Workers are exposed to dust containing crystalline silica for about 8 h per day and are at the risk of developing silicosis and silico-tuberculosis. The exposure to crystalline silica can be occupational or non-occupational. Silica has also been classified as a carcinogen by International Agency for Research on Cancer (IARC). It also increases the risk of tuberculosis, nonmalignant renal disease, and autoimmune diseases.
The exposure to silica dust produces lung diseases like silicosis and silico-tuberculosis.
Crystoballite and tridymite are products of high temperatures and may be observed in volcanic ash and are rarely found in industrial samples. Although identical chemically, they differ from each other in their crystal structure. Free silica occurs in different polymorphic forms like quartz, cristobalite, tridymite, and tripoli. When combined with other elements, the compound is called silicate. Pure crystalline silica that is not combined with any other elements is called free silica.
