What do we mean by "sterility"?

In a "President's Comment" (PDA Newsletter, August 1993) James Akers referred to such numbers, and numerical statements, as: 10(-3), 10(-6), 1cfu/m3, 3cfu/Rodac plate, 90 feet per minute, 0.005 inches of water, 80 degrees C, 20 air changes per hour, and 0.1% with 95% level of confidence. He posed the question "Where did all these numbers come from?" These are, of course all numbers instantly recognisable by those acquainted with the art and science of parenteral manufacture. They are accepted (essential?) parameters of various aspects of this process. But Akers's question carries with it the implicit answer: "They just seemed like a good idea at the time." One might similarly add: 100, 10,000, 100,000, 115 degrees C for 30 minutes, 121 degrees C for 15 minutes, and so on.