SPATIAL PREDICTION OF BIOAVAILABILITY AND RISK OF LEAD IN URBAN SOILS TO CHILDREN PDF Download
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Author: Lauren R. Stewart Publisher: ISBN: Category : Bioavailability Languages : en Pages : 61
Book Description
Lead poisoning in young children is a concern in many urban areas, even 30 years after the banning of Pb-based paint and leaded gasoline. Soil and dust have been found to be prominent lead exposure pathways for children because young children often inadvertently ingest contaminated soil and dust through exploratory hand-to-mouth activities. In 2010, 16.6% of 6,550 children tested in Toledo, OH had blood lead levels (BLLs) above the CDC lead poisoning reference level of 5 μg/dL. The objectives of this study were 1) to quantify the concentration and distribution of total and bioavailable lead in soils of Toledo, OH; 2) to relate total lead and bioavailable lead in soils to BLLs in children; and 3) to model the relationship between BLLs in children and spatial variables such as housing age and road density. Outreach education served as a means to educate students about the dangers of soil lead as well as the importance of sampling protocols in science. Students in Toledo area schools were instructed on proper USEPA soil sampling guidelines and were asked to collect soil samples from their yards. A subsample of 81 soils was analyzed for total lead and bioavailable lead. Site-specific total lead and bioavailability data were used in the USEPA Integrated Exposure Uptake and Biokinetic (IEUBK) model to predict BLLs for children under 7 years of age. A spatial index model was derived using fuzzy sets, analytical hierarchy process (AHP) and weighted linear combination (WLC) to relate 6 spatial predictor variables to the predicted BLLs. It was found that 8.6% of sampled sites had total lead concentrations above the USEPA action level of 400 mg/kg, but 28.4% of soils samples yielded predicted elevated BLLs, suggesting the action level is set too high. The majority of soil samples had lead bioavailability values above 60%, thus increasing the risk of lead poisoning. The spatial variables influencing risk of lead poisoning from most important to least important were age of housing, road density, percent impervious surfaces, home value, household income and soil type. The data predict that lead poisoning disproportionately affects children from low socioeconomic status families.
Author: Lauren R. Stewart Publisher: ISBN: Category : Bioavailability Languages : en Pages : 61
Book Description
Lead poisoning in young children is a concern in many urban areas, even 30 years after the banning of Pb-based paint and leaded gasoline. Soil and dust have been found to be prominent lead exposure pathways for children because young children often inadvertently ingest contaminated soil and dust through exploratory hand-to-mouth activities. In 2010, 16.6% of 6,550 children tested in Toledo, OH had blood lead levels (BLLs) above the CDC lead poisoning reference level of 5 μg/dL. The objectives of this study were 1) to quantify the concentration and distribution of total and bioavailable lead in soils of Toledo, OH; 2) to relate total lead and bioavailable lead in soils to BLLs in children; and 3) to model the relationship between BLLs in children and spatial variables such as housing age and road density. Outreach education served as a means to educate students about the dangers of soil lead as well as the importance of sampling protocols in science. Students in Toledo area schools were instructed on proper USEPA soil sampling guidelines and were asked to collect soil samples from their yards. A subsample of 81 soils was analyzed for total lead and bioavailable lead. Site-specific total lead and bioavailability data were used in the USEPA Integrated Exposure Uptake and Biokinetic (IEUBK) model to predict BLLs for children under 7 years of age. A spatial index model was derived using fuzzy sets, analytical hierarchy process (AHP) and weighted linear combination (WLC) to relate 6 spatial predictor variables to the predicted BLLs. It was found that 8.6% of sampled sites had total lead concentrations above the USEPA action level of 400 mg/kg, but 28.4% of soils samples yielded predicted elevated BLLs, suggesting the action level is set too high. The majority of soil samples had lead bioavailability values above 60%, thus increasing the risk of lead poisoning. The spatial variables influencing risk of lead poisoning from most important to least important were age of housing, road density, percent impervious surfaces, home value, household income and soil type. The data predict that lead poisoning disproportionately affects children from low socioeconomic status families.
Author: Bobby G. Wixson Publisher: CRC Press ISBN: 1351361023 Category : Science Languages : en Pages : 141
Book Description
Until the publication of this new book there had been a lack of well-founded guidelines for evaluating concentrations of lead in soil and its relationship to human health. Thus, much confusion has existed among regulatory agencies, industries, public health officials, and the medical community about the evaluation and remedying of lead-contaminated soils. Lead in Soil: Recommended Guidelines represents the combined efforts of a multi-disciplinary international task force from the Society for Environmental Geochemistry and Health (SEGH) whose members are experts in the fields of lead pollution and toxicology. It provides an international consensus concerning environmental lead and blood lead-especially in children. The task force evaluated the evidence and made recommendations for guidelines to appraise lead concentration. It also studied the influence of soil and other sources of lead on blood lead concentrations. A model was prepared that allows the user to select appropriate target levels of blood lead while allowing for a variety of environmental situations or regulatory criteria.
