte has an oxidation-reduction potential of +600 to +1200 mV and a typical pH range of 3.5––8.5, but the most potent solution is produced at a controlled pH 5.0–6.3 where the predominant oxychlorine species is hypochlorous acid.
• Chloramine is often used in drinking water treatment.
• Chloramine-T is antibacterial even after the chlorine has been spent, since the parent compound is a sulfonamide antibiotic.
• Chlorine dioxide is used as an advanced disinfectant for drinking water to reduce waterborne diseases. In certain parts of the world, it has largely replaced chlorine because it forms fewer byproducts. Sodium chlorite, sodium chlorate, and potassium chlorate are used as precursors for generating chlorine dioxide.
• Hydrogen peroxide is used in hospitals to disinfect surfaces and it is used in solution alone or in combination with other chemicals as a high level disinfectant. Hydrogen peroxide is sometimes mixed with colloidal silver. It is often preferred because it causes far fewer allergic reactions than alternative disinfectants. Also used in the food packaging industry to disinfect foil containers. A 3% solution is also used as an antiseptic.
• Hydrogen peroxide vapor is used as a medical sterilant and as room disinfectant. Hydrogen peroxide has the advantage that it decomposes to form oxygen and water thus leaving no long term residues, but hydrogen peroxide as with most other strong oxidants is hazardous, and solutions are a primary irritant. The vapor is hazardous to the respiratory system and eyes and consequently the OSHA permissible exposure limit is 1 ppm (29 CFR 1910.1000 Table Z-1) calculated as an eight hour time weighted average and the NIOSH immediately dangerous to life and health limit is 75 ppm.^[16] Therefore, engineering controls, personal protective equipment, gas monitoring etc. should be employed where high concentrations of hydrogen peroxide are used in the workplace. Vaporized hydrogen peroxide is one of the chemicals approved for decontamination of anthrax spores from contaminated buildings, such as occurred during the 2001 anthrax attacks in the U.S. It has also been shown to be effective in removing exotic animal viruses, such as avian influenza and Newcastle disease from equipment and surfaces.
• The antimicrobial action of hydrogen peroxide can be enchanced by surfactants and organic acids.^[17] The resulting chemistry is known as Accelerated Hydrogen Peroxide and is produced by Virox Technologies Inc.^[18] A 2% solution, stabilized for extended use, achieves high-level disinfection in 5 minutes, and is suitable for disinfecting medical equipment made from hard plastic, such as in endoscopes.^[19] The evidence available suggests that products based on Accelerated Hydrogen Peroxide, apart from being good germicides, are safer for humans and benign to the environment.^[20]
• Iodine is usually dissolved in an organic solvent or as Lugol's iodine solution. It is used in the poultry industry. It is added to the birds' drinking water. In human and veterinary medicine, iodine products are widely used to prepare incision sites prior to surgery. Although it increases both scar tissue formation and healing time, tincture of iodine is used as an antiseptic for skin cuts and scrapes, and remains among the most effective antiseptics known.^{[citation needed]}
• Ozone is a gas used for disinfecting water, laundry, foods, air, and surfaces. It is chemically aggressive and destroys many organic compounds, resulting in rapid decolorization and deodorization in addition to disinfection. Ozone decomposes relatively quickly, however, so that tap water chlorination cannot be entirely replaced by ozonation, as the ozone would decompose already in the water piping. Instead, it is used to remove the bulk of oxidizable matter from the water, which would produce small amounts of organochlorides if treated with chlorine only.
• Peracetic acid is a disinfectant produced by reacting hydrogen peroxide with acetic acid. It is broadly effective against microorganisms and is not deactivated by catalase and peroxidase, the enzymes that break down hydrogen peroxide. It also breaks down to food safe and environmentally friendly residues (acetic acid and hydrogen peroxide), and therefore can be used in non-rinse applications. It can be used over a wide temperature range (0-40°C), wide pH range (3.0-7.5), in clean-in-place (CIP) processes, in hard water conditions, and is not affected by protein residues.
• Performic acid is the simplest and most powerful perorganic acid. Formed from the reaction of hydrogen peroxide and formic acid, it reacts more rapidly and powerfully than peracetic acid before breaking down to water and carbon dioxide.
• Potassium permanganate (KMnO₄) is a red crystalline powder that colours everything it touches, through a strong oxidising action. This includes staining "stainless" steel, which somehow limits its use and makes it necessary to use plastic or glass containers. It is used to disinfect aquariums and is also widely used in community swimming pools to disinfect ones feet before entering the pool. Typically, a large shallow basin of KMnO₄/water solution is kept near the pool ladder. Participants are required to step in the basin and then go into the pool. Additionally, it is widely used to disinfect community water ponds and wells in tropical countries, as well as to disinfect the mouth before pulling out teeth. It can be applied to wounds in dilute solution.
• Potassium peroxymonosulfate, the principal ingredient in Virkon, is a wide-spectrum disinfectant used in laboratories. Virkon kills bacteria, viruses, and fungi. It is used as a 1% solution in water, and keeps for one week once it is made up. It is expensive, but very effective, its pink colour fades as it is used up so it is possible to see at a glance if it is still fresh.

