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Think Safety When Choosing the Proper Disinfectant or Sterilant
By Bill Feil
Disinfecting or sterilizing environmental surfaces or equipment is not themost glamorous task that one performs in his or her typical workday. It is,however, critical to proper infection control in the acute care and alternatecare settings. The selection of which germicidal product to use may not alwaysbe obvious. If you were to look carefully at the products in your facility, youmay find 5-10 products that are registered as either disinfectants or sterilants.How do you know which product to use? The answer is simple: think safety.
Safety in this setting has many meanings: safety or assurance that theproduct selected will provide the efficacy required to disinfect or sterilizethe surface to be decontaminated; safety for the person using the antimicrobialproduct; safety for the surface which is being treated; safety for others beingexposed to that and other surfaces; and finally, safety for the environment.Every time someone uses a disinfectant product, they are knowingly orunknowingly making decisions in each of these areas.
Assurance of product efficacy
The first safety decision is safety, or assurance that the product selectedwill provide the proper efficacy. This is not a new topic in the infectioncontrol arena. In fact, most of today's guidelines still reference a processoutlined in 1968 by Spaulding.1 In his process, he divided itemsrequiring disinfecting or sterilizing into three categories: critical,semicritical, and noncritical. Each category has its own recommendations for thedegree of decontamination that would be necessary. This process has continued toevolve with time and many very useful guidelines have already been written andare periodically updated. These include:
These guidelines provide very detailed strategies to ensure that theselection of a disinfectant or sterilant is appropriate for the risk associatedwith a particular surface or instrument.
The guidelines above2,3,4 help you determine the class of productrequired to properly decontaminate the surface. Using this knowledge base,healthcare workers must then select a product that meets these requirements. Theonly way to do this is by thoroughly reading the product labels. There is awealth of information on the label. Both the Environmental Protection Agency(EPA) and the Food and Drug Administration (FDA) review and approve productlabels. This is to ensure that the information required to make proper productselection is contained on the label. The label also indicates the proper uses ofthe product, including the sites of application (bathrooms, floors, etc.) aswell as dilution instructions. At first glance these may seem confusing, but ifyou understand what each section provides, the label will provide theinformation required to make the proper decision. Periodically there arearticles written to help understand label content and regulations,5but if you are in doubt, contact the chemical manufacturer and get the answersneeded to make the correct decision.
Once you have selected the product, it must be used properly. Although thisseems obvious, it is often overlooked. Chemical manufacturers are required togenerate data to substantiate all label claims. If the product is usedincorrectly, there is no assurance that you have performed the job you intended.There are several critical steps in using a disinfectant or sterilant. Forconcentrated products, the first is the dilution. What does 1/2 ounce/gallonlook like in a mop bucket? In a spray bottle? The free pouring of germicides isa recipe for disaster. If you are going to use a dilutable product, use thedispenser provided by the chemical manufacturer. If you disagree, do a simpletest. Take one of the products in your area and find a graduated cup, beaker, orother reservoir and ask 5-10 of your associates to pour out one ounce. For mostproducts, one ounce is about 30 mL. You will be surprised at the results.Remember, a dispenser doesn't have to be a piece of equipment on the wall. Thereare many unit-dose products available which are essentially simplifieddispensers.
Using chemical dispensers also is not foolproof. Dispensers require routinemaintenance. Most dispensers have metering tips that may become partiallyobstructed or even plugged over time. This will vary greatly depending on thewater conditions in your area of the country. You need to verify that yourdispenser is working properly. In addition to proper dilution, you need toensure that the proper quality of water is being used. Again, the product labeldetails the quality of water that can be used to dilute the product. Using theincorrect water source can and will affect the efficacy of the product. Not onlyshould it be of the proper water hardness, but it should be routinely monitoredfor non-coliform bacteria.6
Ready-to-use germicides are always an option. For these products, themanufacturer ensures that the product has been properly prepared and is ready tobe delivered to the surface. There is a cost for this convenience, but in manycases it does have a place in the surface decontamination strategy.
Once you have diluted the product correctly, you must determine whether thesurface needs to be pre-cleaned. Many products are registered as one-stepcleaner/disinfectants. This claim is intended for situations with low soiling.The laboratory test is typically performed using a 5% soil challenge. Thegeneral rule of thumb is, if it looks dirty, it should be pre-cleaned first.Applying the disinfectant in two separate applications can accomplish this. Ifthe product does not have the one-step cleaner/disinfectant claim, you shouldalways pre-clean, even if the surface appears clean.
