Hazards of Silica and Health Effects of Silicosis

Occupational exposures to respirable crystalline silica occur in a variety of industries and occupations because of its extremely common natural occurrence and the wide uses of materials and products that contain it. At least 1.7 million U.S. workers are potentially exposed to respirable crystalline silica [NIOSH 1991], and many are exposed to concentrations that exceed limits defined by current regulations and standards.

Silicosis, usually a nodular pulmonary fibrosis, is the disease most associated with exposure to respirable crystalline silica. Although the reported mortality associated with silicosis has declined over the past several decades, many silicosis associated deaths still occur (nearly 300 deaths were reported each year during the period 1992-1995) [NIOSH 1996a; Althouse 1998]. In addition, the number of silicosis associated deaths among persons aged 15 to 44 has not declined substantially [CDC 1998a,b]. An unknown number of workers also continue to die from silica-related diseases such as pulmonary tuberculosis (TB), lung cancer, and scleroderma. The number of cases of silicosis and silica-related diseases in the United States today is unknown.

Source: http://www.cdc.gov/niosh/docs/2002-129/02-129a.html

Engineering Controls for Silica in Construction

As per NIOSH - Construction workers may be exposed to hazardous dust containing silica during construction tasks, including tuckpointing brick, grinding concrete, breaking concrete pavement with a jackhammer, and cutting block and brick. The National Institute for Occupational Safety and Health (NIOSH) found that exposure could be reduced through the use of engineering controls, including the use of local exhaust ventilation to capture dust at its source and the use of water sprays to suppress dust where it is produced. These pages provide information about those controls and utilize video-exposure monitoring clips to demonstrate their effectiveness.

For more information go to http://origin.cdc.gov/niosh/topics/silica/constructionControlMain.html

Symptoms of Silicosis as Per OSHA

What are the symptoms of silicosis?

Silicosis is classified into three types: chronic /classic, accelerated, and acute.
Chronic/classic silicosis, the most common, occurs after 15–20 years of moderate to low exposures to respirable crystalline silica. Symptoms associated with chronic silicosis may or may not be obvious; therefore, workers need to have a chest
x-ray to determine if there is lung damage. As the disease progresses, the worker may experience shortness of breath upon exercising and have clinical signs of poor oxygen/carbon dioxide exchange.

In the later stages, the worker may experience fatigue, extreme shortness of breath, chest pain, or respiratory failure.

Accelerated silicosis can occur after 5–10 years of high exposures to respirable crystalline silica. Symptoms include severe shortness of breath, weakness, and weight loss. The onset of symptoms takes longer than in acute silicosis.

Acute silicosis occurs after a few months or as long as 2 years following exposures to extremely high concentrations of respirable crystalline silica. Symptoms of acute silicosis include severe disabling shortness of breath, weakness, and weight loss, which often leads to death.

Source: http://www.osha-safety.org/osha_crystalline_silica.asp

Where are General Industry Employees Exposed to Crystalline Silica Dust

Where are general industry employeesexposed to crystalline silica dust?

The most severe exposures to crystalline silicaresult from abrasive blasting, which is done to cleanand smooth irregularities from molds, jewelry,and foundry castings, finish tombstones, etch orfrost glass, or remove paint, oils, rust, or dirt formobjects needing to be repainted or treated. Otherexposures to silica dust occur in cement and brickmanufacturing, asphalt pavement manufacturing,china and ceramic manufacturing and the tool anddie, steel and foundry industries. Crystalline silicais used in manufacturing, household abrasives,adhesives, paints, soaps, and glass. Additionally,crystalline silica exposures occur in the maintenance,repair and replacement of refractory brickfurnace linings.In the maritime industry, shipyard employeesare exposed to silica primarily in abrasiveblasting operations to remove paint and cleanand prepare steel hulls, bulkheads, decks, andtanks for paints and coatings.

Source: www.osha.gov

Silica, Crystalline, Silicosis Safety Issues

Recognizing potential hazards is key in preventing and minimizing the effects of silica exposure. Silicosis is a disabling, nonreversible and sometimes fatal lung disease caused by overexposure to respirable crystalline silica. The following references aid in recognizing crystalline silica hazards and health effects.

What is crystalline silica?

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.

What are the hazards of crystalline silica?

Silica exposure remains a serious threat to nearly 2 million U.S. workers, including more than 100,000 workers in high risk jobs such as abrasive blasting, foundry work, stonecutting, rock drilling, quarry work and tunneling. 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 rockdrillers. 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 the formation of scar tissue, 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 causes lung damage and adds to the damage caused by breathing silica dust.

Source: www.OSHA.gov