[Mortality among workers in the pulp-paper industry. A successive follow up of the cohort].

After five successive years of observation the authors present a verified evaluation of the delayed health effects in the pulp and paper industry workers (with particular regard to mortality from malignant neoplasms). The cohort studied consisted of 10,460 workers employed for at least 12 months between 1967 and 1990 in the plants manufacturing sulfate pulp, paper, board and paper products. Subjects were assigned to three subcohorts according to the work areas: 1. pulp mill workers; 2. paper mill workers (paper and board as well as their products); 3. other workers. The workers were enrolled in the subcohort if they were employed for at least one year in one of these departments. One subject could be included in more than one subcohort. The vital status of the cohort was determined through a variety of sources over an observation period of 28 yrs (1967-95). Mortality data were analysed in terms of cause-specific standardized mortality ratios (SMRs) with expected deaths count based on the national mortality rates in Poland. The results of a twenty three-year cohort observation, published earlier, showed the lowered overall mortality (explained by a "healthy worker effect") and the excess of deaths from malignant neoplasms for some sites (peritoneum, prostate, brain). Due to a small number of deaths recorded, kind of exposure and its duration, were left out of the analysis. The results presented in this paper, obtained after five successive years of the male cohort observation, showed an excess of deaths from cancers of the respiratory tract and peritoneum. In the female cohort an excess of brain cancers was found. Only an excessive mortality from malignant neoplasms of the respiratory system was coherent with the exposure to higher concentrations of wood, paper and board dust. An excess mortality from diseases of the circulatory system was found in both males and females employed in paper production.