Long-term epidemiological observation of asbestos-related diseases in Poland, 1970-2015

Background

Occupational exposure to asbestos constitutes a major public health concern. Despite this in many countries, data and registration systems for occupational asbestos-related diseases are non-existent or poorly developed.

Aims

To analyse the incidence of occupational asbestos-related diseases in Poland between the years 1970 and 2015, with particular emphasis on the periods after introduction of a ban on asbestos and following introduction of a surveillance programme.

Methods

Analysis based on all medically recognized cases, certified as occupational diseases and reported obligatorily from all over the country to the Central Register of Occupational Diseases.

Results

During the period 1970-2015, 4983 cases were reported as asbestos-related diseases. The most prevalent were asbestosis, lung cancer, diseases of pleura or pericardium and mesothelioma. A considerable increase in the number of such cases from the beginning of their registration until 2004 occurred after introduction of the Amiantus programme, a nationwide programme of periodic medical examinations for former asbestos workers.

Conclusions

Introduction of a medical surveillance programme improved case recognition and allowed a more reliable estimate of the number of reported asbestos-related diseases.

Genome-wide analysis implicates microRNAs and their target genes in the development of bipolar disorder

Bipolar disorder (BD) is a severe and highly heritable neuropsychiatric disorder with a lifetime prevalence of 1%. Molecular genetic studies have identified the first BD susceptibility genes. However, the disease pathways remain largely unknown. Accumulating evidence suggests that microRNAs, a class of small noncoding RNAs, contribute to basic mechanisms underlying brain development and plasticity, suggesting their possible involvement in the pathogenesis of several psychiatric disorders, including BD. In the present study, gene-based analyses were performed for all known autosomal microRNAs using the largest genome-wide association data set of BD to date (9747 patients and 14 278 controls). Associated and brain-expressed microRNAs were then investigated in target gene and pathway analyses. Functional analyses of miR-499 and miR-708 were performed in rat hippocampal neurons. Ninety-eight of the six hundred nine investigated microRNAs showed nominally significant P-values, suggesting that BD-associated microRNAs might be enriched within known microRNA loci. After correction for multiple testing, nine microRNAs showed a significant association with BD. The most promising were miR-499, miR-708 and miR-1908. Target gene and pathway analyses revealed 18 significant canonical pathways, including brain development and neuron projection. For miR-499, four Bonferroni-corrected significant target genes were identified, including the genome-wide risk gene for psychiatric disorder CACNB2. First results of functional analyses in rat hippocampal neurons neither revealed nor excluded a major contribution of miR-499 or miR-708 to dendritic spine morphogenesis. The present results suggest that research is warranted to elucidate the precise involvement of microRNAs and their downstream pathways in BD.

A genome-wide association study of anorexia nervosa

Anorexia nervosa (AN) is a complex and heritable eating disorder characterized by dangerously low body weight. Neither candidate gene studies nor an initial genome-wide association study (GWAS) have yielded significant and replicated results. We performed a GWAS in 2907 cases with AN from 14 countries (15 sites) and 14 860 ancestrally matched controls as part of the Genetic Consortium for AN (GCAN) and the Wellcome Trust Case Control Consortium 3 (WTCCC3). Individual association analyses were conducted in each stratum and meta-analyzed across all 15 discovery data sets. Seventy-six (72 independent) single nucleotide polymorphisms were taken forward for in silico (two data sets) or de novo (13 data sets) replication genotyping in 2677 independent AN cases and 8629 European ancestry controls along with 458 AN cases and 421 controls from Japan. The final global meta-analysis across discovery and replication data sets comprised 5551 AN cases and 21 080 controls. AN subtype analyses (1606 AN restricting; 1445 AN binge-purge) were performed. No findings reached genome-wide significance. Two intronic variants were suggestively associated: rs9839776 (P=3.01 × 10(-7)) in SOX2OT and rs17030795 (P=5.84 × 10(-6)) in PPP3CA. Two additional signals were specific to Europeans: rs1523921 (P=5.76 × 10(-)(6)) between CUL3 and FAM124B and rs1886797 (P=8.05 × 10(-)(6)) near SPATA13. Comparing discovery with replication results, 76% of the effects were in the same direction, an observation highly unlikely to be due to chance (P=4 × 10(-6)), strongly suggesting that true findings exist but our sample, the largest yet reported, was underpowered for their detection. The accrual of large genotyped AN case-control samples should be an immediate priority for the field.

