Clean And Mean: Effective Targeting For Disinfectants And Disinfectant Combinations

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 Iodine disinfectant | Chlorine as a disinfectant | Phenolic disinfectants | Quaternary Ammounium compounds | Cresylic acids | Disinfectant combinations of Cresylic and Phenolic | Glutaraldehyde

Chemical disinfectants are essential to profitable poultry and swine production. They will assume even more importance as competition increases, animal population densities increase and the industry is forced to adopt new measures in response to media and politically generated concerns about Salmonella, Camphylobacter and Listeria.

Knowing a few definitions and a little bit about test requirements will help you read a label with better understanding.

A hard surface disinfectant is required to kill 100% of the bacteria, molds and viruses claimed on the label. Testing is performed on a smooth, hard surface - either glass or polished stainless steel. The standard test conditions are 10 minutes at 20 C. A disinfectant will not kill bacterial endospores, i.e., the spores of Clostridium sp. or Bacillus sp.. In the U.S.A. a disinfectant can be registered as a limited disinfectant, an agricultural disinfectant or a hospital disinfectant. Efficacy test requirements will differ for each of these. A disinfectant may be tested in hard water and in the presence of an organic soil load (5% blood serum), but it does not have to bear these claims to be registered. Read the label. If tests were performed in hard water and serum, the label will tell you. Absence of this information on the label indicates the product was not tested in hard water or serum.

A limited disinfectant might be a toilet bowl cleaner which is required to kill gram negative intestinal bacteria (Salmonella, E. coli) but not Staphylococcus aureus ATCC 6538 or Pseudomonas aeruginosa. A careful examination of the product label will disclose this to you.

A disinfectant may be registered solely for agricultural use (poultry, swine, etc.) by testing S. aureus, Salmonella choleraesuis ATCC 10708 and one other pathogen selected by the researcher. Testing against the chemically resistant Pseudomonas aeruginosa ATCC 15442 is not required. The agricultural claim is a non-medical claim and is a little less stringent than the requirements for hospital (medical) use. The hospital or medical disinfectant claim is the strongest and most stringent claim. The minimum test organisms are S. aureus, S. choleraesuis and P. aeruginosa.

A "sanitizer" is defined as a chemical that reduces bacteria to a "safe" level. There are two types of sanitizer claims. One is the hard surface sanitizer's claim for non-food contact surfaces. This claim only requires a 99.9% kill of test organisms dried on a glass slide. The standard test organisms are S. aureus ATCC 6538 and Klebsiella pneumoniae ATCC 4352. This is a much less stringent claim than any of the disinfectant claims. The other type of sanitizing claim is for pre-cleaner food contact surfaces. This requires the Germicidal and Detergent Sanitizer's Test which tests S. aureus and Escherichia coli ATCC 11229 in solution. It is not even a hard surface test. The kill required is 99.999% in 30 seconds in A.O.A.C. hard water. No soil load is used. This is a less stringent test than even the hard surface sanitizer's test.

Table 1 of the appendix summarizes the labeling information supplied to this point.

A sporicide kills 100% vegetative bacteria and bacterial endospores. Sporicidal action is not obtained on environmental surfaces in a 10 minute contact. Sporicides are used on medical equipment where an exposure time of hours instead of minutes is possible. For our purposes, sporicides do not exist.

It is also important to remember that disinfectant tests are performed on smooth, non-porous hard surfaces (glass and polished stainless steel). These surfaces may be adequately representative of critical control points encountered in hospitals and other medical application areas. They are not representative of surfaces encountered in the farm environment (unpainted lumber, dirt floors, unsealed concrete, rusty metal and tar paper). Thus, a disinfectant formulated and tested for hospital use may not be adequate to meet the demand in our industry.

A disinfectant is composed of one or more chemicals. These chemicals react with organic matter (soils) and organisms. In reacting, the chemicals are consumed. Rough, porous surfaces are harder to disinfect than smooth surfaces. Porous surfaces are also harder to clean than smooth surfaces. Porous surfaces will therefore have heavier soil loads after cleaning, which further increases the difficulty of disinfection.

