Methods used to control the growth of microorganisms and the transmission of infectious disease involve stopping the growth of the microorganism for a period of time, reducing the number of microorganisms to a safe level, or destroying the microorganisms. The degree of effectiveness depends on the number of microorganisms, the type of microorganism, their physiological state, such as the stage of growth or formation of endospores, and the environment in which they are growing (glassware, instruments, tissue, food).