To date, the presence of a variety of chemical substances has been found in drinking water, food, fruits, vegetables, ambient air, and household products. Chemical substances have also been introduced into our food, fabrics, onto our fields, and into our medicines. Identification of newer molecules and compounds, and preparations of newer formulations, such as organochlorines; PCBs, dioxins, epoxy resins and polycarbonate plastics; drugs and pharmaceutical products; food additives; insecticides and pesticides; pigments and colors; phthalates and paints; metals like lead, cadmium, and mercury; metal finishing, plastics, lubricating oils, inks, hairspray and insect repellents; breakdown products of industrial solvents, detergents, common industrial and laboratory solvents, synthetic leather products, and many more, is probably an unending process. Proper application of all these and many other chemical substances has caused rapid changes in global scientific technology and will make life very different in the future.