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.     

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.     

Socioeconomic and occupational risk factors for pancreatic cancer: a cohort study in Sweden

OBJECTIVE: The objective of this study was to examine the associations between socioeconomic/occupational factors and pancreatic cancer. METHODS: The Swedish Family-Cancer Database was used to calculate standardized incidence ratios for different social classes and occupational groups. Lung cancer risks were also determined. The reference group was all the economically active population. RESULTS: Farmers were at a decreased risk of pancreatic cancer. A slightly increased risk of pancreatic cancer, independent of lung cancer, was observed for male professionals and administrators and managers. For women, increased risks were observed for cooks and stewards, and glass, ceramic, and tile workers. CONCLUSIONS: The results show that socioeconomic/occupational factors play a small role in the etiology of pancreatic cancer. In addition to smoking, physical inactivity and obesity may contribute to the observed differences.     

Socioeconomic and occupational groups and risk of asthma in Sweden

AIM: To investigate possible associations between hospitalization for asthma and socioeconomic status and occupation. METHODS: A nationwide database was constructed by linking Swedish Census data to the Hospital Discharge Register (1987-2004). The hospital diagnoses of asthma were based on the International Classification of Diseases. Standardized incidence ratios were calculated for different socioeconomic and occupational groups. Ninety-five per cent confidence intervals were calculated assuming a Poisson distribution. RESULTS: A total of 13,202 male and 11,876 female hospitalizations for asthma were retrieved at ages >30 years. The socioeconomic groups with < 9 years of education were associated with a significantly increased risk of hospitalization for asthma. Among male occupations, increased risks were noted for farmers, mechanics and iron and metal workers, welders, bricklayers, workers in food manufacture, packers, loaders and warehouse workers, waiters and chimney sweeps with prolonged exposures in two censuses. For female occupations, increased risks were observed among assistant nurses, religious, juridical and other social science-related workers, drivers, mechanics and iron and metalware workers and wood workers. CONCLUSIONS: The present study suggests that socioeconomic status (low educational level) and occupation have an effect on the population's risk of hospitalization for asthma.     

Incidence of Testicular Cancer and Occupation among Swedish Men Gainfully Employed in 1970

PURPOSE: To estimate occupation-specific risk of seminomas and nonseminoma subtypes of testicular cancer among Swedish men gainfully employed in 1970 over the period 1971–1989.

METHODS: Age-period standardized incidence ratios were computed in a dataset linking cancer diagnoses from the Swedish national cancer register to occupational and demographical data obtained in the census in 1970. Log-linear Poisson models were fitted, allowing for geographical area and town size. Taking occupational sector as a proxy for socioeconomic status, occupational risks were recalculated using intra-sector analyses, where the reference group comprised other occupations in the same sector only. Risk estimators per occupation were also computed for men reporting the same occupation in 1960 and 1970, a more specifically exposed group.

RESULTS: Seminomas and nonseminomas showed a substantial geographical variation. The association between germ-cell testicular tumors and high socioeconomic groups was found mainly for nonseminomas. Positive associations with particular occupations were more evident for seminomas, for which railway stationmasters, metal annealers and temperers, precision toolmakers, watchmakers, construction smiths, and typographers and lithographers exhibited a risk excess. Concrete and construction worker was the only occupation consistently associated with nonseminomas.

CONCLUSIONS: Among the many occupations studied, our results corroborate the previously reported increased risk among metal workers, specifically related with seminomatous tumors in this study. Our results confirm the geographical and socioeconomical differences in the incidence of testicular tumors. These factors should be accounted for in occupational studies. The different pattern of occupations related with seminomas and nonseminomas support the need to study these tumors separately.     

