> Biology? No. A simple example, the LD for a substance. At LD50 you have 50% of samples dying. Here you have a substance with a very strong effect (death), at a high dose (because it kills 50%) and still, the chance of it effecting the sample is 50% (ok, 50% by design of experiment, and you'll have an spectrum of reactions)?
Every living being have different physiology, so there are differences in pharmacokinetics and pharmacodynamics; all of that is explainable at molecular level. LD50 is just statistical indicator, you can even explain why something is lethal at high dose, why is cure at medium dose and why dont play any role on low dose.
