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An analysis of mortality in a cohort of workers employed in the pulp and paper industry, carried out by the authors of this presentation several years ago, indicated an increase of 22% in the risk of mortality from lung cancer. This risk decreased by only 4% after taking account of smoking. The results obtained then were considered as sufficient to undertake further studies aimed at identifying specific occupational factors responsible for an increased risk for mortality from lung cancer in the population under study. The nested case-control study, in which cases (of lung cancer) and controls were selected from the same cohort observed earlier, was approved as the most suitable method for achieving the aforesaid aim. The study covered 79 cases of deaths from lung cancer confirmed by histological and cytological or radiological examinations, and 237 'healthy' controls matched in the ratio of one to three, taking into account gender, date of birth and date of employment. A group of experts carried out in-depth analysis of exposure to harmful factors in each case of death and in each control. Using a questionnaire, specially developed for this purpose, detailed data on smoking habits among persons under study were collected. Odds ratio was used as a measure of a relative risk for death from lung cancer. A crude relative risk and risk adjusted by eliminating the effect of smoking, applying the model of conditional logistic regression, were calculated for individual exposure factors. Smoking proved to be a significant causal factor responsible for the development of lung cancer in the cohort studied. That was evidenced by relative risk accounting for 12.9 for smokers in relation to non-smokers and an enhanced risk with the increasing number of cigarettes smoked daily, the number of smoking years and an accumulated dose. The study does not confirm a hypothesis that chemical factors specific of the pulp and paper industry exert a significant effect on the risk of death from lung cancer. Odds ratios, crude and adjusted for smoking, were lower than one in all distinguished categories of exposure.

The effect of occupational exposure on the circulatory system disorders was evaluated in 802 workers (675 men and 127 women). Occupational histories were analysed, as well as physical and X-ray examinations, laboratory tests (fasting blood cholesterol, triglycerides and glucose) and ECGs were performed. In doubtful cases echocardiography and stress tests on an ergonometer were carried out. Ischaemic heart disease was diagnosed in 1.37% and symptoms suggesting this disease in 6.48% of workers. The incidence of hypertension, anginal pain and dysrhythmias reported were significantly related to workers' age and duration of employment. Smoking, obesity, hypercholesterolaemia and positive family history were found to be most frequent risk factors. Arterial hypertension was diagnosed in 9.48% of workers. Non-occupational factors seem to be mainly responsible for the circulatory system disorders, however, the effects of occupational factors occurring in the cellulose and paper industry which may accelerate the development of ischaemic heart disease, arterial hypertension and dysrhythmias cannot be excluded.

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.

A cohort study was designed to evaluate the risk of death from malignant neoplasms among pulp and paper workers. This paper presents the evaluation of death risk among workers engaged only in the production of paper, paperboard and paper products. The cohort study covered 1,322 males and 1,914 females employed for, at least, one year in a big pulp and paper mill during the period 1968-90. The study of exposure to harmful factors revealed that concentrations of paper and paperboard dusts in this mill exceeded hygienic standards. The analysis of death risk by causes and gender of those under study was based on standardized mortality rate (SMR) calculated using the method of person-year observation. The general population of Poland was used as reference. The results do not confirm excess mortality from lung, stomach and hematopoietic cancers in paper mill workers reported by other authors. However, an elevated risk of bladder cancer in males (SMR = 491, two deaths) and brain cancer in females (SMR = 353, two deaths) was observed. Both SMR values were not statistically significant. Because of small number of deaths, risk according to exposure and latency was not evaluated.

The pulp mill workers are exposed to substances suspected of carcinogenic effect during production and bleaching of chemical paper-pulp. In order to assess the risk of death from malignant neoplasm, a cohort study covering 1,432 males and 546 females, employed in the sulfate pulp mills of a big cellulose and paper plant, was carried out. Those persons had worked in pulp mills during the years 1967-1990 for, at least, one year. The analysis of risk by causes and gender of those under study was based on standard mortality rate (SMR) calculated using the method of person-year observation. The general population of Poland was used as reference. Significant excess mortality from malignant neoplasm of peritoneum (SMR = 2530) and prostate (SMR = 854) was observed among males, however, the number of observed deaths in these groups was small. Excess female mortality was insignificant. It is rather doubtful whether an increased risk of death from some neoplasms, observed in this group (in this phase of exposure identification) could be linked with occupational exposure.

Mortality among workers in the Polish pulp and paper industry was evaluated in retrospective cohort study of 10460 workers who had been employed continuously for at least one year between 1968 and 1990 in the factory producing sulphate pulp, paper, board and paper products. A standardized mortality ratio (SMR) analysis was used to compare death rates for the exposure group with Polish national rates. For all the subjects death due to all causes and all malignant neoplasms were lower than the number expected. The only significantly increased risks were those of malignant neoplasm of brain among women (4 cases, SMR = 318) and of retroperitoneum and peritoneum among men (2 cases, SMR = 659), exposed to high level of wood dust and irritant sulphur compounds. The authors could not find any etiological explanation of the excessive mortality from brain and peritoneum cancers.

The study covered the work environment of a big plant producing sulfate cellulose, paper and paperboard. Measurements of chemical substance concentrations, performed by a local plant laboratory during the years 1976-1991, were analysed with reference to production departments and particular workplaces. Out of 37 substances under study, 16 were found in the air of workplaces. Their concentrations exceeded periodically hygienic standards. The most frequent excess of TLV applied to such compounds as wood dust (including hard beechwood), non-organic dusts containing 2-50% of crystalline silica and below 2% of silica, welding fumes, furfuryl aldehyde, sulfur dioxide, phenol and hydrogen sulfide. A computer-aided registrer of hygienic data facilitated the follow-up of dynamics of exposure to toxic compounds of workers employed at given workplaces.

The results of various epidemiological research indicate that workers in the pulp and paper industry have an increased risk of developing and dying of malignant cancer with a specific location. The paper discusses recent studies in the area. The findings point to an increased risk of stomach cancer in workers occupationally exposed to pulp produced in the sulfite process. Workers making paper and cardboard are especially at risk for lung cancer. Some researchers signal a higher risk of lymphatic system cancer and stoma cancer. On the basis of existing data on exposure in the pulp and paper industry, it is impossible to determine the exact effects of exposure to a given compound or chemical. Assessment of exposure at particular work areas and analysis of data using the job exposure matrix is necessary. This should provide more information about cancerogenic compounds in the pulp and paper industry.