LUNG-CANCER MORTALITY AMONG EUROPEAN ROCK SLAG WOOL WORKERS - EXPOSURE-RESPONSE ANALYSIS/

Objectives: The purpose was to analyze the relationship between semi-q uantitative indices of exposure to manmade vitreous fibers and lung ca ncer mortality among European rock/slag wool (RSW) workers. Methods: T he study population comprised 9,603 male workers employed in RSW produ ction in seven factories in Denmark, Norway, Sweden, and Germany, foll owed up for mortality as of 1990-91. Estimates of past exposure to res pirable fibers were used to calculate cumulative exposure with a 15-ye ar lag and maximum annual exposure based on employment history up to 1 977. Rate ratios were estimated via multivariate Poisson regression, a djusting for country, age, calendar year, time since first employment, and employment status. Results: A total of 159 lung cancer deaths wer e included in the analysis of which 97 among workers with more than on e year of employment. We found nonstatistically significant trends in lung cancer risk according to cumulative exposure. Relative risks (RR) in the four quartiles were 1.0 (reference), 1.3 (95 percent confidenc e interval [CI] = 0.8-2.4), 1.2 (CI = 0.7-2.1), and 1.5 (CI = 0.7-3.0, P test for trend = 0.4). When workers with less than one year of empl oyment were excluded, there was no increased risk; the RRs in the four quartiles were 1.0, 0.9 (CI = 0.4-2.0), 0.8 (CI = 0.3-1.9), and 1.0 ( CI = 0.4-2.7). No trend was present according to maximum annual exposu re. The results were not consistent among countries. Conclusions: We f ound a positive association between exposure to respirable fibers and lung cancer mortality. However, the lack of statistical significance, the dependence of the results on inclusion of short-term workers, the lack of consistency among countries, and the possible correlation betw een exposure to respirable fibers and to other agents reduce the weigh t of such evidence.