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342 Mortality and proportional cancer incidence in Minnesota taconite workers
  1. E M A Allen,
  2. Alexander Mandel,
  3. Ramachandran MacLehose,
  4. Nelson
  1. University of Minnesota, Minneapolis, United States of America


Objective In response to public concerns about health in Minnesota taconite mining workers, we evaluated the mortality and cancer experience in this population.

Methods From a cohort of 44,159 taconite workers born in 1920 or later, we selected 30,360 with at least one year of documented employment. Vital status and causes of death from death certificates were ascertained through December 31, 2007. Cancer diagnoses from 1988 through 2010 were identified by the Minnesota Cancer Surveillance System (MCSS). Standardised mortality ratios (SMRs) and proportional cancer incidence ratios (PCIR) were calculated using Minnesota as the reference population.

Results We identified 9,012 deaths, of which 2,693 were cancers, including 943 lung cancers, and 30 mesotheliomas. Mortality from all causes was near unity (SMR = 1.02, 95% Confidence Interval (CI): 1.00–1.04). Mortality from lung cancer and mesothelioma were higher than expected; SMR = 1.16 (95% CI: 1.09–1.24) and 2.79 (95% CI: 1.88–3.98) respectively. SMRs were elevated for all heart diseases (SMR = 1.10, 95% CI: 1.06–1.14), hypertension with heart disease (SMR = 1.79, 95% CI: 1.37–2.30) and ischaemic heart disease (SMR = 1.11, 95% CI: 1.07–1.16). A total of 6,189 incident cancers were identified by MCSS including 1016 lung cancers, and 51 mesotheliomas. PCIRs for mesothelioma and lung cancer were 3.02 (95% CI: 2.24, 3.98) and 1.22 (95% CI: 1.15–1.30) respectively. Other proportionally elevated cancers include oral, esophageal, stomach, laryngeal, and bladder cancers.

Conclusions This analysis indicates taconite workers have an increased risk for certain cancers and cardiovascular disease. Exposures from taconite operations include crystalline silica, respirable dust and elongated mineral particles, including non-asbestiform amphiboles and cleavage fragments. Exposure to commercial asbestos is also possible. The extent to which such exposures contribute to disease burden is being investigated. Lifestyle factors, such as smoking, could also contribute to disease burden.

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