ABSTRACT
Toxicology is the branch of science concerned with understanding the gross and intrinsic capabilities of a chemical substance on biological systems-that is, on plants, animals, and humans. Toxicology is a multidisciplinary science and closely interrelated with many other branches of science. Chemical substances are required for health, progress, and societal development. In the very close linkage with an array of chemical substances and societal development, human health cannot be ignored. Therefore, thinkers of the past and present around the world framed regulations about the manners and methods of use of chemical substances. There are no safe chemical substances and all are toxic in one way or the other. No chemical substance is absolutely safe. In fact, the safety of a chemical substance depends upon the concentration and manner of exposure and use. This is important and should be very well understood and remembered by all students, industrial workers, and household users who handle, store, transport, and dispose of different chemical substances. Improper and negligent use and management of chemical substances cause injury, death, and disaster. The present chapter focuses on and briey discusses the elements of toxicology vis-à-vis effects of chemical substances and their use.
