Encyclopedia of Environmental Science and Engineering, Volume I and II

224

DISINFECTION

INTRODUCTION

Disinfection is a term which has for many years been used

with different shades of meaning. It has frequently been con-

fused with antisepsis which, although analogous to disinfec-

tion (see later), does not strictly have the same interpretation.

This, particularly when considered in conjunction with other

terminology, means that any article dealing with disinfec-

tion must clearly define the sense in which the term is being

used. Davis (1968) rather vaguely defines a disinfectant as

“a material having powerful germicidal activity and suitable

for use as such.”

Fortunately, at least some of the confusion relating to

disinfection and to similar, but not identical, terms has now

been resolved.

The terms defined in this report have been classified as

shown in Table 1, but only those applicable to this chapter

will be defined here, together with the term chemosterilizer

(Borick, 1968).

Sterilization is the process of destroying or removing all

microbial life.

A sterilant (sterilizer) is an agent used in sterilization

which destroys microbial life, including bacterial spores,

and is thus distinct from a disinfectant. The term “sterilant”

may itself be somewhat confusing, however, for a “chemo-

sterilant” is sometimes used in the Untied States to denote

a “chemical substance used to sterilize insects and render

them incapable of reproduction on mating with non-sterile

partners” (Borick, 1968). Davis (1968) defines a sterilant as

a disinfectant suitable for use in the food industry.

A sporicide is a chemical agent that kills bacterial

spores.

A chemosterilizer (Borick, 1968) refers to a chemical

compound which is used to destroy all forms of microbial

life, and is thus the same as a sterilant defined above. The

term has not been widely used.

Disinfection is the destruction of microorganisms but

not usually bacterial spores. Commercially, the term applies

solely to the treatment of inanimate objects, and does not

necessarily imply that all microorganisms are killed, but

rather that they are reduced to a level not normally harmful

to health.

Antisepsis is the destruction of microorganisms, but not

bacterial spores, on living tissues—not necessarily killing all

microorganisms, but reducing them to a level not normally

harmful to health. The term is thus analogous to disinfection.

A sanitizer is a disinfectant with the connotation also

of cleansing; it is used mainly in the food and catering

industries.

The suffices “-cide” and “-stat” may be added to vari-

ous words to give a precise meaning, e.g., bactericide means

a substance which kills bacteria but not spores, bacteriostat

(bacteristat) a substance which inhibits the growth of bacte-

ria, thereby producing the state of bacteriostasis. Other terms

which are frequently used in this context include the follow-

ing: sporicide (see earlier), fungicide, fungistat, virucide,

microbiocide and biocide.

Not all authorities would agree with all of the defini-

tions listed, and one term in particular which might be hotly

disputed is “antiseptic.” This is often used to denote a chemi-

cal agent usually applied to human skin and acting either

by destroying microorganisms or inhibiting their growth

(Olivant and Shapton, 1970).

Another term which is frequently employed is “detergent -

sterilizers” or “detergent-sterilants”; these consist of two

components, one of which has a cleansing action, and the

other an antimicrobial activity. Unfortunately, “sterilizer”

or “sterilant” has an absolute meaning (see above) and this

would imply that a detergent sterilizer (sterilant) is spo-

ricidal as well as being lethal to other microorganisms,

whereas those compounds which comprise the “sterilizer”

or “sterilant” component are usually not sporicidal. There is

probably, however, need of a term which includes the word

“detergent.” Foster et al. (1953) use “sanitization” to denote

the application of a bacterial process sufficient to render

dairy equipment approximately sterile, this also implying

TABLE 1

Terminologya used in sterilization and disinfection

I. Definitive terms II. Terms in common use

Sterile Disinfectant

Sterilization Disinfectant

Sterilizing agent Antiseptic

-cideb Antisepsis

-stat Sanitizer

-statis Sanitization

a British Standard Glossary of terms.

b Not germicide.

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