Understanding Silica

Silica is the most common mineral in the earth’s crust and comprises 20% of the weight of the crust.  It is found in sand, gravel and all soils and is the principal constituent of 95% of the earth’s rock.

Silica has been used by the industry in abrasives, coal dust, concrete, filter aids, mica, mineral processing, paints, pavement, perlite, plant material, plastic filler, polishing compounds, portland cement, and soapstone, in addition to sand, gravel, slag and soil.  The NIOSH associates the following occupations with risk to silica exposure: mining (cutting or drilling through sandstone and granite); construction (sandblasting, rock drilling, masonry work, jack hammering, tunneling); foundry work (grinding, molding, shake-out and core room); ceramics, clay and pottery; stone cutting (sawing, abrasive blasting, chipping and grinding), glass manufacture, agriculture, shipyards (abrasive blasting); railroads (setting and laying tracks); manufacturing and use of abrasives; manufacturing of soaps and detergents.

Occupational exposure to silica is capable of causing serious health effects.  Silicosis is the primary disease related to exposure.  It can result when sufficient amounts of airborne silica are inhaled and become deposited in the lungs, overwhelming the body’s natural defense mechanisms.  Whether a disease develops depends on the intensity and duration of exposure, and, likely, on individual susceptibility.  Other serious diseases may develop from silicosis.