Mass Balance Tracer Techniques for Integrating in situ Soil Ingestion Rates into Human and Ecological Risk Assessments

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dc.contributor.authorDoyle, James
dc.date.accessioned2012-01-12T17:54:22Z
dc.date.available2012-01-12T17:54:22Z
dc.date.created2012
dc.date.issued2012
dc.identifier.urihttp://hdl.handle.net/10393/20557
dc.identifier.urihttp://dx.doi.org/10.20381/ruor-5350
dc.description.abstractQuantitative soil ingestion studies employing a mass balance tracer approach have been used to determine soil ingestion rate for use in human health risk assessments (HHRAs). Past studies have focused on soil ingestion in populations living in urban/suburban environments and the results have been highly variable. Moreover, there is a paucity of reliable quantitative soil ingestion data to support human health risk assessments of other lifestyles that may be predisposed to ingesting soil, such as indigenous populations following traditional lifestyles. Thus, the primary objective of the research was to determine if populations following lifestyles typical of traditional land use practices in rural or wilderness areas ingest more soil than populations living in urban or suburban environments. Further, the research investigated the use of alternative mass balance tracers, specifically isotopes of the 238U and 232Th decay series, to reduce soil ingestion estimate variability. Mass balance tracer methods were developed and validated in a pilot canine study, and methods using isotope tracers were adapted to permit quantification of sediment ingestion in the benthic fish Moxostoma macrolepidotum (Shorthead Redhorse Sucker). A pilot human soil ingestion study of 7 subjects from an Aboriginal community in British Columbia was conducted over a 3-week period. The mean soil ingestion rate calculated using the daily means of the 4 elemental tracers with the lowest food-to-soil ratios (i.e., Al, Ce, La, Si) was observed to be approximately 74 mg d-1 (standard deviation 91 mg d-1), The median soil ingestion rate was 60 mg d-1, and the 90th percentile was 196 mg d-1. These soil ingestion rate estimates are higher than those currently recommended for HHRAs of adults, and higher than those obtained in most previous studies of adults. However, the estimates are much lower than the earlier qualitative assessments for subsistence lifestyles (i.e., 330-400 mg d-1). The study results also demonstrated that isotopes of the 238U and 232Th decay series radionuclide are not reliable mass balance tracers for estimating soil ingestion in humans; however, they may be useful for quantifying soil and sediment ingestion in wildlife.
dc.language.isoen
dc.publisherUniversité d'Ottawa / University of Ottawa
dc.subjectsoil ingestion
dc.subjectmass balance tracer
dc.subjecthuman health risk assessment
dc.subjectecological risk assessment
dc.subjectradionuclides
dc.subjectAboriginal population
dc.titleMass Balance Tracer Techniques for Integrating in situ Soil Ingestion Rates into Human and Ecological Risk Assessments
dc.typeThesis
dc.faculty.departmentBiologie / Biology
dc.contributor.supervisorBlais, Jules
dc.contributor.supervisorWhite, Paul
dc.embargo.termsimmediate
dc.degree.namePhD
dc.degree.leveldoctorate
dc.degree.disciplineSciences / Science
thesis.degree.namePhD
thesis.degree.levelDoctoral
thesis.degree.disciplineSciences / Science
uottawa.departmentBiologie / Biology
CollectionThèses, 2011 - // Theses, 2011 -

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