Combined delivery of an antiangiogenic protein (angiostatin) and an immunomodulatory gene (interleukin-12) in the treatment of murine cancer

We investigated the feasibility of a novel therapeutic approach to treat neoplastic diseases in mice. This novel strategy consists in delivering a protein (angiostatin) with strong antiangiogenic properties, followed by administration of the interleukin 12 gene that is strongly immunomodulatory and has also some antiangiogenic effects. When angiostatin-mediated antiangiogenic therapy was used in combination with intratumor delivery of the IL-12 gene (a strategy much safer than IL-12 protein administration), this produced a synergistic therapeutic effect.

[Occupational exposure to chemicals in the manufacture of rubber tires]

The work environment of the rubber industry company, producing various types of tires, was assessed and the workers of the plant were included in a cohort study of mortality. Concentrations of twenty chemical substances at 137 workposts were measured by employees of the plant laboratory and the sanitary and epidemiological station in 1981-1996. The mean values and concentration ranges were determined by departments and workposts. The excess of threshold limit values was analyzed. The workposts with exposure to agents possibly carcinogenic to humans were identified. The analysis performed will render it possible to calculate doses of cumulative exposure to given compounds among workers covered by the epidemiological study.

[Health risk among workers employed in rubber footwear plant]

The aim of the study was to assess the health risk of workers performing specific jobs in the process of the rubber footwear production by defining the cause and length of temporary work disability, as well as mortality causes and level. The analysis was carried out in the groups of workers performing the following jobs: mixing, mill operation, pressing and vulcanizing (A); semi-product preparation and calendaring (B); finishing and sorting (C); production of polyvinyl chloride footwear (D); and auxiliary works (E). The sickness absence study covered all workers (208 men and 315 women) employed in a large rubber footwear company and performing all above-listed jobs in 1995. Standardized sick days ratio was used to analyze the risk of temporary work disability. Mortality rate was estimated on the basis of the results of the cohort study performed in the same company among workers who had worked at least three months during the years 1945-1985. The follow-up continued until 31 December 1997. The present study included sub-cohorts composed of 5628 men and 7197 women, performing jobs listed above. The results of both studies indicated the enhanced risk of cardiovascular diseases among workers employed in the basic phases of the production process. The increased risk of the diseases of the digestive system was observed in men and women employed in: finishing, sorting and packing of the products (group C); in men involved in mixing, pressing and vulcanizing (group A); and in women engaged in auxiliary works (group E). In addition, the enhanced risk of sickness absence due to the diseases of the respiratory, digestive, or genitourinary systems was related to the enhanced risk of death from malignant neoplasms in a given site. The analysis showed that the temporary work disability may be regarded as a parameter useful in early assessment of health effects of the work environmental hazards.

Combined delivery of an antiangiogenic protein (angiostatin) and an immunomodulatory gene (interleukin-12) in the treatment of murine cancer

We investigated the feasibility of a novel therapeutic approach to treat neoplastic diseases in mice. This novel strategy consists in delivering a protein (angiostatin) with strong antiangiogenic properties, followed by administration of the interleukin 12 gene that is strongly immunomodulatory and has also some antiangiogenic effects. When angiostatin-mediated antiangiogenic therapy was used in combination with intratumor delivery of the IL-12 gene (a strategy much safer than IL-12 protein administration), this produced a synergistic therapeutic effect.