Is the hospital disinfectant adequate to meet the demand in the hatchery and on the farm, or do we need stronger disinfecting concentrations?

Let us now speculate on the properties of an ideal disinfectant (Table 2, appendix) and then see how some commonly used disinfectants compare.

The ideal hatchery and farm disinfectant may be described as: odorless; colorless; tasteless; effective against Gram (+) and Gram (-) bacteria, pathogenic fungi, major viruses; non-toxic in use; biodegradable; stable in storage; non-volatile for effective residual action; stable under hot and cold conditions; non-irritating to skin of users or animals; non-corrosive to treated surfaces or equipment; fast acting; effective over a broad pH range; effective in hard water and in moderate to heavy soil loads.

Iodine Disinfectant (Iodophor)

(Table 3, appendix)

Iodine is excellent for sanitizing poultry drinking water due to its low toxicity and low pH. A side benefit of iodine use is control of mineral deposits and scale in pipes and drinkers due to the phosphoric acid content. Drinkers require less cleaning and maintenance.

Iodine disinfectant is not good for hatchery disinfection because of its corrosiveness (due both to acid pH and iodine vapors), lack of residual germicidal action, potential staining and poor organic tolerance.

The properties making it less than an ideal choice for disinfecting premises and farm vehicles are its poor organic tolerance, acid character and corrosiveness to equipment. It has been used successfully as a cleaner prior to disinfecting a premise with a phenolic, quaternary or cresylic based disinfectant.

Because of its low toxicity and low irritation at use levels, iodine is an excellent choice for drinkers, feeders and animal contact, i.e., sow shampooing.

Chlorine as a Disinfectant

(Table 4, appendix)

Chlorine is available in liquid or granular form. Liquid is available from 5-15% sodium hypochlorite (bleach). Granular chlorine may be calcium hypochlorite (65-70 % available chlorine) or sodium dichloro-s-triazine trione (56-62% available chlorine). Both dry forms of chlorine have good shelf stability if kept cool and dry. Liquid bleach is stable up a maximum of 7% concentrations. Bleach at higher concentrations (8-15%) loose strength rapidly and must be used within a week or two of manufacture.

Chlorine kills fast and has broad spectrum killing action. It is recommended for sanitizing farm wells and drinking water. It is not used for hatchery disinfecting because of its corrosiveness (by products are hydrochloric and hypochlorous acid), corrosive vapors (reacts with moisture to form hydrochloric acid), poor soil tolerance, pH dependency, lack of residual action and, possibly, bleaching action.

Chlorine is a poor choice for terminal disinfection of farm premises due to poor soil tolerance, corrosion to equipment, volatility, pH dependency and user unfriendliness (pungent odor, skin and eye irritation, bleaching of hair, clothing). Chlorine is a regulated by OSHA, FIFRA, CWA, and CAA.

Chlorine is the most important disinfecting agent in our society. It has been the primary protector of our drinking water, swimming pools, and processed foods and beverages. It has uses that no other chemical has been able to replace for safety, effectiveness and economy. However, as ideally as it is suited for some applications, it is not the chemical of choice for many disinfectant applications.

Phenolic Disinfectants

(Table 5, appendix)

The phenolic disinfectants contain p-tertiary amylphenol, o-benzyl-p-chlorophenol and o-phenylphenol. Like chlorine and iodine, phenolics kill a broad spectrum of bacteria, fungi and viruses. Some are tuberculocidal. Phenolics have a typical "phenolic" or hospital odor. Because of the odor, most are scented. They are non-volatile and exhibit fair bacteriostasis and fungistasis on treated surfaces. They have good soil tolerance and function well in hospital, hatchery and farms environments. They do not bleach, although some have been reported to stain hatchers and setters.

The drawbacks to phenolic uses are poor biodegradability, odor, feline toxicity, pH dependency and adverse skin effects. Fatty foods (butter, eggs, milk) can absorb off flavors from phenols.