Author: Kirsten Schwarz Publisher: ISBN: Category : Lead Languages : en Pages : 138
Book Description
Lead contamination of the urban environment is not a new phenomenon. A great deal of research has focused on the health effects of lead-based paint. Less attention, however, has been given to the potential problem of soil contaminated with lead from the past use of lead-containing products such as lead-based paint and leaded gasoline. Identifying areas of high contamination is necessary in order to prioritize soil remediation and public health efforts. This requires a comprehensive understanding of a highly heterogeneous and dynamic system. This research addresses whether land use or land cover is a better predictor of lead concentrations in soil. Specifically, this research addresses whether landscape features, including trees, lawns, buildings, and roads, can be used to predict lead concentrations in soil. Through a method of rapid assessment of soil lead concentrations, I gathered spatially explicit data from urban residential yards to generate several models that predict the spatial distribution of lead in soil. Using the results of these models, potential inequities associated with the modeled spatial distribution of lead in soil and socio-demographic features were explored. The results of this study suggest that the distribution of lead in urban residential soils is more closely correlated with features of urban land cover compared to metrics of land use. Specifically, the spatial distribution of lead in urban residential soils is strongly influenced by three factors: housing age, distance to the major road networks, and distance to built structures. Through the comparison of various spatial models, this research demonstrates that a greater amount of variation in the data is explained by machine learning techniques compared to traditional modeling techniques. In addition, important correlations between the modeled distribution of lead in soil and socio-demographic features such as race and poverty have been identified. Specifically, a greater amount of soil contamination is predicted to be present in high poverty areas. This research contributes to the growing field of urban ecology by advancing our knowledge of how spatial heterogeneity affects the distribution of a critical pollutant in urban systems. This work also tests the suitability of using land cover as a predictive ecological variable.
Author: Society for Environmental Geochemistry and Health Publisher: CRC Press ISBN: Category : Science Languages : en Pages : 152
Book Description
Until the publication of this new book there had been a lack of well-founded guidelines for evaluating concentrations of lead in soil and its relationship to human health. Thus, much confusion has existed among regulatory agencies, industries, public health officials, and the medical community about the evaluation and remedying of lead-contaminated soils. Lead in Soil: Recommended Guidelines represents the combined efforts of a multi-disciplinary international task force from the Society for Environmental Geochemistry and Health (SEGH) whose members are experts in the fields of lead pollution and toxicology. It provides an international consensus concerning environmental lead and blood lead-especially in children. The task force evaluated the evidence and made recommendations for guidelines to appraise lead concentration. It also studied the influence of soil and other sources of lead on blood lead concentrations. A model was prepared that allows the user to select appropriate target levels of blood lead while allowing for a variety of environmental situations or regulatory criteria.
Author: Jennifer A. Bower Publisher: ISBN: Category : Languages : en Pages : 236
Book Description
Lead (Pb), a trace metal notorious for its impacts on human health, has achieved worldwide environmental dispersal resulting from centuries of use by human society. The toxicity of Pb is governed largely by its mineral form, which is in turn controlled by pH, localized reactivity and soil processes that differ according to soil type, location and Pb source. Given the context of these localized dependencies, or site specificity, efforts to predict Pb toxicity and refine sustainable remediation techniques are most useful when Pb behavior is constrained and predicted within environments with homogeneous conditions, such as a single soil. I evaluated and predicted the behavior of Pb, a typical anthropogenic contaminant, within a single soil using bioaccessibility testing and predictive geospatial modeling to assess potential impacts and refine sustainable remediation methods. To test the hypothesis that Pb speciation is influenced by competitive sorption processes in soils, I investigated changes in mobility and speciation of Pb upon addition of amendments at multiple scales using flow-through column experiments, soil characterization and synchrotron-based x-ray techniques. Kriging and cokriging maps provided a successful estimation of background and total Pb, the latter incorporating housing age as a secondary variable to increase model accuracy, though efforts to automate detection of background Pb were complicated by approximation of building extents, and overall heterogeneity of soil Pb concentration gives high error. Acute Pb heterogeneity is observed at the scale of a single site among near-structure samples. At the city-scale, determination of bioaccessibility revealed that bioaccessible and total Pb are well-correlated, to the extent that bioaccessibility may be predicted for the soil underlying Burlington, VT; this information, combined with predictive blood lead level modeling and the CDC’s recent establishment of 5 μg kg-1 as a threshold for blood lead toxicity, enabled the establishment of a site-specific revised soil Pb limit of 360 mg kg-1, lower than the EPA’s general soil Pb threshold of 400 mg kg-1. Characterization of leached and unleached soil using scanning electron microscope energy dispersive spectroscopy (SEM-EDS) and microfocused x-ray techniques provided a first look at Pb paint species using synchrotron technologies. Pb was present within paint chips as hydrocerussite, but appeared to weather to anglesite over time. Pb also seemed to act as cation bridge, attracting clay minerals electrostatically and becoming incorporated into heterogeneous soil aggregates. Accessory paint elements are identified in soil and within paint chips and may further complicate these systems. Column experiments, at acidic pH, yielded little evidence of Pb mobility change in response to modification of competitive sorbents. Kinetics of Pb release were driven by pH, with Pb solubilizing at pH of ~4.9 as column soil acidifies. This work provides evidence for changes in Pb speciation over time in urban soils impacted by Pb paint, and presents a framework for predictive risk analysis at a local site using experimental and modeling tools. Multiscale observations and analytical results can be used in future efforts to model and refine sustainable remediation solutions within a site-specific context.
