| CANCER INCIDENCE AMONG MINNESOTA TACONITE WORKERS. Elizabeth M Allen*, Bruce H Alexander, Jeffrey H Mandel, Richard F MacLehose, Gurumurthy Ramachandran, (University of Minnesota, Minneapolis Minnesota USA) |
Objective: In response to public concerns about health of Minnesota taconite workers, we evaluated cancer incidence in this population. Methods: Through the Minnesota Cancer Surveillance System (MCSS), we identified incident cancers from 1988 through 2010 in a cohort of 41,200 taconite workers born after 1920. Standardized incident ratios (SIRs) were estimated using population base rates from MCSS. Proportion of in-state deaths was used to adjust person-time of the cohort residing in MN, and thus under MCSS surveillance. Smoking habits from a parallel cross-sectional study of current and former taconite workers and Minnesota population based smoking rates from the Minnesota Adult Tobacco Survey were used to estimate a bias factor for smoking. Results: A total of 6,121 incident cancers were identified by MCSS including 931 lung cancers, and 51 mesotheliomas. Crude SIRs for mesothelioma and lung cancer were 1.4 (95% CI: 1.1-1.9) and 0.8 (95% CI: 0.7-0.8) respectively. After adjusting for out-of-state migration, SIRs were 2.4 (95% CI: 1.8-3.2) for mesothelioma and 1.3 (95% CI: 1.2-1.4) for lung cancer. Other elevated cancers include stomach, laryngeal, and bladder. After adjusting with a bias factor for smoking, lung cancer incidence was as expected in MN (SIR = 1.0, 95% CI: 0.9-1.1). Conclusions: Taconite workers have an increased risk for certain cancers. Exposures from taconite operations include crystalline silica, respirable dust and elongated mineral particles. Exposure to commercial asbestos is also possible. Smoking may also contribute to elevated morbidity rates. The extent to which such exposures contribute to disease burden is being further investigated.
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