Cancer survival and social class in Sweden.

A study of 98,000 cases in the Swedish Cancer Registry from 1961 to 1979 was undertaken. The relative survival by social class was calculated. There was a higher survival probability for white collar workers than for blue collar workers or self-employed farmers for all cancer, as well as for particular cancers, such as, for instance, cancer of the breast and cervix among women and cancer of the rectum among men. For lung cancer, cancer of the stomach, and pancreatic cancer there were no detectable differences in survival probability. The findings can be considered in the light of various possible explanations, for instance, early detection, differential treatment, and host factors.     

Do changes in cardiovascular risk factors explain the increasing socioeconomic difference in mortality from ischaemic heart disease in Finland?

STUDY OBJECTIVE: To estimate the extent to which changes in blood pressure, smoking, and serum cholesterol concentration explain the observed increase in socioeconomic differences in mortality from ischaemic heart disease (IHD) in Finland during the past 20 years. DESIGN: Predicted changes in mortality from IHD were calculated using logistic regression models with the risk factor levels assessed by cross sectional population surveys conducted in 1972, 1977, 1982, and 1987. The subjects included white collar and blue collar workers and farmers. The predicted changes were compared with the observed mortality changes in the same socioeconomic groups in the total population of the same geographical area. SETTING: North Karelia and Kuopio provinces, eastern Finland. PARTICIPANTS: 16,741 men and 16,389 women aged 30-59 randomly drawn from the population registers of the study areas. Mortality data were obtained from the total population in the same areas. MAIN RESULTS: In men, the changes in diastolic blood pressure, total serum cholesterol, and smoking predicted a 28% decline in the mortality from IHD among white collar workers, a 30% decline among blue collar workers, and a 33% decline in farmers. Observed declines in the same socioeconomic groups were 61%, 40%, and 37%, respectively. In women, the predicted decline was 41% among white collar workers, 35% among blue collar workers, and 39% among farmers. The respective observed declines were 57%, 43%, and 20%. CONCLUSIONS: Less than half of the decline in IHD mortality among white collar men was explained by the risk factor changes, while they explained 75% of the decline among blue collar men and 89% of the decline among male farmers. Changes in risk factors did not explain the increasing difference in IHD mortality between the socioeconomic groups, especially among men.

 

     

Cancer incidence among farmers exposed to lindane while sheep dipping

OBJECTIVES: The objective of this study was to determine whether site-specific cancer incidence among farmers exposed to the insecticide lindane (g-hexachlorocyclohexane) while dipping sheep differs from that of the general population in Iceland. METHODS: Cohorts of 7882 men and 429 women, who, according to records on sheep dipping, were sheep owners, were followed from 1962 to 2003 in the Cancer Registry for cancer incidence. The observed number of cancers was compared with expected values, calculated on the basis of person-years of risk and cancer incidence in the general population of Iceland. RESULTS: For men the standardized incidence ratio (SIR) for all cancer sites was 0.79, with a 95% confidence interval (95% CI) of 0.76-0.83. For both the men and the women a significantly increased risk for lip cancer was found, with SIR of 1.50 (95% CI 1.08-2.04) and 9.09 (95% CI 1.02-32.82), respectively. The SIR for several cancer sites were lower than unity for both the men and women. Examples were cancers of the colon, rectum, pancreas, stomach, lungs, kidney, bladder, and brain and nervous system. CONCLUSIONS: The decreased risk of most cancers among these sheep farmers agrees with findings reported previously among farmers from other countries, as well as in Iceland. Cancer of the lip was the only cancer type in significant excess among both genders, and the stomach cancer rates were near unity, but, in previous studies on Icelandic farmers, an increase had been found for stomach cancer. The site-specific cancer incidence for sheep-dipping farmers did not differ substantially from that of the general population.     

Occupation and stomach cancer in a cohort of Swedish men

Using the Cancer-Environment Registry of Sweden, which links the 1960 census information on employment with cancer incidence data from 1961–1979, we conducted a systematic, population-based assessment of stomach cancer incidence by industry and occupation for men in Sweden. Nearly 17,000 stomach cancer cases were diagnosed during the 19 years of follow-up. Stomach cancer incidence was elevated among miners and quarrymen, farmers and fishermen, and craftsmen and production workers. Men who held white collar jobs, including professional and technical, administrative and management, clerical, and sales jobs, had a reduction in stomach cancer incidence. Examination of specific jobs revealed generally elevated rates of stomach cancer among men who may be exposed to dusty work environments, such as quarry workers, stone cutters, circular and plane operators, construction workers, crane operators, heavy laborers, and shop and construction metal workers. These occupational associations mostly were observed for stomach cancers of noncardia origin, and no significant associations were found with cardia cancers. We had no information on dietary or other potential confounding factors and cannot make inferences about the role of occupation per se, but the current findings support those of earlier investigations and add to the evidence of a small but significant occupational role in stomach carcinogenesis.     

