Silicosis has plagued gold miners in Southern Africa for more than a century but the mines have been slow to tackle the problem…[S]ilicosis is a silent, invisible disease. It creeps slowly into the lungs, breaking down their ability to function over time. The deformities can only be detected by X-ray. According to a former director of the South African National Institute for Occupational Health, Professor Tony Davies, silicosis is caused by microscopic silica dust particles. Silica is found in the ore that contains gold…Silicosis "is irreversible and no treatment has been known to be effective"…It can take up to 15 years for a miner to become ill.