Occupational exposures and health outcomes among Minnesota taconite mining workers

Abstract

Background/Objective: Minnesota taconite mining workers are exposed primarily to non-asbestiform elongate mineral particles and cleavage fragments. The health risk of these exposures is not understood nor has it been widely studied. There has been growing concern among the Minnesota community as to whether exposures obtained during taconite mining operations are a threat to human health. The objective of this research is to characterize the overall health of taconite mining industry workers in Minnesota and to identify the exposure risk of developing lung cancer.Methods: To attain this objective, three studies of taconite mining workers were undertaken. First, an overall mortality analysis was conducted in which mortality rates in a cohort of Minnesota taconite mining workers was compared with mortality rates in the general Minnesota population. Second, an overall cancer incidence analysis was conducted in which cancer rates in the same cohort was compared with cancer rates in the Minnesota population. Third, a nested case-control analysis of lung cancer was conducted in which exposures among lung cancer cases identified in the cohort was compared with exposures among two age matched controls per case.Results: The mortality analysis identified an increase in risk of death from mesothelioma, lung cancer, hypertensive heart disease, and ischemic heart disease. The cancer incidence analysis identified an increase in incident mesothelioma, lung, laryngeal, stomach, and bladder cancers among taconite workers as compared to what would be expected in the general Minnesota population. Results of the lung cancer case-control analysis indicated no increase in risk of lung cancer with increasing exposure levels obtained while working in the taconite industry.Conclusions: The results of the three studies combined suggest that exposure to non-asbestiform elongate mineral particles does not increase the risk of lung cancer. Elevated risk of mortality and cancer incidence identified in the initial analyses are likely due to lifestyle factors such as smoking. This research suggests that the study population may benefit from health promotion campaigns to help reduce incidence and mortality from certain diseases but occupational exposures are likely not the source of the increase in disease risk. This research adds to the uncertainties regarding non-asbestiform elongate mineral particle exposure and provides evidence that these unique exposures do not pose a great threat to human health.