Original article

Scand J Work Environ Health 2002;28(6):411-417    pdf


Cancer incidence among workers in the asbestos-cement producing industry in Norway

by Ulvestad B, Kjærheim K, Martinsen JI, Damberg G, Wannag A, Mowé G, Andersen A

Objectives The incidence of cancer among employees of a Norwegian asbestos-cement factory was studied in relation to duration of exposure and time since first exposure. The factory was active in 1942-1968. Most of the asbestos in use was chrysotile, but for technical reasons 8% amphiboles were added.

Methods For the identification of cancer cases, a cohort of 541 male workers was linked to the Cancer Register of Norway. The analysis was based on the comparison between the observed and expected number of cancer cases. Standardized incidence ratios (SIR) and 95% confidence intervals (95% CI) were estimated. Period of first employment, duration of employment, and time since first employment were used as indicators of exposure. Poisson regression analysis was used for the internal comparisons.

Results The standardized incidence ratio was 52.5 (95% CI 31.1-83.0) for pleural mesothelioma, on the basis of 18 cases. The highest standardized incidence ratio was found for workers first employed in the earliest production period (SIR 99.0, 95% CI 51.3-173). No peritoneal mesothelioma was found. The standardized incidence ratio for lung cancer was 3.1 (95% CI 2.1-4.3), but no dose-response effect was observed. The ratio of mesothelioma to lung cancer cases was 1:2.

Conclusions This study showed a high incidence of mesothelioma and a high ratio of mesothelioma to lung cancer among asbestos-cement workers. The high incidence of mesothelioma was probably due to the fact that a relatively high proportion of amphiboles was used in the production process.

The following article refers to this text: 2004;30(1):64-70