Quaternary Ammonium Compounds (Quats)

(Table 6, appendix)

The ingredient statement on a quat label will show alkyl dimethyl benzyl ammonium chloride or didecyldimethylammonium chloride as at least one of the ingredients.. These also kill a broad range of bacteria, fungi and viruses. A few carry tuberculocidal claims. The quats are considered odorless, tasteless and colorless in use solution. They are non-volatile and are the most effective residual bacteriostats and fungistats. Use solutions are non-toxic, exhibit minimum irritation potential and will not stain or bleach surfaces. Quats are the least corrosive of the common classes of disinfectants. Quats are biodegradable. There has never been a report of a quaternary ammonium compound accumulating in the environment. Quats are effective over a wide pH range (2- 14).

Quats also perform well as farm and farm premise disinfectants. The can be applied to shell and hatching eggs. They are safe on any surface not harmed by water.

Examples of low toxicity of quats to man and animals include the use of quats as swimming pool algaecides and the inclusion of 40-100 ppm quaternary ammonium compound in poultry drinking water.

Quats are my preference of all the disinfectants for hatchery disinfection. Properly formulated, they kill all the organisms of concern in the hatchery. Their unsurpassed residual disinfecting action is a key property for their success in the hatchery. There are many warm, moist areas in the hatchery and the residual disinfecting action is very important. Quats are more user friendly than most disinfectants, including phenolics. They are less irritating, not odorous and mix easier in water. Phenolics are water insoluble compounds while quats are more readily water soluble.

Cresylic Acids

(Table 7, appendix)

Saponified cresylic acids have use as farm premise disinfectants. Cresylic acids exhibit good gram negative bactericidal action, such as Salmonella, Shigella, E. coli, etc. Cresylic acid is not very effective against P. aeruginosa or gram (+) bacteria, Staphylococci and Streptococci. Because of the strong, persistent odor and limited germicidal action, cresylic acid has not been used in hatcheries, hospitals or, indeed, anywhere except farm houses. Cresylics have good soil tolerance, which is another reason for popularity is premise disinfectants.

Disinfectant Combinations of Cresylic acid/Phenolic Combinations

(See Table 8, appendix)

Properly formulated combinations of cresylics and phenolics incorporate the best features of both components. The combination is effective against a very broad spectrum of bacteria, fungi and viruses. The cresylics (low order disinfectants) have a sparing action on the more reactive (higher order disinfectants) phenolic components when placed in contact with organic soils. Cresylic and cresylic/phenolic combination products are favored for disinfecting of dirt floors in animal pens and poultry houses. They are useful for premise disinfection but their odor is too strong to be used in hatcheries, hospitals, or other indoor areas where disinfectants are in frequent use.


(Table 9, appendix)

Glutaraldehyde is a 5 carbon chain aldehyde closely related to formaldehyde. It is volatile, but much less so than formaldehyde. Disinfection requires 1-2% active glutaraldehyde for effectiveness. The products sold to the animal health industry are sanitizers - not disinfectants. They are usually used at 1,000 ppm glutaraldehyde. Some may go as high as 2,500 ppm. Users of glutaraldehyde products may think they are disinfecting, but they are only sanitizing. Read and Understand the Label.

Glutaraldehyde is not very user friendly. Its vapors are irritating to eyes, nose and throat. It causes asthmatic symptoms in hypersensitive individuals. Prolonged or repeated skin contact can cause allergic reactions.

Disinfectants are not all created equal and you cannot always predict the effectiveness of a disinfectant by an examination of the active ingredients on a label. The efficacy of active ingredients is influenced by other chemicals used in the formulation. The other additives may either enhance efficacy, not alter efficacy or reduce efficacy. While there are some general rules a formulator new disinfectants can follow, there is more art than science involved. Development of a good disinfectant requires a lot of mixing, testing, remixing and retesting.

The formulator must know for what final end use market his product will be used. Different disinfectant use types have differing performance, cost and aesthetic requirements. .See Table 10 of the appendix for a listing of different types of use sanitizers and disinfectants.

