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Modeling the Pathways of Manganese (Mn) Exposure from Air, Soil, and Household Dust to Biomarker Levels in 7-9 Year Old Children Residing Near a Mn Refinery

Stolfi, Adrienne
http://orcid.org/0000-0001-8049-4562
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133090389903

Abstract Details

2020, PhD, University of Cincinnati, Medicine: Epidemiology (Environmental Health).
Introduction: Manganese (Mn) is an essential trace element necessary for normal growth and development, that in excess can be neurotoxic. Excess environmental Mn can occur due to industrial emissions, but exposure pathways from environmental sources to biomarker levels, and ultimately to neurological outcomes have not been determined. Objectives: The objectives of this dissertation are to 1) determine ambient air Mn exposure levels in a population living near the longest operating ferromanganese refinery in North America, using atmospheric dispersion modeling, 2) evaluate associations between modeled ambient air, soil, and indoor dust Mn collected from residences in the exposure area, and 3) determine pathways from environmental measures of Mn to blood, hair, and toenail Mn levels in exposed children using structural equation modeling (SEM). Methods: Data are from the Communities Actively Researching Exposure Study (CARES), a cross-sectional study conducted from 2008-2013 in the Marietta, Ohio area to investigate neurological effects of Mn exposure in 7-9 year old children. Emissions from the Mn refinery were modeled using the U.S. Environmental Protection Agency (EPA) regulatory air dispersion model AERMOD. Average annual ambient air Mn concentrations were determined for census blocks within 32 km of the refinery, and for CARES participants’ homes and schools. Monthly modeled ambient air concentrations for 2009-2010 were compared to concentrations from a stationary air sampler in Marietta to evaluate accuracy of the model. Exposures by census blocks were determined to estimate population sizes exposed to air Mn levels exceeding 50 ng/m3, the U.S. EPA guideline. SEM was performed to determine pathways of exposure from air, soil, and indoor dust Mn separately for blood, hair, and toenail Mn. Additional data included in the models were heating, ventilation and air conditioning in the home, average hours/week spent outside by the participant, parent education, and child gender. Results: Median (IQR) ambient air Mn (ng/m3) ranged from 6.3 (8.1) to 43.1 (38.2) across the years. For monthly air Mn in 2009-2010, the median (IQR) modeled air Mn was 18.4 (7.6) (ng/m3), and measured air Mn was 20.3 (12.4). All measures of model accuracy were within acceptable limits. Population sizes exposed to >50 ng/m3 of ambient air Mn ranged from 959 in 2010 to 56,210 in 2008. Given the significantly low emissions in 2010, this year was omitted from the final SEM. In the SEM models, pathways from ambient air Mn to indoor dust Mn, and from indoor dust Mn to hair and toenail Mn were statistically significant. Significant indirect pathways from ambient air and soil Mn to hair and toenail Mn through indoor dust Mn were also observed. No pathways of exposure to blood Mn were observed in the study. Conclusions: AERMOD modeling can provide a means of estimating ambient air Mn levels in populations exposed to environmental Mn sources. Based on the modeling, residents in the Marietta area are at times exposed to levels that exceed U.S. EPA guidelines. Ambient air Mn, soil Mn, and indoor dust Mn are important exposure pathways leading to increased levels of hair and toenail Mn.
Kelly Brunst, Ph.D. (Committee Chair)
Florence Fulk, Ph.D. (Committee Member)
Erin Haynes, Dr.P.H. (Committee Member)
Tiina Reponen, Ph.D. (Committee Member)
Heidi Sucharew, Ph.D. (Committee Member)
148 p.
Epidemiology
manganese; biomarkers; air dispersion modeling; exposure; structural equation modeling

Recommended Citations

Citations

  • Stolfi, A. (2020). Modeling the Pathways of Manganese (Mn) Exposure from Air, Soil, and Household Dust to Biomarker Levels in 7-9 Year Old Children Residing Near a Mn Refinery [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133090389903

    APA Style (7th edition)

  • Stolfi, Adrienne. Modeling the Pathways of Manganese (Mn) Exposure from Air, Soil, and Household Dust to Biomarker Levels in 7-9 Year Old Children Residing Near a Mn Refinery. 2020. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133090389903.

    MLA Style (8th edition)

  • Stolfi, Adrienne. "Modeling the Pathways of Manganese (Mn) Exposure from Air, Soil, and Household Dust to Biomarker Levels in 7-9 Year Old Children Residing Near a Mn Refinery." Doctoral dissertation, University of Cincinnati, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1592133090389903

    Chicago Manual of Style (17th edition)

ucin1592133090389903
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