Indoor air pollution from solid fuels and risk of upper aerodigestive tract cancers in central and eastern Europe

BACKGROUND

Indoor air pollution from solid fuels is a potentially important risk factor for cancer, yet data on cancers from organs other than the lung are scarce. We investigated if indoor air pollution from coal and wood are risk factors for additional cancers, particularly that of the upper aerodigestive tract (oral cavity, larynx, pharynx and esophagus) in the high-risk areas of central and eastern Europe.

METHODS

We used data from multi-center hospital-based case-control study of 1065 histologically confirmed upper aerodigestive tract cancer cases and 1346 controls. Standardized questionnaires were used to collect information on residential fuel use for cooking and heating. Using unconditional logistic regression, we calculated odds ratios (ORs) and 95% confidence intervals (95% CIs) for upper aerodigestive tract cancer risk after adjusting for potential confounders.

RESULTS

Lifelong wood use was associated with pharyngeal and esophageal (OR 4.05, 95% CI: 1.30-12.68 and OR 2.71, 95% CI: 1.21-6.10, respectively). We observed an exposure-response relationship between duration of wood use and risk of pharyngeal cancer among those who had never used coal (P(trend)=0.04), ruling out the possibility of residual confounding by coal. Similarly, we observed an increased risk of laryngeal cancers and head & neck cancers among those who always used coal, with a noted exposure-response relationship (P(trend)<0.01).

CONCLUSIONS

Our results suggest a possible role of indoor air pollution from solid fuel use in head and neck carcinogenesis in the high risk area of central and eastern Europe.

Genomic copy number alterations in clear cell renal carcinoma: associations with case characteristics and mechanisms of VHL gene inactivation

Array comparative genomic hybridization was used to identify copy number alterations in clear cell renal cell carcinoma (ccRCC) patient tumors to identify associations with patient/clinical characteristics. Of 763 ccRCC patients, 412 (54%) provided frozen biopsies. Clones were analyzed for significant copy number differences, adjusting for multiple comparisons and covariates in multivariate analyses. Frequent alterations included losses on: 3p (92.2%), 14q (46.8%), 8p (38.1%), 4q (35.4%), 9p (32.3%), 9q (31.8%), 6q (30.8%), 3q (29.4%), 10q (25.7%), 13q (24.5%), 1p (23.5%) and gains on 5q (60.2%), 7q (39.6%), 7p (30.6%), 5p (26.5%), 20q (25.5%), 12q (24.8%), 12p (22.8%). Stage and grade were associated with 1p, 9p, 9q, 13q and 14q loss and 12q gain. Males had more alterations compared with females, independent of stage and grade. Significant differences in the number/types of alterations were observed by family cancer history, age at diagnosis and smoking status. Von Hippel–Lindau (VHL) gene inactivation was associated with 3p loss (P<E-05), and these cases had fewer alterations than wild-type cases. The fragile site flanking the FHIT locus (3p14.2) represented a unique breakpoint among VHL hypermethylated cases, compared with wild-type cases and those with sequence changes. This is the first study of its size to investigate copy number alterations among cases with extensive patient, clinical/risk factor information. Patients characterized by VHL wild-type gene status (vs sequence alterations) and male (vs female) cases had more copy number alterations regardless of diagnostic stage and grade, which could relate to poor prognosis.

Occupational exposure to dusts and risk of renal cell carcinoma

BACKGROUND

Occupational exposures to dusts have generally been examined in relation to cancers of the respiratory system and have rarely been examined in relation to other cancers, such as renal cell carcinoma (RCC). Although previous epidemiological studies, though few, have shown certain dusts, such as asbestos, to increase renal cancer risk, the potential for other occupational dust exposures to cause kidney damage and/or cancer may exist. We investigated whether asbestos, as well as 20 other occupational dust exposures, were associated with RCC risk in a large European, multi-center, hospital-based renal case-control study.

METHODS

General occupational histories and job-specific questionnaires were reviewed by occupational hygienists for subject-specific information. Odds ratios (ORs) and 95% confidence intervals (95% CIs) between RCC risk and exposures were calculated using unconditional logistic regression.

RESULTS

Among participants ever exposed to dusts, significant associations were observed for glass fibres (OR: 2.1; 95% CI: 1.1-3.9), mineral wool fibres (OR: 2.5; 95% CI: 1.2-5.1), and brick dust (OR: 1.5; 95% CI: 1.0-2.4). Significant trends were also observed with exposure duration and cumulative exposure. No association between RCC risk and asbestos exposure was observed.

