Mortality from malignant neoplasms among workers of an asbestos processing plant in Poland: results of prolonged observation.

OBJECTIVES The study on mortality from cancer among workers of an asbestos plant manufacturing asbestos yarn, cloth, cords, packings, stuffing, brake linings and asbestos-rubber sheets was launched in the 1980s. The present paper discusses the results of further tracing of asbestos workers of the same plant. MATERIALS AND METHODS The study cohort covered 4497 workers employed at the asbestos plant in 1945-1980. The follow-up of the cohort continued until 31 December 1999. Deaths by causes were analyzed using standardized mortality ratio (SMR) calculated by the person-years method. The mortality pattern of the general population of Poland was used as reference. RESULTS The availability of the cohort was 93.1% (2805 men and 1382 women were traced). Mortality from malignant neoplasms in total (281 deaths among men, SMR = 118, 95%CI: 105-133 and 135 deaths among women, SMR = 159, 95%CI: 133-188) as well as that from lung cancer (102 deaths among men, SMR = 126, 95%CI: 103-153 and 18 deaths among women, SMR = 259, 95%CI: 153-409) were significantly higher than in the general population. Unlike earlier stages of analysis, the present study revealed an increased risk of pleural mesothelioma (2 deaths among men, SMR = 510, 95%CI: 62-1842 and 3 deaths among women, SMR = 2033, 95%CI: 419-5941). Mortality analysis among workers with asbestosis and in those without diagnosed asbestosis, did not reveal direct association between the risk of asbestos-induced lung cancer and previously diagnosed asbestosis. CONCLUSIONS The prolonged cohort tracing showed an increased risk of asbestos-related cancers. It concerned mainly workers hired by the plant between 1945-1955, when the working condition were most strenuous.