Misclassification of occupation-based socioeconomic position and gender comparisons of socioeconomic risk

AIMS: Because occupational classification systems tend to be less precise in the female sector of the working market there has been concern that this might imply more misclassification of socioeconomic position among women, biasing comparisons of gender-specific socioeconomic differences in risk. METHODS: The Stockholm Heart Epidemiology Program (SHEEP) is a population-based case-control study of risk factors for incident myocardial infarction. The study base included all Swedish citizens aged 45-70 in Stockholm County during 1992-94, 550 female and 1201 male cases, and 776 female and 1538 male controls. The use of an occupational classification as the base for categorizing socioeconomic position was compared with socioeconomic position based on detailed self-reported information on job titles and work tasks. RESULTS: Women are categorized into fewer occupational categories than men and the socioeconomic heterogeneity within occupational categories is substantial for women as has been reported by others. However, despite more occupational categories for male types of jobs the socioeconomic heterogeneity within occupational categories is actually larger for men, implying larger misclassification among men. In simulations with different levels of socioeconomic misclassification among women, the effects on the gender comparison of socioeconomic differences in disease risk were small and they were mostly compensated for by less misclassification among men. CONCLUSIONS: The findings do not support the assumption that misclassification of socioeconomic position among women due to a restricted working market and a crude occupational classification for female jobs is an important issue when comparing measures of socioeconomic inequalities in health between men and women.     

Occupation and upper aerodigestive tract cancers: a follow-up study in Sweden

OBJECTIVES: We sought to examine the associations between occupation and upper aerodigestive tract cancers at various anatomic sites. METHODS: The Swedish Family-Cancer Database was used to calculate standardized incidence ratios for different occupational groups, adjusted for age, period, and socioeconomic status. RESULTS: Male dentists showed an increased risk for tongue cancer; hairdressers had an increased risk for tongue and larynx cancers among men and pharynx cancer among women; launderers and dry cleaners showed an increased risk for pharynx cancer among men and lip cancer among women; outdoor occupations such as fishermen, seamen, transport, and construction workers showed increased risks for lip cancer. CONCLUSIONS: Although smoking and alcohol drinking can explain some of these results, increased risks found for dentists, hairdressers, and launderers and dry cleaners may partly be explained by their work-related exposures; increased risks of lip cancer in outdoor occupations can be explained by sunlight exposure.     

Occupational status, educational level, and the prevalence of carotid atherosclerosis in a general population sample of middle-aged Swedish men and women: results from the Malmö Diet and Cancer Study

The associations among educational level, occupational status, and atherosclerosis were investigated during 1992-1994 in a general population sample of 4,176 Swedish men and women. Carotid artery intima-media thickness (IMT) and carotid stenosis were determined by B-mode ultrasound. Socioeconomic differences in mean carotid IMT and odds ratios for carotid stenosis prevalence were estimated. In women, the associations among educational level, occupational status, and IMT were weak. In men, there was no association between education and IMT, while low occupational status was associated with a thicker IMT. Women with low education had an increased odds of carotid stenosis compared with women with high education (odds ratio (OR) = 2.04, 95% confidence interval (CI): 1.53, 2.73), while this pattern was weaker among men. Women in manual occupations had an increased odds of carotid stenosis compared with women in high- or medium-level nonmanual occupations (OR = 1.75, 95% CI: 1.29, 2.36), which could not be seen among men. After adjustment for risk factors, the association between IMT and occupational status in men disappeared, while the associations among educational level, occupational status, and carotid stenosis in women persisted. The results imply that the atherosclerotic process is associated with socioeconomic status in both sexes, and they also indicate the possibility of sex differences in the mechanisms connecting socioeconomic status to atherosclerosis.     

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.     

Socioeconomic differences in the progression of carotid atherosclerosis in middle-aged men and women with subclinical atherosclerosis in Sweden

While the persistence of socioeconomic differences in cardiovascular disease (CVD) has been recognized for many years, less is known about whether socioeconomic factors are of importance to CVD before symptoms of the disease appear. In this study the associations among educational level, occupational status and progression of atherosclerosis were investigated in 1016 Swedish middle-aged men and women with signs of subclinical atherosclerosis, i.e., carotid plaque (defined as focal intima-media thickness (IMT) > 1.2 mm). IMT in the common carotid artery (CCA) and in the carotid bifurcation area, as well as carotid plaque score, was determined by B-mode ultrasound. Results showed only weak associations between educational level, occupational status and age-, sex- and baseline IMT-adjusted progression of IMT in the CCA. However, in the age, sex- and baseline IMT-adjusted analyses, those in unskilled manual occupations showed a significantly higher yearly progression of carotid IMT in the bifurcation area compared to those in high- or medium-level non-manual occupations. Those with primary education tended to show a higher yearly progression of carotid IMT in the bifurcation area compared to those with completed secondary education. After adjustment for risk factors, the magnitude of these associations were somewhat attenuated. Similar patterns of associations were seen for the change of carotid plaque score. We conclude that low socioeconomic status (SES) is associated with progression of atherosclerosis in a middle-aged population with signs of subclinical atherosclerosis. Even though socioeconomic differences in cardiovascular risk factor levels could explain part of the found differences in progression rate in women, the mechanisms involved remain to be further established.     