Phenolics

Phenolics are active ingredients in some household disinfectants. They are also found in some mouthwashes and in disinfectant soap and handwashes.

• Phenol is probably the oldest known disinfectant as it was first used by Lister, when it was called carbolic acid. It is rather corrosive to the skin and sometimes toxic to sensitive people. Impure preparations of phenol were originally made from coal tar, and these contained low concentrations of other aromatic hydrocarbons including benzene, which is an IARC Group 1 carcinogen.
• o-Phenylphenol is often used instead of phenol, since it is somewhat less corrosive.
• Chloroxylenol is the principal ingredient in Dettol, a household disinfectant and antiseptic.
• Hexachlorophene is a phenolic that was once used as a germicidal additive to some household products but was banned due to suspected harmful effects.
• Thymol, derived from the herb thyme, is the active ingredient in some "broad spectrum" disinfectants that bears ecological claims.
• Amylmetacresol is found in Strepsils, a throat disinfectant.
• Although not a phenol, 2,4-dichlorobenzyl alcohol has similar effects as phenols, but it cannot inactive viruses.

Quaternary ammonium compounds

Quaternary ammonium compounds ("quats"), such as benzalkonium chloride, are a large group of related compounds. Some concentrated formulations have been shown to be effective low-level disinfectants. Typically, quats do not exhibit efficacy against difficult to kill non-enveloped viruses such as norovirus, rotavirus, or polio virus. Newer synergous, low-alcohol formulations are highly effective broad-spectrum disinfectants with quick contact times (3–5 minutes) against bacteria, enveloped viruses, pathogenic fungi, and mycobacteria. However, the addition of alcohol or solvents to quat-based disinfectant formulas results in the products' drying much more quickly on the applied surface, which could lead to ineffective or incomplete disinfection. Quats are biocides that also kill algae and are used as an additive in large-scale industrial water systems to minimize undesired biological growth.

Silver

Silver has antimicrobial properties, but compounds suitable for disinfection are usually unstable and have a limited shelf-life. Silver dihydrogen citrate is a chelated form of silver that maintains its stability. SDC kills microorganisms by two modes of action: 1) the silver ion deactivates structural and metabolic membrane proteins, leading to microbial death; 2) the microbes view SDC as a food source, allowing the silver ion to enter the microbe. Once inside the organism, the silver ion denatures the DNA, which halts the microbe's ability to replicate, leading to its death. This dual action makes SDC highly and quickly effective against a broad spectrum of microbes. SDC is non-toxic, non-caustic, colorless, odorless, and tasteless, and does not produce toxic fumes. SDC is non-toxic to humans and animals: the United States Environmental Protection Agency classifies it into the lowest toxicity category for disinfectants, category IV.

A meta-analysis of 26 studies by the Cochrane Collaboration found that, while most were small and of poor quality, there was not enough evidence to support the use of silver-containing dressings or creams, as generally these treatments did not promote wound healing or prevent wound infections. Some evidence suggested that silver sulphadiazine had no effect on infection, and actually slowed healing.^[21]

Copper alloy surfaces

Main articles: Antimicrobial properties of copper and Antimicrobial copper-alloy touch surfaces

Copper-alloy surfaces have natural intrinsic properties to destroy a wide range of microorganisms (e.g., E. coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Clostridium difficile, influenza A virus, adenovirus, and fungi).^[22][23][24] In addition, extensive tests on E. coli O157:H7, methicillin-resistant Staphylococcus aureus (MRSA), Staphylococcus, Enterobacter aerogenes, and Pseudomonas aeruginosa sanctioned by the United States Environmental Protection Agency (EPA) using Good Laboratory Practices found that when cleaned regularly, some 355 different copper alloy surfaces:

• Continuously reduce bacterial contamination, achieving 99.9% reduction within two hours of exposure;
• Kill greater than 99.9% of Gram-negative and Gram-positive bacteria within two hours of exposure;
• Deliver continuous and ongoing antibacterial action, remaining effective in killing greater than 99.9% of bacteria within two hours;
• Kill greater than 99.9% of bacteria within two hours, and continue to kill 99% of bacteria even after repeated contamination;
• Help inhibit the buildup and growth of bacteria within two hours of exposure between routine cleaning and sanitizing steps.

