Investigating Occupational Exposure to Monocyclic Aromatic Hydrocarbons and Lung Cancer in Males of the Metropolitan Montréal Area
Lung Cancer , Benzene , Toluene , Xylene , MAH , Occupational Epidemiology
Background: Monocyclic aromatic hydrocarbons (MAHs) are a family of chemicals that include benzene, toluene, and xylene. These three chemicals are ubiquitous agents that are present in a number of occupational and environmental circumstances. Currently, there is limited and inconsistent evidence to suggest that exposure to MAHs is associated with lung cancer in humans. Objectives: The primary objective of this thesis is to explore the associations of lifetime occupational exposure to MAHs and lung cancer risk. Secondary objectives include 1) investigating these associations stratified by smoking status, and, 2) exploring the associations between MAH exposures and major histological types of lung cancer. Methods: The data used in this thesis is from a Montréal-based case-control study of lung cancer conducted by a team of researchers led by Dr. Jack Siemiatycki of l’Université de Montréal. The final study population was comprised of male Canadian citizens with a total of 733 cases of lung cancer and 894 controls frequency matched on age and sex. Multivariate unconditional logistic regression was performed to assess the associations between MAH exposures and lung cancer. Results: Exposure to MAHs is suggestive of a slightly increased risk of lung cancer. Exposure to toluene and xylene is associated with an increased risk for adenocarcinoma of the lung. Substantial exposure to benzene is suggestive of an increased risk for squamous cell carcinoma of the lung. There is no evidence to suggest that the risk of lung cancer associated with exposure to MAHs differs according to smoking history. Conclusions: The findings of this thesis suggest that occupational exposure to MAHs may be associated with increased risk of lung cancer. These findings contribute to the literature, which currently lacks quality studies reporting on the carcinogenic effects of toluene and xylene. In addition, these findings build on the growing body of evidence that suggests benzene-exposed workers are associated with an increased risk of lung cancer.