A toxin (from Ancient Greek: τοξικόν toxikon) is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded. The term was first used by organic chemist Ludwig Brieger (1849–1919).
For a toxic substance not produced within living organisms, "toxicant" and "toxics" are also sometimes used.].
Toxins can be small molecules, peptides, or proteins that are capable of causing disease on contact with or absorption by body tissuesinteracting with biological macromolecules such as enzymes or cellular receptors. Toxins vary greatly in their severity, ranging from usually minor and acute (as in a bee sting) to almost immediately deadly (as in botulinum toxin).
Toxins are often distinguished from other chemical agents by their method of production - the word toxin does not specify method of delivery (compare with venom and the narrower meaning of poison – all substances that can also cause disturbances to organisms). It simply means it is a biologically produced poison. There was an ongoing terminological dispute between NATO and the Warsaw Pact over whether to call a toxin a biological or chemical agent, in which the NATO opted for biological agent, and the Warsaw Pact, like most other countries in the world, for chemical agent.]
According to a International Committee of the Red Cross review of the Biological Weapons Convention, "Toxins are poisonous products of organisms; unlike biological agents, they are inanimate and not capable of reproducing themselves." and "Since the signing of the Convention, there have been no disputes among the parties regarding the definition of biological agents or toxins..."]
According to Title 18 of the United States Code, "...the term "toxin" means the toxic material or product of plants, animals, microorganisms (including, but not limited to, bacteria,viruses, fungi, rickettsiae or protozoa), or infectious substances, or a recombinant or synthesized molecule, whatever their origin and method of production..."]
A rather informal terminology of individual toxins relate them to the anatomical location where their effects are most notable:
- Hemotoxin, causes destruction of red blood cells (hemolysis)
- Phototoxin, causes dangerous photosensitivity
Related terms are: