Objectives To map the cumulative incidence of asbestosis, silicosis, and coal workers' pneumoconiosis (CWP) by Regional District (RD) in British Columbia, Canada for the period 1995 to 2006 and to compare the variation in cumulative incidence with historic patterns of respirable dust exposure.
Methods Cases of asbestosis, silicosis, and CWP were defined from administrative health records, including related accepted workers' compensation claims, diagnoses in hospital discharge records, or at least two visits in physician outpatient records. Cases were linked to the 32 RD in the year of meeting the case definition for the 12 years between 1995 and 2006. Cumulative incidence was calculated using the BC population aged 15 or older in 2006 for men and women, and mapped. Known historic and current sources of high asbestos, coal and silica exposure were also mapped.
Results Cumulative incidence rates varied geographically by twenty-fold for all pneumoconioses. For men, the highest cumulative incidence rate was found for asbestosis in the Kootenay Boundary RD (202/100 000), a region that includes a large aluminum smelter, and the Powell River RD (192/100 000), a region with pulp and paper manufacturing. The highest rates for CWP (34/100 000) and silicosis (61/100 000) were in the East Kootenay RD, a region associated with mining. Similar trends were observed among women although they tended to have lower rates.
Conclusions The association of geographic variation in the cumulative incidence of pneumoconioses with historic sources of respirable dust exposure provides face validity to the use of administrative medical databases for occupational health disease surveillance.