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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Relationship between urinary levels of organophosphate metabolites and pesticide exposures among rural school boys of the Western Cape

Molomo, Ntsubise Regina 16 February 2021 (has links)
Background: Biomonitoring of pesticides is an objective measure of short-term pesticide exposure as it measures possible exposure in the human body. Current evidence on the relationship between demographic, socio-economic and pesticide exposure risk factors and urinary levels of organophosphate (OP) pesticide metabolites among children is generally incomplete and conflicting in some cases. There is therefore a need for further research. Objectives: This study investigated the relationship between socio-economic, demographic and reported pesticide exposure related activities and characteristics in relation to urinary levels of three dialkyl phosphate (DAP) metabolites (diethyl phosphate (DEP), dimethyl phosphate (DMP) and dimethyl triphosphate (DMTP)) among boys living in the rural areas of the Western Cape, South Africa. Methods: This was an analysis of data collected during a cross- sectional study of 183 boys from three agricultural intense areas in the Western Cape of South Africa between April 2007 and March 2008. Measurements included a questionnaire on demographic, socio-economic and pesticide exposure risk factors and analysis of spot urine samples for DAP metabolites. Results: Most of the boys (70%) lived on farms with a median age of 12 years (range: 5.0 - 19.5 years). The median concentrations of DAP, DEP, DMP and DMTP were 68.3 ng/ml (IQR= 27.9; 129.5), 5.5 ng/ml, 32.6 ng/ml and 16.7 ng/ml, respectively. The sum of the three DAP levels wasinversely associated with age. Children older than 14 years had less DAP levels (β = -68.1; 95% CI: -136.8,0.6) than children 9 years and younger. DAP levels also varied significantly with residential area, with the levels highest in Grabouw (apple farming), followed by Hex River Valley (grape farming) (β= -52.1; 95% CI: -97.9, -6.3) then Piketberg (wheat farming) (β= -54.2; 95% CI:-98.8, -9.7). Other weaker and non-significant associations with increased DAP levels were found with increased household income, member of household work with pesticides, living on a farm, drinking water from an open water source and eating crops from the vineyard and or garden. Conclusion: The study found younger age and living in and around an apple and grape farms, to be associated with increased urinary DAP concentrations among the school children provide evidence that younger age and residential area can be associated with increased urinary DAP concentrations among boys. Additionally, there are other household and behavioural characteristics that are associated with elevated urinary DAP levels. Further studies with larger sample sizes and longitudinal designs to improve the statistical power and the associations found are recommended. The study provided more insight to incomplete and inconclusive evidence of previous studies.
2

Gottshall Early Reading Intervention: A phonics based approach to enhance the achievement of low performing, rural, first grade boys.

Gottshall, Dorothy Lee 12 1900 (has links)
Learning to read is critical for quality of life and success in our society. Children who cannot read well face unsuccessful educational careers and limited job choices. Recently, policy makers and educators have made progress toward increasing the reading achievement of America's children. Still up to 60% of boys who live in poverty cannot read or read two years below grade level. In this experimental study, I designed and examined the effects of the Gottshall Early Reading Intervention (GERI) to determine if direct instruction with a small group, phonics based approach would increase the literacy achievement of low performing, rural, first grade boys. Participants were selected according to Texas Primary Reading Inventory (TPRI) scores, matched them across race, ethnicity, and socio-economic status, and randomly assigned them to experimental/control group. Three times per week for 15 weeks, boys in the experimental group attended 30-minute pullout sessions taught by trained professionals in addition to classroom reading instruction. Control group members received classroom reading instruction only. Findings reveal no significant differences in reading gains across all variables. However, descriptive data indicate higher percentages of gains for the experimental group on four out of five reading components with rate of gain higher on fifth. Statistics also show that Hispanics are more likely to benefit.

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