Data from the Mine Safety and Health Administration (MSHA) and primary exposure monitoring measurements made in the taconite industry for the time period 1955 to present have been obtained. Review of the MSHA data has been completed.
Data on historical exposure monitoring measurements from companies has been obtained and the assessment of current exposures at the currently operational mines is continuing. Based on these measurements the workforce is being divided into similarly exposed groups (SEGs). Two workers from each SEG are being sampled for fibers and respirable dust and silica. At the same time, area samples are being obtained for more detailed analysis. Area samples include real-time monitoring for particle number, surface area and mass concentrations. On-site testing is expected to be completed by February 2011.
Historical work history records from the cohort of taconite workers are being reviewed to map the detailed work histories into similarly exposed groups (SEGs) to be able to use the information obtained from the Occupation Exposure Assessment.
The cohort of taconite workers has been matched with mortality records and the Minnesota Cancer Surveillance System (MCSS) to identify deaths and cases of cancer among the group. Acquisition of death certificates and cause of death information will be completed by January 2011.
Testing at the Virginia Regional Medical Center in Virginia, MN was completed in August and testing at the Bay Area Medical Center in Silver Bay, MN was completed in October. Over 1800 individuals participated (approximately 1300 workers and 500 spouses) in the screening which included a limited physical exam, a chest X-ray, a blood draw, breathing tests and completing a questionnaire. Analysis of the data is underway and will incorporate the exposure information obtained in the Occupational Exposure Assessment to further understand the lung tests results.