Toxicology

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Toxicology (from the Ancient Greek words τοξικός toxikos "poisonous" and λόγος logos) is a branch of biology, chemistry, and medicine (more specifically pharmacology) concerned with the study of the adverse effects of chemicals on living organisms.[1] It also studies the harmful effects of chemical, biological and physical agents in biological systems that establishes the extent of damage in living organisms. The relationship between dose and its effects on the exposed organism is of high significance in toxicology. Factors that influence chemical toxicity include the dosage (and whether it is acute or chronic); the route of exposure, the species, age, sex and environment. A toxicologist is a scientist or medical personal who specializes in the study of symptoms, mechanisms, treatments and detection of venoms and toxins; especially the poisoning of people. To work as a toxicologist one should obtain a degree in toxicology or a related degree like biology, chemistry or biochemistry. Toxicologists do many different duties including research in the academic, nonprofit and industrial fields, product safety evaluation, consulting, public service and legal regulation.

History[edit]

Lithograph of Mathieu Orfila

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 the modern father of toxicology, having given the subject its first formal treatment in 1813 in his Traité des poisons, also called Toxicologie générale.[4]

In 1850, Jean Stas gave the evidence that the Belgian Count Hippolyte Visart de Bocarmé killed his brother-in-law by poisoning him with nicotine.[5]

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.[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".

Basic traditional toxicology[edit]

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).

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. [7]

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. One example of a test that has been developed is Corrositex, a toxicology test that is much more accurate than animal testing. 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]

Dose response complexities[edit]

Most chemicals display a classic dose response curve – at a low dose (below a threshold), no effect is observed.[15] Some show a phenomenon known as sufficient challenge – a small exposure produces animals that "grow more rapidly, have better general appearance and coat quality, have fewer tumors, and live longer than the control animals".[16] A few chemicals have no well-defined safe level of exposure. These are treated with special care. Some chemicals are subject to bioaccumulation as they are stored in rather than being excreted from the body;[17] these also receive special consideration.

Toxicology as a profession[edit]

Requirements[edit]

To work as a toxicologist one should obtain a degree in toxicology or a related degree like biology, chemistry or biochemistry. Bachelor's degree programs in toxicology cover the chemical makeup of toxins and their effects on biochemistry, physiology and ecology. After introductory life science courses are complete, students typically enroll in labs and apply toxicology principles to research and other studies. Advanced students delve into specific sectors, like the pharmaceutical industry or law enforcement, which apply methods of toxicology in their work. The Society of Toxicology (SOT) recommends that undergraduates in postsecondary schools that don't offer a bachelor's degree in toxicology consider attaining a degree in biology or chemistry. Additionally, the SOT advises aspiring toxicologists to take statistics and mathematics courses, as well as gain laboratory experience through lab courses, student research projects and internships.

Duties[edit]

Toxicologists do many different more duties including research in the academic, nonprofit and industrial fields, product safety evaluation, consulting, public service and legal regulation. In and order to research and assess the effects of chemicals, toxicologists perform carefully designed studies and experiments. These experiments help identify the specific amount of a chemical that may cause harm and potential risks of being near or using products that contain certain chemicals. Research projects may range from assessing the effects of toxic pollutants on the environment to evaluating how the human immune system responds to chemical compounds within pharmaceutical drugs. While the basic duties of toxicologists are to determine the effects of chemicals on organisms and their surroundings, specific job duties may vary based on industry and employment. For example, forensic toxicologists may look for toxic substances in a crime scene, whereas aquatic toxicologists may analyze the toxicity level of wastewater.

Compensation[edit]

The salary for jobs in toxicology is dependent on several factors, including level of schooling, specialization, experience. The U.S. Bureau of Labor Statistics (BLS) notes that jobs for biological scientists, which generally include toxicologists, were expected to increase by 21% between 2008 and 2018. The BLS notes that this increase could be due to research and development growth in biotechnology, as well as budget increases for basic and medical research in biological science.

See also[edit]

References[edit]

  1. ^ Schrager, TF (October 4, 2006). "What is Toxicology". 
  2. ^ Hodgson, Ernest (2010). A Textbook of Modern Toxicology. John Wiley and Sons. p. 10. ISBN 0-470-46206-X. [dead link]
  3. ^ Levey, Martin (1966). Medieval Arabic Toxicology: The Book on Poisons of ibn Wahshiya and its Relation to Early Native American and Greek Texts. 
  4. ^ "Biography of Mathieu Joseph Bonaventure Orfila (1787–1853)". U.S. National Library of Medicine. 
  5. ^ Wennig, Robert (April 2009). "Back to the roots of modern analytical toxicology: Jean Servais Stas and the Bocarmé murder case". Drug Testing and Analysis (England) 1 (4): 153–155. doi:10.1002/dta.32. PMID 20355192. 
  6. ^ "Paracelsus Dose Response in the Handbook of Pesticide Toxicology WILLIAM C KRIEGER / Academic Press Oct01". 
  7. ^ "Existing Non-animal Alternatives". AltTox.org. 8 September 2011. 
  8. ^ Ottoboni 1991.
  9. ^ Ottoboni 1991, Chapter 4: Factors That Influence Toxicity: How Much – How Often.
  10. ^ Ottoboni 1991, Chapter 5: Factors That Influence Toxicity: Route of Exposure.
  11. ^ Ottoboni 1991, Chapter 6: Other Factors That Influence Toxicity.
  12. ^ Ottoboni 1991, Chapter 12: Methods of Study.
  13. ^ Ottoboni 1991, pp. 77-78.
  14. ^ Ottoboni 1991, pp. 114-115.
  15. ^ Ottoboni 1991, p. 80.
  16. ^ Ottoboni 1991, pp. 83-85.
  17. ^ Ottoboni 1991, pp. 85-90.

Works cited[edit]

  • Ottoboni, M. Alice (1991). The dose makes the poison : a plain-language guide to toxicology (2nd ed.). New York, N.Y: Van Nostrand Reinhold. ISBN 0-442-00660-8. 

Further reading[edit]

  • Andresen, Elisa; Küpper, Hendrik (2013). "Chapter 13. Cadmium toxicity in plants". In Astrid Sigel, Helmut Sigel and Roland K. O. Sigel. Cadmium: From Toxicology to Essentiality. Metal Ions in Life Sciences 11. Springer. pp. 395–413. doi:10.1007/978-94-007-5179-8_13.  (subscription required)
  • Thévenod, Frank; Lee, Wing-Kee (2013). "Chapter 14. Toxicology of cadmium and its damage to mammalian organs". In Astrid Sigel, Helmut Sigel and Roland K. O. Sigel. Cadmium: From Toxicology to Essentiality. Metal Ions in Life Sciences 11. Springer. pp. 415–490. doi:10.1007/978-94-007-5179-8_14.  (subscription required)

External links[edit]