What is silicosis?
Silicosis is scarring and thickening of the lungs caused by inhalation of silica dust. Silicosis reduces lung capacity and can cause symptoms such as chronic cough.
- Crystalline silica dust, including quartz and cristobalite
Workers in construction, mining, and manufacturing industries are at an increased risk for developing silicosis due to occupational silica exposure. Tasks such as drilling or grinding concrete, sandblasting, and stonecutting can lead to high levels of exposure.
The greatest risks of silicosis were observed among workers employed in the mining and processing sectors.
Based on the ODSS results, the mining, quarrying, and oil well industry is at a significantly increased risk of silicosis. Within the mining industry, the gold quartz and uranium mining sectors have particularly high risks of silicosis. By occupation, the highest risk of silicosis is observed among mining foremen, who tend to be longstanding workers within the mining industry and likely incur significant exposure to silica dust over their careers. Drilling and blasting occupations also showed high risks of silicosis.
- Gold quartz mines: 19 times the risk
- Uranium mines: 29 times the risk
- Rock and soil-drilling occupations: 19 times the risk
- Iron foundry workers: 9.6 times the risk
Mineral, metal, clay, and chemical processing occupations
These processing occupations are at an increased risk of silicosis. This work involves cutting and handling materials such as stone, clay, and brick, which would expose workers to high levels of crystalline silica.
- Processing occupations (mineral, metal, clay, chemical): 2.3 times the risk
Machining and related occupations include welding and flamecutting and metalworking-machine operators. This work involves handling and shaping metals, wood, clay, glass and other raw materials. Tasks include buffing, grinding, and polishing these materials, which leads to dusty work environments and potential exposure to crystalline silica.
- Metalworking-machine operators: 1.7 times the risk
- Welding and flamecutting: 1.3 times the risk
Based on the ODSS results, some workers in the construction industry and construction occupations are at increased risks of silicosis. The handling and use of raw materials in construction occupations could lead to dusty work environments and possible exposure to silica dust.
- Excavation grading, paving and related occupations: No increased risk
- Other construction trades occupations: No increased risk
- General contractors: 1.3 times the risk
Relative Risk by Industry and Occupation
Figure 1. Risk of silicosis diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1999-2016
Figure 2. Risk of silicosis diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1999-2016
Table of Results
Table 1. Surveillance of Silicosis: Number of cases, workers employed, and hazard ratios in each industry (SIC)
|SIC Code *||Industry Group||Number of cases||Number of workers employed||Hazard Ratio (95% CI) †|
|2/3||Forestry, Fishing and
|4||Mines, Quarries and
|27||18,186||10.6 (6.96, 16.10)|
|5||Manufacturing||74||565,737||1.12 (0.83, 1.50)|
|6||Construction||22||175,679||1.21 (0.77, 1.90)|
and Other Utilities
|7||165,949||0.37 (0.17, 0.78)|
|8||Trade||18||357,388||0.56 (0.34, 0.91)|
|9||Finance, Insurance and
|10||Community, Business and
|37||484,003||0.86 (0.59, 1.26)|
|11||Public Administration and
|12||157,933||0.63 (0.35, 1.13)|
|* SIC: Standard Industrial Classification (1970)|
|† Hazard rate in each group relative to all others|
Table 2. Surveillance of Silicosis: Number of cases, workers employed, and hazard ratios in each occupation (CCDO) group
|CCDO Code *||Occupation Group||Number of cases||Number of workers employed||Hazard Ratio (95% CI) †|
|21||Natural sciences, engineering
|23||Social sciences and
|27||Teaching and related||<5||41,694||1.47 (0.78, 2.75)|
|31||Medicine and health||12||108,760||—|
recreational and related
|0||12,730||0.58 (0.29, 1.13)|
|41||Clerical and related||9||162,138||0.67 (0.30, 1.53)|
|51||Sales||6||123,290||1.08 (0.73, 1.60)|
and animal husbandry
trapping and related
|75||Forestry and logging||0||7,729||18.50 (12.00, 28.5)|
|77||Mining and quarrying,
including oil and gas field
|25||10,051||2.26 (1.33, 3.84)|
(mineral, metal, chemical)
|15||67,243||1.01 (0.50, 2.05)|
(food, wood, textile)
|8||81,535||1.33 (0.87, 2.04)|
|83||Machining and related||25||161,901||0.93 (0.63, 1.37)|
assembling and repairing
|31||276,757||0.84 (0.52, 1.37)|
|87||Construction trades||19||181,408||0.34 (0.15, 0.78)|
|6||143,841||0.78 (0.41, 1.47)|
|93||Materials handling and related,
not elsewhere classified
|95||Other crafts and
|<5||23,409||0.83 (0.49, 1.40)|
|99||Other occupations not elsewhere classified||15||180,651||0.98 (0.64, 1.52)|
|* CCDO: Canadian Classification Dictionary of Occupations (1971)|
|† Hazard rate in each group relative to all others|
Please note that ODSS results shown here may differ from those previously published or presented. This may occur due to changes in case definitions, methodological approaches, and the ongoing nature of the surveillance cohort.