Silicosis and risk of lung cancer or lung tuberculosis: a cohort study

This is a study of cancer mortality, cancer incidence, and incidence of lung tuberculosis among cases of silicosis reported to the National Swedish Pneumoconiosis Register during 1959-1977. Two occupational categories were extracted--"mining, tunneling, and quarrying" (n = 284) and "iron and steel foundries" (n = 428), respectively. Control groups were drawn from a national register of persons undergoing periodic health examinations with regard to silicosis risk. The controls were matched for occupation, age, and time of first exposure. The follow-up was performed through record-linkage operations to computerized information in Swedish Death Statistics, Swedish Cancer Register, and the Swedish Tuberculosis Index. End of follow-up was set at December 31, 1980. In cases drawn from mining, quarrying, and tunneling workers seven deaths in lung cancer were observed and two among the controls. Among iron and steel foundry workers the corresponding numbers were 10 and 6. The values for expected numbers, based on general population statistics, were 1.3 and 2.6, respectively, for these two occupational groups. When cancer incidence statistics were used, the case/control ratio for lung cancer was 2.1 for "mining, quarrying, and tunneling" and 0.6 for "iron and steel foundries." There were 29 cases of lung tuberculosis registered among the silicosis cases during the follow-up period. Only one tuberculosis case was observed among the controls. The results demonstrate that persons with silicosis contracted in the mining, quarrying, and tunneling occupations are subject to an increased risk of lung cancer. The risk is observed when both the general population and a closely matched control population from the same occupations are used for values of reference. The results also demonstrate the high risk of persons with silicosis to contract lung tuberculosis.     

Testicular cancer among Swedish pulp and paper workers

BACKGROUND: The incidence of testicular cancer has increased in recent decades. The aims of the present study were to elucidate whether Swedish paper and pulp mill workers had an increased incidence of testicular cancer, and to investigate whether certain occupational groups within the pulp and paper mill workforce were at increased risk. METHODS: The study was based on the Swedish Cancer Environment Register, which links the incidence of cancer for the period 1971-1990 with 1960 and 1970 National Census data on specific industries and occupations for all employed subjects in Sweden. RESULTS: Among maintenance workers employed both in 1960 and in 1970 in paper mills there was an increased risk for testicular cancer (standardized incidence ratio (SIR) 7.4, 95% confidence intervals (CI) 1.5-22), especially for seminomas (SIR 10.1, 95% CI 2.1-29). Maintenance workers were also at increased risk when analyzing workers employed in 1960, 1970, or both years. CONCLUSIONS: This study indicates an increased risk for testicular cancer, especially seminomas, among maintenance workers, but not among process workers, in Swedish paper mills.     

The relationship between heart problems and mortality in different social classes

The aim of this study is to analyze how relative mortality risk varies between persons with and without heart problems in different social classes. Cox proportional hazards regression was used to analyze relative mortality risk for the period 1968-1996 for a Swedish nationally representative sample of 4585 persons born between 1892 and 1942, and interviewed 1968. Survivors from the original sample were also interviewed in 1974, 1981 and 1991 or 1992. "Heart problems" is defined as the presence of three mild or one severe symptom associated with circulatory problems. Social class is based on occupation. The relative mortality risk varied significantly between social classes and between persons with and without heart problems, among both men and women. These differences were smaller among women than among men. The main results are that there are significant additive interactions between social class and heart problems among men. Men from lower social classes have a more elevated mortality risk than men from higher social classes when they have a heart problem. Among white-collar workers the coefficient of the difference between men with and without heart problems was 0.53. The corresponding difference was significantly larger among workers (1.59, P = 0.01), thus demonstrating an additive interaction. The difference was even greater (1.86) among "unclassifiable" men--those who could not report an occupation that could be coded into a social class, mainly because they were long-term unemployed or on early-retirement pensions. Among women, the mortality difference between white-collar workers with and without heart problems was 0.85. None of the mortality differences between those with and without heart problems in other social classes differed significantly from those of white-collar workers. The mortality difference between women with and without heart problems was, however, large (2.34) among the "unclassifiable". This difference is even larger than the corresponding difference among men.     

