Browsing by Subject "Occupational Health"

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    Determinants of occupational allergic respiratory disease and asthma in spice mill workers
    (2010) Van der Walt, Anita; Jeebhay, Mohamed Fareed
    The aim of this study was to determine the prevalence of occupational allergy and asthma associated with airborne spice and to determine the host and environmental risk factors associated with allergic respiratory disease among spice mill workers. A cross-sectional epidemiological study of 150 currently employed workers in a spice mill was conducted. Environmental exposure assessment entailed the collection of 62 full-shift airborne personal samples on randomly selected individuals employed in various departments of the spice mill using the NIOSH occupational exposure sampling strategy manual. The samples were analysed for inhalable particulate mass, specific spice dust allergens (garlic) and endotoxin using ELISA inhibition (antibodies from sensitised subjects) and chromogenic LAL assays.
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    Illuminating a neglected population: epidemiological and clinical features of silicosis and tuberculosis among former gold miners from Lesotho
    (2023) Maboso, Botembetume; Ehrlich, Rodney
    Background Silicosis, tuberculosis (TB), and human immunodeficiency virus (HIV) infection, singularly and together, are all global health concerns. Southern Africa, with its high HIV and TB prevalence and incidence, is the most affected region by these conditions. The large South African mining industry, especially gold mining, is known as the amplifier of this triple epidemic of silicosis, TB and HIV. Furthermore, ex-mineworkers from South African mines have a higher mortality rate than active mineworkers and the general population. They carry a heavy burden of silicosis, TB, HIV and other pulmonary diseases, which strongly contribute to this higher mortality. Lesotho is a tiny country with about 2.3 million inhabitants of which about 95,000 are exgold miners from South African industry. Over 40% of Basotho ex-gold miners attending invited examinations have silicosis, more than 50% of them have been treated at least once for TB, and 60% have lung lesions on chest x-ray (CXR) suggestive of TB. In this country, many silicosis cases have been treated repeatedly for TB, and some have been documented as MDR-TB on the basis of plain CXR alone, even when bacteriologic tests gave negative results. Objectives To address the problem of TB, in general and the high morbidity and mortality among exgold miners, in particular, we designed three separate studies with the following objectives: (1) To illustrate the challenges in diagnosing active TB in this setting, specifically in distinguishing pulmonary TB (past and current) from silicosis; (2) to assess the performance of the screening CXR and symptoms of cough and fever in the diagnosis of active TB disease using Xpert MTB/RIF sputum test as the reference standard; and (3) to identify predictors of silicosis, tuberculosis, and associated hypoxaemia to better understand the predictive effects of comorbidity, the determinants of severity, and health care implications. Methods Three separate but inter-related sub-studies (two cross-sectional and one case series) were conducted from a single database of men who worked in South Africa gold mines for at least 12 months and visited Mafeteng Occupational Health Service Centre from January 2017 to November 2018. We analysed the medical history information, CXR, and Xpert MTB/RIF sputum test results for all attendees. For sub-study 1, four cases were discussed. For sub-study 2, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV), of CXR and symptoms, in the diagnosis of TB, were computed. For sub-study 3, multiple logistic regression modelling of various variables against silicosis, active TB and hypoxaemia as dependent variables in separate models was carried out. Findings The first study of four cases demonstrated that ex-gold miners from the South African mines present with complex lung disease, with poor agreement between radiological findings and clinical presentations, poor agreement between radiographs suggestive of TB and Xpert MTB/RIF sputum results, and overlap of clinical and radiological presentations of silicosis and TB. The second study composed of 2572 ex-gold miners and revealed CXR sensitivity, specificity, positive predictive value (PPV) and negative predictive values (NPVs) of 0.93 (95% CI: 0.87-0.99), 0.41 (95% CI:0.39-0.99), 0.05 (95% CI:0.04-0.06), and 0.99 (95% CI:0.98-1), respectively. Symptoms, on their own, could only identify about half of the active TB cases (i.e., a sensitivity of 0.45, 95% CI:0.34-0.56). Computing of either an abnormal CXR or symptoms of cough or fever slightly increased the sensitivity (0.96, 95% CI: 0.92-1) while it substantially decreased specificity (0.33, 95% CI: 0.31-0.35). The third study composed of 2678 ex-gold miners and found high odds of silicosis among ex-gold miners who had longer lengths of service (OR: 2.21, 95% CI: 1.68-2.74), higher level of dust exposure (OR: 1.57, 95% CI: 1.28-1.86), a history of past TB (OR: 2.66, 95% CI: 2.21-3.11), shortness of breath (OR: 1.47, 95% CI: 1.14-1.80), and decreased lung function. HIV-infected ex-gold miners had significantly lower odds of silicosis than their colleagues who were HIV-negative (OR: 0.62, 95% CI: 0.50-0.73). There were high odds of active TB among ex-gold miners who had silicosis (OR: 2.30, 95% CI: 1.56-3.08) and those who were HIV-positive (OR: 1.57, 95% CI: 