![]() ![]() Job tasks that are typically associated with exposure to silica include grinding, sandblasting, crushing, chipping, mixing, and plowing.Īccording to the Burden of Occupational Cancer in Canada project, occupational exposure to crystalline silica leads to approximately 570 lung cancers each year in Canada, based on past exposures (1961-2001). Workers can be exposed in industries such as mining, agriculture, and various manufacturing industries. In terms of occupation, the largest occupational groups exposed to silica are construction trades labourers, heavy equipment operators, plasterers and drywallers, and plumbers.Įxposure to crystalline silica, especially quartz, may also occur in a number of other industries and occupations due to its wide and variable use. The largest industrial group exposed is construction. ![]() ĬAREX Canada estimates that approximately 429,000 Canadians are exposed to silica in their workplace. Inhalation is the most important route of occupational exposure to silica. Flours are very fine grades of crystalline silica and are used in the ceramic and pottery industry, in manufacturing chrysotile cement, as a filler in rubber and paints, and as an abrasive in soaps and cleaners. įlours are formed by grinding quartz, quartzite, sand, and sandstone. When sand has more than 98% silica and low iron content it can be used for glass and ceramic production. in municipal water and sewage treatment plants. ![]() It may also be used as a raw material for producing silicon and ferrosilicon metals, or as a filter for large volumes of water, i.e. For example, it may be used in foundry castings, Portland cement, abrasives and sandblasting materials, and hydraulic fracturing. Sand, the most common size fraction of natural crystalline silica, has many applications. This size fraction is not of concern for health effects as it is too large to inhale. Lump silica is used as flux for smelting operations, in silicon and ferrosilicon alloys, and for silica brick. Īpplications for silica differ depending on the particle size, which is divided into three general size categories: lump silica, 0.3 – 15 cm sand, 75 μm – 3 mm and flour, < 75 μm. Besides silicosis and lung cancer, occupational silica exposure has also been linked to pulmonary tuberculosis, chronic obstructive pulmonary disease, and rheumatoid arthritis. Silicosis is typically categorized as chronic (> 10 years exposure), accelerated (high concentrations over 5-10 years), or acute (short term exposure at high concentrations). Silicosis, a non-reversible fibrotic lung disease, is caused by inhaling crystalline silica particles. Increased risk was not evident with exposure to amorphous silica. Epidemiological studies show a relationship between occupational exposure to crystalline silica and increased risk of lung cancer, with the strongest link in quarry and granite workers and workers involved in ceramic, pottery, refractory brick, and diatomaceous earth industries. The 2012 IARC review of Class 1 carcinogens reaffirmed this classification. ![]() IARC’s 1997 classification of crystalline silica as Group 1, a known human carcinogen, is specifically for quartz and cristobalite silica inhaled from occupational sources. Health concerns arise when products containing silica are disturbed by grinding, cutting, drilling, or chipping, which creates respirable dust. Ĭrystalline silica is used extensively in many industrial applications because of its unique physical and chemical properties. There are numerous other synonyms and product names for silica see the International Agency for Research on Cancer (IARC) for more information. Tridymite is found in rocks and is not an important industrial product. Cristobalite also has important industrial uses. Quartz is the most common form of crystalline silica and the most commonly used industrially. Conversion from amorphous to crystalline form can occur at high heat. Silica exists in both crystalline and amorphous (non-crystalline) forms. Silica is one of the most common minerals on earth and is a basic component of soil, sand, and rocks including granite and quartzite. ![]()
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