FALL-KONTROLLSTUDIE ZUR UNTERSUCHUNG DES ZUSAMMENHANGES ZWISCHEN QUARZFEINSTAUB UND LUNGENKARZINOM

Silica dust is supposed to increase the risk of lung cancer for exposed workers. A case control study was performed to investigate the association between lung cancer and silica dust. In the pilot phase of the study 65 cases with lung cancer and 266 controls were recruited. They worked in plants which are member of the Industrial Injuries Insurance Institute for the Stone and Quarry Industries. All workers were exposed to silica dust occupationally. The cancer subjects were taken mainly from the occupational illnesses documentation, and the controls mainly from the Insurance Institute's files on preventive checkups. The exposure was described by peak exposure intensity, time-weighted averages and cumulative exposure. For the analysis, the workers were classified into two groups: low exposed workers with an exposure index below the current threshold limit value (TLV) and high exposed workers (exposure index above TLV). Considering the cumulative exposure, the median for all workers was determined to divide into high or low exposed. Matched pairs were formed to avoid confounding with respect to age (year of birth ± 1) and smoking habits. As a measure for the association between exposure to silica dust and lung cancer the relative risk was used, estimated by the odds ratio (OR). A latency of 10 years was taken in account. For the peak exposure intensity the OR was 0.62 (95% CI: 0.30-1.26), for the time-weighted average exposure it was 0.53 (95% CI: 0.27-1.07). None of both OR was significantly different from 1.0. The OR for the cumulative exposure was 0.54 (95% CI: 0.22-0.92) and statistically significant. An OR = 1.54 was seen when classifying the workers by an exposure level of 0.2 x TLV. In the second part of the study the results of the pilot phase will be evaluated. The primary intension for the pilot phase was to investigate the feasibility of performing a larger study. The results of the pilot study do not support the hypothesis of an association between lung cancer and silica dust.