Risks,survival and trends of malignant melanoma among white and blue collar workers in Sweden

All persons in Sweden, classified as white or blue collar workers in the 1960 Population Census, were followed up for the period 1961–1973 with regard to the occurrence of cancer. The SMRs were calculated for 50 tumour sites and it was found that the crude classification of occupations into white or blue collar workers was particularly important for malignant melanoma risk.The number of malignant melanoma cases among blue collar workers was significantly lower than expected while it was significantly higher than expected among the white collar workers. This was true for men as well as for women. The SMRs were calculated to be 87 and 141 (men) and 79 and 117 (women), respectively.Comparing the relative survival probabilities it was found that white collar workers had a higher probability of survival than blue collar workers. This might indicate that the difference in occurrence could be dependent on early detection as well as differential risk.The incidence of malignant melanoma is increasing faster than any other kind of tumour in Sweden. For the period 1961–1970 the incidence rate increased two-fold for blue collar workers and more than two-fold for white collar workers (men). In absolute terms the white collar workers in the age group 45–64 had an appreciably faster increase in incidence over this period compared to all other groups studied.     

Social patterning of myocardial infarction and stroke in Sweden: incidence and survival

Cardiovascular disease morbidity and mortality rates show marked social patterning in industrialized countries. The aim of this study was to analyze if not only incidence but also survival after acute myocardial infarction (AMI) and stroke differ among socioeconomic groups. Within the framework of the population-based World Health Organization's Multinational Monitoring of Trends and Determinants in Cardiovascular Disease (MONICA) Project, all first-ever AMI (ages 25-64 years) and stroke (ages 25-74 years) events were recorded in northern Sweden during the period 1985-1994. The numbers of first-ever AMI and stroke patients included in the study were 3,466 and 4,215, respectively. Incidence rates for both AMI and stroke showed a distinct social pattern, with high rates in workers and self-employed nonprofessionals and low rates in professionals. The pattern was similar in men and women. In men, early survival after an AMI follows the same socioeconomic pattern, whereas it is less clear if socioeconomic differences in survival contribute to explain differences in mortality in AMI among women and mortality in stroke (both sexes). The high case fatality among male workers and self-employed professionals with AMI is, in turn, attributed to a very marked increase in the risk for sudden death.     

What underlies the high alcohol related mortality of the disadvantaged: high morbidity or poor survival?

STUDY OBJECTIVE: To investigate whether the large socioeconomic differences in alcohol related mortality can be explained by differences in morbidity or differences in survival. DESIGN: Register linkage study. A nationwide hospital discharge register was linked to population censuses for socioeconomic data and to the cause of death register for mortality follow up. SETTING: Finland. PARTICIPANTS: Men and women aged 15 years and older discharged from hospitals with an alcohol related diagnosis in 1991-1996. MEASUREMENTS: Mortality hazard up to the end of 1997 by socioeconomic category was estimated with Cox's regression model. MAIN RESULTS: Socioeconomic differences in alcohol related hospitalisation rates were almost as large as those that have been observed for alcohol related mortality. For example, the rate ratio among male unspecialized workers for any alcohol related hospitalisations was 3.6 as compared with upper white collar workers; among women the rate ratio was 2.7. Depending on gender, age, hospitalisation diagnosis, and cause of death, survival after discharge either showed no socioeconomic differences or it was worse among better off groups. CONCLUSIONS: The study suggests that differences in survival after hospitalisation do not cause the high socioeconomic differences in alcohol related mortality.     

Asbestos, cement, and cancer in the right part of the colon.

