Table 1.

Terms used to describe microbial indicators, index organisms, or other metrics to measure microbial contamination in the environment

Term	Definition and/or purpose	Reference(s)
Process indicator	Used in food and water industries to demonstrate the efficacy of a process or if the process has been compromised	4, 11
Fecal indicator	An organism, such as Escherichia coli, that indicates the presence of fecal contamination	2
Model organism	Organism behaves in the same manner as a pathogen in a given environment or set of conditions; for example, the use of coliphages to model the behavior of human enteric viruses	11, 53
Tracer	Used in transport studies; examples include the use of coliphages or spores to trace groundwater movement or spore transport in aerosol	3, 23, 42, 45
Surrogate for assessment of environmental risk	An organism, particle, or substance used to study the fate of a pathogen in a specific environment	This article