Hazardous Crystalline Silica

Construction workers are exposed to many possible health hazards, one of them being the crystalline silica. Most of you may be unfamiliar with this term, but those who are in the construction field will know what it is. What is crystalline silica? What are its possible health hazards?

Crystalline silica is a basic component of soil, sand, granite, and many other minerals. Quartz is the most common form of crystalline silica. Cristobalite and tridymite are two other forms of crystalline silica. All three forms may become respirable-size particles when workers chip, cut, drill, or grind objects that contain crystalline silica.Airborne dusts are of particular concern as they are associated with widespread occupational lung diseases.

The most severe exposures to crystalline silica result from sandblasting to remove paint and rust from stone buildings, metal bridges, tanks, and other surfaces. Other activities that may produce crystalline silica dust include jack hammering, rock/well drilling, concrete mixing, concrete drilling, and brick and concrete block cutting and sawing. Tunnelling operations; repair or replacement of linings of rotary kilns and cupola furnaces; and setting, laying and repair of railroad track are potential sources of crystalline silica exposure.

Hazards of crystalline silica

Silica exposure poses serious threat to nearly 2 million US workers, including over 100,000 workers in high-risk jobs such as abrasive blasting, foundry work, stone cutting, rock drilling, quarry work and tunnelling. According to the report of the Indian Council for Medical Research (1999), about 30 lakh workers in India are at a high risk of exposure to silica. Out of these, 17 lakh are in mining/quarrying activities, 6.3 lakh in glass and mica industry, and 6.7 lakh in metals industry. In addition, 53 lakh construction workers are at risk of silica exposure.

Occupational exposure to silica occurs at workplaces in factories like quartz crushing facilities (silica flour milling), agate, ceramic, slate pencil, glass, stone quarries and mines. Non-occupational exposure to silica dust can be from industrial sources in the vicinity of the industry as well as non-industrial sources. Recently, public concern regarding non-occupational or ambient exposure to crystalline silica has emerged, making it important to gather information available on non-occupational exposures to silica dust and non-occupational silicosis. The seriousness of the health hazards associated with silica exposure is demonstrated by the fatalities and disabling illnesses that continue to occur in sandblasters and rock drillers.

Crystalline silica has been classified as a human-lung carcinogen. Additionally, breathing crystalline silica dust can cause silicosis, which in severe cases can be disabling, or even fatal. The respirable silica dust enters the lungs and causes formation of scar tissues, thus reducing the lungs’ ability to take in oxygen. There is no cure for silicosis. Since silicosis affects lung function, it makes one more susceptible to lung infections like tuberculosis. In addition, smoking adds to the damage caused by breathing silica dust.

………………………(Read the full article in February Issue of Safety Messenger Magazine 2016)

Author: SubEditor

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