Socioeconomic/occupational risk factors for lymphoproliferative diseases in Sweden

PURPOSE: The aim of the study is to investigate associations between socioeconomic and occupational factors and lymphoproliferative (LP) diseases. METHODS: We performed a follow-up study on the economically active Swedish population, based on the Swedish Family-Cancer Database. Standardized incidence ratios and 95% confidence intervals were calculated in different social classes and occupations. RESULTS: An increased risk for LP diseases was observed for physicians, plumbers, chemical process workers, and food manufacture workers among men and shoe and leather workers, mechanics, iron and metalware workers, and launderers and dry cleaners among women. CONCLUSIONS: Results suggest that socioeconomic and occupational factors have a minor effect on risk for LP diseases. Exposure to organic solvents may increase the risk for some LP diseases, although inconsistencies of findings between subcohorts do not rule out spurious associations.     

Occupations with increased risk of pancreatic cancer in the Swedish population

Aims: To identify occupations with increased risk of pancreatic cancer in the Swedish population gainfully employed in 1970 over the period 1971–89.

Methods: The base population was made up of Swedish men (1 779 646) and Swedish women (1 101 669) gainfully employed at the time of the 1970 census and were still alive and over age 24 on 1 January 1971. Information was drawn from two data sets: the Swedish cancer environment register and a background population register. After 19 years of follow up, 4420 men and 2143 women were diagnosed with histologically confirmed incident pancreatic adenocarcinoma. Log linear Poisson models were fitted, allowing for geographical area and town size. Risk estimators were also calculated for workers reporting the same occupation in 1960 and 1970.

Results: Among women, a statistically significant risk excess of pancreatic cancer was observed for "educational methods advisors", "librarian, archivist, curator", "motor vehicle driver", "typographer, lithographer", "purser, steward, stewardess", "other housekeeping and related workers", and the groups of occupations of "electrical, electronic, and related" and "glass, pottery, and tile workers". Men showed a higher incidence of pancreatic cancer among "technical assistants", "travelling agents", "other metal processing workers", "baker and pastry cook", "docker and freight handler", and "waiters".

Conclusions: This study does not indicate that occupational factors play an important role in the aetiology of pancreatic cancer in Sweden. Few occupations were at increased risk of pancreatic cancer in both men and women, and the associations observed are in accordance with some previous studies from Western countries.

     

Mortality in a Swedish rubber tire manufacturing plant: Occupational risks or an “unhealthy worker” effect?

BACKGROUND: In this cohort study a classification of 12 work categories, with specified common exposures, is used to evaluate the mortality among workers in a Swedish rubber tire plant. METHODS: Mortality among the cohort members is compared with expected values from national rates. Standardized mortality ratios (SMR) were calculated for the total cohort, for sub-cohorts and with the inclusion of a latency requirement. RESULTS: Male workers had increased risks for total mortality, circulatory death, respiratory death, mental disorders, epilepsy, injuries/poisoning, and for alcohol-related death. Many risks were noted among workers exposed to dust, fumes, or vapor. No trend in risk with increasing duration of employment was seen. DISCUSSION: Some established risks for rubber workers could be related to some specified work categories. The highest risks were noted among workers having a very short duration of employment indicating a possible "unhealthy worker effect" associated with life-style factors or to tasks offered to unskilled workers.     

Back and neck pain due to working in a cold environment: a cross-sectional study of male construction workers

Objective

To study whether work in a cold environment increased the risk of musculoskeletal symptoms in the neck and low back among construction workers.

Methods

This cross-sectional study is based on a cohort of male workers in the Swedish construction industry that participated in regular health examinations through a nationwide occupational health service. The analysis is based on workers examined from 1971 to 1974, who answered a questionnaire including questions about neck and back pain. The cohort consists of 134,754 male workers, including 16,496 office workers and foremen. The health examinations of the workers were conducted in provinces covering Sweden from the south to the north, and temperature data were collected for the provinces. In the analyses, the results were adjusted for age, BMI and use of nicotine.

Results

The prevalence’s of neck and low back pain were higher among manual construction workers than among foremen and office workers (24.3 vs. 8.6 % and 16.5 vs. 6.2 %, respectively); the corresponding adjusted ORs for low back and neck pain were 1.59 (95 % CI 1.52–1.66) and 1.39 (95 % CI 1.30–1.49), respectively. Workers in the northern and central provinces had higher ORs for low back and neck pain compared to workers in the southern province. The test for trends showed an increased risk of developing low back and neck pain with decreased outdoor temperature.

Conclusions

Outdoor work in a cold environment may increase the risk of low back and neck pain.     

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.     

