[Does the average dust concentration modify the critical dust dose leading to silicosis?].

This article is based on the established fact that there is a relationship between the probability of the occurrence of silicosis and the inhaled amount of dust, the latter being represented by the concept of "dust dose" which is a product of dust concentration multiplied by the period of exposure. On investigating the "dust dose" values in 179 former coal miners in the East German town of Zwickau, however, we found that the "dust dose" principle does not apply to low to medium dust concentrations. We can now outline our idea of the origin and development of silicosis as follows: Below an initial threshold value of the "dust dose" it is improbable that silicosis will develop. Beyond that value, i.e. at medium dust concentrations, the time that elapses between the beginning of exposure and the onset of the disease is constant, namely, 20 years. However, the "dust dose" values that trigger the disease vary greatly. For dust concentrations beyond a second threshold value matters are as originally expected: the dust dose being constant, the disease will set in the earlier, the higher the dust concentration. To visualize these effects, a smoothing mathematical evaluation method was combined with a variant of the t test.