Successful Epidemiological Cooperation Between China and Germany - Regulatory Risk Assessment for Silica Exposure

摘要

The purpose of epidemiologic investigation in occupational health is to establish a causal association between exposure to work- related environmental factors and the occurrence of occupational diseases or injuries. In the past century this discipline has made significant contributions to expanded knowledge about health risks in the work environment and effective control of many work— related conditions. Occupational epidemiological study is an important tool in quantitative regulatory risk assessment in providing guidelines for effective work safety policies and programs. For this purpose, well- planned, large epidemiological studies with a reasonable number of highly exposed workers with detailed individual exposure information are essentially necessary. However, due to limited availability of epidemiolpgical data (i. e. limited number of highly exposed workers, data protection laws, retention periods of population data), the realization of well — planed, large occupational epidemiological studies in most of the industrialized countries is becoming more and more difficult. In contrary, China has still good epidemiological data for the realization of large epidemiological studies. Therefore, cooperation between China and Germany in epidemiological research is going in popularity. In this presentation, an example is given of a successful epidemiological cooperation between China and Germany in the assessment of the causal association between respirable silica exposure and lung cancer. In a nested case —control study among a cohort of male workers in 29 Chinese mines (tungsten, tin, copper and iron mines) and potteris, exposure to respirable crystalline silica as well as other relevant occupational and non- occupational exposures were evaluated. The relationship between occupational exposure to respirable crystalline silica and lung cancer risk was analyzed using common statistical methods adjusted for other relevant factors such as inorganic arsenic, polycyclic aromatic hydrocarbons (PAHs) , radon, and smoking habits. In a first analysis adjusted for smoking only, a significant trend of increased risk of lung cancer with exposure to respirable crystalline silica was found for tin, copper and iron miners, and pottery workers. However, after other relevant occupational exposures (arsenic, PAHs and radon) were adjusted, no association can be observed between exposure to respirable crystalline silica and lung cancer mortality. The results suggest that the observed excess risk of lung cancer among silica exposed workers is probably due to exposure to other occupational hazards such as arsenic and PAHs rather than due to exposure to respirable silica. This should motivate science and politics to reconsider the health risk and classification of silica exposure because of new epidemiological evidence.