Summary Report: Environmental Particulate Matter Characterization

Abstract

The NRRI characterization studies provide physical (size and shape), mineralogical, chemical, geological, geographical, and historical context to the findings of the University of Minnesota’s School of Public Health (SPH) and the University of Minnesota Medical School (UMMS). The SPH and UMMS findings (Finnegan and Mandel, 2014) showed that mesothelioma is associated with working longer in the taconite industry. However, the SPH and UMMS investigators “…were not able to state with certainty that the association with EMPs and mesothelioma was related to the ore dust or to the use of commercial asbestos or both.” The NRRI findings indicate the following: 1) Low concentrations of PM10, PM2.5, and EMPs in Mesabi Iron Range community air. 2) Elemental iron concentrations in MIR communities were similar to elemental iron concentrations in background sampling locations when taconite mines/plants were inactive. When taconite mines/plants were active, the elemental iron concentrations within communities were found to be statistically higher. 3) Mineralogically and morphologically, the EMPs identified in MIR communities and taconite processing plants were dominated by particles that did not fit the “countable”/”covered” classification criteria. Of the 145 “covered” EMPs identified within the six MIR taconite processing plants, a total of 8 were “countable” (NIOSH, 2011), representing 1.1% of the total number of EMPs, out of 691 total. These EMPs were detected in two taconite plants (seven in one plant and one in another); no other “countable”/”covered” EMPs were detected in the other four plants. 4) The lake sediment study returned similar results, in which 4 of the study’s 790 identified EMPs found in the lake sediment samples met the “countable”/”covered” classification. 5) In comparison to the NIOSH standard, for countable particles, the results from this study show that the community air has significantly lower amounts than the standard. 6) Only one plant and two areas in this plant had countable EMPs above the NIOSH benchmark. 7) The highest particulate matter found was for the Minneapolis reference site in comparison for the Range communities and the other two reference sites. 8) The use of MOUDI sampling techniques is a good method for better understanding not only what is in the air, but also the size of the particles that are in the air. 9) Study of lake sediment can be used to interpret some of the impacts of past industrial activities and to gain a better understanding of the impact of local geology.