Low job control and myocardial infarction risk in the occupational categories of Kaunas men, Lithuania

STUDY OBJECTIVE: To determine the association between adverse psychosocial characteristics at work and risk of first myocardial infarction in the occupational categories of Kaunas men, Lithuania. DESIGN: The analysis was based upon a case-control study among full time working men in the general population of Kaunas. OUTCOME MEASURE: First non-fatal myocardial infarction diagnosed in 2001-2002. The Swedish version of the demand-control questionnaire was used to examine the effect of job control and demands. SETTING: Kaunas, the second largest city in Lithuania, a former socialist country in a transition market economy. PARTICIPANTS: Cases were 203 men 25-64 years of age with a first non-fatal myocardial infarction and controls were 287 men group randomly selected from the study base. MAIN RESULTS: Low job control had a significant effect on myocardial infarction risk in the general 25-64 year old Kaunas male population (OR = 2.68; 95% CI 1.68 to 4.28) after adjustment for age and socioeconomic status. Low job control was a risk factor in the occupational categories of the increased myocardial infarction risk (1st occupational category--legislators, senior officials and managers and the 8th--plant and machine operators and assemblers; OR = 2.78; 95% CI 1.31 to 5.93 and 2.72; 95% CI 1.56 to 4.89, respectively, after adjustment for age and socioeconomic status). Though the adjusted odds ratio estimates were significantly high for the rest of the occupational categories (2nd--professionals, 3rd--technicians and associate professionals, and 7th--craft and related trades workers). CONCLUSIONS: The association between low job control and first myocardial infarction risk was significant for all occupational categories of Kaunas men.     

Does occupational social class predict coronary heart disease after retirement? A 12-year follow-up study in Sweden

AIMS: To examine whether socioeconomic status and coronary heart disease (CHD) risk factors remain significant predictors of CHD among people aged >or=65 years. Previous studies in this age group are few and inconsistent. METHODS: Follow-up study of a simple random sample of Swedish women and men aged >or=65 years interviewed in a national survey 1988-89 and followed up until 31 December 2000, for CHD incidence rates. Cox regression was used to study the association between socioeconomic status (occupation) and CHD, after adjustment for age, sex, physical activity, smoking, BMI, diabetes, and hypertension. Participants with CHD hospitalization two years before the start of the study and those who rated their general health as poor were excluded. RESULTS: Among manual workers and lower-level employees the risk of CHD was significantly higher than among middle-level employees and professionals (49% and 50%, respectively), after adjustment for age and sex. The association between low socioeconomic status and increased CHD risk disappeared after adjustment for the CHD risk factors, which were more prevalent among those with low socioeconomic status. All the CHD risk factors (with the exception of BMI) were associated with increased CHD incidence rates. CONCLUSIONS: Low socioeconomic status remains a significant predictor of CHD among people aged >or=65 years. Healthcare policies among elderly patients should encourage physical activity and smoking cessation in all socioeconomic groups.     

Breast cancer in women and occupation. A review of the evidence

Objective: To summarize current knowledge on occupations with an increased risk of breast cancer among women.Method: Review of all epidemiological studies published in the last 10 years on the relationship between female breast cancer and occupation. Previous studies that were repeatedly cited in subsequent publications were also included.Results: Secretaries, teachers, health professionals, pharmacists, workers in the chemical industry, telephone and radio operators and hairdressers were in the occupations most consistently reported to be high risk. Many of the studies reviewed were unable to take into account the influence of hormonal and reproductive factors or to allow for the strong influence of socioeconomic status, factors that are, moreover, interrelated. These factors would explain the high risk of some of the above-mentioned occupations, as well as the high incidence reported among female managers, professionals, and social and religious workers.Conclusion: These results suggest the existence of exposure or specific risk factors related to occupational environment, which would produce an increased incidence of breast cancer among the women exposed. Currently, it is difficult to disentangle the effect of occupational factors from those due to lifestyle and socioeconomic status. Nevertheless, from a public health point of view, women working in the above-mentioned occupations should be considered as being at higher risk and should be included in preventive and screening programs.     

