Introduction to Toxicants :

This includes the toxicology aspects of the development of new chemicals for commercial use. In some of these use classes, toxicity, at least to some organisms, is a desirable trait; in others, it is an undesirable side effect. Use classes are not composed entirely of synthetic chemicals; many natural products are isolated and used for commercial and other purposes and must be subjected to the same toxicity testing as that required for synthetic chemicals.

Most metals occur in nature in rocks, ores, soil, water, and air, levels are usually low and widely dispersed. More recently metals have found a number of uses in industry, agriculture, and medicine. These activities have increased exposure not only to metal-related occupational workers but also to consumers of the various products. Despite the wide range of metal toxicity and toxic properties, there are a number of toxicological features that are common to many metals. For a metal to exert its toxicity, it must cross the membrane and enter the cell.
                         Toxic effects of metals and its properties 
                                        Agricultural chemicals:
                   Insecticides ,Herbicides,Fungicides,Rodenticides,Fumigants
                       Toxic is a toxicant produced by living organisms