CONCLUSION

Results suggest that increased RCC risk may be associated with occupational exposure to specific types of dusts. Additional studies are needed to replicate and extend findings.

TP53, EGFR, and KRAS mutations in relation to VHL inactivation and lifestyle risk factors in renal-cell carcinoma from central and eastern Europe

Renal-cell carcinomas (RCC) are frequent in central and eastern Europe and the reasons remain unclear. Molecular mechanisms, except for VHL, have not been much investigated. We analysed 361 RCCs (334 clear-cell carcinomas) from a multi-centre case-control study for mutations in TP53 (exons 5-9 in the whole series and exons 4 and 10 in a pilot subset of 60 tumours) and a pilot 50 tumours for mutations in EGFR (exons 18-21) or KRAS (codon 12) in relation to VHL status. TP53 mutations were detected in 4% of clear-cell cases, independently of VHL mutations. In non-clear-cell carcinomas, they were detected in 11% of VHL-wild-type tumours and in 0% of tumours with VHL functional mutations. No mutations were found in EGFR or KRAS. We conclude that mutations in TP53, KRAS, or EGFR are not major contributors to the RCC development even in the absence of VHL inactivation. The prevalence of TP53 mutations in relation to VHL status may differ between clear-cell and other renal carcinomas.

Occupation and renal cell cancer in Central and Eastern Europe

OBJECTIVE

Central and Eastern Europe has among the highest rates of renal cell cancer worldwide. Few studies have been conducted in these areas to investigate the possible role of occupational exposures in renal cell cancer aetiology. The purpose of this study was to examine the association of renal cell cancer with employment in specific occupations and industries.

METHODS

From 1999 to 2003, we conducted a hospital-based case-control study in seven areas of the Czech Republic, Poland, Romania and Russia. A detailed occupational history was collected from renal cell cancer cases and controls, together with information on potential confounders. Odds ratios (ORs) and 95% CI of cancer risk were calculated for having ever been employed in selected jobs and industries, with follow-up analyses examining duration of employment.

RESULTS

A total of 992 histologically confirmed incident renal cell cancer cases and 1459 controls were included in the analysis. An increased risk of renal cell cancer was observed for workers in agricultural labour and animal husbandry (OR 1.43; 95% CI 1.05 to 1.93), particularly among women employed as general farm workers (OR 2.73; 95% CI 1.05 to 7.13). Risk gradients for agricultural work increased with longer employment. An overall increased risk of renal cell cancer was seen among architects and engineers (OR 1.89; 95% CI 1.35 to 2.65), and mechanical engineers (OR 1.71; 95% CI 1.03 to 2.84).

CONCLUSIONS

Our data suggest an association between renal cell cancer and agricultural work, particularly among female workers.

Elaboration of a quantitative job-exposure matrix for historical exposure to airborne exposures in the Polish rubber industry

BACKGROUND

A job-exposure matrix (JEM) for inhalable aerosols, aromatic amines, and cyclohexane soluble matter (CSM) was elaborated based on measurements collected routinely between 1981 and 1996.

METHODS

The data were grouped based on similarities in exposure levels and time trends in different departments, and were analyzed using smoothing splines and mixed effects models.

RESULTS

Although higher than in western European countries, inhalable aerosol exposure decreased after changes in production volume and implementation of exposure reduction measures in mid-1980s. Aromatic amines concentrations first increased following the factory's production volume, but subsequently decreased in more recent years. CSM concentrations were uniformly distributed between departments.

CONCLUSIONS

This JEM provides an overview of historical exposure levels in a large Polish rubber factory and will enable estimation of lifetime exposure for individual workers in a Polish rubber workers cohort and further investigation of the associations between specific exposures and cancer risk.

Tobacco smoking, body mass index, hypertension, and kidney cancer risk in central and eastern Europe

In a case–control study of kidney cancer in four central European countries, with 1097 incident cases and 1476 controls, we found an increased risk for self-reported hypertension and for obesity. Additional unknown risk factors are likely to be responsible for the high rates of kidney cancer in this region.

