Disinfecting 



Disinfection is the process of using an agent or chemical that destroys or removes 

 vegetative forms of harmful micro-organisms in an area or on a surface. Over time, 

 multiple repetitions of cleaning and disinfecting might reach the point of sterility, 

 but from a practical point of view the aim when disinfecting is to diminish the 

 population of micro-organisms to a level at which they are no longer harmful — not 

 eliminate them entirely. It is entirely impractical to consider each instance of cleaning 

 and disinfecting to be an exercise in sterilizing. 



Selecting and Using Disinfectants 



For specific guidance on disinfectant selection and use in association with a 

 disease control program or outbreak situation, please contact the APHIS-VS Area 

 Office. For additional general information regarding disinfectants, see http:// 

 www.aphis.usda.gov/vs and http://www.biosecuritycenter.org on the Web. 



Overview — As a first step in disinfectant selection, select a family of disinfectants 

 that will be effective against the micro-organism(s) of interest. Then determine 

 what companies offer EPA-approved disinfectants containing the active agent ) ou 

 have selected. Get label information on each possible disinfectant so that you can 

 determine dilution requirements and check to see that the company's EPA-approved 

 label indicates effectiveness against the micro-organism of interest. 



EPA approves the use of disinfectants exactly as stated on the label. Ihe dilution 

 listed on the label must be followed exactly unless you have a Section 18 exemption 

 allowing a different dilution. Failure to follow label directions makes the individual 

 and the supervisor liable. Disinfectants are tested and proven effective at the specified 

 dilution. Safety is clearly an issue because higher concentrations of disinfectants 

 are often more dangerous to personnel. Disinfectants must be applied according to 

 label directions. Disinfectant wet time should be observed carefully. A surftice to be 

 disinfected should remain "shiny" wet for at least 10 minutes; damp is not adequate. 

 Porous and rough surfaces will require more disinfectant than smooth surfaces. 



The following subsection briefly describes some of the disinfectants that are available. 

 Please note, however, that the list is not exhaustive. 



Physical Disinfecting Agents — 



1. Heat: An increase in temperature causes an increase in chemical activity, and that 

 in turn causes most disinfectants to work better at higher temperatures. 



2. Moist heat (e.g., hot water, autoclave, steam): This is the most effective physical 

 disinfection method. Through the coagulation of protein, all vegetative micro- 



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