These copper alloys were granted EPA registrations as “antimicrobial materials with public health benefits,"^[25] which allows manufacturers to legally make claims regarding the positive public health benefits of products made with registered antimicrobial copper alloys. EPA has approved a long list of antimicrobial copper products made from these alloys, such as bedrails, handrails, over-bed tables, sinks, faucets, door knobs, toilet hardware, computer keyboards, health club equipment, shopping cart handles, etc. (for a comprehensive list of products, see: Antimicrobial copper-alloy touch surfaces#Approved products). Antimicrobial copper alloy products are now being installed in healthcare facilities in the U.K., Ireland, Japan, Korea, France, Denmark, and Brazil and in the subway transit system in Santiago, Chile, where copper-zinc alloy handrails will be installed in some 30 stations between 2011-2014.^[26][27][28]

Other

The biguanide polymer polyaminopropyl biguanide is specifically bactericidal at very low concentrations (10 mg/l). It has a unique method of action: The polymer strands are incorporated into the bacterial cell wall, which disrupts the membrane and reduces its permeability, which has a lethal effect to bacteria. It is also known to bind to bacterial DNA, alter its transcription, and cause lethal DNA damage.^[29] It has very low toxicity to higher organisms such as human cells, which have more complex and protective membranes.

High-intensity shortwave ultraviolet light can be used for disinfecting smooth surfaces such as dental tools, but not porous materials that are opaque to the light such as wood or foam. Ultraviolet light fixtures are often present in microbiology labs, and are activated only when there are no occupants in a room (e.g., at night).

Common sodium bicarbonate (NaHCO₃) has antifungal properties,^[30] and some antiviral and antibacterial properties,^[31] though those are too weak to be effective at a home environment.^[32]

Lactic acid is a registered disinfectant. Due to its natural and environmental profile, it has gained importance in the market.

Measurements of effectiveness

One way to compare disinfectants is to compare how well they do against a known disinfectant and rate them accordingly. Phenol is the standard, and the corresponding rating system is called the "Phenol coefficient". The disinfectant to be tested is compared with phenol on a standard microbe (usually Salmonella typhi or Staphylococcus aureus). Disinfectants that are more effective than phenol have a coefficient > 1. Those that are less effective have a coefficient < 1.

A less specific measurement of effectiveness is the United States Environmental Protection Agency (EPA) classification into either high, intermediate or low level of disinfection.^[33] High-level disinfection kills all organisms, except high levels of bacterial spores, and is effected with a chemical germicide cleared for marketing as a sterilant by the U.S. Food and Drug Administration (FDA). Intermediate-level disinfection kills mycobacteria, most viruses, and bacteria with a chemical germicide registered as a "tuberculocide" by the EPA. Low-level disinfection kills some viruses and bacteria with a chemical germicide registered as a hospital disinfectant by the EPA.^[34]

Home disinfectants

By far the most cost-effective home disinfectant is the commonly used chlorine bleach (a 5% solution of sodium hypochlorite), which is effective against most common pathogens, including difficult organisms such as tuberculosis (mycobacterium tuberculosis), hepatitis B and C, fungi, and antibiotic-resistant strains of staphylococcus and enterococcus. It even has some disinfectant action against parasitic organisms.^[35]

Positives are that it kills the widest range of pathogens of any inexpensive disinfectant, is extremely powerful against viruses and bacteria at room temperature, is commonly available and inexpensive, and breaks down quickly into harmless components (primarily table salt and oxygen).

Negatives are that it is caustic to the skin, lungs, and eyes (especially at higher concentrations); like many common disinfectants, it degrades in the presence of organic substances; it has a strong odor; it is not effective against Giardia lamblia and Cryptosporidium; and extreme caution must be taken not to combine it with ammonia or any acid (such as vinegar), as this can cause noxious gases to be formed. The best practice is not to add anything to household bleach except water. Dilute bleach can be tolerated on the skin for a period of time by most persons, as witnessed by the long exposure to extremely dilute "chlorine" (actually sodium or calcium hypochlorite) many children get in swimming pools.