Renal cell carcinoma, occupational pesticide exposure and modification by glutathione S-transferase polymorphisms

This study investigated associations between occupational pesticide exposure and renal cell carcinoma (RCC) risk. To follow-up on a previous report by Buzio et al., we also considered whether this association could be modified by glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) genotypes. About 1097 RCC cases and 1476 controls from Central and Eastern Europe were interviewed to collect data on lifetime occupational histories. Occupational information for jobs held for at least 12 months duration was coded for pesticide exposures and assessed for frequency and intensity of exposure. GSTM1 and GSTT1 gene deletions were analyzed using TaqMan assays. A significant increase in RCC risk was observed among subjects ever exposed to pesticides [odds ratio (OR): 1.60; 95% confidence interval (CI): 1.00-2.55]. After stratification by genotypes, increased risk was observed among exposed subjects with at least one GSTM1 active allele (OR: 4.00; 95% CI: 1.55-10.33) but not among exposed subjects with two GSTM1 inactive alleles compared with unexposed subjects with two inactive alleles (P-interaction: 0.04). Risk was highest among exposed subjects with both GSTM1 and GSTT1 active genotypes (OR: 6.47; 95% CI: 1.82-23.00; P-interaction: 0.02) compared with unexposed subjects with at least one GSTM1 or T1 inactive genotype. In the largest RCC case-control study with genotype information conducted to date, we observed that risk associated with pesticide exposure was exclusive to individuals with active GSTM1/T1 genotypes. These findings further support the hypothesis that glutathione S-transferase polymorphisms can modify RCC risk associated with occupational pesticide exposure.

Vitamin D receptor polymorphisms and renal cancer risk in Central and Eastern Europe

Previous studies investigated the role of vitamin D intake and cancer risk. The kidney is a major organ for vitamin D metabolism, activity, and calcium homeostasis; therefore, it was hypothesized that dietary vitamin D intake and polymorphisms in the vitamin D receptor (VDR) gene may modify renal cell carcinoma (RCC) risk. Three common VDR gene polymorphisms (BsmI, FokI, TaqI) were evaluated among 925 RCC cases and 1192 controls enrolled in a hospital-based case-control study conducted in Central and Eastern Europe. Overall associations with RCC risk were not observed; however, subgroup analyses revealed associations after stratification by median age of diagnosis and family history of cancer. Among subjects over 60 yr, reduced risks were observed among carriers of the f alleles in the FokI single-nucleotide polymorphism (SNP) (odds ratio [OR] = 0.61 for Ff and OR = 0.74 for ff genotypes) compared to subjects with the FF genotype (P trend = 0.04; P interaction = 0.004). Subjects with the BB BsmI genotype and a positive family history of cancer had lower risk compared to subjects with the bb allele (OR = 0.60; 95% CI: 0.33-1.1; P trend = 0.05). Genotype associations with these subgroups were not modified when dietary sources of vitamin D or calcium were considered. Additional studies of genetic variation in the VDR gene are warranted.

Genetic variation in five genes important in telomere biology and risk for breast cancer

Telomeres, consisting of TTAGGG nucleotide repeats and a protein complex at chromosome ends, are critical for maintaining chromosomal stability. Genomic instability, following telomere crisis, may contribute to breast cancer pathogenesis. Many genes critical in telomere biology have limited nucleotide diversity, thus, single nucleotide polymorphisms (SNPs) in this pathway could contribute to breast cancer risk. In a population-based study of 1995 breast cancer cases and 2296 controls from Poland, 24 SNPs representing common variation in POT1, TEP1, TERF1, TERF2 and TERT were genotyped. We did not identify any significant associations between individual SNPs or haplotypes and breast cancer risk; however, data suggested that three correlated SNPs in TERT (−1381C>T, −244C>T, and Ex2-659G>A) may be associated with reduced risk of breast cancer among individuals with a family history of breast cancer (odds ratios 0.73, 0.66, and 0.57, 95% confidence intervals 0.53–1.00, 0.46–0.95 and 0.39–0.84, respectively). In conclusion, our data do not support substantial overall associations between SNPs in telomere pathway genes and breast cancer risk. Intriguing associations with variants in TERT among women with a family history of breast cancer warrant follow-up in independent studies.

