Asbestosis

Background

What is asbestosis?

Asbestosis is scarring and stiffening of lung tissue caused by inhalation of asbestos fibres.

Risk factors
    • Asbestos fibres (all types)
    • Asbestos-like fibres

Asbestos exposure is the only known risk factor for asbestosis. Workers within occupations with exposure to asbestos fibres are at an increased risk of this disease. Construction workers, such as insulators, electricians, and plumbers are several occupations that have experienced high rates of this condition. Metal workers and platers and boilermakers are also at an increased risk of asbestosis.

Key Findings

The greatest risks of asbestosis were observed among workers employed in the construction, education services, and some manufacturing industries.

Construction

The construction industry and trades occupations require workers to handle insulation or work in close proximity to insulation. Occupations that may put workers into contact with asbestos include insulators, electricians, and plumbers. The ODSS detected increased risks of asbestosis among home-related building and repairing occupations that may be exposed to asbestos in the work environment.

    • Insulators: 26 times the risk
    • Pipefitters and plumbers: 8 times the risk
    • Electricians and repairmen: 3 times the risk
Metal Manufacturing

Within the metal manufacturing industry, workers are required to operate machinery including boilerplates, furnaces, and other heating apparatuses. Asbestos was commonly used as an insulating material in metalworking machinery. When these materials are disturbed or degrade asbestos fibres are released into the air.

    • Boilermakers: 10 times risk
    • Iron and steel mills: 2.7 times the risk
    • Primary metal workers: 2.3 times the risk
Education and Related Services

Workers within the education and related services sector include not only teachers and administrative staff, but also custodial workers. These workers are possibly exposed to asbestos that was installed as insulation, tiling and other materials in older schools, especially during building maintenance and repair. As asbestos-containing materials degrade, fibres can become airborne and pose a health risk to staff.

    • Education and related services: 1.7 times the risk
Relative Risk by Industry and Occupation

Figure 1. Risk of asbestosis diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1999-2016

The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).

 

Figure 2. Risk of asbestosis diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1999-2016 

The hazard ratio is an estimate of the average time to diagnosis among workers in each industry/occupation group divided by that in all others during the study period. Hazard ratios above 1.00 indicate a greater risk of disease in a given group compared to all others. Estimates are adjusted for birth year and sex. The width of the 95% Confidence Interval (CI) is based on the number of cases in each group (more cases narrows the interval).

Table of Results

Table 1. Surveillance of Asbestosis: 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) †
1 Agriculture <5 27,818
2/3 Forestry, Fishing and Trapping <5 7,857
4 Mines, Quarries and Oil Wells 13 18,210 0.99 (0.57, 1.71)
5 Manufacturing 243 565,700 0.93 (0.80, 1.10)
6 Construction 153 175,617 2.36 (1.97, 2.84)
7 Transportation, Communication and Other Utilities 66 165,930 0.95 (0.73, 1.22)
8 Trade 52 357,376 0.47 (0.35, 0.62)
9 Finance, Insurance and Real Estate 11 19,414 1.31 (0.72, 2.37)
10 Community, Business and Personal Service 98 483,986 0.87 (0.70, 1.09)
11 Public Administration and Defense 63 157,922 0.96 (0.74, 1.24)
         
* SIC: Standard Industrial Classification (1970)    
† Hazard ratio in each group relative to all others    

 

Table 2. Surveillance of Asbestosis: 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) †
11 Managerial, administrative and related 5 26,772 0.65 (0.27, 1.57)
21 Natural sciences, engineering and mathematics 8 22,785 0.94 (0.47, 1.89)
23 Social sciences and related fields 5 24,939 1.63 (0.67, 3.95)
25 Religion 0 113  
27 Teaching and related 8 41,692 1.07 (0.53, 2.15)
31 Medicine and health 10 108,759 0.67 (0.35, 1.27)
33 Artistic, literary, recreational and related <5 12,729  
41 Clerical and related 23 162,132 0.52 (0.34, 0.78)
51 Sales 22 123,283 0.89 (0.58, 1.36)
61 Service 62 298,287 0.67 (0.51, 0.87)
71 Farming, horticultural and animal husbandry 5 40,974 0.39 (0.16, 0.94)
73 Fishing, hunting, trapping and related 0 463
75 Forestry and logging 0 7,730
77 Mining and quarrying, including oil and gas field 6 10,079 0.86 (0.38, 1.92)
81 Processing (mineral, metal, chemical) 37 67,239 1.45 (1.04, 2.02)
82 Processing (food, wood, textile) 18 81,535 0.65 (0.41, 1.04)
83 Machining and related 76 161,878 0.99 (0.78, 1.26)
85 Product fabricating, assembling and repairing 107 276,755 0.84 (0.68, 1.03)
87 Construction trades 230 181,331 3.52 (2.99, 4.15)
91 Transport equipment operating 40 143,836 0.58 (0.42, 0.80)
93 Materials handling and related, not elsewhere classified 19 128,517 0.40 (0.25, 0.62)
95 Other crafts and equipment operating 10 23,406 0.90 (0.48, 1.68)
99 Other occupations not elsewhere classified 55 180,646 0.81 (0.61, 1.07)
         
* CCDO: Canadian Classification Dictionary of Occupations (1971)  
† Hazard ratio 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.