Chronic diseases in self-employed French workers

OBJECTIVE: The objective of this study was to evaluate occupations associated with a high risk of specific chronic diseases in self-employed workers. METHODS: For each occupational category and gender, the observed and expected numbers of prevalent cases for each chronic disease leading to exemption from copayments by the French National Health Insurance System in 2001 were compared using the age-specific self-employed population rates as a reference. RESULTS: Dramatic discrepancies were observed depending on occupational categories, specifically for diabetes mellitus, cardiovascular diseases, mental health disorders, chronic respiratory insufficiency, severe liver disorders, and connective tissue diseases. CONCLUSIONS: Based on this extremely large dataset, several known associations between occupations and specific diseases were confirmed; other potential associations observed require future investigation.     

Stomach cancer and occupation in Sweden: 1971-89

Objectives: To examine the relation between gastric cancer and occupation among men and women gainfully employed in 1970 in Sweden for the period 1971–89 and, more specifically, to evaluate whether any excess of incidence of gastric cancer had also occurred among the subcohort of people reporting the same occupation in 1960 and 1970.

Methods: In both sexes and cohorts, relative risks adjusted for age, period of diagnosis, and geographical risk area were computed for occupational codes specified at one, two, or three level (occupational sector, occupational group, and occupation, respectively). Relative risks were calculated with all other occupations as reference and then, to take socioeconomic status into account, solely other occupations within the same occupational sector were used.

Results: Among men, occupations with increased risk included miners and quarrymen, construction and metal processing workers, supporting the possible causative role of dusty environments in stomach cancer. In men, the results also provide support for increased risks among electrical and mechanical engineers, fishermen, petrol station workers, motor vehicle drivers, butchers and meat preparers, dockers, freight handlers, launderers and dry cleaners. Furthermore, it is worth noting interesting results for women, whose occupational risks have been studied less. Excess risks were found for practical nurses, cashiers, bank employees, engineering and electronic industry workers, food industry, housekeeping and cleaning workers. Due to the many occupations studied, several significant associations may be expected by chance.

Conclusions: The study is explorative but provides support for the relations suggested previously between occupational exposure to dusty environments and stomach cancer, together with some new high risk occupations which should be further studied.

     

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.     

Cutaneous melanoma: hints from occupational risks by anatomic site in Swedish men

Aims: To improve knowledge of the epidemiology of melanoma by comparing occupational risks of cutaneous melanoma (CM) by anatomic site in Swedish workers.

Methods: Male workers employed in 1970 and living in the country in 1960 were followed up from 1971 to 1989 using the Swedish Registers of Death and Cancer. A more specifically exposed subcohort included men reporting the same occupation in 1960 and 1970. For each location, occupational risk ratios (RRs) were extracted from Poisson regression models adjusted by age, period, town size, and geographical area. To diminish the influence of socioeconomic factors, intrasector analyses, comparing only jobs belonging to the same occupational sector, were performed. Risk patterns for different locations were compared.

Results: High RRs for different sites were found among workers exposed to UV sources (dentists, physiotherapists, and lithographers), and sun exposed workers (harbour masters, and lighthouse/related work). Risk excesses were seen in fur tailors, tanners/fur dressers, patternmakers/cutters, electrical fitters/wiremen, telephone/telegraph installers/repairmen, and some glass/pottery/tile workers. Results for lower and upper limbs were significantly correlated but somewhat independent of those found in thorax, the most frequent location. Correlation between head/neck and thorax was moderate. Specific risk excesses were found for rolling mill workers in head/neck, for chimney sweeps in upper limbs, and for aircraft pilots/navigators/flight engineers in lower limbs.

