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Silicosis in non-mining industry on the Witwatersrand
1Department of National Health and Population Development, National Centre for Occupational Health, Johannesburg.
Summary
Silicosis outside South African mines is a serious occupational hazard, with high rates of severe lung disease and early-onset cases linked to significant silica exposure in industries like foundries and ceramics. This highlights the urgent need for better industrial controls and clinical awareness.
Area of Science:
- Occupational Medicine
- Pulmonary Medicine
- Public Health
Background:
- Silicosis outside mining settings in South Africa has been largely overlooked, receiving minimal legislative and public attention.
- A significant number of silicosis cases, including severe progressive massive fibrosis, were observed at the National Centre for Occupational Health clinic between 1972 and 1986.
Purpose of the Study:
- To investigate the prevalence and characteristics of non-mining silicosis in South Africa.
- To identify high-risk industries and patient demographics associated with severe silica exposure.
- To assess clinical and radiological findings and their implications for compensation.
Main Methods:
- Retrospective review of 217 silicosis cases seen at the National Centre for Occupational Health clinic (1972-1986).
- Analysis of patient demographics, occupational history, radiological findings, symptoms, and lung function.
- Comparison of clinical abnormalities between silicosis and progressive massive fibrosis cases.
Main Results:
- Progressive massive fibrosis (PMF) was observed in 21% of cases, with 21% of Black patients diagnosed by age 40 and 18% having exposures under 10 years, indicating intense silica exposure.
- Foundries, ceramics, refractories, and ore/stone crushing industries accounted for 83% of cases.
- High prevalences of symptoms, signs, and lung function abnormalities were noted, with PMF cases showing significantly more clinical issues. Radiologically, mixed opacities were common, but lymphadenopathy and pleural thickening were rare.
Conclusions:
- Intense silica exposures occur in various South African industries outside of mining, leading to significant occupational lung disease.
- Discrepancies in lung function abnormality criteria based on different prediction equations have implications for workers' compensation.
- Recommendations include stricter controls in silica-exposed industries and thorough occupational history-taking by clinicians to improve diagnosis and compensation.