The last step in a disinfection process is the actual application and thetime required to perform the task adequately. Testing of germicides is alwaysconcentration and time dependent. Most germicides require a 10-minute contacttime to disinfect a surface. This is based on the testing methodology requiredby the EPA. Products are beginning to be registered with shorter contact times,but the majority of the products still carry the 10-minute contact time. If youshorten the contact time from what is stated on the label, you may compromisethe efficacy of the product. Take the time to do it correctly. For products thatare sprayed on the surface, make sure you use the proper number of sprays tothoroughly wet the surface. If you don't, you may not be applying sufficientgermicide to provide the efficacy stated on the label.
Safety for the person applying the chemical
The second safety decision is for the person who is applying the chemical tothe surface. There are two aspects to this discussion: safety from the chemicaland safety from the microbes. Proper safety equipment for use of the chemicalgermicide can be found in two locations: the product label and the product MSDS.A germicide's function is to kill microbes on surfaces. There are manyvulnerable surfaces on the human body and these should be protected properly.Chemical manufacturers are required to test products to determine whatprecautions will be necessary to keep users properly protected. These testscategorize sensitivities to the skin, eyes, mucous membranes, etc. The properpersonal protective equipment (PPE) is spelled out and should be used. This iseasy to dictate administratively, but it will require surveillance to ensurethat it is being implemented properly.
In addition to PPE, the label, and MSDS also provide instructions in theevent of accidental exposure to the chemicals. You should have your productMSDSs accessible. This will save time in determining the proper course of actionand will also give instructions so further damage is not done through impropertreatment after the accident has occurred. Finally, the MSDS also containsemergency numbers that can be called for further consultation.
Chemical exposure is not the only concern, however. There have been severalarticles published that further articulate the need for use of proper PPEs.7,8,9These outline the transfer of microorganisms from the contaminated surface tofingertips, gloves, uniforms, other surfaces, and other patients. The use of PPEand proper handwashing protocols can be key elements to stopping the spread ofmany organisms. The benefit of preventing nosocomial infections is worth thecost of the PPE and time to perform proper handwashing after decontaminatingsurfaces. This ensures that you are working in a safe environment and thatothers are also not being unnecessarily exposed due to cross contamination.8
Safety for surfaces
The third safety decision is for the surfaces to be disinfected. Improper useof chemicals can and will cause damage to surfaces. Household bleach has beenrecommended for many applications, however, bleaches can be corrosive to metalsurfaces. Figure 1 depicts the corrosion of stainless steel by chlorine bleach.This damage is not reversible and can be costly.
Resilient floor tiles are another excellent example of surfaces that can beeasily damaged. Floor finishes are sensitive to the pH of the products used toclean them. At the low pHs of some acid bathroom cleaner/disinfectants (<2.5), the floor finish will be stripped off the floor. This can also occur athigh pHs (> 10). Some quaternary surfactant based disinfectants can have pHsin this range.
Plastics can also be damaged. Figure 2 shows chemical damage to a plastic.Although plastics are generally resistant to chemical exposure (chemicalproducts are stored in plastic containers), this is not a guarantee that it issafe for all types of plastic. Many different resin chemistries are utilized inthe acute care and alternate care settings and certain chemicals may not be safeon all plastics. If in doubt, ask the manufacturer of either the chemical or thesurface, or place a small amount of product on the surface and look for damage.
A final concern for surface safety is the application procedure. Manysurfaces are laminated or coated with chemical-resistant materials. The use ofmechanical action can remove the protective coating and expose the non-resistantportion of the surface to the germicide. Figure 3 shows where the protectivecoating on a shower flange was etched away with a scouring pad. This allowed theacid bathroom cleaner to attack the underlying metal. This can be true for othersurfaces as well. Mechanical damage and chemical damage can at times bedifficult to distinguish, but the end result is the same--the surface isirreversibly damaged.
Safety for the environment
The last safety decision is for the environment. This responsibility againfalls primarily on the chemical manufacturers and their suppliers. The EPA orFDA must approve each ingredient in a germicidal formulation for use. There aretwo registration pathways, one for active ingredients (antimicrobials) and onefor inert ingredients. There are many tests required to ensure that thesematerials are safe for the environment. Registering a new active or inertingredient can take several years and millions of dollars. This only ensuresthat, if properly used, the germicide will provide the level of safety to theenvironment that the government agencies require. You need to ensure that theyare used properly and that they are disposed of properly. We all need to do ourpart to minimize the impact on the environment.
Ensuring appropriate selection and safe use of disinfectants and sterilants
How do you ensure that you and others are selecting the proper disinfectant?Education and training are the only ways to accomplish this task. There arethree keys to any education and training program:
In the end, proper selection and safe use of disinfectants and sterilants isa group and individual responsibility. By choosing a particular disinfectant orsterilant, you are making many decisions. Take that responsibility seriously.Educate yourself, obtain the proper training, and most importantly, thinksafety.
William Feil is a scientist for the Professional Products Division of EcolabInc. in Mendota Heights, Minn.