Cancer mortality in rubber tire workers in Poland

The study aimed at assessing cancer risk in a cohort of workers employed in the rubber tire production. The cohort consisted of 17,747 workers (11,660 men and 6087 women) employed in a rubber tire plant for at least three months during the years 1950-1995. The cohort follow-up was completed on December 31, 1995. 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 the reference. The study indicated significantly lower total mortality in the cohort (men: SMR = 72; women: SMR = 62) as compared to the general population, which is an example of a well known "healthy worker effect". The number of deaths from malignant neoplasms was also lower than expected (men: SMR = 67; women: SMR = 64). Only in a very small sub-cohort of men involved in dosing and mixing of raw material for the production of rubber, an excess of total mortality (SMR = 104) and from all cancers (SMR = 115) was found. Mortality from all neoplasms was enhanced (SMR = 108) in the sub-cohort of women employed in the technical service work area. When analyzing individual cancer sites in men of the whole cohort or sub-cohorts, the observed number of deaths from cancers of the lip, tongue, pharynx, stomach, gallbladder, pancreas, peritoneum, articular cartilage, connective tissue, skin, testis, prostate, bladder, kidney, brain, as well as from Hodgkin's disease, multiple myeloma and leukemia was larger than the expected number. Among women the excess mortality was due to cancers of the large myeloma and leukemia. The SMR calculated for these sites were statistically insignificant. The cohort under study was "young" and thus relatively small numbers of deaths were recorded. The excess mortality, based quite frequently on single cases of selected cancer sites, cannot be regarded as a basis for final conclusions. Nevertheless, the fact that these observations are in agreement with the findings of other authors who carried out studies in the rubber industry of other countries justifies the need to follow-up this cohort in the future.

[Mortality in the tire plant workers]

This paper describes a cohort study of the mortality among workers employed in one of Polish tyre plants. The scope of the study was limited to the analysis of mortality from main disease categories. Mortality from particular cancer sites will be discussed in a separate publication. The cohort comprised 17,747 workers (11,660 men and 6,087 women) employed during the years 1950-95 for at least three months in the tyre plant. As of 31 December 1995, the follow-up of the cohort was completed. A detailed analysis of mortality by causes was carried out using standardised mortality ratio (SMR) calculated by the person-years method. The general population of Poland was used as the reference. The results indicated general mortality significantly lower in the cohort (men: SMR = 72; women: SMR = 62), than in the reference population. The number of observed deaths from main disease categories was also lower than those expected. The analysis by specific causes revealed significant excess of deaths, due to hypertensive disease among men (36 deaths, SMR = 142; 95% CI: 99-197). SMRs were also calculated in sub-cohorts identified by activities performed (preparatory works: production of tyres and inner tubes; maintenance; storage; others). General mortality in sub-cohorts was similar to that in the total cohort. After analysis by causes of death, some non-significant excess mortality could be observed. It was very small or it applied only to single cases of death. Excess mortality from hypertensive disease in male maintenance workers (21 deaths, SMR = 262; 95% CI: 162-400) was the only exception. The absence of adverse health effects pronounced by significant excess mortality should be attributed to a relatively short period of exposure among the majority of the followed-up workers (over 58% of workers in the cohort employed in the plant for a period shorter than five years) and to their young age. Almost 56% of workers in the cohort were born in the 1950s or later which means that at the end of the follow-up they were not older than 45 years. In order to complete the final mortality assessment the follow-up should continue.

Direct transfer of IL-12 gene into growing Renca tumors

We investigated the feasibility of transferring naked plasmid DNA containing a therapeutic gene (IL-12) into mice harboring growing Renca tumors. We found that naked DNA transferred into growing Renca and B16(F10) tumors gives higher expression level of reporter gene than complexes of DNA with DDAB/DOPE or DC-Chol/DOPE. Transfer of naked DNA carrying the IL-12 gene into growing Renca tumors causes a distinct therapeutic effect that depends on the time span between inoculation of mice with cancer cells and the beginning of the therapy. Therapy started on day 3 resulted in total cure (100%) of mice.

Mortality of workers at two asbestos-cement plants in Poland

To assess mortality rate among workers occupationally exposed to asbestos, cohort studies were carried out in two asbestos cement plants operating since the 1960s. Asbestos cement sheets for roofing and siding have been manufactured there, using mostly chrisotile, and since 1985 also crocidolite for pressure pipes. In all, the cohort comprised 3,220 workers, including 2,616 male workers. Subject to consideration were the workers employed for at least three months in the period between the onset of the production and 1980. The vital status of the subjects was traced up to 31 December 1991. The availability of the cohort was 96.8%. Workers' mortality was analysed using standardized mortality ratio (SMR). The reference group was the general population of Poland. In the male cohort, 385 cases of death were recorded. Statistically significant excess of mortality from large intestine cancer (7 cases, SMR = 264) and pleural mesothelioma (5 cases, SMR = 2846) was found. In male workers who died from pleural mesothelioma the work history ranged from 12 to 26 years. An excess mortality from pleural mesothelioma was also noted among the female workers (2 cases, SMR = 11,275). No malignant neoplasms of other locations produced significant excess mortality either in the male or female workers.

