Lung Cancer

Background

What is lung cancer?

In Canada, lung cancer is the leading cause of cancer mortality in men and women. Lung cancer is primarily caused by smoking and prevention efforts have largely focused on tobacco control. Based on the Burden of Occupational Cancer Project, approximately 15% of lung cancers are caused by workplace exposures. Workers in a number of occupations are exposed to known lung carcinogens.

Occupational risk factors
      • Dusts and fibres (e.g. asbestos, silica)
      • Combustion products (e.g. diesel engine exhaust, secondhand smoke, soot)
      • Metals and their compounds (e.g. welding fumes, chromium VI, nickel compounds, arsenic)
      • Ionizing radiation (e.g. radon, x-radiation, gamma-radiation)

Based on the Burden of Occupational Cancer study, asbestos, crystalline silica, diesel engine exhaust, and welding fumes are the four most important lung carcinogens in Canada.

Key Findings

The greatest risks of lung cancer are observed among workers employed in mining, construction, and transportation occupations.

Mining

Workers employed in mining have the greatest risk of lung cancer compared to all other industry groups. Work related to mining and quarrying has consistently shown increased lung cancer risks due to a number of hazards including crystalline silica, radon, asbestos and diesel engine exhaust.

    • Mining industry overall: 1.4 times the risk
      • Non-metal mines: 1.4 times the risk
      • Quarries and sand pits: 1.6 times the risk
      • Metal mines: 1.5 times the risk
        • Uranium mines: 1.9 times the risk
    • All mining occupations: 1.5 times the risk
      • Mining and quarrying including oil and gas occupations: 1.5 times the risk
      • Rotary well-drilling and related occupations: 3 times the risk
        • Rock and soil-drilling: 1.6 times the risk
Construction

Workers in construction trades are potentially exposed to a wide range of lung carcinogens.

Elevated risks of lung cancer are seen among workers in excavating, grading, paving and related occupations. This may be due to exposure to numerous lung carcinogens including diesel engine exhaust and crystalline silica dust.

Elevated risk of lung cancer is also detected among workers employed in other construction trades, such as painters and insulators. Historically, insulators have handled asbestos materials when installing or removing insulation materials from buildings. Currently, many construction workers may be exposed to asbestos during renovation, repair, or demolition of older buildings. Painters are also recognized as a high-risk occupation for lung cancer, possibly due to various hazardous chemicals in paint pigments, resins and filaments.

    • All construction trades and occupations: 1.1 times the risk
      • Excavating, grading, paving & related: 1.5 times the risk
        • Excavating, grading & related: 1.8 times the risk
        • Paving, surfacing & related: 1.4 times the risk
      • Foremen in other construction trades: 1.3 times the risk
      • Painters and paperhangers: 1.4 times the risk
      • Insulators: 2.4 times the risk
      • Structural metal erectors: 1.4 times the risk
Transportation sector

Increased lung cancer risks are observed among workers in the transport sector. Workers employed in this sector may be exposed to elevated levels of diesel engine exhaust if they work in or around diesel-powered equipment.

    • Transportation industry overall: 1.2 times the risk
      • Truck transport: 1.6 times the risk
      • Taxicab operations: 1.7 times the risk
    • Railway transport operating occupations: 1.5 times the risk
      • Conductors & brakemen: 1.3 times the risk
      • Locomotive engineers & firemen: 1.2 times the risk
Relative Risk by Industry and Occupation

Figure 1. Risk of lung cancer diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016

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 lung cancer diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 1983-2016 

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 Lung Cancer: 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 377 35,114 0.81 (0.73, 0.89)
2/3 Forestry, Fishing and Trapping 249 10,718 1.15 (1.01, 1.30)
4 Mines, Quarries and Oil Wells 793 23,197 1.42 (1.33, 1.53)
5 Manufacturing 12,677 694,755 0.98 (0.96, 1.00)
6 Construction 3,643 211,532 1.09 (1.05, 1.13)
7 Transportation, Communication and Other Utilities 3,531 197,532 1.14 (1.10, 1.18)
8 Trade 5,391 429,887 0.99 (0.96, 1.02)
9 Finance, Insurance and Real Estate 479 24,020 1.15 (1.05, 1.26)
10 Community, Business and Personal Service 7,263 600,295 0.95 (0.93, 0.98)
11 Public Administration and Defense 3,309 191,086 1.04 (1.01, 1.08)
         
* SIC: Standard Industrial Classification (1970)    
† Hazard ratio in each group relative to all others    

 

 

Table 2. Surveillance of Lung Cancer: 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 346 31,025 1.03 (0.93, 1.15)
21 Natural sciences, engineering and mathematics 287 26,363 0.85 (0.76, 0.96)
23 Social sciences and related fields 250 30,724 1.04 (0.92, 1.18)
25 Religion 0 129 —
27 Teaching and related 334 48,508 0.61 (0.55, 0.68)
31 Medicine and health 1,460 135,441 0.85 (0.80, 0.89)
33 Artistic, literary, recreational and related 131 15,003 1.11 (0.93, 1.32)
41 Clerical and related 2,821 197,533 1.09 (1.05, 1.13)
51 Sales 1,515 148,239 1.06 (1.01, 1.12)
61 Service 5,387 371,271 1.06 (1.03, 1.09)
71 Farming, horticultural and animal husbandry 555 50,263 0.88 (0.81, 0.96)
73 Fishing, hunting, trapping and related 11 558 1.16 (0.64, 2.10)
75 Forestry and logging 216 10,706 1.04 (0.91, 1.19)
77 Mining and quarrying, including oil and gas field 438 13,030 1.46 (1.33, 1.60)
81 Processing (mineral, metal, chemical) 1,417 79,364 1.17 (1.11, 1.24)
82 Processing (food, wood, textile) 1,427 99,361 1.00 (1.07, 1.15)
83 Machining and related 3,613 189,758 1.11 (1.07, 1.15)
85 Product fabricating, assembling and repairing 5,810 328,740 1.01 (0.99, 1.04)
87 Construction trades 4,068 216,068 1.09 (1.06, 1.13)
91 Transport equipment operating 3,668 168,429 1.39 (1.34, 1.44)
93 Materials handling and related, not elsewhere classified 2,519 153,280 1.11 (1.06, 1.15)
95 Other crafts and equipment operating 571 28,353 1.12 (1.03, 1.21)
99 Other occupations not elsewhere classified 3,409 215,574 1.10 (1.07, 1.14)
         
* 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.