Toxinology

Botulinum toxin 3BTA

Toxinology is the specialized area of science that deals specifically with animal, plant, and microbial toxins. Toxinology has been defined as "the scientific discipline dealing with microbial, plant and animal venoms, poisons and toxins".[1] "Toxinology includes more than just the chemistry and mode of action of a toxin. It deals also with the biology of venom- or poison-producing organism, the structure and function of the venom apparatus, as well as the use of the venom or poison, the ecological role of these compounds".[1] Toxinology has also been defined as "the science of toxic substances produced by or accumulated in living organisms, their properties, and their biological significance for the organisms involved".[2]

There is an International Society on Toxinology (IST), founded in 1962, organizing an international congress every three years and regional sectional meetings in intervening years.[3] The IST has, or is in the process of adopting several key initiatives, notably regularising toxin nomenclature (through work of an expert committee), developing the field of clinical toxinology as a global training and accreditation initiative, and supporting efforts to reduce the global toll from snakebite, through the Global Snakebite Initiative. Details of these and other activities, including a Society electronic newsletter are available via the Society web site at www.toxinology.org. The society also has an official journal, Toxicon. A number of countries have established national toxinology societies and these hold national meetings. There are several journals, besides Toxicon, that principally cover toxin research and major discoveries in toxinology can be published in a wide variety of journals, including Nature.

Toxins and toxinology

Toxins are natural substances, or substances produced by living organisms, in contrast to toxic substances from chemicals, which are toxicants. Living organisms producing or using toxins do so as either venoms or poisons. Venoms are toxins, or more commonly, collections of varying toxins, that are used actively against prey or predators, most commonly to subdue, kill and digest prey, or dissuade predators. Poisons of natural origin, that is containing toxins and used by living organisms, are passive and generally used for defence. A predator attempting to molest or eat a poisonous animal, plant or mushroom will suffer adverse effects from the toxins in the poison, varying from mild discomfort to rapid death. Particularly food poisons, but also for a few venoms, the component toxins are not produced by the deploying animal/plant, but are made by micro-organisms and concentrated and used by the deploying animal/plant. A good example is tetrodotoxin, used by a variety of poisonous animals and by a few venomous animals.

Toxins and toxinology is not solely focused on adverse effects. An increasing number of toxins are important as research tools, unlocking secrets of disease, or as diagnostic agents in hospital laboratories, or as therapeutic agents to treat human disease, including anti-cancer agents, anti-epileptic agents, anti-clotting agents, analgesics, anti-hypertensive drugs, to name but a few. This is a very rich field for research.

Venomous animals can be found in a number of Phyla. Some prominent examples include: Phylum Chordata, Subphylum Vertebrata - venomous snakes (approximately 800 species in Families Viperidae, Elapidae, Atractaspididae and Colubridae* (* this family is an artificial construct and will likely be broken up into a variety of new families)), venomous lizards (two species from the Americas - Heloderma horridum and H. suspectum; also recent controversial research has claimed some other lizards can produce toxins, notably varanid lizards), venomous mammals (notably the platypus, also some shrew species), venomous spiny fish (e.g. stonefish, butterfly cod, bullrout, catfish, numerous other species), stingrays. Phylum Arthropoda - spiders, scorpions, ticks (only a few species are venomous, causing paralysis), centipedes, some insects (notably the hymenopterans including bees, wasps and ants). Phylum Mollusca - cone snails and related predatory marine snails, some octopuses (notably the blue-ringed octopus). Phylum Cnidaria (Coelenterata) - true jellyfish, box jellyfish (contains some of the most lethal of all venomous animals), hydrozoans (includes colony "jellyfish" such as Physalia or Portuguese Man O' War), anthozoans (including coral). Phylum Echinodermata - sea urchins. This listing is not exhaustive.

Poisonous animals, mushrooms and plants again cover a diversity of taxonomic groups. In many cases, poisonous animals derive their poison from the environment. This applies to classic marine poisons such as fugu (tetrodotoxin), ciguatera, and the several distinct types of shellfish poisons. In many cases the prime toxin producer is a dinoflagellate. Conversely, mushroom and plant toxins are produced by the organism itself. Plant toxins have long been recognised as poisons, but also as therapeutic agents, if used in the correct dose. A classic example is digitalis, long used as treatment for certain heart conditions. Nevertheless, some plant toxins have become "popular" as self-harm agents, used in suicides. Mushroom toxins include some lethal toxins that can cause painful, drawn out death.

Clinical toxinology

Within toxinology there is a clinical subgroup, clinical toxinologists, who focus on the medical effects in humans of exposure to the toxins in animal venoms or plant poisons. This includes such problems as venomous snakebite, currently considered to afflict >2.5 million people each year, with >100,000 deaths. Information on these medical consequences of toxins can be found in diverse sources, such as the Clinical Toxinology Resources Website and books such as Prof. Mebs book and the CRC book on toxinology. Clinical toxinology does not, yet, enjoy specialist status within medicine, unlike fields such as surgery and radiology. However, a training course in clinical toxinology has existed since 1997 (held in Adelaide, Australia) and efforts are under way to expand this to a true, specialist-level international training program, through an initiative of the International Society on Toxinology. Given the huge impact of toxin-based disease globally, the value of having doctors expert in this area is self-evident.

References

  1. 1 2 Mebs D (2002) Venomous and Poisonous Animals. CRC Press:Boca Raton. pg. 2
  2. ↑ Meier J & White J (1995) Handbook of Clinical Toxicology of Animal Venoms and Poisons. CRC Press:Boca Raton
  3. ↑ "Ist Website Home Page". Toxinology.org. 2012-07-13. Retrieved 2013-04-19.
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