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Toxicity is the degree to which a substance is harmful to humans or animals. Toxicity can be acute or chronic and may be dose-dependent such that items not normally toxic (e.g. water), can be toxic if taken in large quantities. Acute toxicity occurs through short term or highly potent single exposure. Chronic toxicity can occur via long term, less potent exposure.
There are 3 types of toxins: biological, chemical and physical. Biological toxins include bacteria, viruses, and combinations thereof. Chemical toxins include most medications, organic poisons from living organisms, and inorganic toxins such as lead, chlorine gas, mercury, and many more. Physical toxicity is caused by exposure to radiation, concussion, heat and cold, and other mechanisms not always obviously seen as toxic.
Toxins are classified according to global hazards, physical hazards, and environmental hazards. While countries may set their own crtiteria for determining toxicity, a global criteria was established unifying many countries in 2008 with implementation of the Global Harmonized System for Classification of Chemicals and Labelling (GHS). This system is used by the United States Environmental Protection Agency (EPA).
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Very informative article, thanks a lot! By the way, different dictionaries give different definitions of the word "toxicity" (I've consulted several dictionaries at http://www.ebook-search-queen.com/ ), which one to believe? )