Our goal was to investigate occupational exposure to wood dust and analyze the rate of sinonasal cancers in Ontario and across Canada.
Wood dust is classified as a human carcinogen based on evidence of very high risks of sinonasal cancer, particularly adenocarcinomas, in woodworkers. However, controversy remains regarding whether dust from all tree species is carcinogenic and some believe that the risk of cancer is limited to exposure to dust from hardwoods. Wood-dust related sinonasal cancer is considered an important issue in Europe, but not in North America where softwoods are dominant.
Canada has a diverse forest industry. Softwood forests and primary forest industries dominate in the West (e.g. B.C. and Alberta), whereas Central Canada (e.g. Ontario and Québec) have mixed and deciduous forests and a greater wood manufacturing sector.
This project will use measurement data collected from Ontario workplaces to analyze occupational exposure to wood dust in the province. Ontario Cancer Registry data will be used to analyze sinonasal cancer rates. The 1991-2006 Canadian census mortality & cancer cohort will be used to determine the link between occupational exposure to wood dust and sinonasal cancer across Canada.
Investigating occupational wood dust exposure and the link to sinonasal cancer could facilitate a greater understanding of how this carcinogen affects Canadian workers, and lead to future interventions. As well, comparisons between data from Ontario and British Columbia could help clarify the carcinogenicity of different wood species.
An analysis of Ontario workplace measurements of wood dust between 1981 and 1996 found that approximately 72% of the workplaces measured exceeded the current exposure limits for wood dust, and that many measurements were in the range where an increased risk of sinonasal cancer has been observed. However, in a recent analysis of the Ontario Cancer Registry we found that in recent decades the risk of sinonasal cancer has been declining in Ontario (see our Cancer Fact). That decline is primarily due to the decreasing rates of sinonasal squamous cell carcinomas, the most common histology, and may be due to reduced smoking. The rates for adenocarcinomas, which are more strongly related to occupational exposures such as wood dust and which are not associated with smoking, are not sharply declining.
A team in British Columbia is analyzing the BC Cancer registry to compare rates (and trends) of sinonasal cancer in that province to those we found in Ontario.
Future work will examine the link between occupational wood dust exposure and sinonasal cancer in the 1991-2006 Canadian census mortality & cancer cohort.
Paul Demers (Occupational Cancer Research Centre and Cancer Care Ontario)
Anne Harris (Ryerson University)
Victoria Arrandale (Occupational Cancer Research Centre)
Chris McLeod (University of British Columbia)
Mieke Koehoorn (University of British Columbia)