To use chlorine bleach effectively, the surface or item to be disinfected must be clean. In the bathroom or when cleaning after pets, special caution must be taken to wipe up urine first, before applying chlorine, to avoid reaction with the ammonia in urine, causing toxic gas by-products. A 1-to-20 solution in water is effective simply by being wiped on and left to dry. The user should wear rubber gloves and, in tight airless spaces, goggles. If parasitic organisms are suspected, it should be applied at 1-to-1 concentration, or even undiluted. Extreme caution must be taken to avoid contact with eyes and mucous membranes. Protective goggles and good ventilation are mandatory when applying concentrated bleach.

Commercial bleach tends to lose strength over time, whenever the container is opened. Old containers of partially used bleach may no longer have the labeled concentration.

Where one does not want to risk the corrosive effects of bleach, alcohol-based disinfectants are reasonably inexpensive and quite safe. The great drawback to them is their rapid evaporation; sometimes effective disinfection can be obtained only by immersing an object in the alcohol.

The use of some antimicrobials such as triclosan, in particular in the uncontrolled home environment, is controversial because it may lead to the germs becoming resistant. Chlorine bleach and alcohol do not cause resistance because they are so completely lethal, in a very direct physical way.[1]

See also

• Antimicrobials
• Antiseptics
• Diethylene glycol - a raw material for air sanitation
• Hand sanitizer
• Hygiene
• Sanitation Standard Operating Procedures
• Sterilization
• Sunlight

