View source for Toxicology

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'''Editor-in-chief''':  Scott Everett, MD, Pharm D [mailto:reverett336@gmail.com] 

'''Toxicology''' (from the [[Greek language|Greek]] words ''toxicos'' and ''logos'') is the study of the adverse effects of [[chemical]]s on living organisms.<ref>[http://www.toxicologysource.com/whatistoxicology.html "What is Toxicology" -Schrager, TF, October 4, 2006]</ref> It is the study of symptoms, mechanisms, treatments and detection of [[poison]]ing, especially the poisoning of people.

==History==

[[Mathieu Orfila]] is considered to be the modern father of toxicology, having given the subject its first formal treatment in [[1813]] in his ''Trait des poisons'', also called ''Toxicologie generate''.

However, Theophrastus Phillipus Auroleus Bombastus von Hohenheim (1493 - 1541) (also referred to as [[Paracelsus]], from his belief that he was above or beyond the work of [[Celsus]] - the Roman physician from the first century) is widely regarded as "the father" of toxicology. He is credited with the classic toxicology soundbite "All things are poison and nothing is without poison; only the dose makes a thing a poison." The original German [http://de.wikipedia.org/wiki/Gift reads:] "Alle Dinge sind Gift und nichts ist ohne Gift; allein die Dosis macht, dass ein Ding kein Gift ist." This is often condensed to "The dose makes the poison".

The term [[LD50|LD<sub>50</sub>]] refers to the dose of a toxic substance that kills 50 percent of a test population (typically [[rat]]s or other surrogates when the test concerns human toxicity).  [[LD50|LD<sub>50</sub>]] estimations in animals are no longer required for regulatory submissions as a part of [[pre-clinical development]] package.{{Fact|date=February 2007}}

==Relationship between dose and toxicity==

Toxicology studies the relationship between dose and its effects on the living organism. The chief criterion regarding the toxicity of a chemical is the dose, i.e. the amount of exposure to the substance.  Almost all substances are toxic under the right conditions as [[Paracelsus]], the father of modern toxicology said, “Sola dosis facit venenum” (only dose makes the poison). Paracelsus, who lived in the [[16th century]], was the first person to explain the [[dose-response relationship]] of toxic substances.  

Even a benign substance like water can cause harm in excessive amounts.  "Dr. Adrian Cohen was saddened, but not surprised, to hear about the 28-year-old woman who died earlier this month after drinking nearly two gallons of water to try to win a radio station contest." <ref>[http://www.washtimes.com/entertainment/20070125-091730-6743r.htm "The stunt ending you didn't see" - Christian Toto, ''The Washington Times'' - January 26, 2007]</ref>

==Toxicity of Metabolites==

Many substances regarded as poisons are toxic only indirectly. An example is "wood alcohol," or [[methanol]], which is chemically converted to [[formaldehyde]] and [[formic acid]] in the [[liver]]. It is the formaldehyde and formic acid that cause the toxic effects of methanol exposure.  Many [[Medication|drug]] molecules are made toxic in the liver, a good example being [[acetaminophen]] (paracetamol), especially in the presence of [[alcohol]]. The genetic variability of certain liver [[enzyme]]s makes the toxicity of many compounds differ between one individual and the next. Because demands placed on one liver enzyme can induce activity in another, many molecules become toxic only in combination with others. A family of activities that engages many toxicologists includes identifying which liver enzymes convert a molecule into a poison, what are the toxic products of the conversion and under what conditions and in which individuals this conversion takes place.

== See also ==

* [[List of publications in biology#Toxicology|Important publications in toxicology]]
* [[In vitro toxicology]]
* [[Pollution]] 
* [[Toxicity]]
* [[Enzyme inhibitor|Enzyme inhibition]]
* [[Certain safety factor]]

== References ==
<references/>
* Amdur MO, Doull J, Klaassen, CD. 1993. Cassarett and Doull's Toxicology: The Basic Science of Poisons. New York: McGraw-Hill, Inc.
* Gilbert SG. ''A Small Dose of Toxicology – The Health Effects of Common Chemicals''. CRC Press, Boca Raton,  February [[2004]], p 266. [http://www.asmalldoseof.org/]
* Hodgeson E, Levi PE. 1987. A Textbook of Modern Toxicology. New York: Elsevier Science Publishing Co., Inc.

== External links ==
{{wiktionary}}
* [http://www.asmalldoseof.org/ A Small Dose of Toxicology - information on health effects of commmon chemicals] 
* [http://www.atsdr.cdc.gov/ Agency for Toxic Substances and Disease Registry (ATSDR)]
* [http://www.toxicology.org Society of Toxicology]
* [http://www.actox.org American College of Toxicology]
* [http://www.ecetoc.org European Centre for Ecotoxicology and Toxicology of Chemicals]
* [http://www.hazard.com/msds/index.php Toxicity and hazard data on industrial chemicals]
* [http://www.ich.org International Conference on Harmonisation ]
* [http://www.tera.org/iter/  International Toxicity Estimates for Risk Database]
* [http://www.tiaft.org The International Association of Forensic Toxicologists]
* [http://ntp.niehs.nih.gov/ Department of Health and Human Services National Toxicology Program (NTP)]
* [http://toxseek.nlm.nih.gov/ NLM ToxSeek - a meta search engine for Environmental Health & Toxicology]
* [http://toxnet.nlm.nih.gov/ NLM TOXNET - Databases on toxicology, hazardous chemicals, environmental health, and toxic releases.]
* [http://sis.nlm.nih.gov/enviro.html NLM Toxicology and Environmental Health Information Program]
* [http://www.le.ac.uk/mrctox/ Medical Research Council Toxicology Unit]
* [http://www.aapcc.org/ American Association of Poison Control Centers (AAPCC)]
* [http://www.toxicologysource.com/toxscience.html ToxicologySource]
* [http://www.agriculture.purdue.edu/USDA/careers/toxicologist.html Food, Agriculture and Natural Science Careers : Toxicologist] 
* [http://www.toxpath.org/ Society of Toxicological Pathology] 

[[Category:Toxicology]]

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