JUNIPER PUBLISHERS-OPEN ACCESS JOURNAL OF PHARMACY & PHARMACEUTICAL SCIENCES Introduction Paracelsus, the medieval physician, who is often viewed as the father of modern toxicology, was the first person to appreciate that "the dose makes the poison". This essentially means that very toxic materials can be used therapeutically at very low concentrations and conversely even safe materials can be toxic if overdosed. This in turn led to Haber's law, which basically states that, the incidence and/or severity of any toxic effect is dependent on the total exposure to the toxic agent; that is, the exposure concentration (c) rate(or dose) multiplied by the duration time (t) of exposure (i.e. cxt). This law is often utilised in setting exposure limits for toxic components. The major caveat, is that establishing acceptable daily intakes (ADIs) for long-term exposures to a toxic substance when only data from short-term studies are available, does require
