Occupational exposure to diesel engine emissions and risk of lung cancer: evidence from two case–control studies in Montreal, Canada
- 1Unit of Population Health, Centre de recherche du CHUM, Université de Montréal, Montreal, Quebec, Canada
- 2Unit of Epidemiology and Biostatistics, INRS- Institut Armand-Frappier, Laval, Quebec, Canada
- 3Department of Social and Preventive Medicine, Université de Montréal, Montreal, Quebec, Canada
- 4Guzzo – Cancer Research Society Chair in Environment and Cancer, School of Public Health, Université de Montréal, Montreal, Quebec, Canada
- Correspondence to Dr Jack Siemiatycki, Centre de recherche du CHUM, 3875 rue Saint-Urbain, 3rd floor, Montreal (Qc) H2W 1V1, Canada;
Contributors All coauthors contributed significantly to the research. JS designed both studies (I and II) included in this manuscript, developed the methods for assessment of occupational exposures and supervised its implementation. M-EP helped to direct study II and participated in planning analyses. JP conducted the literature review, statistical analysis and prepared the first draft of the article. LR contributed to the design of the studies and the development and coordination of the data collection methods. All coauthors participated in the editing and correction of the final text.
- Accepted 8 June 2012
- Published Online First 26 July 2012
Objective To examine the risk of lung cancer among men associated with exposure to diesel engine emissions incurred in a wide range of occupations and industries.
Methodology 2 population-based lung cancer case–control studies were conducted in Montreal. Study I (1979–1986) comprised 857 cases and 533 population controls; study II (1996–2001) comprised 736 cases and 894 population controls. A detailed job history was obtained, from which we inferred lifetime occupational exposure to 294 agents, including diesel engine emissions. ORs were estimated for each study and in the pooled data set, adjusting for socio-demographic factors, smoking history and selected occupational carcinogens. While it proved impossible to retrospectively estimate absolute exposure concentrations, there were estimates and analyses by relative measures of cumulative exposure.
Results Increased risks of lung cancer were found in both studies. The pooled analysis showed an OR of lung cancer associated with substantial exposure to diesel exhaust of 1.80 (95% CI 1.3 to 2.6). The risk associated with substantial exposure was higher for squamous cell carcinomas (OR 2.09; 95% CI 1.3 to 3.2) than other histological types. Joint effects between diesel exhaust exposure and tobacco smoking are compatible with a multiplicative synergistic effect.
Discussion Our findings provide further evidence supporting a causal link between diesel engine emissions and risk of lung cancer. The risk is stronger for the development of squamous cell carcinomas than for small cell tumours or adenocarcinomas.
- Lung cancer
- occupational exposure
- diesel exhaust
- general expertise
- organ system
- disease type
- public health
- risk assessment
Funding The study was funded by a number of agencies, including the Health Canada, the National Cancer Institute of Canada, the Medical Research Council of Canada and the Canadian Institutes for Health Research. M-EP is the recipient of a Fonds de la recherche en santé du Québec (FRSQ) salary award. JS was the recipient of a Canada Research Chair and holds the Guzzo-SRC Research Chair in Environment and Cancer.
Competing interests None.
Patient consent Signed by all participants. For deceased subjects, it was signed by next of kin.
Ethics approval Ethical approval was obtained for both studies from each participating hospital and university.
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement We have no data sharing policy at the moment.