Food plant sanitizers have to be odorless and cut to the bare minimum of ingredients to keep the cost low. Disinfection is usually not required and sanitizing claims are very acceptable. They will not be perfumed and, if dyed, are lightly dyed. They generally have high dilution rate and low ppm of actives in the use solutions, i.e., -1/4 ounce per gallon of water.. Quats may be 150-200 ppm and not over 400 ppm for this market.

Household disinfectants are lower concentration products. Use solutions may be 2-5 ounces of water. They must be competitively priced and must have a nice odor, nice color and appearance. Claims can be minimal. Hospital disinfectant efficacy requirements do not have to be met. It is more important for the product to clean well, look pretty and to smell good than it is for it to be a highly effective disinfectant. Quat levels used here may range from 350-600 ppm.

Industrial and non-medical institutional products have to be cheap, leave a pleasant after scent, be pleasant to use and perform light cleaning. They will usually be formulated to meet the minimum requirements for registration. Normally a dilution factor of -1 - 2 ounces per gallon is used. Some will go to ounce per gallon. Quat levels will average 400-600 ppm.

Hospitals will use quat levels of 600 - 780 ppm. They will have to provide the minimum required efficacy on smooth, non-porous, hard environmental surfaces. Hospital disinfectants have to be competitively priced. There a lot of vendors anxious to sell products to hospitals. The product will usually have a mild, pleasant or no fragrance and will perform in hard water and a 5% organic serum load. Hospitals do not place an economic value on disinfection. Disinfection is practiced to prevent cross infections and hospital acquired infections, but, unlike the poultry and swine industries, the impact of disinfection on the "bottom line" is not quantified. A hospital administrator may be more concerned with disinfectant cost than he is with "cost effectiveness".

The animal agriculture industry use disinfectants, isolation and biosecurity programs because it is profitable to do so. They are more concerned with profit than initial cost. Records are kept and the values of sanitation and disinfection are known.

Because of the more porous surfaces and higher soil loads found in farms and hatcheries, it is unrealistic to expect a disinfectant formulated for use in the hospital environment to be as effective in farms and hatcheries. BioSentry takes this into account when formulating disinfectants strictly for the animal health industries.

A brief look at some products (all quats) that may be familiar to you will illustrate some of the points I am trying to make. Please, examine Table 11 in the appendix.

Even an expert cannot look at just the active ingredient statement of most disinfectant labels and determine precisely the effectiveness of the product. Germicidal activity can be enhanced, hindered or not affected at all by the non-germicidal components. This is was illustrated in a paper published by Marion Jones, et. al. In 1984. A successful disinfectant formula was examined complete and then by omitting one or more of the inert ingredients at a time. The inerts included sodium metasilicate, sodium hydroxide, non-ionic detergent, tetrasodium ethylenediamine tetraacetate (EDTA) and water. A formulation containing only the inerts was totally ineffective as a disinfectant. The complete formulation was completely effective. Omission of the sodium metasilicate or the nonionic detergent had not effect on the efficacy. Omitting the EDTA or omitting both the sodium hydroxide and the sodium metasilicate significantly reduced disinfectant action. The active ingredients alone did not give compete disinfection.

When formulating a disinfectant for use in farm, hatchery and other livestock or animal environments, the formulator should pay special attention to the following things. The product should be formulated to perform: in hard water up to 400 ppm as CaCO3 and on porous, hard to clean surface encountering heavy organic soil loads. Use solutions should be non-toxic and not unduly irritating to the user. It should not be irritating as used to the poultry or livestock hatched or housed in the treated areas. Residual bacteriostatic and fungistatic action is important, especially in the hatchery. To be residual, the active ingredients must be non-volatile. Biodegradability is important. The product should be effective against the major pathogens of the industry. Formulation should be more performance than cost oriented. We need to understand that our industry uses disinfectants to protect and improve profits. Within reason, performance is more important than cost. For quality control and quality assurance programs it is also advantageous if disinfectant use solutions can be checked for accuracy of dilution with a simple, easy to use test kit that can be used on site.

People are constantly looking for something new, different, more effective, easier to use, etc. is my contention that very effective products are available for our use today. We need to make better use of these products. This includes making better choices for applications, cleaning more completely before disinfecting, applying sufficient concentrations and amounts of disinfectant, applying the right disinfectant to the right place and at the right time. It is important to deal with reputable manufacturers and to be able to read and understand basic labelling information.