OBJECTIVE--The aim was to investigate associations between exposure to mineral fibres and dust, and cancer in subsites within the large bowel. DESIGN--Pooled retrospective cohort studies. SUBJECTS AND SETTINGS--Blue collar workers, employed for at least one year in different trades; asbestos cement or cement workers (n = 2507), other industrial workers (n = 3965), and fishermen (n = 8092). MAIN OUTCOME MEASURES--Standardised incidence ratios (SIRs, national reference rates) were calculated for cause specific cancer morbidity between 1958 and 1989. The observation period began 15 years after first employment. RESULTS--The asbestos cement and cement workers had a slightly increased risk of colorectal cancer (SIR 1.5; 95% confidence interval (95% CI) 1.1-2.0). This was due to an increase only in the right part of the colon (SIR 2.5; 95% CI 1.6-3.8). The ratio of right (7th revision of the International Classification of Diseases ICD-7) 1530-1531)/left (ICD-7 1532-1533) colon cancer among the asbestos cement and cement workers of 4.8 differed significantly from the ratio both among the other blue collar workers (0.4) and among the fishermen (1.5). As the sensitivity and accuracy was insufficient, mortality data did not show the excess of cancers in the right part of the colon. CONCLUSIONS--An increased incidence of cancer in the right part of the colon was evident in the asbestos cement and cement workers. The distribution of cancers within the colon was noticeably different from that in other blue collar workers, indicating that our findings cannot be explained by socioeconomic confounding factors. A detailed and appropriate disease classification, based on incidence data, is necessary in order not to obscure or underestimate effects of exposure in epidemiological studies on colorectal cancer.     

Socioeconomic inequalities and disability pension in middle-aged men

BACKGROUND: The issue of inequalities in health has generated much discussion and socioeconomic status is considered an important variable in studies of health. It is frequently used in epidemiological studies, either as a possible risk factor or a confounder and the aim of this study was to analyse the relation between socioeconomic status and risk of disability pension. METHODS: Five complete birth year cohorts of middle-aged male residents in Malmo were invited to a health survey and 5782 with complete data constituted the cohort in this prospective study. Each subject was followed for approximately 11 years and nationwide Swedish data registers were used for surveillance. RESULTS: Among the 715 men (12%), granted disability pension during follow-up, three groups were distinguished. The cumulative incidence of disability pension among blue collar workers was 17% and among lower and higher level white collar workers, 11% and 6% respectively. With simultaneous adjustment for biological risk factors and job conditions, the relative risk for being granted a disability pension (using higher level white collar workers as reference) was 2.5 among blue collar workers and 1.6 among lower level white collar workers. CONCLUSIONS: Socioeconomic status, as defined by occupation, is a risk factor for being granted disability pension even after adjusting for work conditions and other risk factors for disease.     

Mesothelioma and lung tumors attributable to asbestos among petroleum workers

BACKGROUND: Asbestos exposure has been definitively found to be associated with both mesothelioma and lung cancer. Nevertheless, in the overall population of oil refinery workers potentially exposed to asbestos, many studies clearly show a definitely increased risk of mesothelioma, but no proven excess of lung cancer after comparison to the general population. Through the presentation of new data and the re-appraisal of two recent and independent epidemiological studies conducted in Liguria, Italy, and Ontario, Canada, we attempt to shed light on this apparently paradoxical finding. METHODS: Lung cancer mortality was studied among maintenance workers exposed to asbestos, and among two other subgroups of refinery employees: blue collar and white collar workers. The comparison with blue collar workers was performed in order to take into account the role of healthy worker effect, smoking habit, and the socioeconomic level. The comparison with white collar workers was performed to control for other occupational lung carcinogens. RESULTS AND CONCLUSIONS: Results reveal a consistency between the two studies and show that 96-100% of the mesotheliomas and 42-49% of the lung tumors arising among maintenance workers were attributable to asbestos exposure. Our new analysis, estimating two cases of asbestos-related lung cancer for each case of mesothelioma, confirms published findings on the magnitude of asbestos-related tumors in oil refineries.     

