ABSTRACT
Foods contain not only the nutrients we need (e.g., carbohydrates, proteins, fats, vitamins, inorganic elements) but also a large number of chemicals, some of which are toxic. Plants synthesize toxic chemicals apparently as a primary defense against bacterial, fungal, insect, and other animal predators. These are the normal components that constitute the genetically determined chemical prožle of the plant that serves as food. Some toxic chemicals may enter the food supply by fortuitous natural mechanisms. These may be of microbial origin and may be environmental pollutants, including heavy metals. Chemicals sprayed into plants in the form of pesticides may be present in foods of plant origin and may be transmitted through feed grains to animals. There are also substances added to foods for functional purposes such as preservatives, antioxidants, and calorie reduction agents.
