Manganese (Mn) is an essential element, yet is neurotoxic in excess. The majority of Mn research has been conducted on occupationally exposed adults with few studies focused on an environmentally exposed population. Marietta, Ohio is home to one of the largest airborne Mn emission sources in the United States, a ferromanganese refinery. In preparation for a community-based participatory research study, a preliminary pilot study was initiated to characterize the community’s exposure to Mn in ambient air and to evaluate the relationship between biological indices of Mn exposure and genes associated with Mn metabolism in Marietta area residents. Participants in the pilot study were recruited through newspaper advertisement, fliers and direct mailing. Exposure to ambient Mn was estimated using an air pollution dispersion model, AERMOD. A total of 141 residents participated in the pilot study ranging in age from 2-81 years. Estimated annual average ambient air Mn concentrations in the study area obtained from AERMOD varied from 0.02-2.61 μg/m3. Mean blood and hair Mn values were 9.12 μg/L (SD 3.90) and 5.80 μg/g (SD 6.40 μg/g), respectively and were significantly correlated (r=0.30, p<0.01). Blood and hair Mn was significantly associated within families (r=0.27, p=<0.02 and r=0.43, p<0.01), respectively. The relationship between hair Mn and estimated ambient air Mn became significant when genes for iron metabolism were included in linear models. The preliminary ambient air and biological concentrations of Mn found in this population demonstrate the need for further research into potential health effects. A comprehensive study of neurobehavioral performance and environmental exposure to Mn in children residing in Marietta and a control community is currently underway.

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Source-oriented models are ideally suited to examine the impact of terrain and meteorology and source factors such as stack height when evaluating exposures to air pollutants. A source-oriented, Gaussian plume air pollution dispersion model AERMOD was used to estimate the spatial distribution of elemental mercury (Hg 0 ) from a typical coal-fired boiler emitting 0.001 g Hg 0 /s. Hg 0 was chosen because of its health impact related to potential neurological and reproductive effects which may be especially important for high-risk populations. Results from four simulations using meteorological data from 2004 were compared for flat and hilly terrain from 20-and 55-m stacks at a distance of 1,350 m from the source. Variations within a quadrant were affected primarily by topography. For the 20-m stack, the average annual ambient concentration for individuals living within the northeast (NE) quadrant was significantly lower at 2.5 ng Hg 0 /m 3 (P<0.001; confidence interval (CI), 2.4-2.6) in flat terrain versus 3.3 ng Hg 0 /m 3 in hilly (P<0.001; CI, 1.2-1.3). NE concentrations of the source showed high spatial variability attributed to topography with 1-h maximums of 4.0 ng Hg 0 /m 3 flat versus 7.1 ng Hg 0 /m 3 hilly. Not unexpectedly, average annual concentrations were considerably lower for the 55-m stack although topography remained a significant variable with 0.1 ng Hg 0 /m 3 in flat terrain (p<0.001; CI, 0.11-0.13) and double that exposure at 0.2 ng Hg 0 /m 3 in hilly terrain (p < 0.001; CI, 0.16-0.18). Annual average mercury concentrations due to emissions from the 20-m stack were~20 times higher than ambient concentrations associated with the 55-m stack. A sensitivity analysis was performed for meteorological effects, using meteorological data from years 2001-2005. Varying the roughness factor had no significant effect on the results. For all simulations, the highest concentrations were located in the NE quadrant. During 2001-2005, the highest average annual ambient Hg concentration ranged from 6.2 to 7.0 ng Hg 0 /m 3 for the 20-m stack and 0.3-0.5 ng Hg 0 /m 3 for the 55-m stack. Thus, this model is robust. These results demonstrate the usefulness of a source-oriented model such as AERMOD for incorporating multiple factors for estimating air pollution exposures for communities near point sources. The importance of considering topography, meteorology, and source characteristics when placing air samplers to measure air quality and when using buffer zones to estimate ambient residential exposures is also illustrated. Residential

Introduction: During the past four decades, mercury (Hg) research focused on fish consumption has explained less than 22% of Hg in human blood. One overlooked exposure pathway for infants and young children is the concentration of Hg in soils. Although 75% of the U.S. population lives in urban areas near industrial facilities, minimal data exist regarding the concentration and speciation of Hg in residential soils. Chronic exposure through ingestion of low concentrations of Hg in soils may explain a portion of the blood Hg levels noted in infants. Methods: Three relatively unexposed residential sites in a suburban community were selected. The primary route of contamination was atmospheric deposition. Soils were digested in a nitric acid-hydrofluoric acid solution and analyzed by cold vapor atomic absorption spectrophotometry. Measured concentrations of total Hg in local suburban soil samples were compared to levels measured in a national study of 27 remote and rural sites. The Al-Shahristani pharmacokinetic model, developed after the 1971 Iraqi Methyl Hg poisoning incident, was used to calculate the blood Hg concentration in a hypothetical year-old infant. Results: Soil samples contained Hg concentrations ranging from 0.01 to 0.24 ppm_w. The distribution of Hg in the soil samples was non-linear and non-normal. The mean soil Hg concentrations at the three locations were 0.08, 0.05 and 0.08 ppm. Calculated blood Hg concentrations for a 10 kg, year-old infant due to ingestion of soil (200 mg/day) containing 0.2, 0.4 and 0.8 ppm Hg were 0.08, 0.17 and 0.26 μg/L, respectively. Conclusions: The pilot study data appear to support the hypothesis that chronic, low-level soil ingestion may be a significant source of Hg for infants. Further study is warranted.

This paper describes the recent activities of Electrical and Computer Engineering doctoral students in the design, development, and implementation of lessons for high school mathematics and science classes. The graduate students, called Fellows, worked in secondary classrooms in the Cincinnati Public Schools District as a part of Project STEP at the University of Cincinnati, which is funded by the National Science Foundation GK-12 Program.The Fellows formed partnerships with secondary math and science teachers to generate new lessons, activities, and resources to enhance the STEM skills of high school students. Additionally, the Fellows used their engineering expertise to bring authentic learning experiences into the classroom and introduced concepts in their field of engineering to underserved student populations. This paper discusses observations and reflections by the Fellows regarding aspects of the activities that had the most impact on student learning and interest in engineering, which was measured by selfreported student surveys.