Idiopathic Pulmonary Fibrosis (IPF)

Background

What is idiopathic pulmonary fibrosis (IPF)?

Idiopathic Pulmonary Fibrosis (IPF) is a respiratory disease involving scarring of the lungs resulting in reduced lung capacity. The term idiopathic is used to describe conditions of an unknown cause, but family history and smoking are both thought to be risk factors for IPF. This disease is the most common fibrotic lung disease and is similar to silicosis and asbestosis. IPF has poor five-year survival and treatment options are limited.

Possible occupational risk factors
    • Metal dust
    • Wood dust
    • Animal dust from livestock farming

Because there is not yet a comprehensive understanding of the causes of IPF, the ODSS project sought to understand what occupations and industries were at an increased risk of this disease as an important step toward prevention. Metal and wood dusts are important possible occupational risk factors for IPF.

Key Findings

The greatest risks of IPF were observed among workers employed in the mining, forestry and papermaking, and food and beverage sectors.

Mining

The mining industry overall is at 2 times the risk of IPF. Groups within this industry with elevated risks include the gold quartz and uranium mining sectors, as well as drilling and blasting occupations and cutting and loading occupations. These occupations and industries would likely have significant dust exposure, including metals, silica, and diesel engine exhaust.

    • Gold quartz mines: 3.6 times the risk
    • Uranium mines: 3.2 times the risk
    • Rock and soil drilling occupations: 2 times the risk
Forestry

Workers within the logging and pulp and papermaking industries are at increased risks of IPF. These workers are likely exposed to high levels of wood dust, which is a possible risk factor for IPF.

    • Logging: 1.5 times the risk
    • Occupations in elemental work, pulp and papermaking: 3.8 times the risk
Food and Beverage

Cooks and chefs were at an increased risk of IPF and could be exposed to organic dusts and cooking fumes. Organic dusts such as flour and confectionary materials are known risk factors for other respiratory conditions, but it is not known whether they pose a risk for IPF.

    • Chefs and cooks: 1.5 times the risk
Relative Risk by Industry and Occupation

Figure 1. Risk of idiopathic pulmonary fibrosis diagnosis among workers employed in each industry group relative to all others, Occupational Disease Surveillance System (ODSS), 2006-2016

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 idiopathic pulmonary fibrosis diagnosis among workers employed in each occupation group relative to all others, Occupational Disease Surveillance System (ODSS), 2006-2016 

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 Interstitial Pulmonary Fibrosis: 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 16 27,045 0.91 (0.55, 1.48)
2/3 Forestry, Fishing and
Trapping
12 7,409 1.64 (0.93, 2.90)
4 Mines, Quarries and
Oil Wells
41 16,975 1.83 (1.34, 2.50)
5 Manufacturing 556 544,756 1.07 (0.96, 1.19)
6 Construction 150 169,579 1.05 (0.88, 1.25)
7 Transportation, Communication
and Other Utilities
130 159,895 0.93 (0.78, 1.12)
8 Trade 246 347,992 1.04 (0.91, 1.19)
9 Finance, Insurance and
Real Estate
18 18,604 0.95 (0.59, 1.51)
10 Community, Business and
Personal Service
290 471,113 0.82 (0.71, 0.94)
11 Public Administration and
Defense
160 152,359 1.13 (0.95, 1.33)
         
* SIC: Standard Industrial Classification (1970)
† Hazard rate in each group relative to all others

 

Table 2. Surveillance of Interstitial Pulmonary Fibrosis: 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
18 26,201 0.88 (0.55, 1.40)
21 Natural sciences, engineering
and mathematics
13 22,211 0.73 (0.42, 1.26)
23 Social sciences and
related fields
13 24,536 1.07 (0.62, 1.86)
25 Religion 0 112
27 Teaching and related 29 41,002 0.96 (0.66, 1.40)
31 Medicine and health 72 106,553 0.98 (0.76, 1.26)
33 Artistic, literary,
recreational and related
12 12,453 1.88 (1.06, 3.32)
41 Clerical and related 110 157,487 0.91 (0.75, 1.10)
51 Sales 80 120,688 1.12 (0.89, 1.41)
61 Service 235 289,125 1.01 (0.88, 1.17)
71 Farming, horticultural
and animal husbandry
22 39,795 0.86 (0.56, 1.30)
73 Fishing, hunting,
trapping and related
<5 448
75 Forestry and logging 8 7,301 1.21 (0.60, 2.42)
77 Mining and quarrying,
including oil and gas field
25 9,408 2.11 (1.42, 3.14)
81 Processing
(mineral, metal, chemical)
68 64,951 1.29 (1.01, 1.64)
82 Processing
(food, wood, textile)
73 79,031 1.18 (0.93, 1.49)
83 Machining and related 143 156,151 0.95 (0.80, 1.13)
85 Product fabricating,
assembling and repairing
266 267,522 1.03 (0.90, 1.18)
87 Construction trades 175 174,623 1.05 (0.89, 1.23)
91 Transport equipment
operating
113 138,165 0.90 (0.74, 1.09)
93 Materials handling and related,
not elsewhere classified
111 123,954 1.14 (0.94, 1.39)
95 Other crafts and
equipment operating
26 22,446 1.13 (0.77, 1.67)
99 Other occupations not elsewhere classified 145 174,331 1.07 (0.90, 1.27)
         
* 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.