References

1. ^ ^{a b} www.cdc.gov/oralhealth/infectioncontrol/glossary.htm
2. ^ Cleaning and disinfecting, (2009), Mid Sussex District Council, UK.
3. ^ For a review of the early work in this field, see: Robertson OH, Bigg E, Puck TT, Miller BF (June 1942). "THE BACTERICIDAL ACTION OF PROPYLENE GLYCOL VAPOR ON MICROORGANISMS SUSPENDED IN AIR. I". Journal of Experimental Medicine 75 (6): 593–610. doi:10.1084/jem.75.6.593. PMC 2135271. PMID 19871209. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2135271. 
4. ^ For a review through 1952 see: Lester W, Dunklin E, Robertson OH (April 1952). "Bactericidal effects of propylene and triethylene glycol vapors on airborne Escherichia coli". Science 115 (2988): 379–382. doi:10.1126/Science.115.2988.379. PMID 17770126. 
5. ^ For a review of the toxicity of propylene glycol, see: United States Environmental Protection Agency (September 2006). Reregistration eligibility decision for propylene glycol and dipropylene glycol. EPA 739-R-06-002. 
6. ^ For a review of the toxicity of triethylene glycol, see: United States Environmental Protection Agency (September 2005). Reregistration eligibility decision for triethylene glycol. EPA 739-R-05-002. 
7. ^ Committee on Research Standards (May 1950). "Air Sanitation (Progress in the Control of Air-Borne Infections)". American Journal of Public Health and the Nation's Health 40 (5 Pt 2): 82–88. doi:10.2105/AJPH.40.5_Pt_2.82. PMC 1528669. PMID 15418852. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1528669. 
8. ^ Lester W, Kaye S, Robertson OH, Dunklin EW (July 1950). "Factors of Importance in the Use of Triethylene Glycol Vapor for Aerial Disinfection". American Journal of Public Health and the Nation's Health 40 (7): 813–820. doi:10.2105/AJPH.40.7.813. PMC 1528959. PMID 15425663. http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1528959. 
9. ^ ^{a b} FDA/CFSAN - Food Safety A to Z Reference, "Bacteria" http://vm.cfsan.fda.gov/~dms/a2z-b.html
10. ^ ^{a b} Moorer WR (August 2003). "Antiviral activity of alcohol for surface disinfection". International Journal of Dental Hygiene 1 (3): 138–42. doi:10.1034/j.1601-5037.2003.00032.x. PMID 16451513. 
11. ^ ^{a b} van Engelenburg FA, Terpstra FG, Schuitemaker H, Moorer WR (June 2002). "The virucidal spectrum of a high concentration alcohol mixture". The Journal of Hospital Infection 51 (2): 121–5. doi:10.1053/jhin.2002.1211. PMID 12090799. 
12. ^ Lages SL, Ramakrishnan MA, Goyal SM (February 2008). "In-vivo efficacy of hand sanitisers against feline calicivirus: a surrogate for norovirus". The Journal of Hospital Infection 68 (2): 159–63. doi:10.1016/j.jhin.2007.11.018. PMID 18207605. 
13. ^ "Clean & Disinfect Mold, Bacteria & Viruses in any Environment". http://www.urthpro.com. Retrieved 2010-11-18. 
14. ^ "The Urth Technology". http://urthtech.com/index.php?option=com_content&view=article&id=47:the-urth-technology&catid=34:aboutus&Itemid=53. Retrieved 2010-11-18. "UrthMED™ has been proven to kill Clostridium Difficile (C.Diff) spores on hard, non-porous surfaces, in a surprisingly user friendly formula." 
15. ^ Weber DJ, Barbee SL, Sobsey MD, Rutala WA (December 1999). "The effect of blood on the antiviral activity of sodium hypochlorite, a phenolic, and a quaternary ammonium compound". Infection Control and Hospital Epidemiology 20 (12): 821–7. doi:10.1086/501591. PMID 10614606. 
16. ^ http://www.cdc.gov/niosh/idlh/intridl4.html
17. ^ U.S. Patent 7,632,523
18. ^ http://www.viroxtech.com/ahp/default.aspx
19. ^ Omidbakhsh et al (2006). "A new peroxide-based flexible endoscope-compatible high-level disinfectant". American Journal of Infection Control 34 (9): 571–577. doi:10.1016/j.ajic.2006.02.003. PMID 17097451. 
20. ^ Sattar et al (Winter 1998). "A product based on accelerated hydrogen peroxide: Evidence for broad-spectrum activity". Canadian Journal of Infection Control: 123–130. 
21. ^ Cochrane Collaboration: Topical silver for preventing wound infection, 2009
22. ^ http://en.wikipedia.org/wiki/Antimicrobial_properties_of_copper
23. ^ http://en.wikipedia.org/wiki/Antimicrobial_copper_touch_surfaces
24. ^ Copper Touch Surfaces
25. ^ EPA registers copper-containing alloy products, May 2008
26. ^ http://www.rail.co/2011/07/22/chilean-subway-protected-with-antimicrobial-copper
27. ^ http://construpages.com.ve/nl/noticia_nl.php?id_noticia=3032&language=en
28. ^ http://www.antimicrobialcopper.com/media/149689/pr811-chilean-subway-installs-antimicrobial-copper.pdf
29. ^ Allen MJ, White GF, Morby AP (2006). "The response of Escherichia coli to exposure to the biocide polyhexamethylene biguanide". Microbiology (Reading, Engl.) 152 (Pt 4): 989–1000. doi:10.1099/mic.0.28643-0. PMID 16549663. http://mic.sgmjournals.org/cgi/content/full/152/4/989. 
30. ^ Zamani M, Sharifi Tehrani A, Ali Abadi AA (2007). "Evaluation of antifungal activity of carbonate and bicarbonate salts alone or in combination with biocontrol agents in control of citrus green mold". Communications in Agricultural and Applied Biological Sciences 72 (4): 773–7. PMID 18396809. 
31. ^ Malik YS, Goyal SM (May 2006). "Virucidal efficacy of sodium bicarbonate on a food contact surface against feline calicivirus, a norovirus surrogate". International Journal of Food Microbiology 109 (1–2): 160–3. doi:10.1016/j.ijfoodmicro.2005.08.033. PMID 16540196. 
32. ^ William A. Rutala, Susan L. Barbee, Newman C. Aguiar, Mark D. Sobsey, David J. Weber, (2000). "Antimicrobial Activity of Home Disinfectants and Natural Products Against Potential Human Pathogens". Infection Control and Hospital Epidemiology (The University of Chicago Press on behalf of The Society for Healthcare Epidemiology of America) 21 (1): 33–38. doi:10.1086/501694. JSTOR 10. PMID 10656352. 
33. ^ tpub.com > LEVELS OF DISINFECTION Retrieved on Feb 14, 2010
34. ^ cdc.gov > Sterilization or Disinfection of Medical Devices Date last modified: August 20, 2002. Content source: Division of Healthcare Quality Promotion (DHQP)
35. ^ EPA's Registered Sterilizers, Tuberculocides, and Antimicrobial Products Against HIV-1, and Hepatitis B and Hepatitis C Viruses. (Obtained January 4, 2006)

External links

• Ohio State University lecture on Sterilization and Disinfection
• What Germs Are We Killing? Testing and Classifying Disinfectants
• Disinfectant Selection Guide
• Disinfectant and Non-Chlorine Bleach -- Office of DOE Science Education