Glutathione S -transferase polymorphisms, cruciferous vegetable intake and cancer risk in the Central and Eastern European Kidney Cancer Study

High consumption of cruciferous vegetables has been associated with reduced kidney cancer risk in many studies. Isothiocyanates, thought to be responsible for the chemopreventive properties of this food group, are conjugated to glutathione by glutathione S-transferases (GSTs) before urinary excretion. Modification of this relationship by host genetic factors is unknown. We investigated cruciferous vegetable intake in 1097 cases and 1555 controls enrolled in a multicentric case-control study from the Czech Republic, Poland, Romania and Russia. To assess possible gene-diet interactions, genotyped cases (N = 925) and controls (N = 1247) for selected functional or non-synonymous polymorphisms including the GSTM1 deletion, GSTM3 3 bp deletion (IVS6 + 22-AGG) and V224I G>A substitution, GSTT1 deletion and the GSTP1 I105V A>G substitution. The odds ratio (OR) for low (less than once per month) versus high (at least once per week) intake of cruciferous vegetables was 1.29 [95% confidence interval (CI): 1.02-1.62; P-trend = 0.03]. When low intake of cruciferous vegetables (less than once per month) was stratified by GST genotype, higher kidney cancer risks were observed among individuals with the GSTT1 null (OR = 1.86; 95% CI: 1.07-3.23; P-interaction = 0.05) or with both GSTM1/T1 null genotypes (OR = 2.49; 95% CI: 1.08-5.77; P-interaction = 0.05). These data provide additional evidence for the role of cruciferous vegetables in cancer prevention among individuals with common, functional genetic polymorphisms.

Reproductive risk factors for endometrial cancer among Polish women

We conducted a population-based case-control study of reproductive factors in Warsaw and Lódź, Poland, in 551 incident endometrial cancer cases and 1925 controls. The reproductive variable most strongly related to risk was multiparity, with subjects with three or more births having a 70% lower risk than the nulliparous women. The reduced risk was particularly strong below 55 years of age. Subjects with older ages at a first birth were also at reduced risk even after adjustment for number of births. Ages at last birth or intervals since last birth were not strongly related to risk. Spontaneous abortions were unrelated to risk, but induced abortions were associated with slight risk increases (odds ratios=1.28, 95% confidence intervals 0.8-2.1 for 3+ vs no abortions). The absence of effects on risk of later ages at, or short intervals since, a last birth fails to support the view that endometrial cancer is influenced by mechanical clearance of initiated cells. Alternative explanations for reproductive effects should be sought, including alterations in endogenous hormones.

Established breast cancer risk factors by clinically important tumour characteristics

Breast cancer is a morphologically and clinically heterogeneous disease; however, it is less clear how risk factors relate to tumour features. We evaluated risk factors by tumour characteristics (histopathologic type, grade, size, and nodal status) in a population-based case-control of 2386 breast cancers and 2502 controls in Poland. Use of a novel extension of the polytomous logistic regression permitted simultaneous modelling of multiple tumour characteristics. Late age at first full-term birth was associated with increased risk of large (> 2 cm) tumours (odds ratios (95% confidence intervals) 1.19 (1.07-1.33) for a 5-year increase in age), but not smaller tumours (P for heterogeneity adjusting for other tumour features (Phet) = 0.007). On the other hand, multiparity was associated with reduced risk for small tumours (0.76 (0.68-0.86) per additional birth; Phet = 0.004). Consideration of all tumour characteristics simultaneously revealed that current or recent use of combined hormone replacement therapy was associated with risk of small (2.29 (1.66-3.15)) and grade 1 (3.36 (2.22-5.08)) tumours (Phet = 0.05 for size and 0.0008 for grade 1 vs 3), rather than specific histopathologic types (Phet = 0.63 for ductal vs lobular). Finally, elevated body mass index was associated with larger tumour size among both pre- and postmenopausal women (Phet = 0.05 and 0.0001, respectively). None of these relationships were explained by hormone receptor status of the tumours. In conclusion, these data support distinctive risk factor relationships by tumour characteristics of prognostic relevance. These findings might be useful in developing targeted prevention efforts.

A Database of Exposures in the Rubber Manufacturing Industry: Design and Quality Control

The concerted action EXASRUB was initiated to create a database management system for information on occupational hygiene measurements that could be used to develop exposure models in the European rubber manufacturing industry. Quality of coding was assessed by calculating percentages of agreement and Cohen's kappa statistics (kappa) for an intra- and inter-centre recoding of randomly selected subsets of the measurements. In a 6-month period, 59 609 measurements from 523 surveys in 333 factories from as early as 1956 to 2003 were coded. The database consists primarily of measurements of N-nitrosamines (36%), rubber dust (23%), solvents (14%) and rubber fumes (10%). Coding of epidemiologically relevant information was done consistently with inter-centre kappa between 0.86 and 1.00. For occupational hygiene information, values of kappa were estimated to be between 0.67 and 1.00. The proposed method resulted in a large quantity of exposure measurements with auxiliary information of varying completeness and quality. Analyses showed that coding of epidemiologically relevant information in such a multi-centre, multi-country study was coded consistently. Larger errors however, occurred in coding of occupational hygiene information. This was primarily caused by lack of information in the primary records of measurements, emphasizing the importance of having a universal system in place to collect and store measurement information by occupational hygienists for future use.

