Asbestos

Asbestos (pronounced: /æsˈbɛstəs/ or /æsˈbɛstɒs/) is a term used to refer to six naturally occurring silicate minerals. All are composed of long and thin fibrous crystals, each fiber being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes. Asbestos is a well known health hazard, and use of it as a building material is now banned in many countries. Inhalation of the fibres can lead to various lung conditions, including asbestosis and cancer.Chrysotile asbestosAsbestos fibersAsbestosBlue asbestos (crocidolite). The ruler is 1 cm.Blue asbestos, teased to show the fibrous nature of the mineral Asbestos (pronounced: /æsˈbɛstəs/ or /æsˈbɛstɒs/) is a term used to refer to six naturally occurring silicate minerals. All are composed of long and thin fibrous crystals, each fiber being composed of many microscopic 'fibrils' that can be released into the atmosphere by abrasion and other processes. Asbestos is a well known health hazard, and use of it as a building material is now banned in many countries. Inhalation of the fibres can lead to various lung conditions, including asbestosis and cancer. Archaeological studies have found evidence of asbestos being used as far back as the Stone Age to strengthen ceramic pots, but large-scale mining began at the end of the 19th century when manufacturers and builders began using asbestos for its desirable physical properties. Asbestos use was widespread during the 20th century until public recognition of the health hazards, beginning in the 1970s, of asbestos dust led to its outlawing by courts and legislatures in mainstream construction and fireproofing in most countries. Despite this, at least 100,000 people a year are thought to die from diseases related to asbestos exposure. Despite the severity of asbestos-related diseases, the material has been used widely all around the world, and most pre-1980s buildings are thought to contain asbestos. Many developing countries also still support the use of asbestos as a building material, and mining of asbestos is ongoing, with the top producer Russia producing around one million metric tonnes in 2015. The word 'asbestos', first used in the 1600s, ultimately derives from the Ancient Greek ἄσβεστος, meaning “unquenchable” or “inextinguishable”. The name reflects use of the substance for wicks that would never burn up. It was adopted via the Old French abestos, which in turn got the word from Greek via Latin, but in the original Greek, it actually referred to quicklime. It is said by the Oxford English Dictionary to have been wrongly used by Pliny for asbestos, who popularized the misnomer. Asbestos was referred to in Greek as amiantos, meaning 'undefiled', because it was not marked when thrown into a fire. This is the source for the word for asbestos in many languages, such as the Portuguese amianto. It had also been called 'amiant' in English in the early 15th century, but this usage was superseded by 'asbestos'. The word is pronounced /æsˈbɛstəs/ or /æsˈbɛstɒs/. People have used asbestos for thousands of years to create flexible objects, such as napkins, that resist fire. In the modern era, companies began producing asbestos consumer goods on an industrial scale. Now people recognize the health hazard that asbestos dust poses, and it is banned or strictly regulated around the world. Asbestos use dates back at least 4,500 years, when the inhabitants of the Lake Juojärvi region in East Finland strengthened earthenware pots and cooking utensils with the asbestos mineral anthophyllite (see Asbestos-ceramic). One of the first descriptions of a material that may have been asbestos is in Theophrastus, On Stones, from around 300 BC, although this identification has been questioned. In both modern and ancient Greek, the usual name for the material known in English as 'asbestos' is amiantos ('undefiled', 'pure'), which was adapted into the French as amiante and into Spanish and Portuguese as amianto. In modern Greek, the word ἀσβεστος or ασβέστης stands consistently and solely for lime. The term asbestos is traceable to Roman naturalist Pliny the Elder's manuscript Natural History, and his use of the term asbestinon, meaning 'unquenchable'. While Pliny or his nephew Pliny the Younger is popularly credited with recognising the detrimental effects of asbestos on human beings, examination of the primary sources reveals no support for either claim. Wealthy Persians amazed guests by cleaning a cloth by exposing it to fire. For example, according to Tabari, one of the curious items belonging to Khosrow II Parviz, the great Sassanian king (r. 531–579), was a napkin (Persian: منديل‎) that he cleaned simply by throwing it into fire. Such cloth is believed to have been made of asbestos imported over the Hindu Kush. According to Biruni in his book, Gems, any cloths made of asbestos (Persian: آذرشست‎, āzarshost) were called shostakeh (Persian: شستكه‎). Some Persians believed the fiber was the fur of an animal, called the samandar (Persian: سمندر‎), which lived in fire and died when exposed to water, which was where the former belief that the salamander could tolerate fire originated.