A population based survey of attendance at screenings in urban areas]

To clarify the present situation of screenings in urban areas, a population based survey on attendance at screenings was conducted in Kitakyushu City. Self-administered mailed questionnaires were sent to three thousand randomly selected subjects 40 years of age or over living in Kitakyushu City. The results are summarized as follows: 1. Considerable differences were observed in the number of people who were offered screenings at work sites for those between the ages of 40-59 compared to those 60 years of age or over, and between full-time employees and part-time or self-employed workers. 2. Among people who obtained stomach examinations, middle age men mainly received cancer screenings at work sites, while women or older men were mainly examined when they went to clinics or hospitals when abdominal discomforts occurred. Among women who received uterine examinations, all age groups mainly received cancer screenings at city administered screenings at clinics or hospitals, and rates decreased as age increased. 3. Among people who did not obtain stomach examinations, many middle age people wanted to be examined for stomach cancer but were unable to, while older people did not think it necessary. In the case of uterine cancer screening, middle age women did not want to receive it, while older women did not think it necessary. 4. For those people who are not offered cancer screenings at workplaces, it is assumed that those who have a positive attitude toward screening will obtain it, if offered, at sites conducted by the local government.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cause of death among workers of a refinery in Rome]

We evaluated mortality among subjects employed in an oil refinery plant in Rome, Italy. We studied two subgroups of refinery employees: blue collar and white collar workers. A total of 682 men (505 blue collars, 148 white collars, 29 unknown) employed between 1965 and 1992, were followed up for mortality since employment in the plant to July 1999. Standardized Mortality Ratios (SMR), and their 90% Confidence Intervals (90% CI), comparing mortality rates of the cohort members with those of the general population of the Lazio region. For blue collar workers, we performed analyses by latency since first employment and by duration of employment for selected cancer sites. We observed 94 total deaths (100.8 expected) (SMR = 0.93; 90% CI = 0.78-1.11) among blue collar workers and 16 total deaths (31.7 expected) (SMR = 0.50; 90% CI = 0.32-0.77) among white collar workers, and a large deficit of deaths from non-neoplastic cardiovascular diseases (respectively SMR = 0.60; 90% CI = 0.41-0.86 and SMR = 0.18; 90% CI = 0.03-0.56). All cancer mortality was slightly increased only in blue collars (SMR = 1.27 CI = 0.97-1.65). There was an excess risk from cancer of the lung (20 obs SMR = 1.80, 90% CI = 1.19-2.62), bladder (5 obs SMR = 3.19, 90% CI = 1.26-6.72), and benign/unspecified cancer of the brain (4 obs SMR = 4.11, 90% CI = 1.12-10.6). The lower mortality from cardiovascular disease indicates the presence of a strong healthy worker effect. The findings of elevated mortality from cancer of the lung and bladder in blue collar workers are in agreement with those of other studies. Confounding factors from cigarette smoking might have played only a marginal role in influencing the results. Exposure to polynuclear aromatic hydrocarbons (PAHs) is a plausible explanation for the excesses found.     

Squamous cell skin cancer in the North-west of England, 1967-69, and its relation to occupation

ABSTRACT During the three years 1967-69, 781 cases of squamous cell carcinoma of the skin were reported to the Manchester Regional Cancer Registry. The proportions of males to females were significantly different (p <0·001) among the skin cancer sites. The age-specific incidence rates were significantly different (p <0·001) between the sexes for the five-year age groups of 55 years and above. Full occupational histories were obtained on 598 (77%) patients; a further 148 (19%) patients gave one main occupation only, while the remaining 35 (4%) patients were untraced. The numbers of patients observed in broad occupational groups (occupational orders) were compared with the numbers expected using the 1931 and 1951 censuses. For all skin cancer sites combined the occupations of farming and textiles were found to have highly significant excesses of 150% and 135% respectively for males. The corresponding excesses for females were 30% for textile workers and varied from 1140% to 590% for farmers, but only for the farmers were the excesses highly significant. For males the occupation of metal worker also showed excesses of 38% and 23% which were of borderline significance. The association between occupation and individual skin cancer sites was then considered. For males there were excesses in the arm for the occupational orders of chemical workers, paper/printing workers and fishermen, and in the ears for builders, but these excesses were of borderline significance. There was a significant difference (p <0·05) in the proportion of male patients with atopic skin conditions in each cancer site. However, this was not found for the female patients. For both male and female patients no significant associations were found between the skin site and either eye colour, residence in the tropics or smoking habit.     

Lung cancer: is there an association with socioeconomic status in The Netherlands?

