- Title
- Levels of selected heavy metals in garden soil in Walmer Township and Wells Estate, Port Elizabeth
- Creator
- Ogunfowora, Ebunoluwa Juliana
- Subject
- Environmental health -- South Africa -- Port Elizabeth
- Subject
- Environmental chemistry Pollution -- Physiological effect
- Date Issued
- 2019
- Date
- 2019
- Type
- Thesis
- Type
- Masters
- Type
- MTech
- Identifier
- http://hdl.handle.net/10948/42990
- Identifier
- vital:36722
- Description
- Heavy metals are naturally occurring elements that have high densities. Heavy metals have been found to have applications in various sectors such as the industrial, domestic, agricultural and medical sectors, thus resulting in environmental pollution which may pose a hazard to human health. Heavy metals such as arsenic, cadmium, manganese, lead and mercury rank among the priority metals that are of public health significance, and they are commonly found in garden soils. In this study, residential garden soils were sampled in dwelling sites in Wells Estate and Walmer Township, and analysed for mercury, cadmium, arsenic, manganese and lead. A cross sectional design was employed in this study. The research was carried out in two phases; the first phase involved soil sample collection, preparation and laboratory work for the determination of heavy metal concentrations. The second phase focused on the social aspect of the study population which included the use of a pre-approved questionnaire and face-to-face interviews for the collection of human health related information at each dwelling site where soil samples were collected. The research protocol was approved by the Health Sciences Faculty Postgraduate Studies Committees (FPGSC) of Nelson Mandela University. Garden soil from residential yards of Wells Estate (near an industrial site, ̴ 2 km) and Walmer Township (further away from the industrial site (̴ 22 km), but relatively close to Port Elizabeth airport, ̴ 2 km) were sampled over a total of six sampling sessions resulting in 100 soil samples. Fifty soil samples were collected in Wells Estate and fifty soil samples in Walmer Township during the month of May 2017. Surface soil samples were collected from the top 2 cm of the soil using a sterile stainless-steel spoon. In addition to the collection of soil samples, a visual inspection of the house was undertaken to collect information about the house characteristics, geographic location (GPS coordinates) and characteristics of the surrounding area. Soil samples were prepared for analysis by grinding and drying followed by heavy metal determination using an X-ray fluorescence (XRF) analyser (Bruker s1 TITAN Analyser, USA). A face-to-face questionnaire was administered to a suitable respondent at each dwelling site to obtain information related to health symptoms such as coughing, fever, chest pains, earache, sore throat, headaches, rapid breathing, sneezing, running/blocked nose, teary watery eyes, cancer, hypertension, heart diseases and mental illness. The mean concentrations of heavy metals were in the order manganese>lead>arsenic for both study sites. In Walmer Township soil samples, the mean concentrations of heavy metals determined were 154.8 mg/kg, 84.4 mg/kg and 5.4 mg/kg for manganese, lead, and arsenic, respectively. Mean concentrations of heavy metals as determined in Wells Estate were 322.2 mg/kg, 11.5 mg/kg, and 3.4 mg/kg for manganese, lead and arsenic, respectively. Manganese concentration across the study sites are below the guideline levels for USA (630 mg/kg) and South African (1500 mg/kg). About 2.0% of the sample exceeded the South African lead guideline level of 230 mg/kg, while 4.1% exceeded European lead level of 400 mg/kg in Walmer Township. Lead levels in Wells Estate were all below the South African, European and United States guideline levels. By contrast, 2.0% of the sample exceeded the South African arsenic guideline level of 48 mg/kg, 2.0% exceeded European arsenic guideline level of 50 mg/kg and 2.0% exceeded USA arsenic guideline level of 11 mg/kg in Walmer Township, while 2.0% exceeded USA arsenic guideline level of 11 mg/kg in Wells Estate. Mann Whitney U test showed statistically significant differences between lead levels (U=1527, p < 0.001) and manganese levels (U=2632, p < 0.001) across study sites. Soil manganese level showed significant association with age of house (crude OR: 0.34, 95% CI: 0.14-0.83, p =0.016). Using data obtained from the questionnaire, a multivariate logistic regression analysis was performed to examine the relationship between soil heavy metals and the various health outcomes. In Walmer Township, manganese showed association with dry cough (OR: 11.35, 95% CI: 1.08-119.20) and sneezing (OR: 11.30, 95% CI: 1.09-116.67). Manganese was also associated with wet cough (OR: 0.19 95% CI: 0.05-0.70), dry cough (OR: 0.22, 95% CI: 0.06-0.83) and watery eye (OR: 4.55, 95% CI: 1.01-20.58) in Wells Estate. Dry cough (OR: 0.31, 95% CI: 0.16-0.64), sneezing (OR: 2.18, 95% CI: 1.06-4.48) and watery eye adjusted (OR: 3.71, 95% CI: 1.63-8.48) were also associated with manganese in the total sample. Confounding factors such as overcrowding (adjusted OR = 2.23; 95% CI: 1.11-4.48) and air pollution (adjusted OR = 2.76; 95% CI:1.39-5.50), predicted wet cough and sneezing, respectively, across the total sample. Heavy metal concentration in most of the study dwellings of Walmer Township and Wells Estate were below the safe limit recommended by United States, European and South Africa soil reference levels. Nevertheless, we found a strong association between manganese and respiratory symptoms such as dry cough and sneezing in Walmer Township, as well as a strong association between manganese and watery eyes in Wells Estate. There was no evidence of associations between heavy metal exposure and gastrointestinal symptoms, chronic diseases and mental illness.
- Format
- xix, 174 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Health Sciences
- Language
- English
- Rights
- Nelson Mandela University
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