Direct transfer of IL-12 gene into growing Renca tumors

We investigated the feasibility of transferring naked plasmid DNA containing a therapeutic gene (IL-12) into mice harboring growing Renca tumors. We found that naked DNA transferred into growing Renca and B16(F10) tumors gives higher expression level of reporter gene than complexes of DNA with DDAB/DOPE or DC-Chol/DOPE. Transfer of naked DNA carrying the IL-12 gene into growing Renca tumors causes a distinct therapeutic effect that depends on the time span between inoculation of mice with cancer cells and the beginning of the therapy. Therapy started on day 3 resulted in total cure (100%) of mice.

Mortality in the cotton industry workers: results of a cohort study

The cohort consisted of persons found on the payroll of one of the Lódź cotton plants in 1964-1993 who were employed in the plant for at least 10 years. Death risk by causes was analysed using standardised mortality ratios (SMRs) calculated by the person-years method. The general population of Poland was used as the reference. In all, 7892 people were observed. As of December 31, 1995, the follow-up was completed for 7545 people (2852 men and 4693 women), i.e. the availability of the cohort was 95.6%. A total of 2069 deaths were recorded; the information on the cause of death was available for 97% of the subjects. In the male cohort, the level of the general mortality was the same as in the general population (SMR = 99). However, there was a significant increase in the number of deaths from diseases of the digestive system (SMR = 142) and larynx cancer (SMR = 188). The analysis of the results by production departments revealed in the weaving department significantly higher mortality from atherosclerosis (SMR = 141), peritoneal carcinoma (SMR = 1057) and melanoma (SMR = 677); and in the spinning department the increased risk of the hypertensive disease (SMR = 239), atherosclerosis (SMR = 175), and Hodgkin's disease (SMR = 768). Mortality in the female cohort was lower than that in the general population (SMR = 88). None of the disease groups or tumour sites caused statistically significant excess deaths either in the total cohort or in subcohorts selected according to departments. Special attention was paid to the chemical processing departments where chemicals used could contribute to the increased risk of death from cancer. Our analysis did not reveal any significant increase either in the total cohort of the workers employed in those departments or in the cohorts analyzed by duration of employment. Our results confirm the lower risk of lung cancer in the analysed group as compared with that in the general population. The numerous, but statistically insignificant increases in the incidence of malignant tumours at some specific sites detected in the subcohorts, distinguished according to the duration of employment or department, confirm the reported findings on the incidence of oral cavity, nose, throat, and larynx tumours among people exposed to harmful agents in the cotton industry.

Cancer risk in workers of the pulp and paper industry in Poland. A continued follow-up

A mortality cohort study was undertaken among Polish pulp and paper workers. This paper concentrates on neoplasms mortality among men and women employed continuously for at least one year in the factory producing sulphate pulp, paper board and paper products. A retrospective observation carried out till 31 December 1995 covered 10,460 workers employed during the years 1968-1990. The cohort accessibility was 99%. Cancer risk was evaluated on the basis of standardized mortality ratio (SMR) calculated according to the person-years method. The general population of Poland was the reference population. The results of a 23-year cohort observation, published earlier, showed a lowered overall mortality from all causes and from all malignant neoplasms, and a significant excess of death from peritoneum and prostate cancer among pulp mill male subcohort. The conclusion was drawn that a 'young' cohort and relatively short follow-up period might have affected the results. The results presented in this paper, obtained after further five years of observation showed in the male cohort an excess of deaths from cancer of respiratory tract and peritoneum (lung SMR = 122, nasal cavities SMR = 587, peritoneum SMR = 562). An approximate correction for smoking habits resulted in only 4 decreased risk estimates for lung cancer, indicating a small positive confounding effect of smoking in this material. In female cohort an excess of brain cancer was found (SMR = 355). Only the excess mortality from cancers of nose, lung and peritoneum was coherent with the exposure to higher concentrations of wood dust, pulp, paper and board dust. It may support a hypothesis that these factors as well as dust pollutants, not yet identified in this study, may be considered as one of the risk factors contributing to the incidence of neoplasms of these sites.

