RESUMO
International and national programmes to eliminate silicosis have been initiated with the inference that exposure to quartz is associated with silicosis. Experimental evidence is presented by numerous investigators to indicate that pathogenicity of the polymorphs of silica is related to their crystalline structure; origin; and various surface properties. As a result; in the risk assessment process; silica cannot be dealt with as a single hazard entity. Accordingly; if elimination of silicosis is to be achieved in South Africa; standard values for quartz; the main crystalline form of silica polymorphs; should be adopted which will be protective enough against the species with the greatest adverse activity existing in the South African working environment