A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents

Background We conducted a population‐based case‐control study in Montreal, Canada, to explore associations between hundreds of occupational circumstances and several cancer sites, including colon. Methods We interviewed 497 male patients with a pathologically confirmed diagnosis of colon cancer, 1514 controls with cancers at other sites, and 533 population‐based controls. Detailed job histories and relevant potential confounding variables were obtained, and the job histories were translated by a team of chemists and industrial hygienists into a history of occupational exposures. Results We found that there was reasonable evidence of associations for men employed in nine industry groups (adjusted odds ranging from 1.1 to 1.6 per a 10‐year increase in duration of employment), and in 12 job groups (OR varying from 1.1 to 1.7). In addition, we found evidence of increased risks by increasing level of exposures to 21 occupational agents, including polystyrene (OR for “substantial” exposure (ORsubst) = 10.7), polyurethanes (ORsubst = 8.4), coke dust (ORsubst = 5.6), mineral oils (ORsubst = 3.3), polyacrylates (ORsubst = 2.8), cellulose nitrate (ORsubst = 2.6), alkyds (ORsubst = 2.5), inorganic insulation dust (ORsubst = 2.3), plastic dusts (ORsubst = 2.3), asbestos (ORsubst = 2.1), mineral wool fibers (ORsubst = 2.1), glass fibers (ORsubst = 2.0), iron oxides (ORsubst = 1.9), aliphatic ketones (ORsubst = 1.9), benzene (ORsubst = 1.9), xylene (ORsubst = 1.9), inorganic acid solutions (ORsubst = 1.8), waxes, polishes (ORsubst = 1.8), mononuclear aromatic hydrocarbons (ORsubst = 1.6), toluene (ORsubst = 1.6), and diesel engine emissions (ORsubst = 1.5). Not all of these effects are independent because some exposures occurred contemporaneously with others or because they referred to a group of substances. Conclusions We have uncovered a number of occupational associations with colon cancer. For most of these agents, there are no published data to support or refute our observations. As there are few accepted risk factors for colon cancer, we suggest that new occupational and toxicologic studies be undertaken focusing on the more prevalent substances reported herein. Am. J. Ind. Med. 39:531–546, 2001. © 2001 Wiley‐Liss, Inc.