Limit Value Assessment for Respirable Coal Mine Dust in Germany

Abstract

Abstract Occupational limit values for airborne noncarcinogenic substances are defined as threshold limit values in Germany. This concept presumes a “hockey stick” relationship between mean shift concentrations and health effects. A population-based threshold limit value (in Germany called the MAK value) is defined as the maximum value on the exposure scale below which a constant baseline risk is observed. This concept was originally developed for toxic substances and is modified to handle the case of fibrogenic dust exposure. The incidence of profusion category 1/1, International Labor Organization (ILO) 1980 of coal workers' pneumoconiosis (CWP) is used as the outcome measure to evaluate the health effects of respirable coal mine dust. The basic concept is modified firstly to analyze the dependence of disease incidence on the mean long-term concentration, allowing for linear and nonlinear effects of time since first exposure, and secondly to handle incomplete clearance in terms of a time-dependent thres...