TY - CHAP M1 - Book, Section TI - Principles of Toxicology A1 - Eaton, David L. A1 - Gilbert, Steven G. A2 - Klaassen, Curtis D. A2 - Watkins III, John B. Y1 - 2015 N1 - T2 - Casarett & Doull’s Essentials of Toxicology, 3e AB - A poison is any agent capable of producing a deleterious response in a biological system.A mechanistic toxicologist identifies the cellular, biochemical, and molecular mechanisms by which chemicals exert toxic effects on living organisms.Toxicogenomics permits mechanistic toxicologists to identify and protect genetically susceptible individuals from harmful environmental exposures, and to customize drug therapies based on their individual genetic makeup.A descriptive toxicologist is concerned directly with toxicity testing, which provides information for safety evaluation and regulatory requirements.A regulatory toxicologist both determines from available data whether a chemical poses a sufficiently low risk to be marketed for a stated purpose and establishes standards for the amount of chemicals permitted in ambient air, industrial atmospheres, and drinking water.Selective toxicity means that a chemical produces injury to one kind of living matter without harming another form of life even though the two may exist in intimate contact.The individual or “graded” dose–response relationship describes the response of an individual organism to varying doses of a chemical.A quantal dose–response relationship characterizes the distribution of responses to different doses in a population of individual organisms.Hormesis, a “U-shaped” dose–response curve, results with some xenobiotics that impart beneficial or stimulatory effects at low doses but adverse effects at higher doses.Descriptive animal toxicity testing assumes that the effects produced by a compound in laboratory animals, when properly qualified, are applicable to humans, and that exposure of experimental animals to toxic agents in high doses is a necessary and valid method of discovering possible hazards in humans. SN - PB - McGraw-Hill Education CY - New York, NY Y2 - 2024/03/28 UR - accesspharmacy.mhmedical.com/content.aspx?aid=1113948507 ER -