INTRODUCTION Photo credit to: http://sciencegames.4you4free.com/poisons_toxicologist.gif “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy.”  – Paracelsus (1493-1541) The quotation above illustrates that all chemicals could be toxic but the degree of the effect depends on the dose or degree of exposure.             Toxicology is defined as the scientific study of...