Browsing by Author "White, Neil"

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    The long-term respiratory health effects of the herbicide, paraquat, among Western Cape workers
    (1996) Dalvie, Mohamed Aqiel; White, Neil; Myers, Jonny
    Objective: Paraquat is a commonly used herbicide worldwide and is a well-documented cause of pulmonary fibrosis in studies of laboratory animals and in humans following high dose exposure (usually accidental or as parasuicide). The respiratory effects of long-term, low dose paraquat exposure have not been fully evaluated. We set out to evaluate the possible effects of paraquat spraying among deciduous fruit farm workers in the Western Cape, South Africa. Methods: A cross-sectional study of 126 workers was performed. Administered questionnaires generated information on exposure, respiratory symptoms and confounding variables. Spirometry and gas transfer were measured and chest radiographs performed. Oxygen desaturation on exercise testing was by oximetry during a modified stage one exercise test. Results: No association was found between long-term paraquat exposure and reported symptoms, spirometry (FVC, FEVl, FEVl/FVC) and gas transfer (TLco and Kco) or chest radiography. Multivariate analysis showed a significant relationship between measures of long-term paraquat exposure and arterial oxygen desaturation during exercise (p < 0.05). Conclusion: Previous studies have also not shown a significant relationship between measures of paraquat exposure and standard tests of lung function. Arterial oxygen desaturation during exercise represents a more sensitive test. Our findings indicate that working with paraquat under usual field conditions for a long period is associated with abnormal exercise physiology in a dose dependant fashion.
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    Meteorologically estimated exposure but not distance predicts asthma symptoms in schoolchildren in the environs of a petrochemical refinery: a cross-sectional study
    (BioMed Central Ltd, 2009) White, Neil; teWaterNaude, Jim; van der Walt, Anita; Ravenscroft, Grant; Roberts, Wesley; Ehrlich, Rodney
    BACKGROUND: Community concern about asthma prompted an epidemiological study of children living near a petrochemical refinery in Cape Town, South Africa. Because of resource constraints and the complexity of refinery emissions, neither direct environmental measurements nor modelling of airborne pollutants was possible. Instead a meteorologically derived exposure metric was calculated with the refinery as the putative point source. The study aimed to determine whether (1) asthma symptom prevalences were elevated compared to comparable areas in Cape Town and (2) whether there was an association between asthma symptom prevalences and the derived exposure metric. METHODS: A cross-sectional study was carried out of all consenting school children aged 11 to 14 years attending schools in a defined area, utilizing the International Study of Asthma and Allergy in Childhood (ISAAC) written and video questionnaires. Information was collected on potential confounders, e.g. parental history of atopic disease, active and passive smoking by the participant, birth order, number of children in the home and distance from a major road. The exposure metric combined residential distance of each child from the refinery with a wind vector in the form of wind speed, wind direction and proportion of the year blown. RESULTS: A total of 2,361 children from 17 schools met the criteria for inclusion. In multivariate analysis, meteorologically estimated exposure (MEE), but not simple distance from the refinery, was positively associated with having to take an inhaler to school [odds ratio per interquartile range (OR) 1.22, 95% confidence interval (CI) 1.06-1.40], and with a number of video elicited asthma symptoms, including recent waking with wheezing (OR 1.33, 95% CI 1.06-1.66) and frequent wheezing at rest (OR 1.27, 95% CI 1.05 - 1.54). Symptom prevalences were higher than in other areas of the city, with frequent waking with wheezing being in great excess (OR 8.92, 95% CI 4.79-16.63). CONCLUSION: The results support the hypothesis of an increased prevalence of asthma symptoms among children in the area as a result of refinery emissions and provide a substantive basis for community concern. The methodology also provides a low cost means of testing hypotheses about point source pollutant effects on surrounding populations of children.
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    Respiratory symptoms and chronic obstructive pulmonary disease : prevalence and risk factors in a predominantly low-income urban area of Cape Town, South Africa
    (2006) Jithoo, Anamika; Bateman, Eric D; White, Neil; Burney, Peter
    The continuing worldwide increase in the incidence of chronic obstructive pulmonary disease (COPD) has led to international initiatives to improve surveillance and identify preventable risk factors for this and related chronic lung diseases. The studies reported here aimed to examine the prevalence and risk factors for respiratory symptoms and COPD; to introduce and test surveillance methodologies; and to inform treatment and control measures for this disease. The Lung Health Survey 2002 sampled 3512 individuals aged ≥ 15 years from an urban population of 36,334 in the predominantly low-income area of Ravensmead and Uitsig, Cape Town, South Africa. Information on respiratory symptoms, risk factors and healthcare utilisation was collected using a respiratory questionnaire which included questions that had been validated elsewhere. In 2005, a subsample of 960 persons aged ≥ 40 years participated in the Burden of Obstructive Lung Disease (BOLD) study comprised of a questionnaire and pre and postbronchodilator spirometry, in order to assess the prevalence of COPD. A high prevalence of respiratory symptoms of 38.3% was reported. Tobacco smoking showed a consistent positive association with chronic bronchitis, wheeze, dyspnoea and cough. Strong associations with cannabis smoking, pulmonary tuberculosis, occupational exposures and low socioeconomic status were found. The association of cannabis smoking with respiratory symptoms suggest that it may be a risk factor for COPD. The BOLD study revealed an exceptionally high prevalence of COPD in both men and women aged 40 years and older (29% and 20%, respectively) reflecting the very high prevalence of smoking in both sexes in the test area. The majority of those affected had moderate to severe disease, that is, symptoms with spirometric impairment (GOLD Stage II and higher). Even non-smoking women had a comparatively high prevalence of CO PO (12.6%), attributable to other risk factors such as tuberculosis and occupational exposures. Previous pulmonary tuberculosis was shown to be a strong predictor of COPD, which warrants further study. Review of healthcare utilisation confirmed significant under-recognition and under-treatment within local health services. These results confirm the need to prioritise preventative and treatment strategies for obstructive lung disease in South Africa.