[Occupational lead poisoning in Poland]

During the years 1970-1996, 8,414 cases (8,176 among men and 238 among women) of lead poisoning, recognised as occupational disease, were registered with the peak in 1972-1976 (500-800 cases per year). An in-depth analysis of 7,893 (men) reported in the period between 1970 and 1992 revealed that repeated poisonings in the same person were observed quite frequently. Among 4,556 men poisoned by lead during the period under study, in every third men the disease was diagnosed at least twice. Almost half of men with occupational lead poisoning received the occupational disease certification after the exposure lasting less than five years. The majority of persons poisoned by lead (64.3%) were employed in plants located in the Katowice voivodship. More than half of men with occupational lead poisoning (54.1%) was exposed to maximum concentrations of lead, exceeding MAC values by two hundred times. A diminishing number of occupational lead poisoning observed during the 1990s does not reflect a real-level of occupational exposure. The majority of cases reported apply to large plants or industrial complexes where the prevention of poisonings is rather well organised. But dispersed small production and service enterprises, where acute cases of poisoning may lead to irreversible organic changes create a great problem. One of the prerequisites for effective prevention of occupational lead poisoning is to identify and to make a complete inventory of workplaces where lead occurs, as well as to identify workposts hazardous to worker's health, and to monitor lead concentrations in the air.

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.

[Mortality of men with occupational lead poisoning in Poland]

The cohort method was used in the study. A retrospective observation covered 4.556 males with occupational disease, manifested by lead poisoning, diagnosed during the years 1970-1992. Mortality risk analysis by causes was based on standardized mortality ratios (SMRs) calculated by person-years method. Their statistical significance was assessed by means of the test based on Poisson distribution. The general adult male population was adopted as the reference population. The state of the cohort as of 31 December 1992 was considered. The cohort accessibility was 95.6%. The study revealed increased total mortality among lead poisoned males (670 deaths; SMR = 108; 95% CI: 100-116). Significant excess mortality was observed in diseases of the digestive system (37 deaths; SMR = 148; 95% CI: 104-204), including chronic hepatitis and cirrhosis (19 deaths; SMR = 173; 95% CI: 104-270); malignant neoplasms of respiratory and intrathoracic organs (82 deaths; SMR = 135; 95% CI: 107-168), including malignant neoplasm of larynx (13 deaths; SMR = 213; 95% CI: 113-364). In the subcohort with high exposure, death risk was significantly enhanced in comparison to the general population (153 deaths; SMR = 129; 95% CI: 109-151). In addition, significant excess of malignant neoplasms was observed (43 deaths; SMR = 151; 95% CI: 109-203) including liver (4 deaths; SMR = 419; 95% CI: 114-1073) and respiratory and intrathoracic organs tumors (21 deaths; SMR = 175; 95% CI: 108-268).

[Cancer risk in asbestos-cement industry workers in Poland]

A cohort study was carried out in order to evaluate the cancer risk in the asbestos-cement industry workers. The cohort consisted of workers employed in four asbestos-cement plants. One of those plants was established in 1924, the other three in the 1960s and 1970s. Currently only two of these plants continue their production. The plants used mainly chrysotile asbestos as well as crocidolite and amosite. Amphibolite asbestos was used before the mid-nineteen eighties in production of pressure pipes utilising about 15% of the total quantity of asbestos used. The measurements of the asbestos fibre concentration at work-sites have been taken occasionally since the mid 1980s, thus, the determination of a cumulative dose for individual persons in the cohort and the evaluation of the dose-effect relationship were not feasible. It could only be supposed that the concentrations at the preparatory work-site during first years of the plants' operation accounted for several tens fibres/cm3 in the production that employed the dry method. The cohort consisted of workers employed in the plant for at least three months between beginning of the plant during the post-war period, and 1980, that is during the period when amphibolite asbestos was in use. The retrospective observation was completed on 31 December 1991. The analysis of the death risk by causes was based on a standardized mortality ratios (SMRs) calculated using the person-years method. Statistical significance of SMRs was assessed by means of Poisson distribution one-sided test. The general population of Poland was used as the reference population to estimate the death risk. The cohort comprised 4,712 persons (3,563 males and 1,149 females). Of this number 4,500 persons (3,405 males and 1,095 females) were followed. The cohort availability were 95.5%. Male mortality, both total (473 deaths; SMR = 83) and due to malignant neoplasms (108 deaths; SMR = 86) was lower than in the general population. An excess of deaths from neoplasm of the pleura was by about 23 times higher (5 deaths; SMR = 2,288) and from neoplasm of the large intestine by two times higher (7 deaths; SMR = 214). Among females (41 deaths; SMR = 50) death risk was lower than in the reference population. At a low level of total mortality from neoplasms (13 deaths; SMR = 52) a statistically significant excess of deaths from neoplasm of the pleura (2 deaths; SMR = 2,112) was observed. In the plants investigated the analysis revealed a considerably diversified mortality from asbestos-related neoplasms. The incidence of pleura mesothelioma should be attributed to the use of considerable quantities of crocidolite asbestos and high concentrations of fibres in the air in plants II and IV, particularly during the first years after their establishment. In view of a long period of latency the excess of this neoplasm can be expected till 2020.