Levels of 1-hydroxypyrene,symptoms and immunologic markers in vulcanization workers in the southern Sweden rubber industries

OBJECTIVES: The aim of this study was to determine urinary 1-hydroxypyrene (1-HP) levels in contemporary Swedish vulcanization workers and in controls. These levels were used as an index substance for vulcanization fumes, as well as a biomarker for polycyclic aromatic hydrocarbons (PAHs). The risk of symptoms and changed levels of immunologic markers were investigated in relation to the 1-HP levels. METHODS: Included in the study were 163 exposed workers and 106 controls. Medical and occupational histories were obtained by structured interviews. Symptoms were recorded and immunologic markers analysed in blood by routine analysis methods. Levels of 1-HP were determined by liquid chromatography and fluorescence detection. RESULTS: The highest levels of 1-HP were found among exposed workers using injection and compression vulcanization and lower levels were found among exposed workers vulcanizing with salt bath, hot air, microwaves or fluid-bed. Compared to controls, exposed workers had increased risks of eye symptoms, nosebleeds, burning and dry throat, hoarseness, severe dry cough, nausea and headache. Furthermore, exposed workers had elevated levels of neutrophils and total IgG (immunoglobulin subclass G). However, only for severe dry cough an evident exposure-response relationship with urinary 1-HP levels was found. CONCLUSIONS: This work clearly shows increased levels of urinary 1-HP in Swedish vulcanization workers. Furthermore, it demonstrates an increased risk of several symptoms and elevated levels of some immunologic markers in these workers. However, no obvious exposure-response relationships were found.     

Renal cell cancer among architects and allied professionals in Sweden.

The Swedish Cancer-Environment Registry was used to evaluate a recent report of a large excess risk of renal cell cancer among architects in Los Angeles. We identified 131 renal cell cancers among male Swedish architects and allied professionals during a 19-year follow-up period (1961-1979). Compared with the Swedish population, there was no significant excess of renal cell cancer among architects and allied professionals (standardized incidence ratio (SIR) = 1.15; 131 cases). Although it was not possible to estimate the risk for architects alone, the SIR was only 1.06 (16 cases) in a subset of professionals employed in architectural and engineering firms. However, a significant increase in risk (SIR = 1.38) was observed in a related group of workers employed as engineers and construction supervisors in the home construction industry.     

Gliomas among men employed in the Swedish pulp and paper industry

OBJECTIVES: This study investigated whether previous findings of an increased risk of gliomas among workers in some pulp and paper mills could be confirmed for all Swedish pulp and paper mill workers and whether the increase could be attributed to certain occupational groups. METHODS: The study was based on the Swedish Cancer Environment Register, which links the incidence of cancer from 1971 to 1990 and the 1960 and 1970 census data on codes of occupation and industry for the whole population. Standardized incidence ratios (SIR) were used to estimate the risks for men in different occupations in pulp (N = 28,142) and paper (N = 39,169) mills in 1960, 1970 or both years as compared with those of all gainfully employed men in Sweden. RESULTS: Maintenance workers employed in pulp or paper mills in 1960, 1970 or both years, as well aspulp workers, showed an increased incidence of gliomas in 1971-1990 [SIR 1.5, 95% confidence interval (95% CI) 1.1-2.1 and SIR 1.5,95% CI 1.0-2.2, respectively], whereas the incidence among process workers in paper mills was lower than expected (SIR 0.6, 95% CI 0.3-0.9). Taken together, all employed men in the pulp mill industry had an increased incidence of gliomas (SIR 1.3, 95% CI 1.0-1.7). CONCLUSIONS: Pulp mill workers, but not paper mill workers, were found to have more gliomas in 1971-1990 than expected. There was an increased risk of gliomas among maintenance workers in both pulp and paper mills. Few risk factors for brain tumors are recognized, and the causes of the increase are not obvious.     

Occurrences of leukemia subtypes by socioeconomic and occupational groups in Sweden

OBJECTIVE: The objective of this study was to examine the associations between socioeconomic/occupational factors and histologic subtypes of leukemia. METHODS: The Swedish Family-Cancer Database was used to calculate standardized incidence ratios for different social classes and occupational groups. RESULTS: The overall standardized incidence ratio was close to unity between different socioeconomic groups, except for female manual workers with a significantly decreased risk. Among male occupations, increased risks were noted for sales agents, seamen, and chemical process workers. For female occupations, increased risks were observed among mechanics, iron and metalware workers, hairdressers, and launderers and dry cleaners. CONCLUSIONS: The present study suggests that socioeconomic/occupational factors have a minor effect on the risk of leukemia. Occupational groups with possible exposure to organic solvents and other chemicals such as chemical process workers, mechanics, iron and metalware workers, and launderers and dry cleaners may entail true risk for leukemia.     