Conclusions: High RRs in the trunk among occupations with UV exposure from artificial sources suggest an effect not restricted to exposed sites. An unusual distribution of cases and RRs in chimney sweeps, rolling-mill, or glass/pottery/tile workers suggests local effects of exposures. The not previously reported risk excess in this job and in fur related processes, and the RR in electrical fitters and telephone/telegraph installers deserve further investigation. Disparities between locations, as RRs in thorax and limbs, may reflect differences in aetiological mechanisms.

     

Socioeconomic status and cardiovascular disease among men: the Korean national health service prospective cohort study

OBJECTIVES: We examined the association between socioeconomic status (SES) and myocardial infarction and stroke subtypes, including the possible mediating influence of cardiovascular risk factors. METHODS: We evaluated data on 578756 Korean male public servants aged 30 to 58 years from August 1, 1990, to July 31, 2001. RESULTS: SES had inverse associations with mortality because of myocardial infarction and stroke subtypes, which were not changed by an adjustment for, or stratification by, cardiovascular risk factors. For nonfatal events, SES had positive, null, and inverse associations with myocardial infarction, ischemic stroke, and hemorrhagic stroke, respectively. The association between SES and nonfatal myocardial infarction depended on the presence of risk factors and was positive only among men who had cardiovascular risk factors. Case-fatality after hospital admission for cardiovascular diagnoses was significantly lower among higher SES groups, even after risk factor adjustment. CONCLUSIONS: Inverse SES associations with cardiovascular diseases were not mediated by cardiovascular risk factors among men who were undergoing economic transition. Socioeconomically patterned access to medical care may partly explain these socioeconomic gradients.     

Socioeconomic and occupational groups and Parkinson’s disease: a nationwide study based on hospitalizations in Sweden

Objectives  The aim of this study was to investigate whether there is an association between socioeconomic status, occupation and hospitalization for Parkinson’s disease (PD). Methods  A nationwide database was constructed by linking the Swedish Census to the Hospital Discharge Register to obtain data on all first adult hospitalizations for PD diagnosed in Sweden during the study period from 1987 to 2004. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were calculated. Results  A total of 8,870 males and 3,724 females first hospitalizations for PD were retrieved during the study period for adults aged 30 and older. Significantly increased SIRs for hospitalization for PD were found for men with high socioeconomic status. Among male occupations, increased SIRs were noted for several occupational groups such as teachers, administrators and managers, farmers, sales agents, wood workers, and painters and wall paperhangers. For female occupations, an increased risk was observed only among assistant nurses. The significant SIRs varied between 1.08 and 1.60. Conclusions  The socioeconomic and occupational groups used in the present study have a relatively small effect on the population’s likelihood of hospitalization for PD but could give a notion of future research on specific occupational exposures.     

Cancer morbidity in workers at aluminum foundries and secondary aluminum smelters

In a Swedish cohort of workers (n = 6,454) from seven aluminum foundries and three secondary aluminum (scrap) smelters there was no overall excess risk of cancer among male or female workers less than 85 years of age (males: 325 observed cases, standardized incidence ratio (SIR) 1.02, 95% confidence interval (CI) 0.91–1.13; females: 22 cases, SIR = 0.95, 95% CI = 0.60–1.44). In male workers, however, significantly elevated risk estimates were observed for cancer of the lung (51 cases; SIR = 1.49, 95%CI = 1.11–1.96), anorectal cancer (33 cases; SIR 2.13, 95%CI = 1.47–2.99), and sinonasal cancer (4 cases; SIR = 4.70, 95%CI = 1.28–12.01). There was no increase of urinary bladder or liver cancer. Lung cancer risks were highest in workers with a short duration of employment (<5 years) suggesting determinants of risk related to socioeconomic factors rather than the occupational environment under study, but there were also indications of a lung cancer hazard from sand casting of aluminum for 10 years or more (SIR = 2.10, 95%CI = 1.01–3.87). The increase in anorectal cancer could not be etiologically related to occupational determinants of risk. Sand casting of aluminum aside, the cancer risk in secondary aluminum smelting seems to be lower than in primary aluminum smelting and in iron and steel founding, respectively. Am. J. Ind. Med. 32:467–477, 1997. © 1997 Wiley-Liss, Inc.