Lung Cancer Burden Of Occupational Exposure To Radon In Canada

Calvin GE, Utrecht University, Netherlands
KIM J. 1 , PETERS C. 2 , DEMERS P. 1

1 Occupational Cancer Research Centre, Cancer Care Ontario, Toronto, Canada
2 Department of Health Sciences, Carleton University, Ottawa, Canada

Purpose: Estimate the proportion of Canadians exposed to radon in all occupational environments and calculate lung cancer cases attributable to these exposures.
 
Methods: Radon exposure for workers in high-risk occupations (e.g. underground mining) and indoor workers were assessed separately. High-risk workers who were likely to have exposure >800 Bq/m3 were identified by occupational hygienists, by occupation and industry, from the 2006 Canadian census. Indoor workers were also identified by industry and occupation, by first excluding outdoor workers exposed to solar radiation in the CAREX Canada SUNJEM, then removing workers in well-ventilated workplaces by expert assessment. To account for the increased likelihood of radon exposure on lower floors, building height adjustment factors were applied to reduce exposure population in urban areas. The exposure distribution of these indoor workers was modeled, by province, using radon measurements from a survey of federal buildings in Canada.
 
Combining the exposure assessment above and the population model developed for the Canadian Occupational Cancer Burden project, we estimated the fraction of lung cancers in 2011 attributable to occupational radon exposure during 1961 – 2001. Relative risks were calculated using the BEIR VI exposure-age-concentration risk model.
 
Results: Approximately 4.4 million indoor and 26,000 high-risk Canadian workers were exposed to radon from 1961-2001. The majority (79%) of exposed indoor workers had exposures below 50 Bq/m3. In total, 67 new cases of lung cancer in 2011 were attributable to occupational radon exposure in Canada, representing 0.25% of incident lung cancers.
 
Conclusions: Lung cancer attributable to occupational radon exposure is low in Canada. Most exposure and disease burden are associated with low radon concentrations, below the WHO reference level of 100 Bq/m3.
 
Funding Sources: Canadian Cancer Society, Canadian Partnership Against Cancer.