Toxicology

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Toxicology (from the Ancient Greek words τοξικός - toxicos "poisonous" and 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. It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people.

History

File:Mathieu Joseph Bonaventure Orfila.jpg

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. Ibn Wahshiya wrote the Book on Poisons in the 9th or 10th century.

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.

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.

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. 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

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 Template: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.

Factors that influence chemical toxicity:

• Dosage
  • Both large single exposures (acute) and continuous small exposures (chronic) are studied.
• Route of exposure
  • Ingestion, inhalation or skin absorption
• Other factors
  • 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. 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. 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.

Dose response complexities

Most chemicals display a classic dose response curve - at a low dose (below a threshold), no effect is observed. 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". 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. These also receive special consideration.

Toxicologist duties

Toxicologists do many different 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.

Toxicology starting pay

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. Salary.com notes that the median annual salary for toxicologists as of 2011 was $84,000.

Requirements for a toxicologist

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.

See also

• Aquatic toxicology
• Automatism (toxicology)
• Certain safety factor
• Children's Environmental Exposure Research Study (CHEERS) (in the US)
• Dose-response relationship
• Ecotoxicology
• Entomotoxicology
• Environmental toxicology
• Enzyme inhibition
• Forensic toxicology
• In vitro toxicology
• Indicative limit value
• Medical toxicology
• Overdose
• Pollution
• Toxicity
• Toxicogenomics
• Toxicology Mechanisms and Methods (journal)

Further reading

• (2013) "Chapter 13. Cadmium toxicity in plants" Astrid Sigel, Helmut Sigel and Roland K. O. Sigel Cadmium: From Toxicology to Essentiality, 395–413, Springer.
• (2013) "Chapter 14. Toxicology of cadmium and its damage to mammalian organs" Astrid Sigel, Helmut Sigel and Roland K. O. Sigel Cadmium: From Toxicology to Essentiality, 415–490, Springer.

External links

• Toxicology at the Open Directory Project
• National Library of Medicine's "Toxicology Tutor" provides basic information on the science of toxicology.
• Toxipedia
• Society of Toxicology

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