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Respirable crystalline silica – microscopic particles of silica can be become airborne and inhaled when cutting, sawing, grinding, or drilling rock or concrete. Silica is used for foundry molds and cores, so exposure can occur when grinding on castings. Fracking uses silica. About 2.3 million individuals in the U.S. are exposed to silica at work.
Silica, crystalline (airborne particles of respirable size) – Silicon carbide whiskers – Simazine: 122-34-9 Sodium dimethyldithiocarbamate: 128-04-1 Sodium fluoroacetate: 62-74-8 Soots, tars, and mineral oils (untreated and mildly treated oils and used engine oils) – Spirodiclofen: 148477-71-8 Spironolactone: 52-01-7 Stanozolol: 10418-03-8
Silica occurs in three forms: crystalline, microcrystalline (or cryptocrystalline) and amorphous (non-crystalline). "Free" silica is composed of pure silicon dioxide, not combined with other elements, whereas silicates (e.g., talc , asbestos , and mica ) are SiO 2 combined with an appreciable portion of cations .
Colloidal silica gel with light opalescence. Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum.
Hazard statements form part of the Globally Harmonized System of Classification and Labelling of Chemicals (GHS). They are intended to form a set of standardized phrases about the hazards of chemical substances and mixtures that can be translated into different languages.
Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide).The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2.
Many people accredit the idea of government responsibility for the protection of its workers in the workplace to Franklin D. Roosevelt in the Great Depression era. The formation of the National Conference of Governmental Industrial Hygienists (later to be renamed the American Conference of Governmental Industrial Hygienists) in 1938 was a direct response to this idea.