Oxidative-stress markers in blood of lung cancer patients occupationally exposed to carcinogens

The study covered 152 lung cancer patients and 210 controls. The results of the study indicated decreased selenium (Se) concentrations and lowered activity of erythrocyte antioxidant enzymes (glutathione peroxidase, superoxide dismutase, glutathione-S-transferase) in the blood of lung cancer patients, as well as significantly increased concentrations of vitamin E in erythrocytes and thiobarbituric acid reactive substances in the plasma of the study population. Low plasma Se concentrations (< 45.7 microg/L) enhance the estimated risk of lung cancer (odds ratio = 3.047, p < 0.001). A more precise exposure assessment is required to identify the association between lung cancer incidence and occupational exposure to carcinogens.

Glutathione S-transferase M1 and P1 metabolic polymorphism and lung cancer predisposition

Individual susceptibility to different environmental agents is expected to be associated with alterations in metabolism of xenobiotics. Thus, genetic polymorphism of glutathione S-transferase (GST) can be recognized as a potential risk modifier in lung cancer development. The distribution of GSTM1 and GSTP1 genotypes was studied in a group of 138 diagnosed lung cancer patients and in 165 controls living in central Poland and RFLP-PCR technique was applied. The frequency of GSTM1 null genotype and GSTP1 Val single and duplicated alleles was similar among patients and controls. GSTM1 homozygous deletion was most prevalent in small-cell carcinoma groups (adjusted odds ratio (OR): 2.32, 95% confidence interval (CI): 0.98-5.52). In patients and controls, GSTM1A genotype was most frequent (34.1% vs. 37.0%). The estimated lung cancer risk for GSTM1 null, GSTP1 Ile/Val and GSTP1 Val/Val combined genotype was 1.44 (95% CI: 0.73-2.83), suggesting the absence of modifying effect of defective GSTM1 and GSTP1 alleles on lung cancer predisposition.

[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.

[Occupational risk factors for breast cancer in the epidemiological studies]

The paper reviews data on the occupational risk factors, which role in the etiology of breast cancer in women has been analyzed and estimated in the epidemiological studies. The results of the studies are presented and discussed. An increased incidence or risk of death from breast cancer was observed in some studies among teachers, nurses and physicians, managerial occupations, beauticians and hairdressers, chemists, telephone and telegraph operators, workers of the pharmaceutical and chemical industry. Some epidemiological studies indicate that breast cancer incidence might be related to occupational exposure to electromagnetic fields, ionizing radiation, low physical activity, organic solvents, selected pesticides. However, owing to inconsistency of the study results and methodological weaknesses (imprecise classification of exposure, low response rate, uncontrolled confounding) no definite conclusion can be drawn.

Mortality pattern in the cohort of workers exposed to carbon disulfide

The objective of the study was to assess mortality in the cohort of the viscose factory workers occupationally and environmentally exposed to carbon disulfide. Male workers employed for at least one year during 1950-1985 in the production or maintenance departments, living in the vicinity of the plant, were enrolled into the study. Of the 2,878 workers in the cohort, 2,762 were successfully traced, yielding 76,465 person-years. Mortality assessment was based on the standardized mortality ratio using a person-years method. The general male population of Poland was considered as a reference group. Total mortality in the cohort was higher than in the general male population in Poland (SMR = 108). A significantly increased risk of deaths was observed for all cardiovascular (SMR = 114) and cerebrovascular (SMR = 208) diseases. Analyses showed a significantly elevated risk of death from the circulatory system diseases in the men of the "highly exposed" group, spinners and those who were first employed before 1974. A statistically significant trend of mortality from all cardiovascular diseases in relation to the level of exposure (assessed qualitatively) was evident. No clear relationship between duration of exposure and the risk of death was found.

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.

[Occupational monitoring of lung cancer in epidemiologic studies]

This paper addresses the problem of diagnosing occupational lung cancer faced in different countries. The risks of lung cancer attributed to occupational exposure in selected epidemiological studies are presented. Evidenced and probable lung carcinogens, as well as occupations and industries responsible for the increased risk for the incidence of this pathology are discussed in the light of epidemiological studies.

[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.

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.

