Containment: Pathogens cannot survive for long, once they have left the human host. They have co-evolved over thousands of years with the human race and can thrive only within the narrow chemical and environmental parameters of the human body. Containing the excreta for an extended period of time brings about the death of pathogens and reduces the risk of infecting new hosts through ingestion —the primary pathway for enteric pathogen transmission

Competition: The competition among composting organisms for available carbon and other nutrients is intense.

• Human pathogens become food for the well-adapted aerobic soil organisms that thrive in the Carousel.
• When the available nutrients are consumed, the microorganisms begin to consume their own protoplasm to obtain energy for cell maintenance. When this occurs, the microorganisms are said to be in the “endogenous phase.”
• When these organisms die, their protoplasm and cellular matter is digested by other organisms.
• Eventually, if no new food sources are presented, all the energy will be released and the matter fully oxidized. The end of this phase results in an end product that is stable and safe.

Antagonism: Some composting organisms produce toxic substances that harm, inhibit, or kill other organisms. For example, the actinomycete Streptomyces grieus produces streptomycin, a well-known antibiotic. The soil bacterium Bdellovibrio bacteriovorus parasitizes the infamous Echerichia coli (E. coli) and multiplies within the host cell, eventually killing it.

Adverse Environmental Factors: Factors such as pH, temperature, moisture, and ammonia content also play important roles in pathogen multiplication or death.