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Title: Health Effects of Crystalline Silica
Silicosis is one of the oldest known occupational diseases, identified as far back as ancient Greece. Silicosis is a disabling, nonreversible and sometimes fatal lung disease caused by breathing in a large amount of crystalline silica.
Chronic or "classical" silicosis is the most common type. It typically appears 20-40 years after exposure and progresses even if exposure ceases.
Accelerated silicosis may occur 5-15 years after exposure that is more intense. It progresses more rapidly than classic chronic silicosis. It is considered a variant of chronic silicosis.
Acute silicosis results form an overwhelming exposure to crystalline silica and may occur within weeks of the exposure. An immune mechanism may be involved.
The development of silicosis is dependent on the size of the crystalline silica dust particle (with respirable particles smaller than 5 micrometers being the most hazardous), the percentage of crystalline silica in the dust in the air, the dust concentration that is breathed, and the duration of exposure.
Silicosis exposure and resultant disease are a continuing problem.
--Silicosis was associated with 13,744 U.S. fatalities from1968-1990. Still about 200 silicosis deaths in U.S. every year
--Silicosis was the underlying cause of death of 868 men and 46 women in non-mining occupations from 1985-1992