Gold Fields Limited on Monday opposed the certification of a class of mineworkers who have tuberculosis saying there is no evidence to prove that exposure to silica dust underground causes the disease. Gold Fields is one of 32 gold mining companies that are opposing the certification of a landmark class action lawsuit in the high court in Johannesburg. The purpose of the class action‚ brought against the gold mining industry of South Africa‚ is to claim damages on behalf of mineworkers who have silicosis and TB‚ as well as the families of those who have died of the diseases.The mineworkers claim they contracted silicosis and TB on the mines as a result of their prolonged exposure to excessive levels of silica dust underground.The workers say the mining companies are to blame because they consistently and systemically failed for generations to protect mineworkers against excessive levels of the dust and the concomitant risks of silicosis and TB.Willem van der Linde SC‚ for Gold Fields‚ said silicosis was caused by the inhalation of excessive amounts of silica dust while TB was caused by a type of germ.Van der Linde said there were many factors which contributed to the development of TB including age‚ alcohol use‚ HIV and smoking. He said a potential TB claimant could have contracted the disease in a number of ways.He said about 90% of new recruits to the South African gold mines had latent TB. This meant the new recruit had been previously exposed to TB and his immune system had contained the disease.Van der Linde said TB incidence rates on gold mines did not differ from the general South African population.He said in Gold Fields‚ the incidence was 1919 cases per 100000‚ and in a similar age and sex matched group of the general population there were 1900 cases per 100000 people.Van der Linde also said the TB incidence rates on gold mines did not differ significantly from other mines such as platinum.He said the relationship between over-exposure to silica dust and TB was so weak that the correct route was for a mine worker who thinks he has TB without silicosis to pursue the case individually.If the certification is granted‚ it could lead to the largest class action lawsuit in South African history. The application continues. - RDM News Wire, TMG Courts and Law..