Browsing by Author "Ehrlich, Rodney I"

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    Absenteeism and musculoskeletal pain : an interactive network of variables
    (2000) Boshoff, Susan; Bridger Robert S,; Ehrlich, Rodney I
    Bibliography: leaves 79-84.
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    Aspects of medical waste disposal in the Cape Peninsula
    (1996) Tolosana, Sandra; Ehrlich, Rodney I; Brown, Alec C
    Hazardous waste management practices at ten medical institutions in Cape Town were studied and tests undertaken to determine concentrations of specific chemicals and radioactivity in liquid effluent outflows, as well as emissions from incinerators. To investigate the sewage outflow for Chemical Oxygen Demand (COD), N, pH and heavy metals, a continuous sampler was installed at two hospitals and a Medical School. Samples were analysed by atomic absorption spectrometry for As, Hg, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and Fe. Mercury levels ranged from l-70μg l⁻¹, exceeding the Environmental Target Quality of 0.04μg l⁻¹, and the South African General Effluent Standard of 20μg l⁻¹ . All other heavy metals were below General Effluent Standard Limits. In addition, a sludge sample from the Athlone Wastewater Plant was tested for Hg, realising 6mg kg⁻¹ on a dry weight basis, which was within Department of Health (DOH) Guidelines of 10 mg kg⁻¹. Samples of incinerator bottom ash analysed for heavy metal content gave Hg concentrations of 1.1-4.0mg kg⁻¹, and Zn concentrations of 5.1-11.0g kg⁻¹. Incinerator ash was also analysed for radio-activity and substantial levels of ¹²⁵I (332-650 bq kg⁻¹ ), and Ga⁶⁷ (9186bq kg⁻¹) recorded, which exceeded the South African limits of 200bq kg⁻¹. In Cape Town, hospital incinerators are old, burn large amounts of plastics and produce toxic emissions. They are all situated in residential or inner-city areas, and even though there is legislation dealing with emissions and chemical waste, these laws are not being enforced. Based on the above results, an investigation was carried out to assess attitudes to and knowledge of hazardous waste in the ten institutions. One thousand questionnaires were administered to staff, and the data from the 80% response rate statistically analysed. Results suggest that there is an urgent need for an holistic approach to toxic waste management, encompassing enforceable legislation coupled with on-going educational programmes and strong support from top management and all levels of staff.
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    An assessment of the extent of environmental mercury contamination in the vicinity of Thor Chemicals, Cato Ridge, Kwa Zulu-Natal, South Africa and the subsequent health risk communities consuming fish in the area are exposed to
    (1999) Oosthuizen, Jacques De Villiers; Ehrlich, Rodney I
    Environmental mercury pollution of the Valley of a Thousand Hills area of KwaZulu-Natal, South Africa, in particular the river system below the Thor Chemicals mercury recycling plant, has been a topic of heated debate for a number of years. Thor Chemicals was established as a mercury recycling plant in the mid-1980' s and it processed mercury waste imported from various countries. A number of factory workers were subsequently exposed to high levels of mercury vapour causing the death of a worker. Upon investigation it was found that in addition to the occupational exposures of workers, mercury waste had been discharged into the river systems of the Valley of a Thousand Hills. During the 1998 South African Parliamentary session, questions were raised regarding the lack of adequate monitoring and research directed at quantifying human health risks in the region. A number of Government departments were accused of apathy and incompetence in adequately addressing the issue. Fish forms an important part of the diet of the local community living in the Valley of a Thousand Hills. Children, in particular, are frequently observed fishing in the rivers, thus placing these individuals at risk should the fish be contaminated with mercury. The aims of this study were: to determine the extent of environmental mercury pollution of the river system downstream from the Thor Chemicals plant, and to quantify the human health risk associated with fish consumption in the region. Samples of streambed sediment, algae, cattle hair, fish and human hair, were obtained from the study area as well as from a control area upstream from the Thor Chemicals plant. These were analysed to determine the concentration of mercury in each sample. Mercury levels in the study group were compared to mercury levels in the control areas.
