13:30 - 15:30, No.2 Conference Room
Workshop E
Epidemiology and Public Health
Chairs: Gunnar Hillerdal and Kohki Inai
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Sophia Kisting, Mohamed Jeebhay
Occupational and Environmental Health Research Unit, School of Public Health and Family Medicine, University of Cape Town, South Africa [not- attended]
ABSTRACT
Chrysotile asbestos was mined in South Africa from the early part of the 20th century. African Chrysotile Asbestos (ACA), the biggest mine and mill started operations in 1937 and closed in 2002. From 1975 to 1992 production of chrysotile in South Africa remained on average at 100,000 tons per year (with ACA contributing more than 90%) and declined to around 20,000 ton in 2000.
The number of workers employed at ACA in the 1960's and 1970's were between 2000 and 2600 at its peak. In the 1990's the numbers declined gradually and were reduced to about 250 by 2000. Annual average asbestos fibre level counts reported by ACA for the period 1977 to 1995 were below 1 fibre per ml with the exception of 1977 (2.5 fibres per ml),1979 (2 fibres per ml) and 1983 (1.21 fibres per ml).
The National Union of Mineworkers (NUM) in South Africa, requested occupational medical practitioners to conduct audits of occupational health surveillance programmes at ACA mine. The audit process of medical records, chest radiographs and lung function tests was completed prior to retrenched workers being repatriated to their homes which included neighboring countries Swaziland and Mozambique.
Between 1995 and 2000 the medical records, chest radiographs and lung function tests of more than 1,200 ACA asbestos mine-workers were assessed for asbestos related diseases. The prevalence of asbestos related diseases (ILO score >= 1/0) for the different evaluations varied between 21 and 36%. The findings are comparable to the high prevalence of pneumoconiosis (mainly silicosis and associated tuberculosis), reported by other investigators, among migrant workers from the Eastern Cape Province of South Africa (22-37%) and neighbouring Botswana (26-31%).
The findings of these audits suggests an enormous disease burden associated with exposure to chrysotile asbestos in spite of the recorded low fibre levels and highlights the importance of worker organization in negotiating exit medical examinations of retrenched workers.
The information so obtained contributed to:
- the revision of the exposure standard for asbestos due to the health risks associated with chrysotile asbestos
- the inclusion of medical surveillance in the new asbestos regulations
- the insertion of post-employment medical surveillance in retrenchment agreements negotiated by trade unions
- heightened the impetus for civil litigation among asbestos exposed workers and community members