Author: Sandra LeighAnne Walser Publisher: ISBN: Category : Soil pollution Languages : en Pages : 202
Book Description
Urban soils around the world have been found to possess elevated concentrations of toxic trace metals such as As, Cd, Cu, Pb, Mn, Hg, Zn known to pose human health risks. Tightening environmental legislation and further elucidation of the detrimental health impacts from trace metals has necessitated more efficient means of contamination assessment, as well as greater public awareness. Within this thesis, I sought to develop an array of tools to holistically approach the socially relevant environmental challenges derived from heavy metal soil contamination. These tools consist in providing means to simplify Pb, Zn and Cu analysis in-situ, develop strategies to increase participatory sampling and outreach, and characterize Pb contamination in NE US cities through GIS.To improve pXRF accuracy and precision for metals in soils, it is necessary to produce measurement corrections as a function of affecting variables (moisture, organic matter content and grain size heterogeneity). Urban forest soil samples were subjected to pXRF measurement of Pb, Cu and Zn under artificially increasing soil moisture, organic matter, and particle size heterogeneity for correction development. A correction equation was successfully obtained for moisture effects but was not feasible for organic matter and particle size heterogeneity trials, highlighting the difficulty to accurately determine contamination in-situ for all metals. Application of the soil moisture correction equation on 120 surface soils proved successful at minimizing the effects of moisture on measured Pb, Cu, and Zn concentrations. However, similar performance to a simple dilution-based correction equation suggested that empirical correction may not be necessary. To generate a comprehensive dataset on lead distribution within the Burlington (VT) area while simultaneously empowering at-risk communities on lead contamination, I carried out a community science project based on a novel educational/outreach partnership project model. This program was designed to recruit high school students as community scientists to sample soil and water from their homes for analysis at UVM. The community science project successfully incorporated a diverse group of young community scientists into a project important to their community's health. This also enabled mass sampling in areas of concern, and we have identified 19 properties (out of 228) with soil Pb concentrations above the EPA safe level. Remote implementation, necessitated by Covid-19, resulted in easily transferable project content organized into a project website for easy dissemination and reproduction. To properly identify soil contaminated areas, as well as understanding key distribution factors, spatial prediction of trace metals is an important tool. Utilizing surface soil samples collected in a gridded fashion from three New England cities, I performed areal kriging to predict the distribution of soil Pb as well as identify effective cofactors. Despite the highly variable concentrations typical of soil Pb, areal kriging provided a means to minimize the effects of small-scale Pb distribution heterogeneity. Incorporation of structure age summarized to the census block level provided slight improvements in model accuracy and minimized underestimation of Pb concentrations. The results of these studies have demonstrated that our ability to address trace metal contamination may be improved upon through further development of identification and education methodologies. Soil contamination is a strong environmental justice challenge that deserves greater attention and my thesis developed promising tools to provide affordable and accurate soil analysis, empower affected communities and incorporate social variables into contamination assessment.
Author: Lauren R. Stewart
Author: Lauren R. Stewart
Author: 
Author: Bobby G. Wixson
Author: Kirsten Schwarz
Author: Society for Environmental Geochemistry and Health
Author: 
Author: Jennifer A. Bower
Author: Brian E. Davies
Author: Deborah E. Morrison-Ibrahim
Author: Sandra LeighAnne Walser