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    Hospital admission patterns of childhood respiratory illness in Cape Town and their association with air pollution and meteorological factors
    (1993) Truluck, Timothy Francis; Ehrlich, Rodney I; Von Schirnding, Yasmin Elizabeth Roberta; Fuggle, Richard Francis
    The aims of this study were (a) to examine the profile of hospital admissions for selected respiratory illnesses for two major hospitals in Cape Town, and (b) to analyse the association of such admissions with air pollution indicators and meteorological variables. The first part of the study investigated the admission patterns of coloured and African children under twelve years of age who were diagnosed as suffering from asthma or acute respiratory infections at two major teaching hospitals in Cape Town. Computerized hospital admission records covering the years 1988-1990 from the overnight holding wards of the Red Cross War Memorial Children's Hospital and Tygerberg Hospital were used to determine patterns with respect to diagnosis, gender, race, age and date of admission. During the three year study period, respiratory admissions at both hospitals accounted for 15 078 (47.3%) out of a total of 31 887 admissions. Acute respiratory infections accounted for 63.6% and asthma 37.4 % of these respiratory admissions. Two factors of interest were noted: (1) Considerably more males than females were admitted with both asthma and acute respiratory infections. (2) Asthma admissions to Red Cross Hospital among African children were proportionally much less than those of coloured children when compared to the proportions of admissions for acute respiratory infections. After removal of the seasonal effect, a multiple linear regression model was fitted to the data to determine the individual associations between admissions and ambient environmental variables. Significant associations were found between: (1) acute respiratory infections and oxides of nitrogen, soiling index, and temperature; (2) asthma and oxides of nitrogen (3) total admissions and soiling index, average temperature and minimum temperature (negative). The study concluded that despite generally low levels of air pollution in Cape Town, childhood respiratory admissions to Red Cross War Memorial Children's Hospital and Tygerberg Hospital were statistically significantly associated with some ambient air pollutants as well as temperature. However, given the nature of both the exposure and admissions databases, these results should be treated with caution. More representative site selections for air pollution monitors, as well as searching and controlling for possible confounding factors (i.e. indoor air pollution, parental smoking, overcrowding), would allow a better understanding of the current air pollution problem and the possible effects on the respiratory health of children in metropolitan Cape Town.
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    Predictors of occupational sensitisation to grain dust allergens and changes in lung function among grain mill workers in Cape Town
    (1998) Jeebhay, Mohamed Fareed; Ehrlich, Rodney I
    Occupationally-related airway diseases, including asthma and chronic obstructive lung disease, have emerged as having substantial public health importance. The aim of this study was to identify the predictors of occupational sensitisation to grain dust allergens and changes in lung function among grain mill workers in Cape Town. There were two major objectives of the study. Firstly, to determine which of the following factors determine the distribution of serum ECP (eosinophilic cationic protein): age, gender, grain dust exposure, smoking status, atopy and sensitisation to workplace allergens. Secondly, to investigate the risk factors associated with the following outcomes: i) sensitisation to occupational allergens; ii) diagnosis of occupational asthma; iii) diagnosis of chronic obstructive airways disease; and iv) longitudinal changes in lung function. The risk factors studied included age, gender, smoking habits, occupational exposure, lung function status on baseline survey (1989), and allergic sensitisation assessed at follow up (1996). The methods employed involved a repeat measures cross-sectional design including a cohort followed up at different points over a seven year period. Survey instruments included a questionnaire, spirometry and allergy tests (phadiotop, RAST for wheat, rye, Lepidoglyphus destructor, Tyrophagus putrescentiae and Sitophilus granarius). The results indicated an association of grain dust with pulmonary function and allergic sensitisation to grain dust constituents. After adjusting for known confounders such as age, gender and smoking, significant associations were found between employment duration and both decrements in lung function and sensitisation to wheat grain. A