Environmental exposure to uranium in a population living in close proximity to gold mine tailings in South Africa.

BACKGROUND: Gold mining activities in South Africa resulted in contamination of residential environment with uranium-rich wastes from mine tailings. Health of the people living around the mine tailings could be affected by uranium exposure due to its hazardous chemotoxic and radiological properties. METHODS: We conducted a cross-sectional study to assess i) uranium (U) concentrations in individual hair samples of children and adults living in close proximity to mine tailings in Northeast- Soweto in Johannesburg, South Africa, and ii) the association between U concentrations in hair and various factors, including zone of residence, socio-demographic and housing characteristics. Sampling sites were divided into three zones based on the distance between a dwelling and a cluster of mine tailings (zone 1: <= 500 m, zone 2: 2-3 km away, zone 3: 4-5 km away). U concentrations in hair samples were measured using inductively coupled plasma mass spectrometry. To test the association between U concentrations and selected factors we used robust regression models with log-transformed U concentrations. RESULTS: Among 128 subjects with available U measurements, 63 (49%) were children (ages 7-15 years) of which 38 were girls, the remaining 65 (51%) were adult females. Mean (median) U concentration in hair samples was 143 (92) µg/kg. In the mutually adjusted analyses, only an inverse association between age and U concentration in hair remained statistically significant, with geometric mean in children being 2.1 times higher compared to adults (P < 0.001). There was no evidence of an association between zones and U concentration (P = 0.42). CONCLUSIONS: There was little evidence of association between U concentration in hair and distance from the mine tailings within the 5 km range, but overall concentrations were elevated compared to general population samples in other parts of the world. Children had statistically significantly higher geometric mean of uranium concentration in hair compared to adults. The results are important for improvement of mining waste policies and implementation of health monitoring and protective measures in populations at risk. ARTICLE CATEGORY: Research Article.

Elevated soil and blood lead levels with increasing residential proximity to a mine tailings facility in Soweto, South Africa.

Mining has long been associated with the release of a range of toxic metals including lead, elevated levels of which have been found in land surrounding mine dumps as far afield as Spain, India, Macedonia and Nigeria. Mining has been a key pillar of economic development in South Africa for around a century and a half, and has left a legacy of major environmental contamination, with the poorest experiencing the highest burden of exposure. The current study was undertaken to ascertain the concentrations of lead in soil and in the blood of adults and children residing at increasing distances from a cluster of large tailings facilities (MTFs) in greater Johannesburg, South Africa. Through a cross-sectional survey data on household characteristics were collected through a questionnaire survey, and supplemented with samples of soil from household gardens, together with blood samples from child-adult pairs from all households included in the study. Soil lead concentrations decreased significantly (median = 35.7 mg/kg closest to the mine tailings facility (MTF) and 8.6 mg/kg at the furthest point in the study site) with increasing distance from the MTF. Blood lead levels were highest in both adults (median = 3.0 µg/dL) and children (median = 4.0 µg/dL) who lived closest (≤500 m) to the MTF, and lowest (1.4 µg/dL in adults and 2.5 µg/dL in children) in those who lived furthest away (4-5 km). The study findings point to a need for greater emphasis on the precautionary principle in environmental health and for health impact assessments to inform decisions on planning, especially with regard to the location of human settlements relative to major, polluting development initiatives.

Overcrowding and health in two impoverished suburbs of Johannesburg, South Africa.

BACKGROUND: Rapid urbanization, unmatched by an associated supply of housing, has resulted in overcrowding in the cities of many developing countries, including in Johannesburg, South Africa. Household overcrowding has been associated with a range of ill-health outcomes, including acute respiratory infections and diarrhoeal diseases. The aim of this study was to describe the levels of household crowding, and examine associations with respiratory and gastrointestinal symptoms in selected two low-income neighbourhoods in Johannesburg. METHODS: Questionnaire data from a panel study conducted over an 11-year period between 2006 and 2016 were extracted to conduct the analyses. Structured questionnaires, designed to collect information on housing conditions, socio-economic and health status were administered to adult representatives of households occupying the primary dwelling on pre-selected study sites. RESULTS: Over the 11-year study period, levels of overcrowding remained unchanged. Around 57.6% of dwellings in the study neighbourhoods were determined to be overcrowded in relation to international guidelines. Results from the multiple logistic regression analyses indicated that crowded dwellings were associated with elevated levels of acute respiratory and gastrointestinal symptoms, as well as fever/chills. CONCLUSION: Respondent perceptions varied from objective measures of overcrowding. Crowded dwellings were associated with elevated reports of acute respiratory and gastrointestinal symptoms, as well as fever/chills.

Environmental Silica Dust Exposure and Pulmonary Tuberculosis in Johannesburg, South Africa.

BACKGROUND: Occupational crystalline silica dust exposure is associated with an elevated risk of pulmonary tuberculosis (PTB). However, there is less evidence for an association with environmental silica dust exposure. METHODS: A cross-sectional study of 310 participants was conducted in an exposed community living within 2 km of gold mine tailings and an unexposed population residing more than 10 km from the nearest gold mine tailing. Chest radiographs (n = 178) were read for PTB, past or current, by three readers. RESULTS: Past or current PTB was radiologically identified in 14.4% (95%CI 9.2-21.8) in the exposed and 7.5% (95%CI 2.8-18.7) in the unexposed groups. Multivariate logistic regression models suggested that PTB prevalence was independently associated with exposure to second-hand smoke (OR = 8.13, 95%CI 1.16-57.22), a lower body mass index (OR = 0.88, 95%CI 0.80-0.98), previous diagnosis and treatment of PTB (OR = 8.98, 95%CI 1.98-40.34), and exposure to dust in the workplace from sand, construction, and/or mining industries (OR = 10.2, 95%CI 2.10-50.11). CONCLUSION: We found no association between PTB and environmental exposure to gold mine tailing dust. However, workplace silica dust exposure is a significant risk factor for PTB in South Africa, and PTB patients of working age should be screened for silica exposure.

Low Levels of Awareness of Lead Hazards among Pregnant Women in a High Risk--Johannesburg Neighbourhood.

BACKGROUND: The widespread use of lead and elevated risk of lead exposure in South African children justifies a need for high levels of awareness of the sources, exposure pathways, and measures to reduce this risk in children. This study aimed to determine the levels of knowledge of lead hazards among pregnant women in an area where children had already been established to be at a high risk of lead exposure and poisoning. METHODS: Following informed consent, a structured questionnaire was administered to 119 pregnant women attending antenatal clinic services at Rahima Moosa Mother and Child Hospital, west of central Johannesburg. Questions were asked about social, demographic and residential characteristics, as well as knowledge, perceptions, behaviours and practices in relation to child lead hazards. CONCLUSION: Overall awareness of the dangers of lead in pregnancy was low (11%). Amongst those who had heard of it, only 15% thought that lead could cause detrimental health effects. A consequence of this low level of awareness of lead hazards is a high potential for the participants and their children to unwittingly be exposed to environmental lead from various sources, thereby undermining preventative approaches.