[Incidence of occupational diseases in Poland]

The paper is aimed at presenting the incidence of occupational diseases in Poland. The analysis was performed on the basis of the information included in 'occupational disease certificates'. All sanitary and epidemiological stations throughout the country are committed to send these certificates to the Central Register of Occupational Medicine in The Nofer Institute of Occupational Medicine in Lódź. The incidence of occupational diseases during the three recent years (1996-97-98) was the subject of a thorough analysis. In all, 11,318, 11,685 and 12,017 cases of occupational diseases, respectively were registered over those three years. The corresponding rates were 116.0, 116.9 and 117.3, respectively per 100,000 people employed. In 1998, diseases of the voice organ predominated (30.4%) of all occupational diseases) and they were followed by hearing impairment (28.2%), infectious and parasitic diseases (9.9%), pneumoconioses (8.2%), dermatoses (6.4%), vibratory syndrome (2.9%) and poisoning (2.5%). These disease categories constituted over 88% of all occupational diseases registered in that year. Diseases of the voice organ which showed the greatest growth dynamic were mainly diagnosed among teachers. Neither in the United States nor in the member states of the European Union, this pathology is included into the list of occupational diseases. In view of high rates of its incidence in our country it has become one of essential problems of occupational medicine. In Poland, particular attention is paid to infectious and parasitic diseases among which hepatitis occupies the first place (65%), mostly among health service workers. The decrease in hepatitis incidence observed in the 1990s has been due to an intensive vaccination programme in this group of workers. The incidence of occupational hepatitis became rather stable and accounted for 940 cases per year, however the incidence of hepatitic C increased at the same time. Lower rates of incidence of 'classic' occupational diseases, such as poisoning, pneumoconioses or vibratory syndrome are a positive observation. It is also interesting to note that the rate of occupational diseases diagnosed in advanced stage has also diminished. When analyzing occupational diseases one should bear in mind that the majority of pathologies already diagnosed result from long-term effect of exposure to harmful factors. In all, 93% of cases of occupational diseases emerged after a ten-year exposure. The highest rates, taking account of sections of activity, were found in mining and quarrying, health service, agriculture, hunting and forestry.

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.

Occupational cancer in central European countries

The countries of central Europe, including Poland, the Czech Republic, Slovakia, Hungary, Romania, and Bulgaria, suffer from environmental and occupational health problems created during the political system in place until the late 1980s. This situation is reflected by data on workplace exposure to hazardous agents. Such data have been systematically collected in Skovakia and the Czech Republic since 1977. The data presented describe mainly the situation in the early 1990s. The number of workers exposed to risk factors at the workplace represent about 10% of the working population in Slovakia and 30% in Poland. In Slovakia in 1992 the percentage of persons exposed to chemical substances was 16.4%, to ionizing radiation 4.3%, and to carcinogens 3.3% of all workers exposed to risk factors. The total number of persons exposed to substances proven to be carcinogens in Poland was 1.3% of the employees; 2.2% were exposed to the suspected carcinogens. The incidence of all certified occupational diseases in the Slovak Republic was 53 per 100,000 insured employees in 1992. Cancers certified as occupational cancers are skin cancer caused by occupational exposure to carcinogens, lung cancer caused by ionizing radiation, and asbestosis together with lung cancer. Specific information on occupational cancers from Romania and Bulgaria was not available for this paper. It is difficult to predict a trend for future incidences of occupational cancer. Improved control technology, governmental regulatory activity to reduce exposure, surveillance of diseases and risk factors, and vigilant use of preventive measures should, however, ultimately reduce occupational cancer.

[The effect of systemic changes on sick-day absenteeism in the workplace. II. Causes of work disability among persons under termination of employment]