Non-Hodgkin's lymphomas and occupation in Sweden

Objectives: To investigate whether there is a risk excess of non-Hodgkin's lymphoma among Swedish workers associated with particular occupations. Methods: The base population was made up of Swedish men (1,779,646) and women (1,101,669) who were gainfully employed at the time of the 1970 census, had also been present in the 1960 census and were still alive and older than 24 years as of 1 January, 1971. They were followed up for 19 years until the end of 1989. Age- period standardised incidence ratios were computed in a dataset linking cancer diagnoses from the Swedish national cancer register to occupational and demographic data obtained in the census of 1970. Log-linear Poisson models were fitted, allowing for geographical area. Risk estimators per occupation were also computed for workers reporting the same occupation in 1960 and 1970, a more specifically exposed group. Results: There were 7,610 non-Hodgkin's lymphomas reported in the study cohort, 5,391 cases in men and 2,219 in women. A relative risk of over 1.20 and statistically significant was observed in men among accountants and auditors, secretaries and typists, auctionists, non-specified rail and road transport workers, telecommunications traffic officers, telegraph and radio operators, photographic-laboratory workers and other production and related work. The risk excess was confirmed in men with the same occupation in both censuses. In women, only three occupations achieved statistical significance: metal platers and coaters, truck and conveyor operators and store and warehouse workers. Conclusions: The risk excess observed in telecommunication and transport workers could be explained by electromagnetic radiation exposure. We did not find a risk excess in agricultural occupations, that has been largely documented by other study groups. Received: 3 August 2000 / Accepted: 30 March 2001     

Ischemic heart disease mortality among miners and other potentially silica-exposed workers

BACKGROUND: Some previous studies have observed an increased mortality regarding ischemic heart disease (IHD) among miners and industrial sand workers. The purpose was to study the occurrence of IHD mortality among silica-exposed workers. METHODS: Male miners, well borers, dressing plant workers, and other mine and stone workers were identified in the Swedish National Census of 1970. The total cohort (n = 11,896) was followed from 1970 until December 31, 1995 and linked to the Cause of Death Register. The referent group comprised all gainfully employed men identified in the same census. The Standardized Mortality Ratio was calculated as the ratio between observed and expected numbers of deaths. RESULT: An increased risk due to IHD mortality was observed among miners, well borers, dressing plant workers, and other mine and stone workers. CONCLUSION: These results indicate a possible relation between silica-dust exposure and IHD. The increased risk of IHD mortality is unlikely explained by smoking habits. Shift work might explain some of the increased risk. A low-grade inflammation in the lungs as a result of dust exposure is discussed as a possible cause. However, the key message is that better dose estimates and better confounding control is needed to study the possible relation between silica-dust exposure and IHD.     

Symptoms and immunologic markers among vulcanization workers in rubber industries in southern Sweden

OBJECTIVES: The aim of this study was to estimate the risk of symptoms and the possible derangement of levels of immunologic markers for contemporary Swedish rubber workers. Furthermore, the relation between exposure and these biomarkers of response was examined using urinary levels of 2-thiothiazolidine-4-carboxylic acid (TTCA), which reflect the exposure. METHODS: Included in the study were 166 exposed workers and 117 controls. Medical and occupational histories were obtained in structured interviews. Symptoms were recorded, and immunologic markers were analyzed in blood. Urinary levels of TTCA were determined by liquid chromatography tandem mass spectrometry. RESULTS: Compared with the controls, the exposed workers had increased risks of eye symptoms [odds ratio (OR) 3.0], nose bleeds (OR 4.0), burning and dry throat (OR 3.0), hoarseness (OR 2.4), severe dry cough (OR 3.8), nausea (OR 4.3), and headache (OR 2.5). When the exposed workers were divided into three groups according to the TTCA levels, the highest risks were observed among the exposed workers with intermediate TTCA levels. Furthermore, the exposed workers in all of the TTCA subgroups had elevated concentrations of total immunoglobulin G when compared with the controls. Elevated concentrations of leukocytes, neutrophils, and eosinophils were observed in the group with high TTCA levels. CONCLUSIONS: This work shows an increased risk of several symptoms and elevated levels of some immunologic markers among exposed workers in Swedish rubber industries. In addition, relationships between urinary levels of TTCA and some biomarkers of response were reported.     

