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Concepts Poison Venom Toxicant (Toxin) Acceptable daily intake Acute toxicity Bioaccumulation Biomagnification Fixed Dose Procedure LD50 Lethal dose Toxic capacity Toxicity Class

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Toxicology (from the Greek words toxicos and logos) is 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.

Contents 1 History 2 Relationship between dose and toxicity 3 Toxicity of metabolites 4 Subdisciplines of toxicology 5 Chemical toxicology 6 See also 7 References 8 Further reading 9 External links

[edit] History

Mathieu Orfila is considered to be the modern father of toxicology, having given the subject its first formal treatment in 1813 in his Traité des poisons, also called Toxicologie générale.^[2]

Theophrastus Phillipus Auroleus Bombastus von Hohenheim (1493–1541) (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.^[3] 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; if only the dose makes a thing not a poison." This is often condensed to: "The dose makes the poison".

An even earlier writer on toxicology was Ibn Wahshiya (Arabic: أبو بكر أحمد بن وحشية Abu Bakr Ahmed ibn Wahshiyah ), who wrote the Book on Poisons in the 9th or 10th century.^[4]

[edit] Relationship between dose and toxicity

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 under 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). LD₅₀ estimations in animals are no longer required for regulatory submissions as a part of pre-clinical development package.^{[citation needed]}

The conventional relationship (more exposure equals higher risk) has been challenged in the study of endocrine disruptors.

[edit] 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. As for drugs, many small molecules are made toxic in the liver, a good example being acetaminophen (paracetamol), especially in the presence of chronic alcohol use. The genetic variability of certain liver enzymes 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.

[edit] Subdisciplines of toxicology

There are various specialized subdisciplines within the field of toxicology that concern diverse chemical and biological aspects of this area. For example, toxicogenomics involves applying molecular profiling approaches to the study of toxicology.^[5] Other areas include Aquatic toxicology, Chemical toxicology, Ecotoxicology, Environmental toxicology, Forensic toxicology, and Medical toxicology.

[edit] Chemical toxicology

Chemical toxicology is a scientific discipline involving the study of structure and mechanism related to the toxic effects of chemical agents, and encompasses technology advances in research related to chemical aspects of toxicology. Research in this area is strongly multidisciplinary, spanning computational chemistry and synthetic chemistry, proteomics and metabolomics, drug discovery, drug metabolism and mechanisms of action, bioinformatics, bioanalytical chemistry, chemical biology, and molecular epidemiology.

[edit] See also

[edit] References

[edit] Further reading

• Nelson, Lewis H.; Flomenbaum, Neal; Goldfrank, Lewis R.; Hoffman, Robert Louis; Howland, Mary Deems; Neal A. Lewin (2006). Goldfrank's toxicologic emergencies. New York: McGraw-Hill, Medical Pub. Division. ISBN 0-07-147914-7. 
• Richards IS. 2008. Principles and Practice of Toxicology in Public Health. Jones and Bartlett Publisher, Sudbury Massachusetts.

[edit] External links

Look up toxicology in Wiktionary, the free dictionary.

• Gilbert SG. A Small Dose of Toxicology – The Health Effects of Common Chemicals. CRC Press, Boca Raton, February 2004, p 266.
• Critical Reviews in Toxicology, A peer-reviewed academic research journal covering all aspects of toxicology, edited by Dr. Roger O. McClellan.
• Agency for Toxic Substances and Disease Registry (ATSDR)
• American College of Medical Toxicology
• European Centre for Ecotoxicology and Toxicology of Chemicals
• Department of Health and Human Services National Toxicology Program (NTP)
• American Association of Poison Control Centers (AAPCC)
• Info. Tox. International Inc.