decrement of 278 ml in FEY 1 and 328 ml in FYC was associated with occupational sensitisation to wheat (and rye). Increasing employment duration resulted in annual decrements of 18.3 ml in FEY1 and 23 ml in FYC for every year employed. The odds for developing occupational asthma was only mildly elevated (OR=l.35) with increasing employment duration. Age, however, was found to be protective (OR=0.85). Although we were unable to demonstrate a relationship between across-week changes in lung function, at inception, and rapid longitudinal lung function decline, our findings suggested that longitudinal change was related to the degree of airway obstruction at inception. Sensitisation to grain dust allergens was also found to be an independent predictor for FEY 1 and FYC. The prevalence of sensitisation was the highest for wheat (26.4%), followed by Tyrophagus putrescentiae (22.6%), rye (21.7%), Lepidoglyphus destructor (15.1 %) and Sitophilus granarius (15.1 %). Sensitisation to wheat was highly correlated with sensitisation to rye (r = 0.92) and so were Lepidoglyphus destructor and Tyrophagus putrescentiae (r = 0.85). Although a large proportion of the workforce ( 41.5 % ) were sensitised to occupational allergens, the prevalence of respiratory symptoms was between 15.6% and 23.9%. There were 16.7% of workers with health outcomes which fulfilled our criteria for occupational asthma. Atopic workers in our study had at least a nine-fold increased odds of becoming sensitised to grain dust allergens (OR: 8.9-74.7) and a two-fold increased odds of developing occupational asthma (OR= 1.9-84.9). Furthermore, the study found that smokers had a twofold increased odds of becoming atopic, thereby placing them at greater risk of developing respiratory health problems. The mean ECP in this population was 15.4 ug/1 (SD:2.5). Although 45.3% of the workers were atopic, it was not found to be predictor of elevated ECP levels. We were however able to demonstrate a significant association between ECP and sensitisation to grain allergens. Workers sensitised to wheat (positive RAST) had, on average, 1. 78 ug/1 higher ECP levels. The odds of having an elevated ECP (> 15 ug/1) increased by 2.9 for workers sensitised to wheat grain. In conclusion, the results of the study indicate that selection effects are in operation, demonstrating the health worker effect. The findings also suggest that across week reactions may be less sensitive than the across shift changes in predicting rapid longitudinal decline in lung function. While we were able to characterise the distribution of ECP according to exposure, we were however unable to define the temporal relationship between elevated between exposures, ECP and lung function outcomes due to limitations of the study design.
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    Understanding blood pressure dynamics in the South African population: a latent variables approach to the analysis and comparison of data from multiple surveys
    (2017) Cois, Annibale; Ehrlich, Rodney I; Er, Şebnem
    Background: The 2015 edition of the Global Burden of Diseases Study identified elevated systolic blood pressure─ defined as systolic blood pressure greater than the minimum risk category of 110–115 mm Hg ─ as the largest single contributor to the global burden of disease, responsible for 211.8 million disability adjusted life years lost, up 8.8% in the last decade. Middle‐income countries are currently bearing the highest share of this burden, and, because of the rapid demographic transition towards larger and older populations, the burden is bound to increase rapidly in the coming years, unless age‐specific values of blood pressure are substantially reduced to compensate for the unfavourable demographic changes. Achieving this more favourable blood pressure distribution in populations undergoing rapid changes in their socioeconomic structure requires knowledge of the mechanisms underlying temporal variations of blood pressure and the relationships of such variations with socioeconomic variables.However, evidence on these mechanisms and reliable information on the temporal trends of blood pressure themselves are scant outside high‐income countries. Given the large gain in health that would result in low‐ and middle‐income countries if an optimal blood pressure were to be achieved in large sectors of the population, there is little doubt that temporal trends in the distribution of blood pressure in these populations and their possible determinants are an open and important area for investigation. Objectives: Objectives of the study were: 1. To assess the level of quality and comparability of blood pressure data collected in a series of large‐scale surveys carried out between 1998 and 2015 in South Africa, a middle‐income country undergoing rapid demographic and epidemiological transition; 2. To explore the