[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.

Cancer mortality among pulp and paper workers in Poland. A cohort study

Mortality among workers in the Polish pulp and paper industry was evaluated in a cohort study of 10,460 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. Three subcohorts were formed according to the work areas. A standardized mortality ratio (SMR) analysis was used to compare death rates for each group exposed with Polish national rates. Mortality from all causes and from all malignant neoplasms, both in the female and in male cohorts was lower than that observed in the general population. In the pulp male subcohort a significantly elevated risk of death from peritoneum cancer (2 obs, SMR = 2,530) and prostate cancer (4 obs, SMR = 854) was recorded, although overall mortality from all causes and from all malignant neoplasms was lower than expected. The excess of deaths from neoplasms in other sites was statistically nonsignificant in all subcohorts. This study did not confirm the excess mortality from lung, stomach and lymphatic cancers found by other authors. The "young" cohort and a relatively short follow-up period (23 years) might have affected the results.

[Occupational neoplasms in Poland in the years 1971-1994]

The analysis of the incidence of malignant neoplasms, recognised as occupational disease, in Poland during the years 1971-94 was based on occupational disease certificates sent obligatory to the Nofer institute of Occupational Medicine (Lódz) by all sanitary and epidemiological stations under the Ministry of Health and Social Welfare and the Polish State Railways. During the period study 1118 occupational neoplasms were diagnosed, including 1042 cases (93.2%) of neoplasms in males. Among males malignant Ineoplasms of lung (36.1%), larynx (25.5%), bladder (14.7), skin (6%), lymphatic and haematopoietic tissue (3.4%) and pleura (2.9%) were most common. The rate occupational neoplasms in the total number of neoplasms registered accounted for 0.11% in males and 0.01% in females. PAH (29.1%), asbestos dust (18.8%), ionizing radiation (13.8%), chromium and its compounds (13.5%) and benzidine (9.8%) belong to the most frequent causes of malignant neoplasms in males, and ionizing radiation (31.5%) and asbestos dust (30.3%) in females. The number of neoplasms recognised as occupational disease is very low. Underestimation of occupational neoplasms is very common throughout the world, but it is particularly high in Poland if we take the incidence of pleura mesothelioma as an example. This is mainly due to: (1) the lack of clinical and morphological specificity of occupationally induced neoplasms; (2) a long latency; (3) the influence of other factors confounding the effect of occupational exposure; (4) a relatively small number of occupational carcinogens identified thus far; (5) limited knowledge of occupational carcinogens and criteria for occupational disease certification, and unsatisfactory interviewing skills among doctors who diagnose cancer disease. The identification of a harmful factor and the size of exposure to it, belongs to the weakest point in certifying the occupational background of the disease. The essential conclusions presented stress the urgent need for establishing the system facilitating the diagnosis and certification of occupational neoplasms.

