Environmental exposure to asbestos in asbestos cement workers: a case of additional exposure from indiscriminate use of industrial wastes.

The paper presents data on cancer risk, especially pleural mesothelioma and lung cancer, among the workers of asbestos cement plant who living in the vicinity of the plant, were also environmentally exposed to asbestos. In 1959 an asbestos cement factory was founded in the rural area of south-eastern Poland. Apart from chrysotile asbestos, crocidolite was used till 1985 chiefly for the manufacture of pressure pipes. The blue asbestos made up 15% of the mean annual tonnage of the processed asbestos. It was found that soon after asbestos production had started the process wastes were made available to local community, particularly to the workers of that factory. For over twenty years asbestos wastes of all kinds, both wet (process sludge) and dry (from pipe and sheet grinding) were exploited for the hardening of roads, paths, farmyards and sports fields and as construction material components. For the evaluation of cancer risk due to occupational exposure to asbestos a cohort of 1,526 workers employed in this factory was observed till the end of 1996. The cohort availability was 95.6%. Standardized mortality ratio (SMR) was calculated using the man-years method. The reference population was the general population of Poland. The results of the study demonstrated a statistically significant increase in the risk of a) pleural mesothelioma--over an 80-fold excess among males and over a 200-fold one among females; b) lung cancer in females--over a 6-fold excess; c) colon cancer in males--over a 3-fold excess. In the 1990 ten new cases of pleural mesothelioma in the cohort were reported. As compared to other asbestos-cement cohorts in Poland, observed at the same time, this cohort presented a very high risk of pleural mesothelioma. The analysis of 16 cases of pleural mesothelioma found in the cohort from 1987 to 1997 revealed 4 cases with very short employment period (3.5 months-5 years) including two cases with relatively short latency period (11-12 years). In order to find explanation of these findings, additional investigations were made. The epidemiological study indicated that all these persons were at the same time subject to non-occupational exposure associated with massive utilization of commonly available asbestos-cement wastes as road surface material.