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Crystalline Silica in the Workplace

Crystalline silica is becoming well-known for being a potential health hazard in jobsites across Canada. It is used extensively in many industrial applications because of its unique physical and chemical properties. Health concerns arise when silica-containing products are disturbed by grinding, cutting, drilling or chipping, creating respirable particulate.

Silica, or silicon dioxide, is a naturally occurring material. In its crystalline form, it is commonly known as quartz, and is the earth’s second-most common element. Silica is not on its face dangerous, but when disturbed can create silica “dust” particles which when inhaled can clog the lungs, making it difficult to process oxygen. Quartz is the most common form of crystalline silica and the most commonly used industrially.

Industries and operations in which exposure to crystalline silica can occur include all of the following:

  • Construction
  • Glass products
  • Pottery products
  • Structural clay products
  • Concrete products
  • Foundries
  • Paintings and coatings
  • Refractory products
  • Proppant for hydraulic fracturing in oilfield applications
  • Ready-mix concrete
  • Cut stone and stone products
  • Refractory installation and repair
  • Railroad track maintenance
  • Hydraulic fracturing for gas and oil
  • Abrasive blasting in
    o Maritime work
    o Construction
    o General industry

Health Effects

If crystalline silica dust particles are inhaled, a number of health problems may arise such as silicosis, lung cancer, chronic obstructive pulmonary disease (COPD), emphysema or pulmonary tuberculosis.

Silicosis

Silicosis, the most common lung condition, is caused when crystalline silica particles are inhaled and deposited in the lungs. The lung tissue can react by developing lumps and scarring around the trapped silica particles. If the lumps and scarring grow too large in the lungs, breathing may become affected and have serious health consequences.

Three types of silicosis can develop over time: chronic silicosis, accelerated silicosis, and acute silicosis. These conditions are dependent on various factors such as particle type, size (particles larger than 10 microns in diameter tend to be deposited in the nose or throat rather than the lungs), concentration of silica dust in the air, and length of time a person is exposed to the silica dust.

  1. Chronic silicosis- may develop due to ongoing (chronic) exposure to relatively low concentrations over a long period of time (i.e. ten or more years).
  2. Accelerated silicosis- may develop five to ten years after the first exposure to high concentrations.
  3. Acute silicosis- may develop after exposure to very high concentrations of respirable silica. Symptoms may appear within a few weeks to five years of the initial exposure. This disease is usually associated with a history of repeated exposures to tasks that produce small particles of airborne dust with a high silica content (e.g. sandblasting, rock drilling, or quartz mining).

Protecting your health

As silica is commonly encountered on the jobsite, it is imperative that workers are protected from potentially harmful health effects. Currently, there is no cure for silicosis, and for this reason early detection is extremely important. Employers who have workers exposed to silica should protect the worker’s health by having periodic testing (health assessments) so changes in health status can be detected and the appropriate interventions can be made.

A health assessment for silica-exposed workers consists of a thorough health history (including the worker’s previous work and non-work exposure to crystalline silica or other dusts), a chest X-ray, a radiologist’s report, a lung function test and a physician’s written interpretation and explanation of the assessment results. Once a baseline has been established, workers should be monitored throughout there employment to determine if any lung conditions have developed.

SureHire provides services for early identification, intervention, and surveillance of lung and respiratory diseases. These services include pulmonary function testing, pre-employment chest x-ray, medical surveillance, and even a silica-exposed worker program. The silica-exposed worker program is targeted health monitoring performed periodically to assess the health of a worker or group of workers who are exposed to respirable crystalline silica. For more information on the Silica-Exposed Worker Program and other lung health testing services, click here.

Health screening is just one way to prevent the harmful effects of silicosis. However, other preventative measures. should be taken, including the use of personal protective equipment, administrative controls-such as worker and employer education, engineering controls- such as installing local ventilation hoods and using silica substitutes in abrasive blasting.

Further Reading:

https://work.alberta.ca/documents/WHS-PUB_ch059.pdf
https://www.work.alberta.ca/documents/WHS-PUB_ch059.pdf
http://www.canadianunderwriter.ca/features/silica-liability-ready-to-explode/
https://www.osha.gov/dsg/topics/silicacrystalline/

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