possibility of applying a series of latent variables techniques to improve the comparability of data from the different sources and to minimise the effect of measurement and representation error on the estimation of cross‐sectional relationships and temporal trends; 3. To estimate changes in the distribution of blood pressure and derived quantities ‐‐‐ such as prevalence of uncontrolled hypertension ‐‐‐ in the South African adult population between 1998 and 2015, taking into account between‐surveys differences and measurement and representation error that could lead to artefactual conclusions; 4. To estimate the extent to which the estimated changes in the blood pressure distribution during the study period could be explained by concurrent changes in the distribution of a series of biological, behavioural and socioeconomic risk factors. Methods: A series of techniques within the general framework of structural equation modelling were applied to jointly analyse the data and estimate the temporal trends and relationships of interest. Results: The average systolic and diastolic blood pressure of South African adult women has progressively decreased since 2003‐2004, reversing the previous rising trend. Among men, the reversal happened only for the systolic blood pressure, while the average diastolic blood pressure continued rising, although at a lower pace than previously.In both genders, this pattern resulted in a reduction of the prevalence of uncontrolled hypertension between 2003‐2004 and 2014‐2015, by 8 percentage points among women and by 4.5 percentage points among men. This consistent and rapid decrease cannot be explained by changes in the age structure of the population, smoking and alcohol consumption habits, distribution of body mass index or urbanization. The diffusion of antihypertensive treatment and, among women, cohort effects and rapidly increasing educational level partly explain the recent trend, but a substantial part of the observed decrease remains unexplained by the factors available in our analyses. Large seasonal variations in both systolic and diastolic blood pressure are present in the South African population, and their magnitude is greater among population strata with low socioeconomic status. From a methodological point of view, there were two further results of this study. First, estimates of blood pressure and related quantities from the eight large‐scale population surveys carried out in South Africa between 1998 and 2015are not directly comparable, because of methodological differences and overall data quality. Second, structural equation modelling (and, within this general framework, multiple group modelling, normal‐censored regression, mixture analysis with skew‐normal distributions and the use of additional parameters and phantom variables) represent a viable and advantageous alternative to current methods of comparative analysis of blood pressure data. Conclusions: Encouraging signs regarding the future development of the burden of diseases related to elevated blood pressure in the South African population emerge from this study. Age‐specific prevalence of uncontrolled hypertension seems to be decreasing, especially among women, and this decrease is accompanied by declining mortality for cardiovascular disease, particularly for stroke, recorded in burden of mortality studies. The reasons of this decrease are largely unexplained and warrant further investigation. However, among the possible drivers analysed in this study, increased accessibility and efficacy of antihypertensive treatment are likely to be playing a role in the observed decrease in blood pressure. The growing obesity epidemic, on the contrary, is likely to be limiting the achievable benefits. Both of these factors can be targeted to maintain and improve the current decline in population values of blood pressure and prevalence of hypertension. The large seasonal variations of blood pressure and their unequal distribution across socioeconomic strata also suggest that interventions to reduce exposure to low temperatures might have public health benefit. From the point of view of the epidemiological investigation, the results of this study suggest that the current methods for the analysis of survey data on blood pressure and the measurement protocols for future data collections should be improved to increase between‐surveys comparabilityand gather more reliable information on temporal changes in BP and gain better understanding of their drivers. Specifically, analytical methods should take explicitly into account known sources of measurement and representation error to reduce their biasing effects, especially when inter‐survey comparisons are involved. Protocols for future studies should routinely include collection of auxiliary information and/or explicit validation of devices and procedures in the specific population.