1.04-2.10). Furthermore, there were high odds of hypoxaemia among those with a history of past-TB (OR: 1.48, 95% CI: 1.17- 1.79) and those with silicosis (OR: 2.41, 95% CI: 1.92-2.90), while the odds of hypoxaemia were significantly lower among HIV-infected ex-gold miners. Conclusions These studies demonstrate that mining work, and prominently exposure to silica dust, continue to cause morbidity in ex-gold miners, years after exposure has ceased, imposing a health cost on the poor ex-miner and the health system of their countries. They highlight the permanency of the situation caused by silica exposure; reveal the gap in the compensation system, either through the government (i.e., ODMWA, CCOD) or nongovernment channels (i.e., Tshiamiso Trust, Q(h)ubeka Trust), by demonstrating that silicainduced and aggravated conditions impose persistent/lifelong health costs to ex-gold miners that exceed current compensation. Consequently, they highlight the needs for the compensation system and law enforcement agencies to consider providing for and extending support for mining-induced medical needs (i.e., long-term management of chronic lung diseases, ambulatory or long-term oxygen therapy) to ex-gold miners, including those outside of South Africa borders. There is a need for training of healthcare providers in the labour sending communities in the diagnosis and management of mining-induced medical problems (silicosis, TB, silicotuberculosis, COPD, etc.). Clinicians and policy makers need to consider adjusting the new TB management policy to the predictive values of symptoms and the CXR in diagnosing active TB in this population. In addition to action to provide access to diagnosis, care and compensation, we need further research into the combined lung disease burden, and special health service and social security needs of this long neglected population.
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    Obstructive Lung Disease among tobacco farmers in Malawi
    (2020) Moyo, Yotam Mgonjetsi; Adams, Shahieda; Jeebhay, Mohamed
    Introduction and aim Tobacco farmers are exposed to toxic workplace hazards such as nicotine and pesticides in addition to known agriculture related hazards like dust, and ergonomic factors. Nicotine and pesticide exposure have been linked to the development of chronic respiratory diseases. This study was aimed at determining the prevalence of obstructive lung disease among tobacco farmers in Malawi and its association to nicotine and pesticide exposure. Methods A cross-sectional study was conducted comprising of 279 current workers across four flue-cured tobacco farms in rural Zomba district of Malawi during a tobacco growing season. The assessment involved the use of a modified ECRHS questionnaire and questions on pesticides and nicotine exposure. Voluntary HIV testing was offered to individuals who did not know their HIV status. Health outcomes assessment involved the use of both symptom and spirometry-based diagnoses of obstructive lung disease. The data was analyzed using STATA 14 computer software and included bivariate and multivariate logistic regression analysis. Results The study had predominantly male participants (68%) with a total mean age of 37.7 years, majority (73%) of whom had attained primary education or higher, with 20% being current smokers. Participants had a mean employment duration of 7.3 years and 62% indicated that they worked mainly with tobacco while 57% were involved in pesticides application. HIV prevalence was 16%. The prevalence of current asthma (ECRHS) was 20% whilst for asthma score≥2 it was 23%. The prevalence of chronic bronchitis, work related ocular nasal symptoms and work- related chest symptoms were 17%, 20% and 29%, respectively. Airflow Limitation measured as FEV1 < LLN was 14% (NHANES and sample reference). The prevalence of moderate to severe obstruction was 4%. The prevalence of green tobacco sickness (a proxy for nicotine exposure) in the past year was 26% with an average of 3 episodes within that period. Most workers were exposed to pesticides with 72% reporting exposure during spraying of pesticides while 83% reported re-entry into fields soon after spraying. The main pesticide in use was organophosphates (18%). The majority (51%) of participants reported use of organophosphate pesticides at home. In multivariate analysis nicotine exposure and associated tasks were significantly associated with all respiratory outcomes (OR range 1.78-7.26). Pesticide application was positively associated with all the symptom-based respiratory outcomes (OR 1.96- 2.62) except for work related chest symptoms. Exposure during spraying was significantly associated with asthma score≥2 (OR 2.09, CI 1.01-4.31), current asthma (OR 2.57, CI 1.22-5.40), and work related ocular nasal symptoms (OR 2.43, CI 1.17- 5.04) while pesticide drift was associated with current asthma (OR 2.62, CI 1.00-6.86) and work related ocular nasal symptoms (OR 3.00, CI 1.18-7.62). In spirometry-based outcomes duration of pesticide exposure was significantly associated with FEV1/FVC< LLN (OR 5.11, CI 1.57-16.66), FEV1/FVC< 70% (OR 4.58, CI 1.17-17.98) and moderate to severe obstruction (OR 13.25, CI 1.69-103.93). Nicotine exposure was not significantly associated with spirometry-based outcomes. Conclusion In conclusion, this study showed that tobacco farmers in Malawi have a higher prevalence of asthma and chronic bronchitis compared to the general population or tobacco farmers in other settings. Additionally, exposure to nicotine and pesticides is strongly associated with the prevalence of obstructive lung diseases among these farmers.