A number of mathematical models have been developed
over the past century to represent the
dose-response curve of a microbial population exposed
to a disinfectant. Beginning with the Chick-Watson
model and continuing through the Gard, Hom, and
delayed Chick-Watson models, these representations
have in common their foundation on the concept that
the interaction between a microorganism and a disinfectant
is a kinetic process similar to that between
chemicals undergoing a reaction.
The author reviews the development of these models
and proposes an alternative interpretation based on the
diversity of the microbial population in its resistance to
a disinfectant. If additional research confirms its validity,
this hypothesis should help explain the variability
seen in microorganisms' responses to a specific disinfectant.
A better understanding of how microorganisms are
inactivated will assist utilities in complying with regulatory
requirements and may lead to improved engineering
designs for meeting those requirements. Includes 23 references, table, figures.