Toronto • May 28-29, 2010 • Student Day and Workshops: May 27
Paper: Time trends for asbestosis, silicosis, and coal workers’ pneumoconiosis in British Columbia
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Session : 6. Occupational disease
Day/Time: Friday at 13:30
Room: St. Patrick Room, 3rd Floor
Objectives:
Pneumoconioses are fibrotic lung diseases typically associated with high levels of respirable dust exposure. Fibrogenic dust exposure levels have been decreasing since the 1970s driven by recognition of the hazards and lowering of workplace exposure limits. Surveillance efforts for pneumoconiosis have traditionally relied on death certificates or workers’ compensation data, which have significant limitations. We used outpatient and hospital, as well as compensation data, to examine whether the incidence of the pneumoconioses is decreasing.
Methods:
Data on all outpatient and hospital visits between 1991 and 2007 for asbestosis, silicosis, and coal workers’ pneumoconiosis (CWP) were obtained from the BC Ministry of Health. Data on accepted claims was obtained from WorkSafeBC. Data sets were linked by PopData BC and a case was defined as a person with an accepted compensation claim (WCC), any diagnosis in hospital discharge records (HDR), or at least two visits in the outpatient records (OPR). Trends were assessed for men and women between 1992 and 2006. Pneumoconioses are progressive and, except in the case of exceptionally high exposures, take decades to develop. To assess whether exposure levels are decreasing we examined trends in data collected by the Workers’ Compensation Board of British Columbia and Ontario’s Ministry of Labour. We also examined trends in occupational exposure limits, Stats Canada employment data, and Natural Resources Canada production data.
Results:
1561 cases of asbestosis were identified (702 OPR/461 HDR/11 WCC/287 combination; 97% male). 388 cases of silicosis were identified (52 OPR/268 HDR/21 WCC/22 combination; 86% male). 388 cases of CWP were identified (71 OPR/303 HDR/5 WCC/1 combination; 72% male). Among men, 1992 to 2006 asbestosis incidence increased from 5.5 to 6.2/100000, silicosis and CWP decreased from 2.3 to 0.3/100000 and 2 to 0.4/100000, respectively. Similar trends were observed among women, based on small numbers. Since the 1970s exposure to asbestos, silica, and coal dust appear to have decreased, although there is still the potential for high exposures to smaller groups.
Conclusions:
The decreasing rates of silicosis and CWP are consistent with the decreasing prevalence of high exposures over time. This could be due to a difference in the latency/induction periods or a lower threshold for reporting in the datasets. The latter is compatible with the different pattern of case ascertainment. Increasing asbestosis rates are compatible with mesothelioma rates, but asbestosis is thought to have a different dose-response relationship with asbestos. These results are based on administrative databases and the numbers may not be precise. However, using data from this combination of sources is useful for surveillance of these serious work-related diseases.
