Abstract
Abstract
Biotransformation—or the process by which the body changes the chemical structure of an exogenous chemical—is an essential component in the development of toxic responses to chemicals found in the workplace and general environment. There are hundreds of biotransformation enzymes that act on chemicals to change their chemical structure within the body. Many of these biotransformation enzymes (often called “drug‐metabolizing enzymes,” or DMEs) also play essential roles in the formation and elimination of important endogenous biomolecules, such as steroid hormones, neurotransmitters, and other signaling molecules. However, a subset of these enzymes appears to exist primarily for the purposes of detoxifying exogenous chemicals (xenobiotics). Because most of these enzymes are not essential to life, genetic polymorphisms are common and can impart large differences in susceptibility to certain chemicals found in our workplace, diet, or general environment. This chapter discusses the large multi‐gene families of enzymes that are involved in oxidation, reduction, hydrolysis, and conjugation of xenobiotics. Although the purpose of biotransformation processes is to facilitate both the detoxication and elimination of xenobiotics from the body, it often happens that short‐lived, reactive intermediates are formed in the process, and these may be more toxic than the parent molecule. Understanding the pathways of biotransformation, and how these pathways can contribute to both acute and chronic toxic effects of xenobiotics, is an important part of the field of toxicology as it pertains to workplace and environmental exposures to toxic substances.