Toxic Substances
In the context of biology, toxic substances are substances that can cause damage, illness, or death to organisms, usually by chemical reaction or other activity on the molecular scale, when a sufficient quantity is absorbed by an organism. Legally and in hazardous chemical labeling, poisons are especially toxic substances; less toxic substances are labeled "harmful", "irritant", or not labeled at all.
In medicine, particularly veterinary and in zoology, a poison is often distinguished from a toxin and venom. Toxins are poisons produced via some biological function in nature, and venoms are usually defined as biologic toxins that are injected by a bite or sting to cause their effect, while other poisons are generally defined as substances which are absorbed through epithelial linings such as the skin or gut.
Toxins are referred to as naturally produced substances, such as the bacterial proteins that cause tetanus and botulism. A distinction between the two terms is not always observed, even among scientists.
Animal toxins that are delivered subcutaneously (e.g. by sting or bite) are also called venom. In normal usage, a poisonous organism is one that is harmful to consume, but a venomous organism uses poison to defend itself while still alive. A single organism can be both venomous and poisonous.
Within chemistry and physics, a poison is a substance that obstructs or inhibits a reaction, for example by binding to a catalyst. For example, see nuclear poison.
Paracelsus, the father of toxicology, once wrote: "Everything is poison, there is poison in everything. Only the dose makes a thing not a poison." The phrase "poison" is often used colloquially to describe any harmful substance, particularly corrosive substances, carcinogens, mutagens, teratogens and harmful pollutants, and to exaggerate the dangers of chemicals. The legal definition of "poison" is stricter. A medical condition of poisoning can also be caused by substances that are not legally required to carry the label "poison".
Uses of toxic substances
Throughout these years, intentional application of toxic substances has been used as a method of assassination, murder and suicide. On the whole, however, toxic substances are usually not used for their toxicity, but may be used for their other properties. The property of toxicity itself has limited applications: mainly for controlling pests and weeds, cleaning and maintenance, and for preserving building materials and food stuffs. Where possible, specific agents which are less poisonous to humans have come to be preferred.
Many toxic substances still in use are used for their chemical and physical properties rather than being poisonous. Many medications, such as aspirin and Tylenol, are toxic if ingested in sufficiently large quantities. Even alcohol can become toxic if too much is ingested in a short period of time. In laboratory environments, the most effective, easiest, safest, option for use in a chemical synthesis may be a poisonous material. If a toxic substance possesses these properties more exactly than a non-toxic one, the toxic substance is superior. Chromic acid is an example of such a simple to use reagent, but reactivity, in particular, is important. Hydrogen fluoride is both poisonous and extremely corrosive. However, it contains high free energy for silicon, which is exploited by using hydrogen fluoride to etch glass or to manufacture silicon semiconductor chips.
On the other hand, there are certain medical treatments make use of the toxicity of certain substances such as antibiotics. Antibiotics are highly disruptive to micro-organisms while having no effects upon humans. Another thing, the drugs which are used in chemotherapy are toxic, quite.
Decontamination of Toxic Substances
The absorption of toxic substances may be able to be decreased through gastric decontamination if the toxin was recently ingested. Gastric decontamination may be achieved using:
▪ Activated charcoal – treatment of choice to prevent absorption of poison. This activated charcoal is ineffective against metals, sodium, potassium, alcohol, glycol, acids and alkalis.
▪ Nasogastric aspiration – it involves the placement of a tube via nose down to the stomach of the person. The stomach contents are then removed through suction. It is usually used for liquid ingestions where activated charcoal is ineffective.
▪ Gastric lavage/stomach pump – it is where a tube is inserted into the stomach, followed by the pouring of water or saline down to the tube.
▪ Whole bowel irrigation – this is achieved by giving the patient large amounts of polyethylene glycol solution. Its major uses are following ingestion of sustained release drugs, toxins that are not absorbed by activated charcoal and for the removal of ingested packets of drugs.
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