ABSTRACT
Following the entry into a living organism and translocation, a pollutant may be stored, metabolized, or excreted. Some chemicals that are stored may remain in the body for years without exhibiting appreciable effects. One such chemical is dichlorodiphenyltrichloroethane (DDT). Subsequent to the entry of an environmental chemical into a mammalian organism, chemical reactions occur within the body to alter the structure of the chemical. The process of xenobiotic metabolism contains two phases commonly known as Phase I and Phase II. In Phase I reactions, a chemical may acquire a reaction group. Phase II reactions, on the other hand, are synthetic or conjugation reactions. In the two phases of reactions, the lipophilic foreign compound is first oxidized so that a functional group is introduced into the molecule. Although hepatic enzymes that catalyze Phase I and II reactions are primarily to detoxify xenobiotics, they also participate in the metabolism or detoxification of endogenous substances.
