title: A case-control study of mesothelioma in Minnesota iron ore (taconite) miners.
abstract: OBJECTIVE
  An excess of mesothelioma has been observed in iron ore miners in Northeastern Minnesota. Mining and processing of taconite iron ore generate exposures that include elongate mineral particles (EMPs) of amphibole and non-amphibole origin. We conducted a nested case-control study of mesothelioma in a cohort of 68,737 iron ore miners (haematite and taconite ore miners) to evaluate the association between mesothelioma, employment and EMP exposures from taconite mining.
  
  
  METHODS
  Mesothelioma cases (N=80) were identified through the Minnesota Cancer Surveillance System (MCSS) and death certificates. Four controls of similar age were selected for each case with 315 controls ultimately eligible for inclusion. Mesothelioma risk was evaluated by estimating rate ratios and 95% CIs with conditional logistic regression in relation to duration of taconite industry employment and cumulative EMP exposure [(EMP/cc)×years], defined by the National Institute for Occupational Safety and Health (NIOSH) 7400 method. Models were adjusted for employment in haematite mining and potential exposure to commercial asbestos products used in the industry.
  
  
  RESULTS
  All mesothelioma cases were male and 57 of the cases had work experience in the taconite industry. Mesothelioma was associated with the number of years employed in the taconite industry (RR=1.03, 95% CI 1.00 to 1.06) and cumulative EMP exposure (RR=1.10, 95% CI 0.97 to -1.24). No association was observed with employment in haematite mining.
  
  
  CONCLUSIONS
  These results support an association between mesothelioma and employment duration and possibly EMP exposure in taconite mining and processing. The type of EMP was not determined. The potential role of commercial asbestos cannot be entirely ruled out.
authors.affiliation: Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Christine S
authors.initials: CS
authors.lastname: Lambert
authors.affiliation: Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Alexander
authors.affiliation: Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Gurumurthy
authors.initials: G
authors.lastname: Ramachandran
authors.affiliation: Division of Epidemiology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Richard F
authors.initials: RF
authors.lastname: MacLehose
authors.affiliation: Division of Epidemiology, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Heather H
authors.initials: HH
authors.lastname: Nelson
authors.affiliation: Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Ryan
authors.affiliation: Division of Environmental Health Sciences, University of Minnesota, Minneapolis, Minnesota, USA.
authors.forename: Jeffrey H
authors.initials: JH
authors.lastname: Mandel
mesh_terms: D000328:Adult; D000395:Air Pollutants, Occupational / Q000009:adverse effects; D016022:Case-Control Studies; D004651:Employment; D005260:Female; D005290:Ferric Compounds / Q000009:adverse effects; D006801:Humans; D007501:Iron / Q000009:adverse effects*; D016015:Logistic Models; D008175:Lung Neoplasms / Q000209:etiology* / Q000401:mortality; D008297:Male; D008654:Mesothelioma / Q000209:etiology* / Q000401:mortality; D008903:Minerals; D008906:Mining; D008910:Minnesota / Q000453:epidemiology; D009784:Occupational Diseases / Q000209:etiology* / Q000401:mortality; D016273:Occupational Exposure / Q000009:adverse effects*; D052638:Particulate Matter / Q000009:adverse effects*; D012307:Risk Factors; D017640:Silicates / Q000009:adverse effects*; D014937:Work
chemical_list: D000395:Air Pollutants, Occupational; D005290:Ferric Compounds; D008903:Minerals; D052638:Particulate Matter; D017640:Silicates; C026703:taconite; C000499:ferric oxide; D007501:Iron