During the period of transformations and restructuring of workplaces in Poland, the reduction of employment becomes quite common, what seems to make a considerable impact on sick absenteeism. The analysis presented aimed at defining how far the risk of sick absenteeism increases among workers under termination of employment because of different reasons, and indicating morbidity causes in case of which sick absenteeism is most extensive. The study was carried out in one of the largest plants of the motor car industry (before the process of restructuring), and it covered a cohort of 5,373 men and 3,215 women employed during the years 1989-94. The workers who terminated their employment during those years made 77% of the whole cohort under study. The case index, calculated as the ratio of the number of cases to the number of man-days under observation, was taken as an analysis parameter. Poisson regression model involving a number of variables (age, departments, current workers, workers discharged according to particular reasons, and the period preceding the termination of employment) was used in the statistical analysis. The study indicated an increased risk of sick absenteeism in the group of workers approaching the termination of employment in comparison with that among current workers. The highest risk of work disability, both among men and women, was observed in persons leaving their jobs because of long-lasting illness or disability pension. The highest risk indices were noted in men whose sick absenteeism was caused by neoplasms (RR = 14.42); endocrine secretion disorders (RR = 4.83); cardiovascular disorders (RR = 3.60); mental disorders (RR = 3.04); and diseases of the musculoskeletal system (RR = 2.95); and in women with neoplasms (R = 6.42); diseases of the musculoskeletal system (RR = 4.01); and cardiovascular diseases (RR = 3.99). Risk of sick absenteeism was over 50% higher among retiring workers than among current workers (RR = 1.50 for men; and RR = 1.53 for women). Among workers discharged because of economic reasons, statistically significant risk of sick absenteeism was also observed (RR = 1.51 for men; and RR = 1.37 for women). In the group of workers leaving their jobs, following the agreement of the parties, an increased risk of sick absenteeism was noted in men (RR = 1.45). The economy transformation processes make a considerable impact on the occurrence of sick absenteeism in workplaces. Workers leaving their jobs because of health problems or of their own accord, as well as those discharged because of economic reasons belong to the highest risk groups.

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.

Sickness absence in a rubber plant in Poland

The disease-related temporary incapacity for work, its causes and duration are essential factors in the assessment of health status of the occupationally active population. The aim of the present study was to investigate the main causes of work disability among the rubber industry workers, with special regard to sickness absence among workers directly enganged in manufacture. The study was performed in 1995 on a sample of 973 workers (456 males and 517 females) at a plant producing rubber footware. The number of days of work disability from a particular disease, frequency and duration per year were examined. The analysis concerned such parameters of sickness absence as the lost time rate, average duration of absence, and percentage of workers on a sick-leave. The results revealed that during the period under study the main medical causes of the sickness absence included: a) for males--cardiovascular diseases (48% of the total sickness absence), respiratory diseases (18%), gastrointestinal disease (8%) and the nervous system and sense organs diseases (8%); b) for females--cardiovascular diseases (24%), respiratory diseases (16%), pregnancy, childbirth and puerperium complications (11%) and neoplasms (10%). The sickness absence of workers directly involved in the manufacture appeared to be by 72% higher than that noted for workers of other departments, with the age- and gender-standardized lost time rate of 4.74. The differences can be related mainly to a higher percentage of the sick in the group of 'production workers' (43%) as compared to the 'non-production' ones (28%). The findings of our study indicate that in the rubber industry workers a high rate of absence due to some groups of diseases may be associated with exposure to hazardous agents in their work environment.

[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.

[Morbidity of occupational diseases in Poland in the years 1994-1996]

The authors analysed all cases of occupational diseases diagnosed in Poland over the last three years. The following variables were considered: age, gender of patients, duration of exposure to factors inducing occupational disease, nosologic units, and the types of work places by the European Activity Classification and their localization by voivodships. The obtained results helped to formulate the following conclusions: 1. The number of occupational diseases in the period under study ranged annually between 11,156 and 11,320 cases. The incidence rates (number of cases/100,000 employed) fell within 116-131. 2. The general incidence of occupational diseases was shaped by: hearing impairment, chronic diseases of voice organs, communicable and invasive diseases, pneumoconioses, skin diseases, vibratory syndrome and poisoning. 3. The majority of diagnosed diseases occurred at least after 10 years of occupational exposure to causal factor. 4. The highest incidence of occupational diseases by the European Activity Classification was observed in mining and quarrying, manufacture, education and health services. 5. The analysis of the occupational disease incidence in individual work places indicated a number, however small, of enterprises which are a major source of these diseases.

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.

[Documentation problems for occupationally related neoplastic diseases]

The author suggests procedures which can improve the process of identifying an occupational background of neoplastic diseases, bearing in mind a low number of reported cases of occupational cancer in Poland and a concurrent lack of justification (on the basis of data included in a notification from) for some of them. Controversy over diagnosis of neoplasms induced by ionizing radiation is also highlighted. The improved certification of work-related neoplastic diseases must involve each phase of an occupational disease diagnosis: clinical diagnosis with complete and correct medical history, morphological confirmation of the diagnosis, indispensable in the case of cancer, with identification of the primary site of the cancer, identification of causal factor and the exposure size, and occupational disease notification. The author also indicated shortcomings of an occupational disease notification form in regard to neoplastic diseases and suggested its modification.

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.