STUDY OBJECTIVE--To evaluate if there are differences in lung cancer incidence between socioeconomic groups in the Netherlands and if so, if smoking habits and other lifestyle characteristics could explain these differences. DESIGN--Prospective cohort study. Baseline measurement included information on socioeconomic status, smoking habits, and other covariates by means of a self-administered questionnaire. Follow up was established by computerised record linkage to cancer registries and a pathology register. SETTING--Population originating from 204 municipalities in The Netherlands. PARTICIPANTS--58,279 men aged 55-69 years in September 1986. After 3.3 years of follow up 490 microscopically confirmed incident lung cancer cases were detected. MAIN RESULTS--An inverse association between lung cancer risk and highest level of education was found, which persisted after adjustment for age, smoking, dietary intake of vitamin C, beta-carotene and retinol (rate ratio (RR) highest/lowest level of education = 0.52, 95% CI 0.33, 0.82, trend p < 0.001). Men with a lower white collar profession had a significantly lower relative rate of lung cancer compared with blue collar workers (RR = 0.66, 95% CI 0.47, 0.96), but after adjustment for smoking habits this difference was reduced (RR = 0.73, 95% CI 0.51, 1.08). CONCLUSIONS--There is an inverse association between highest level of education and lung cancer, which is still apparent after adjustment for age, smoking, dietary intake of vitamin C, beta-carotene and retinol. The significantly lower lung cancer risk of lower white collar workers compared with the risk of blue collar workers could be partially explained by smoking habits.     

Deaths from primary brain cancers, lymphatic and haematopoietic cancers in agricultural workers in the Republic of Ireland.

STUDY OBJECTIVE--To ascertain if agricultural workers in the Republic of Ireland had a higher than expected mortality from brain and haematopoietic cancers than occurred in the general population. DESIGN--The Central Statistics Office of Ireland provided computer analysis of all deaths coded as cancer of the brain, ICD 191, and of lymphatic and haematopoietic cancers, ICD codes 200-208, by socioeconomic, sex, and age groups, from 1971 to 1987. The deaths were then analysed by socioeconomic group and compared with the expected number of deaths in the general population. SETTING--A cluster of four deaths from primary brain cancer, three from leukaemia, and one from Hodgkin''s disease, occurred in the research and technical staff of the former Agricultural Institute of the Republic of Ireland in men under the age of 65. This raised the question, were farmers more likely to get these forms of cancer due to exposure to herbicides or fertilisers? SUBJECTS--All deaths in the Republic of Ireland from 1971 to 1987 by socioeconomic group. MAIN RESULTS--Although deaths reported as due to primary brain cancers had increased in all socioeconomic groups in the two time periods studied, there was no greater increase in farmers and a smaller increase in other agricultural workers and fishermen. Deaths from Hodgkin''s disease and multiple myeloma, and to a smaller extent from leukaemia, had also increased. The increase in reported mortality of these haematopoietic cancers in farmers was no greater and in other agricultural workers it was less than in the general population. CONCLUSION--There was no evidence that farmers had any greater increase in mortality from these cancers than the general population. The cluster of brain and haematopoietic cancers in research and technical staff at the Agricultural Institute of the Republic of Ireland does not reflect a high risk of these cancers among the general farming population, but strongly supports the need for a compilation of a register of causes of death of laboratory workers in a number of countries.     

Occupational risks for renal cancer in Sweden

A systematic assessment was made of the occurrence of renal cancer among men by industrial and occupational classification using the Cancer-Environment Registry, which links cancer incidence (1961-79) and census data (1960) with industry and occupation for all employed individuals in Sweden. Data were analysed separately for cancers of the renal parenchyma and pelvis. Significantly increased risks for renal cell cancer were observed for several professional and white collar occupations, including physicians and others in the health care industry. By contrast, the risks for renal pelvis cancer tended to be higher among blue collar workers, especially in the machine industry. Deficits of both cancers occurred among farmers. The findings of the survey are considered as aetiological clues that may deserve further study, although some associations support observations in other countries.     

Occupational risks for renal cancer in Sweden.

A systematic assessment was made of the occurrence of renal cancer among men by industrial and occupational classification using the Cancer-Environment Registry, which links cancer incidence (1961-79) and census data (1960) with industry and occupation for all employed individuals in Sweden. Data were analysed separately for cancers of the renal parenchyma and pelvis. Significantly increased risks for renal cell cancer were observed for several professional and white collar occupations, including physicians and others in the health care industry. By contrast, the risks for renal pelvis cancer tended to be higher among blue collar workers, especially in the machine industry. Deficits of both cancers occurred among farmers. The findings of the survey are considered as aetiological clues that may deserve further study, although some associations support observations in other countries.     