Lung function in relation to 2-thiothiazolidine-4-carboxylic acid and genetic effect modification among rubber workers in Sweden

OBJECTIVE:: What is the risk of impaired lung function in contemporary Swedish rubber workers and are there modifying effects of genetic variants? METHODS:: Included in the study were 159 rubber exposed and 118 not-rubber exposed workers. Lung function was analyzed as forced vital capacity percent of predicted and forced expiratory volume in 1 second percent of predicted. Levels of 2-thiothiazolidine-4-carboxylic acid (a marker of carbon disulfide and vulcanization fumes) was assessed with liquid chromatography tandem mass spectrometry. Polymorphisms in glutathione-related genes were analyzed by Taqman-based allelic discrimination and ordinary polymerase chain reaction. RESULTS:: There was an association between increasing levels of 2-thiothiazolidine-4-carboxylic acid and impaired lung function among exposed workers. The association was modified by glutathione S-transferase alpha 1 (GSTA1)-52 and GSTP1-114. GSTM1 had an influence on lung function among unexposed workers. CONCLUSIONS:: There may be a risk of impaired lung function in contemporary rubber workers. Gene-modifying effects may be considered in risk assessments.     

Cancer morbidity in Swedish asphalt workers

BACKGROUND: Some studies have indicated an increased risk of lung cancer among asphalt workers. This study investigates the risk of lung cancer in Swedish asphalt workers. METHODS: A cohort of 6,150 asphalt workers, mainly employed in road construction, was compared to the general population, and to a reference group of construction workers not exposed to asphalt fumes. The exposure to polyaromatic hydrocarbons (PAH) at paving in Sweden during the 1980s and 1990s were estimated to be in the order of one or a few micrograms per cubic meter, but must have been higher in earlier years. RESULTS: Thirty-two lung cancer cases were observed among asphalt workers. The relative risk (SIR) and 95% confidence intervals were 0.98 (0.67-1.39). The corresponding relative risk, as compared to a group of construction workers and adjusted for smoking habits, was 1.03 (0.70-1.45). We found no increased risk for other cancers investigated or death in other lung diseases. CONCLUSIONS: Asphalt workers do not have any increased lung cancer risk from exposure to fumes and gases from asphalt at the exposure levels that occurred in Sweden during the 1960s and 1970s.     

Cancer incidence among Swedish pulp and paper mill workers: a cohort study of sulphate and sulphite mills

Purpose

Associations between various malignancies and work in the pulp and paper industry have been reported but mostly in analyses of mortality rather than incidence. We aimed to study cancer incidence by main mill pulping process, department and gender in a Swedish cohort of pulp and paper mill workers.

Methods

The cohort (18,113 males and 2,292 females, enrolled from 1939 to 1999 with >1 year of employment) was followed up for cancer incidence from 1958 to 2001. Information on the workers’ department and employment was obtained from the mills’ personnel files, and standardized incidence ratios (SIRs) were calculated using the Swedish population as reference.

Results

Overall cancer incidence, in total 2,488 cases, was not increased by work in any department. However, risks of pleural mesothelioma were increased among males employed in sulphate pulping (SIR, 8.38; 95 % CI, 3.37–17) and maintenance (SIR, 6.35; 95 % CI, 3.47–11), with no corresponding increase of lung cancer. Testicular cancer risks were increased among males employed in sulphate pulping (SIR, 4.14; 95 % CI, 1.99–7.61) and sulphite pulping (SIR, 2.59; 95 % CI, 0.95–5.64). Female paper production workers showed increased risk of skin tumours other than malignant melanoma (SIR, 2.92; 95 % CI, 1.18–6.02).

Conclusions

Incidence of pleural mesothelioma was increased in the cohort, showing that asbestos exposure still has severe health consequences, and highlighting the exigency of strict asbestos regulations and elimination. Testicular cancer was increased among pulping department workers. Shift work and endocrine disruptors could be of interest in this context.     

Exposures in the painting trades and paint manufacturing industry and risk of cancer among men and women in Sweden

Using data from the 1960 and 1970 Swedish censuses and the Swedish Cancer Register for 1971 to 1989, this study investigated variations in cancer risk by gender associated with employment in painting trades and paint manufacturing. Among men, standardized incidence ratios were significantly increased for lung cancer among painters and lacquerers; bladder cancer among artists; and pancreas cancer, lung cancer, and nonlymphocytic leukemia among paint and varnish plant workers. Risks for women were elevated for cancers of the esophagus, larynx, and oral cavity among lacquerers and for oral cancer among glaziers. These findings are consistent with the report of the International Agency for Research on Cancer that classified painting as an occupationally related cause of cancer and provide further evidence that the risk of certain cancers is increased by exposures in the paint manufacturing process.