ABSTRACT
Toxicology traditionally has been defined as the science of the study of qualitative and, more importantly, quantitative aspects of injurious effects of chemicals and physical agents in a subject or in a population of subjects. Paracelsus had already recognized nearly five hundred years ago that there is no such thing as nonpoisonous and that the dose alone makes a poison not to be poisonous. Even endogenous body constituents and food stuffs can be deleterious to an organism if present in excessive quantities over prolonged periods of time. Thus, in addition to the dose, time is the second important variable that the science of toxicology deals with.
