VANCOUVER - Pulp and paper workers employed for 15 or more years in British Columbia mills that used the Sulfite process for the production of pulp, developed more pleural and rectal cancers than men from the general population, according to a new BC Cancer Agency study.

However, researchers found NO significantly increased cancer risk for the men who worked exclusively in the Kraft process, now the dominant pulping method in British Columbia and where the vast majority of workers are stationed.

Cancer incidence among 30,157 male pulp and paper workers employed for at least one year between 1950-1992 was examined by cross-referencing employee records with the National Cancer Registry.

Of these workers, 20,373 (68%) worked in the Kraft process only; 5,249 (17%) worked only in the Sulfite process and; 4,535 (15%) worked in both processes.

The research team, led by Dr. Pierre Band of Health Canada and Dr. Nhu Le of the BC Cancer Agency, also report an excess risk of prostate and stomach cancers, as well as leukemias, for those who worked in both the Kraft and Sulfite processes for 15 or more years. The excess risk was only associated with workers who were employed in both processes; no excess risk for prostate or stomach cancer was found among those who worked exclusively in the Kraft process or only in the Sulfite process.

"Higher incidence of pleural cancer within the pulp and paper industry is likely due to previous exposure to asbestos," said Dr. Nhu Le, co-principal investigator and leader of the BC Cancer Agency's Occupational Oncology Research Program. "But to our knowledge this is the first cohort study to report an increased risk for prostate cancer."

"The findings will be examined more closely in the second phase of the study, which will focus on workers' exposure to specific substances in an effort to identify chemicals, or groups of chemicals, that could be potential risk factors for cancers," Dr. Le explained. "The ultimate aim would be to improve the health of workers in the industry."

"The research team received excellent support from both forestry industry union and management while conducting this study," Dr. Le added. "Both played a critical role in helping us to collect the comprehensive data needed for the study and to disseminate the findings to the stakeholders."

The Forest Industry Health Research Program (FIRHP) and the Workers Compensation Board of British Columbia funded the BC Cancer Agency study.

The FIHRP is a non-profit society dedicated to funding research in health and safety in the pulp and paper industry. Representatives from the Communication Energy and Paper Workers Union, the Pulp Paper and Woodworkers of Canada, and the industry, are involved in the selection of research projects that will be funded.

View the study: Cohort Cancer Incidence Study of Pulp and Paper Mill Workers in British Columbia, Canada, appears in the current issue of the Scandinavian Journal of Work, Environment and Health

Background

Criteria for inclusion in study

• Mill must have started production in 1970 or earlier  
• Minimum of 1,000 workers employed by the mill  
• Availability of records for all employees  
• Of the 21 mills eligible in British Columbia, 14 met above criteria and were included in the study  
• The main industrial process of the 14 mills was pulping; however seven also included paper making  
• Wood may be converted to pulp by a number of processes, the most prevalent in Canada being chemical.

About the data collection: 

• Data collection included full name, dates of birth, hire and termination of employees  
• Data was cross-referenced with data within the National Cancer Registry  
• The National Cancer Registry monitors all occurrences and deaths from cancer in Canada  
• All male workers with at least one year of employment in 14 pulp and paper mills between January 1, 1950 and December 31, 1992 were studied  
• Information on tobacco smoking and other cancer risk factors related to lifestyle was not available.

Terms:

• Kraft process: alkaline-based method for the production of pulp  
• Sulfite process: acidic-based method for the production of pulp