Toxicology


Toxicology (from the Greek words ? - toxicos "poisonous" and logos) is a branch of biology, chemistry, and medicine concerned with the study of the adverse effects of chemicals on living organisms.[1] It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people. Lithograph of Mathieu Orfila See also: History of poison Dioscorides, a Greek physician in the court of the Roman emperor Nero, made the first attempt to classify plants according to their toxic and therapeutic effect.[2] Ibn Wahshiya wrote the Book on Poisons in the 9th or 10th century.[3] Mathieu Orfila is considered to be the modern father of toxicology, having given the subject its first formal treatment in 1813 in his Traite des poisons, also called Toxicologie generale.[4] In 1850 Jean Stas gave the evidence that the Belgian Count Hippolyte Visart de Bocarme killed his brother-in-law by poisoning with nicotine[5] Theophrastus Phillipus Auroleus Bombastus von Hohenheim (14931541) (also referred to as Paracelsus, from his belief that his studies were above or beyond the work of Celsus - a Roman physician from the first century) is also considered "the father" of toxicology.[6] He is credited with the classic toxicology maxim, "Alle Dinge sind Gift und nichts ist ohne Gift; allein die Dosis macht, dass ein Ding kein Gift ist." which translates as, "All things are poison and nothing is without poison; only the dose makes a thing not a poison." This is often condensed to: "The dose makes the poison" or in Latin "Sola dosis facit venenum". The relationship between dose and its effects on the exposed organism is of high significance in toxicology. The chief criterion regarding the toxicity of a chemical is the dose, i.e. the amount of exposure to the substance. All substances are toxic unde

the right conditions. The term LD50 refers to the dose of a toxic substance that kills 50 percent of a test population (typically rats or other surrogates when the test concerns human toxicity). The conventional relationship (more exposure equals higher risk) has been challenged in the study of endocrine disruptors. Toxicity is species-specific, lending cross-species analysis problematic. Newer methods are available to bypass animal-testing. A nontechnical popularization of traditional toxicology is available in the book the Dose Makes the Poison.[8] Factors that influence chemical toxicity: Dosage[9] Both large single exposures (acute) and continuous small exposures (chronic) are studied. Route of exposure[10] Ingestion, inhalation or skin absorption Other factors[11] Species Age Sex Health Environment Individual characteristics Foods safe for humans are not necessarily safe for pets. A young healthy pregnant woman in a supportive environment has a different set of chemical sensitivities than an aged homeless male drug addict. Chemicals safe to drink may not be safe to inject. Eating a peanut is life-threatening for some. The classic experimental tool of toxicology is animal testing.[12] Alternative tests have been and are being developed. Separate test protocols are used for acute and chronic toxicity, irritation, sensitization (allergies), reproductive toxicity and carcinogenesis (cancer). Few antidotes to poisons exist.[13] Treatment usually consists of removing the poison, repairing damage and providing life support. The testing of one chemical for its cancer-causing properties took 5 years, cost more than $6.5 million in 1980 and utilized 24,000 mice.[14] The field is under pressure to simultaneously eliminate the human risks of chemical exposure while reducing time, cost and animal testing.