Wood-dust exposures and cancer of the colon.

Previous studies of workers exposed to wood dusts have shown a decreased risk of cancer of the colon in these workers. However, none of these studies adequately controlled for potential confounders, such as physical activity, diet, and family history of colorectal cancer. The purpose of this case-control study was to evaluate the association between exposure to wood dust and risk for colon cancer after adjusting for potential confounders. Four hundred nineteen male cases of adenocarcinoma of the colon, identified from the Los Angeles County Cancer Surveillance Program, were individually matched to neighborhood controls based on gender and date of birth. Exposure to wood dust was associated with reduced risk of colon cancer that was partially masked before adjustment for confounders, and was limited to workers with frequent exposures that had begun at least 30 years before diagnosis [unadjusted and adjusted ORs, respectively, to exposures 5+ times a week beginning 30+ years before diagnosis = 0.63 (95% CI 0.36-1.13) and 0.39 (95% CI 0.20-0.77)]. This study provides additional evidence that heavy exposure to wood dusts may be associated with reduced risk of colon cancer in males after adjustment for other known causes of colon cancer.