William E. Brown, Ph.D.,
BioSentry Inc.,
1481 Rock Mountain Boulevard,
Stone Mountain, Georgia, USA 30083


Table 2. Properties of an Ideal Farm/Hatcher Disinfectant

Odorless or low odorUser friendly, esp. indoors, daily use, around eggs, feed and food
Broad spectrum biocideKill bacteria, molds, viruses that affect health and growth
BiodegradableEnvironmentally acceptable
Non-volatileEffective residual germicidal action No harmful or corrosive vapors
Stable during storageStable in hot or cold storage
Freeze/thaw stabilityFreezing occur in transit & storage
Fast killing actionMust kill before surface dries
Hard water toleranceWater may have as high as 400 ppm water hardness as CaCO3
High soil toleranceFarm surfaces contain high organic loads on porous surfaces
Effective over wide pH rangepH of waters vary. Other factors may also influence pH at which disinfectant must act
Non-corrosiveMust not corrode or damage treated surfaces or equipment
Non-toxic at useMust not be toxic to applicator of animals housed in treatment area.
Non-irritatingNo irritation to skin, eyes, mucous membranes during use
Not flammableFlash point >100oF
Not a strong oxidizerFire and explosion hazards can exist if improperly stored or handled

Table 3. Properties of Iodophor Disinfectants
Odorless or low odorYes. Good for indoors, frequent use and around food, feed and water
Broad spectrum biocideKill bacteria, molds, viruses that affect health and growth
BiodegradableEnvironmentally acceptable
VolatileNot good residual germicidal action Vapors can corrode
Stable during storageStable for 2 years
Freeze/thaw stabilityYes
Fast killing actionYes
Hard water toleranceExcellent to 400 ppm
High soil tolerancePoor
Effective over wide pH rangeNo. Effective only in acid pH
CorrosivityCorrosion can occur due to acid pH and iodine vapors
Non-toxic at useUse solutions are not toxic to man or livestock
Non-irritatingUse solutions do not irritate skin, or mucous membranes. Vapors of use solution are not eye irritants during use.
Not flammableFlash point >200oF
Not a strong oxidizerNo fire or explosion hazards exist

Table 4. Properties of Chlorine as a Disinfectant
Odorless or low odor1-3 ppm, low; 200 ppm, moderate; 1-5% pungent odor
Broad spectrum biocideKill bacteria, molds, viruses that affect health and growth
BiodegradableEnvironmentally acceptable but some concerns with chloro organics formed.(THMs)
VolatileYes. .No residual disinfection. Vapors corrosive, Can be harmful
Stable during storageLiquid bleach stable to 7%. Above 7% unstable. Powders reasonably stable in cool, dry storage
Freeze/thaw stabilityYes
Fast killing actionVery fast kill
Hard water toleranceGood hard water tolerance.
Organic soil toleranceVery poor
Effective over wide pH rangeNo. Poor effect above pH 9. Unstable in acid pH medium
CorrosivitySolutions and vapors form HOCl and HCl, as well as oxidation
Non-toxic at useHigher concentrations (0.5-5%) may be toxic to man and animals exposed
Non-irritatingNo irritation to skin, eyes, mucous membranes during use
Not flammableFlash point >200oF
    1. Liquid bleach
    2. Granular forms
    1. Caustic pH. Oxidizer, but not fire hazard
    2. Strong oxidizer. Potential fire hazard.

Table 5. Properties of Phenolic Disinfectants
Odorless or low odorPhenolic odor. May absorb into some foods. Usually scented to mask odor.
Broad spectrum biocideKill bacteria, molds, viruses that affect health and growth
BiodegradablePoorly degraded in environment. Monitored in effluents
Not volatileLeaves residual bacteriostatic film. Desirable in hatchery and field
Stable during storageYes. Good shelf life up to 3 years.
Freeze/thaw stabilityYes
Fast killing actionYes
Hard water toleranceGood hard water tolerance.
Organic soil toleranceGood
Effective over wide pH rangeOptimum pH range 10-11, except for LpH which is acidic
CorrosivityGenerally safe on surfaces not harmed by water.
Non-toxic at useUse solutions generally safe
Irritation potentialOther than some mild skin irritation, use solutions are not injurious to man or animals.
Not flammableFlash points vary with formulation
Not oxidizersDo not bleach and generally do not stain.