Occupational cancer mortality in Illinois white and black males, 1979-1984, for seven cancer sites

A death certificate mortality odds ratio study of seven cancer sites was conducted by using 1979-1984 data on Illinois deaths in white and black males. Cancer sites selected include stomach, pancreas, lung, prostate, bladder, brain, and non-Hodgkin's lymphomas. This surveillance study was undertaken to detect occupational associations that might suggest further avenues of research. Some of the occupations and industries found to have elevated cancer risks and that are consistent with previous studies include: brickmasons and stonemasons (stomach); metal workers (pancreas, lung); photoengravers and lithographers (pancreas); butchers (lung); locomotive operators and truck drivers (lung); farmers (prostate, brain, non-Hodgkin's lymphoma); mechanics and repairers, especially auto mechanics (prostate); physicians (brain); glass products manufacturing workers (brain); and communications industry (brain) and chemical plant workers (non-Hodgkin's lymphomas). It was also noted that for black males, the death certificate occupational data are of limited usefulness due to the high percentage of missing or inexact information. The Division of Vital Records in the State of Illinois should make an effort to improve the reporting of this data through additional training of the funeral directors and hospital clerks who collect this information and by follow-up of incomplete or missing data.     

Variation in the risk for liver and gallbladder cancers in socioeconomic and occupational groups in Sweden with etiological implications

Objectives: To examine the associations between socioeconomic/occupational factors and liver cancer at various anatomic sites (including primary liver, gallbladder and other cancers). Methods: We carried out a follow-up study on the economically active Swedish population, based on the Swedish Family-Cancer Database. Standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated in different social classes and occupations. Results: For primary liver cancer, farmers were at a decreased risk; increased risks were observed for male sales agents, journalists, seamen, waiters, cooks and female beverage manufacture workers. Similar patterns were observed for gallbladder cancer; workers employed as journalists, sales agents, cooks and stewards, and public safety workers showed increased risk. Only male transport workers showed increased risk of cancers in other parts. Conclusions: Occupations with high consumption of alcohol and/or high prevalence of smoking associated with a risk of liver and gallbladder cancers. The present study suggests that the effects of socioeconomic factors on liver cancer of different subsites are similar; alcohol drinking is a risk factor of gallbladder cancer because of the covariation of primary liver and gallbladder cancers in occupational groups.     

Deaths and tumours among workers grinding stainless steel: a follow up.

OBJECTIVE: To study cause specific mortality and cancer morbidity in workers exposed to the dust of grinding materials, grinding agents, and stainless steel, especially with regard to a possibly increased risk of respiratory, stomach, and colorectal cancer. METHODS: Retrospective cohort study, using reference cohorts of blue collar workers and population rates for comparison. The exposed cohort comprises workers with at least 12 months employment time at two plants, producing stainless steel sinks and saucepans (n = 727). Also, reference cohorts of other industrial workers (n = 3965) and fishermen (n = 8092) were analysed. The observation period began 15 years after the start of employment. Standardised mortality or incidence ratios (SMRs, SIRs; county reference rates) were calculated for cause-specific mortality between 1952 and 1993, and for cancer morbidity between 1958 and 1992. RESULTS: In the exposed cohort, overall mortality, cardiovascular mortality, and all malignant mortality and morbidity were slightly lower than expected. Also, the risk estimates for cancer in the upper and lower respiratory tracts and for stomach cancer were lower than expected. There was an increase in morbidity from colon cancer, which was explained by an excess of tumours in the sigmoid part only. Here, the risk estimates were higher in workers with long employment time (1-14 years: four observed cases, SIR 1.7, 95% confidence interval (95% CI) 0.4 to 4.5; > or = 15 years: three observed cases, SIR 4.3, 95% CI 0.9 to 13) and the increased risk was especially pronounced among those first employed before 1942. A slight nominal excess of rectal cancers (nine observed cases, SIR 1.4, 95% CI 0.6 to 2.6), and a significant excess of prostate cancer morbidity (36 observed cases, SIR 1.7, 95% CI 1.2 to 2.4) were found. These risk estimates did not, however, increase with employment time. CONCLUSIONS: The finding of an increased risk of cancer in the sigmoid part of the colon, which was not found in the reference cohorts, and with indication of a relation between duration of employment and response, is consistent with a causal relation. The limited size of the exposed cohort makes a detailed exposure-response analysis unstable, and the confidence limits are wide. Albeit slightly raised, the risk estimate for rectal cancer in the exposed cohort was not different from the estimate among the other industrial workers.