Milton Leitenberg: Because it turns out that the assumption in the past was not physiologically correct, that's all.

Gennadiy N. Lepeshkin: If someone receives an infectious dose, either epidermically, or through the lungs, the eyes or the gastrointestinal tract, that person would demonstrate symptoms within six days. If the dose is infectious. That is, if he receives a large enough dose to get sick. If he doesn't receive a dose large enough to get sick, he won't get sick.

Leitenberg: Well, it's tough; it's not so, that's all. What else can I say? It turns out, in the real world this experiment hasn't been done. No one has ever used this stuff in war. No one has ever, at least that we know, done it experimentally on prisoners. Right? We did in this country, Brucellosis, during World War II. Nobody ever tried Anthrax. The curve means, by definition, this... this is called a probit slope: there are some people in the population that will get a lethal dose at, not eight thousand spores, but six thousand five hundred. And some at three thousand three hundred. And some at hundred. And some teeny, little number at fifty. That's the definition. So you don't have to get eight thousand and above to get a lethal dose.