Block 5: Silicosis and Coal Workers’ Pneumoconiosis - Burden Of Silicosis And CWP In South Africa

BURDEN OF SILICOSIS AND CWP IN SOUTH AFRICA:

Historically, at the onset of gold mining this was known to be significant.

• Prevalence amongst Free State active miners (1987): 0.87 - 1.38% (Cowie).
• Prevalence amongst 227 Botswana retired gold miners (1997): 31.8% (Steen)
  • (29.0% gave a history of TB treatment).
• Prevalence amongst 228 E. Cape retired gold miners (1998): 36.4% (Trapido)
  • (51.1% gave a history of TB treatment).

The table below illustrates the silicosis prevalence and exposure response relationships in older black mineworkers on a South African goldmine (SIMHEALTH 606)

BURDEN OF CWP IN SOUTH AFRICA:

The table below is taken from publised data in: Respiratory Health of South African Coalminers (2002): Rajen Naidoo.

A total of 896 workers participated in the study, of whom 212 were ex-miners and 684 currently employed.

Summary of findings:

• Measured dust levels within South African legal standards.
• Disease prevalences considerably lower than that those seen among South African gold miners.
• Significant associations between dust exposure and health outcomes.
• Loss of FEV1 in a 40 year old, 1.7m tall current miner is 1.33ml per mg/m³ for each year exposed.
• Magnitude of the loss of lung function is of about the same size as would be expected from five years of aging - without exposure.

TB case rates in different sectors of the SA mining industry:

• TB incidence 3 - 5% in gold mining.
• Gold miners have a 30 - 50% working lifetime risk of requiring treatment for TB.
• Rates in coal and platinum mines are higher than the general population.