Exposure Health Risks
WorkSafeBC
Breathing in silica dust can cause permanent damage to the lungs:
Health Effects
Occupational exposure to RCS Dust is associated with the development of silicosis, lung cancer, and pulmonary tuberculosis and chronic pulmonary disease. Exposures may also be related to the development of autoimmune disorders, chronic renal diseases, and other adverse health effects. Acute silicosis can occur just weeks or months after a high exposure, and can be fatal. The other delayed health effects can appear years later.
The following table shows the predicted exposure-response relationship for the risk of developing silicosis. It should be noted that these risk predictions only apply when individual exposures do not exceed absolute concentrations of 2 mg/m3. The risks rise to exceptionally high levels if average exposures exceed this value, even for short periods of just a couple of months. These numerical risks are derived from a Scottish coalminers study (source) .
| PREDICTED RISKS OF DEVELOPING SILICOSIS | 15 years exposure to crystalline silica (8-hour time weighted average ("TWA")) mg/m3 | Equivalent cumulative exposure mg/m3 x years | Risk of developing silicosis 15 years post-exposure as indicated by international Labour Organization score 2/1+ |
|---|---|---|
| 0.02 | 0.3 | 0.25% |
| 0.04 | 0.6 | 0.5% |
| 0.1 | 1.5 | 2.5% |
| 0.3 | 4.5 | 20% |
| Source: Health and Safety Executive (UK) (2002): Respirable crystalline silica - phase 1: variability I fibrogenic potency and exposure-response relationships for silicosis | ||
The National Institute for Occupational Safety and Health ("NIOSH") has classified three types of silicosis with different timelines regarding its development: chronic, accelerated or acute (source) :
- Chronic silicosis is the most common form and tends to develop after 10 or more years of exposure to crystalline silica at low levels. Symptoms can range from very mind to disabling or even fatal.
- Accelerated silicosis can occur with higher levels of crystalline silica exposures over a period of time from 5 to 15 years. Symptoms are the same as chronic or ordinary silicosis except that they appear sooner and can progress rapidly.
- Acute silicosis can occur after only weeks or months of exposure to very high concentrations of crystalline silica. Death occurs within weeks. The lungs drown in their own fluids.