A mortality study of workers with reported chronic occupational carbon disulfide poisoning

A mortality cohort study was carried out on 2,291 workers, including 169 women, with chronic occupational CS2 poisoning diagnosed during the years 1970-90. Information on vital status was available for 98.2% as of December 31, 1992. Mortality assessment was based on the standardized mortality ratio using the person-years method. The general population of Poland was the reference population. The number of subjects who died during the period of observation accounted for 658 men and 21 women. The analysis of mortality in male subjects showed statistically significant excess of deaths from the circulatory system diseases (SMR = 139), in this from ischaemic heart disease (SMR = 137), cerebrovascular disease (SMR = 188) and colon cancer (SMR = 233). Over a two-fold increased risk of death from diseases of the nervous system and sense organs, although statistically insignificant, was also observed. Among women a statistically significant risk of death from atherosclerosis was noted (SMR = 286). An elevated risk of death from the circulatory system diseases and from ischaemic disease (IHD) agrees with the results of some other cohort studies carried out in the viscose rayon workers. The increased mortality from malignant neoplasms is an unusual finding in cohorts of workers exposed to CS2. Our own data reported here showed a significantly increased mortality from colon cancer (9 cases). All these cases were noted in workers of the two oldest rayon plants and they require a detailed analysis. Further survey is also needed to elucidate the excess of deaths from the nervous system and sense organs diseases.

[Prevalence of pleural malignant mesothelioma in Poland in 1980-1993]

Malignant pleural mesothelioma is subject of special interest for environmental epidemiologists due to its proven cause-effect relationship with the exposure to asbestos dust, particularly crocidolite. The paper discusses the prevalence trends and geographical distribution of pleural mesothelioma in Poland based on the death rate analysis. In 1993 the crude death rate for that neoplasm was found to be 4.48 per 1 million for men and 3.14 per 1 million for women. While interpreting the numerical data, such aspects were considered as the problems with histopathological diagnosis of pleural mesothelioma; the long latency period of 30-40 years; and consequently, the possibility that for the male population the results may have been affected by other causes of death owing to its relatively short average lifespan. The volume and types of asbestos used in Poland were also taken into account.

[Mortality from malignant neoplasms in men occupationally exposed to asbestos dust]

The authors present the results of cancer risk evaluation in the cohort of men occupationally exposed to chrysotile asbestos dust in the plant involved in the production of asbestos packings, uneven fabric, yarn, cords, asbestos and rubber cardboards and friction materials. A retrospective observation, carried out till 31 December 1990, covered 2,403 men employed during the years 1945-73. The cohort accessibility accounted for 90.5%. Cancer risk was evaluated on the basis of standardized mortality ratio (SMR) calculated according to the person-years method. A slightly higher mortality from malignant neoplasms was found in the cohort than in the general population (160 deaths; SMR = 108). A significant excess mortality applied only to one site, namely large intestine (9 deaths; SMR = 232). In the subcohort of workers exposed to a high dose of asbestos dust, a significant increase in total cancer risk was revealed (30 deaths; SMR = 150), including neoplasm of stomach (8 deaths; SMR = 223), large intestine (3 deaths, SMR = 582) and liver (3 deaths, SMR = 373). No significant increase in mortality from lung cancer was observed.

[Risk of death from malignant neoplasms among paper mill workers]

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.

[Assessment of lung cancer risk due to environmental asbestos dust exposure in the general population]

Assessment of lung cancer risk due to environmental asbestos dust exposure in the general population was based on the model of risk extrapolation from the occupational (in asbestos-cement plant) to the environmental concentrations. 24-h determinations of asbestos fibre concentrations in the air varied considerably, from 0.4 f/l to 4.6 f/l. The lung cancer risk due to environmental exposure of the general population to asbestos dust has been estimated to be 22 cases p.a. This seems to be very low, considering that the total number of deaths from lung cancer in Poland in 1992 was about 17.5 thousand. The environmental asbestos exposures and their health effects are limited mainly to the areas located in the vicinity of asbestos plants and are attributable primarily to improper utilization of the plant wastes (for example as the surface of local roads and sports grounds at schools) and their unathorized disposal. The incidence of pleural mesothelioma among the inhabitants of those areas seems to be endemic. The endemic character of pleural mesothelioma occurrence has been recently revealed in the vicinity of one of major Polish asbestos and cement plant.