Toxicity

Toxicology is the scientific discipline that studies the detection, effects, and mechanisms of action of poisons and toxic chemicals. Toxicity is a relative phenomenon that depends on the inherent structure and properties of a chemical and on its dose. Dose-response curves are typically generated in laboratory animals exposed to various amounts of a chemical.

Despite the inherent limitations of toxicity testing in animals, several important toxicologic principles have been established by this experimental approach. Exogenous chemicals are absorbed after ingestion, inhalation, or skin contact, and then distributed to various organs.

Chemicals are frequently metabolized, often by multiple enzymatic pathways, to products that may be more toxic or less toxic than the parent chemical. One or more of these products then interacts with the target macromolecule, resulting in a toxic effect.

The site of toxicity is frequently the site where metabolism or excretion of toxic metabolites occurs. The dose administered (external dose) may not be the same as the biologic effective dose delivered to the target organ and target macromolecule.

See also

 xenobiotics

• xenobiotic metabolism

References

 Snyder JW: Mechanisms of toxic cell injury. Clin Lab Med 10:311, 1990.

 Coon MJ, et al: Cytochrome P450: peroxidative reactions of diversozymes. FASEB J 10:428, 1996.

 Gonzalez FJ: The use of gene knockout mice to unravel the mechanisms of toxicity and chemical carcinogenesis. Toxicol Lett 120:199, 2001.