Page 633 - Materials Chemistry, Second Edition

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604 Waste Management Practices: Municipal, Hazardous, and Industrial

TABLE 20.8
Selected Antimicrobial Efficacy Claims for Microbial Inactivation
Specific Claim Definition
Sporicide/Sterilant An agent intended to inactivate all living microorganisms, especially bacterial spores
Tuberculocide An agent intended to inactivate mycobacteria, especially Mycobacterium tuberculosis
Tuberculocidal efficacy assumes inactivation of all viruses, fungi, and vegetative bacteria
Virucide An agent intended to destroy viruses. Virucidal efficacy may vary in regard to lipophilic and
hydrophilic viruses
Fungicide An agent that inactivates fungi including fungal spores
Bactericide An agent that inactivates vegetative bacteria but not bacterial spores
Germicide An agent that inactivates one or more pathogenic microorganisms (May include sporicide,
tuberculocide, virucide, fungicide, or bactericide)
Adapted from EPA (1984); RTI, Final Report, 1993. Reproduced with kind permission of Research Triangle Institute.

claims such as bactericidal, fungicidal, virucidal, sporicidal, etc. The chemically resistant species
B. stearothermophilus (ATCC 12980 or ATCC 10149) are commonly employed to demonstrate a
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10 reduction of viable spores. These organisms may be available in commercial suspensions or as
prepared spore strips.
A sufficient number of B. stearothermophilus spores must be added to the treatment system to
demonstrate satisfactory reduction. Disinfection systems are tested by comparing samples from the
procedure with and without the test chemical. The recovered samples are neutralized, filtered, and
inoculated onto soybean–casein digest agar, streaked to quantify the samples, and incubated at 55°C
for at least 48 h. After incubation the organisms must be quantified to confirm the appropriate level
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of spore reduction. The chemically treated spores should demonstrate a 10 reduction in compari-
son with spores treated with tap water.

20.9.9 OPERATIONAL ISSUES
The effectiveness of disinfection treatment is a function of (U.S. EPA, 1986; Turnberg, 1996):

● Characteristics of the disinfectant
● The concentration of the active ingredient
● Type of microorganisms in the waste
● Degree of contamination
● Characteristics of the waste
● Contact time of the disinfectant with waste sample

Other relevant factors (e.g., pH, presence of electrolytes, complex formation, and adsorption
such as binding to small molecules or ions, macromolecules, or soil) will additionally influence the
effectiveness of a specific disinfectant (U.S. EPA, 1986; Turnberg, 1996).
Microbial inactivation by chemical agents is a function of the active ingredient concentration
and the pH of the prepared solution, among other factors. It is essential to ensure that the formula-
tion will not be diluted during the treatment process to the point where it is no longer effective.
Some antimicrobial chemicals such as quaternary ammonium compounds and halogens may be
readily inactivated when in contact with organic matter (e.g., whole blood) or hard water (Ca and
Mg). Depletion of the chemical disinfectant can also occur through consumption of the chemical
agent by interaction with microorganisms, loss through volatilization, chemical decomposition, or
metabolism by the microorganism itself (Kostenbauder, 1983; Turnberg, 1996). Such potential
interference must be considered when selecting a formulation and its concentration for the treat-
ment of medical waste (RTI, 1993).