Table 6. Properties of Quaternary Ammonium Disinfectants
Odorless or low odorOdorless unless scented
Broad spectrum biocideKill bacteria, molds, viruses that affect health and growth
BiodegradableYes. No evidence of quats ever accumulating in the environment
Not volatileLeaves excellent germicidal residual

No harmful or corrosive vapors

Stable during storageYes. Quats are stable indefinitely
Freeze/thaw stabilityYes (vary with formula)
Fast killing actionYes
Hard water toleranceGood hard water tolerance.(may vary with formula)
Organic soil toleranceGood
Effective over wide pH rangeYes. Quats are active from pH 2-14.
CorrosivityGenerally safe on surfaces not harmed by water. The least corrosive of the primary disinfectants.
Non-toxic at useUse solutions generally safe
Irritation potentialOther than some mild skin irritation, use solutions are not injurious to man or animals.
Not flammableFlash points vary with formulation, but not should be flammable
Not oxidizersWill not bleach or stain treated surfaces

Table 7. Properties of Saponified Cresylic Disinfectants
OdorStrong phenolic odor
Low order disinfectantTakes high ppm for effect
Not broad spectrumKills gram (-), not gram (+) bacteria
VolatilitySlowly volatile. Odors linger long time. Not acceptable for indoor or frequent use.
Organic soil toleranceGood
Storage stabilityGood
Kill timeFast, where effective
CorrosivityCresylics are saponified. Safe for most metals and premise surfaces. May soften rubber seals and some plastic materials.
Hard water toleranceGood
ToxicityConcentrate strong irritant to skin and eyes. Use solutions mild skin irritants and moderate eye irritants.

Table 8. Properties of Cresylic/Phenolic Combination
OdorStrong phenolic odor
High order disinfectantTakes low ppm for effect
Broad spectrum killKills gram (+), gram (-) bacteria, fungi and many viruses
VolatilityPhenolics not volatile, cresylics volatile. Thus, some residual germicidal action obtained. Odors may linger several days. Useful for premise disinfection but not hatchery or other indoor areas. Do not use in areas where disinfectant is frequent.
Organic soil toleranceVery good
Storage stabilityGood
Kill timeFast
CorrosivitySafe for most metals and premise surfaces. May soften rubber seals and some plastic materials.
Hard water toleranceExcellent
ToxicityConcentrate strong irritant to skin and eyes. Use solutions mild skin irritants and moderate eye irritants.
Recommended use areasFarm premise clean up. Do not use in hatchery or in egg rooms.
BiodegradableCresylics degrade. Phenolics do so poorly

Table 9. Properties of Glutaraldehyde
OdorMild, irritating to nose and throat
Low order disinfectantTakes high ppm for effect. Sanitizing takes 1,000-2,500 ppm. Disinfecting takes 1-2%.
Spectrum of killKills gram (-), not gram (+) bacteria

Sporicidal at 2% and long contact time.

VolatilitySlowly volatile. Not effect residual germicide as it is normally used (1,000-2,500 ppm).
Organic soil toleranceGood
Storage stabilityAcceptable. Poor stability if held to long at 98 F or if allowed to reach 16 F
Kill timeFast, where effective
CorrosivitySanitizing solutions are safe for most farm surfaces and it has been used for vehicles
Hard water toleranceGood
ToxicityCauses irreversible eye damage. Harmful if inhaled or swallowed. Repeated or prolonged contact can cause allergic reactions. Causes asthmatic symptoms in hyper-active individuals.
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For more information about the content of this document, contact Brenda L Reimer.
This information published to the web on October 28, 1996.
Last Reviewed/Revised on July 15, 2008.