Toxicology: A Brief Introduction to Fundamentals, Chemistry, and Biochemistry

Toxicology: A Brief Introduction to Fundamentals, Chemistry, and Biochemistry, is designed as a brief overview of toxicology with an emphasis upon the chemistry and biochemistry of toxic substances, that is, toxicological chemistry and biochemistry.

Chapter 1, What is Toxicology?, is an overview of toxicology in general. It begins by defining poisons, kinds of toxic substances, and toxicology followed by discussion of factors that influence toxic effects including the routes taken by such substances in the body from exposure to elimination. The key concept of the dose-response relationship is defined and discussed. Toxicity ratings, relative toxicities, sublethal effects, reversibility, margin of safety, hypersensitivity, and hyposensitivity are discussed. The chapter also discusses kinetic and nonkinetic toxicology, the dynamic phase in which toxicants may be involved as well as toxification and detoxification of toxicants including synergism, potentiation, and antagonism. Also covered are receptors of toxicants, behavioral and physiological responses, reproductive and developmental effects, mutagenesis and carcinogenesis.

Chapter 2, Toxicological Biochemistry, provides the basis for later discussion of the chemistry and biochemistry of specific substances. The major classes of biochemicals carbohydrates, proteins, lipids (fats, oils, and hormones), and nucleic acids are defined and discussed. A definition of enzymes and how they function is followed with a discussion of metabolism and energy-yielding processes in metabolism. The second segment of the chapter deals with the biochemistry of toxic substances and toxicological chemistry including how toxicants are metabolized, the conversion of protoxicants to toxic forms, Phase 1 and Phase 2 reactions of toxicants and their biochemical and toxic effects. The chapter concludes with a discussion of the biochemical processes involved with mutagenesis, carcinogenesis, and endocrine disruption.

Chapter 3 covers a wide range of specific toxicants by chemical class. It begins with a discussion of elements usually considered to be toxic (especially heavy metals), and toxic elemental forms of elements not normally regarded as toxic including ozone, white phosphorus, and elemental halogens. Next is a discussion of toxic inorganic compounds such as cyanide and nitrogen oxides. Of the organometallic compounds discussed are organolead compounds organotin compounds, and carbonyls. Discussion of organic compounds begins with hydrocarbons including the simple asphyxiant alkane gases (methane), the generally more toxic alkenes, the aromatic compounds (benzene and carcinogenic benzo(a)pyrene). The oxygen-containing organic compounds discussed include oxides, alcohols, ethers, alcohols, phenols, carboxylic acids, and acid anhydrides. The toxic organonitrogen compounds include amines, including some of the carcinogenic aromatic amines, nitriles, nitro compounds, potentially carcinogenic nitrosamines, and organonitrogen pesticides. Toxic organohalides, include carbon tetrachloride, carcinogenic alkenyl vinyl chloride, and highly persistent and bioaccumulative polychlorinated biphenyls (PCBs). Organohalide pesticides, now generally banned, are covered as a separate category. Among the organosulfur compounds discussed are the highly odorous thiols and sulfur mustard, a deadly vesicant (blistering agent). The discussion of organophosphorus compounds centers around the potentially deadly organophosphates. Warfare agents and potential agents for terrorism, of which the ones of greatest concern are the nerve agent organophosphates, such as Sarin, are discussed The chapter concludes with mention of several toxic natural products, such as deadly botulism toxin produced by anoxic bacteria, and aflatoxins synthesized by some fungi.