Where do we go in occupational neuroepidemiology?
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Biomedical subjects
Publications and source records attributed to O Axelson.
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OBJECTIVES: The purpose of this study was to search for evidence of an association between occupational arsenic exposure and diabetes mellitus, as implied by the relation of this disease to arsenic in drinking water in a recent study from Taiwan. METHODS: A case-referent analysis on death records of 5498 individuals in the art glass producing part of southeastern Sweden was performed. Out of all the enrolled subjects, 888 were glass workers. According to occupational title, glassblowers, foundry workers, and unspecified workers were regarded as potentially exposed to arsenic. Persons with a diagnosis of diabetes mellitus either as an underlying or contributing cause of death were considered cases. Referents were decedents without any indication of cancer, cardiovascular disease, or diabetes. RESULTS: A slightly elevated risk [Mantel-Haenszel odds ratio (MH-OR) 1.2, 95% confidence interval (95% CI) 0.82-1.8] was found for diabetes mellitus among the glassworks employees, especially in combination with cardiovascular disease (MH-OR 1.4, 95% CI 0.81-2.3). For the glassblowers, other foundry workers and unspecified glassworkers probably exposed to arsenic, the M-H odds ratio was 1.4 (95% CI 0.92-2.2). Unspecified glass workers, who probably included persons with high exposure, carried the higher risk (MH-OR 1.8, 95% CI 1.1-2.8). CONCLUSIONS: The observations from this study provide limited support for the possibility that occupational arsenic exposure could play a role in the development of diabetes mellitus. Many other metallic compounds are also used in art glass production, however, and there is a possibility of confounding.
OBJECTIVES: Exposure to organic solvents increases the risk of neuropsychiatric disability or chronic toxic encephalopathy (CTE). Polymorphisms in the biotransformation of xenobiotics and solvents may influence individual susceptibility to develop toxic effects. In this study the problem of whether there could be any association between the glutathione S-transferase M1 (GSTM1) null genotype and the risk for CTE, with regard to solvent exposure, was investigated. METHODS: Sixty patients referred to a clinic because of some degree of psychiatric or neurological symptoms, as well as exposure to solvents, were examined by means of a validated questionnaire and psychometric testing. The degree of exposure to solvents was assessed by a thorough interview. According to clinical findings, the patients were classified into three categories as those with solvent-induced CTE, those with incipient CTE, and those who were non-CTE patients. Afterwards, leukocyte DNA (deoxyribonucleic acid) was isolated and the GSTM1 null genotype was determined by an assay based on polymerase chain reaction, blindly with regard to both exposure and disease status. RESULTS: The relative proportion (RP) of GSTM1 null genotypes was significantly increased for patients with a diagnosed CTE when they were compared with non-CTE patients (RP 2.55, 95% confidence interval 1.0-6.2). Dichotomizing the patients by high and low exposure revealed an increased risk for both GSTM1 gene carriers and the GSTM1 null genotype in the high-exposure group, the relative risks (RR) being 4.5 and 7.9, respectively. The chi-square for the Mantel extension for trend was 6.2 (P = 0.025). CONCLUSIONS: The GSTM1 null genotype acts as a risk modifier for CTE among patients occupationally exposed to solvents. The risk seems to increase in a dose-dependent fashion.
OBJECTIVES: This case-referent study was performed to investigate the possibility of nonspecific air pollution at workplaces increasing the risk of bronchial asthma for formerly healthy adults. METHODS: Seventy-nine cases of asthma, diagnosed at a lung clinic, among persons aged 20-65 years were compared with 304 referents drawn randomly from the population of the catchment area. Questionnaire information was obtained regarding occupation, exposure to suspect allergens, place of residence, smoking habits, and atopy. The subjects' occupations were categorized into four air pollution classes based on how the referents reported air pollution in their respective occupations. RESULTS: Three years or more of work in air-polluted occupations resulted in an odds ratio of 3.0 (OR) (95% confidence interval 1.5-6.1) in a comparison with work in occupations with slight or no air pollution. Stratification of the material for smoking habits or atopy did not alter the results. Nor did the exclusion of specific exposures to asthmatogenic agents such as ioscyanates, stainless steel welding, or aluminum salts change the effects of the nonspecific air pollution at workplaces. Smoking per se was associated with an almost doubled risk for asthma (OR 1.9, 95% confidence interval 1.1-3.4). CONCLUSION: The results of this study support an association between occupational exposure to nonspecific air pollution and the development of bronchial asthma.
This study was performed in order to evaluate how individual characteristics, as well as ergonomic, organizational and psychosocial factors in the work situation are associated with early symptoms in the neck and shoulder area. Nine hundred randomly drawn subjects of the working population in a semi-rural community in Sweden were mailed a questionnaire comprising the Nordic questionnaire on musculoskeletal symptoms, questions on ergonomic, organizational and psychosocial work conditions, life style factors, and background factors. The total response rate was 73% (n = 637). Questions on ergonomic work conditions and on organizational and psychosocial work conditions provided the measures of exposure. Prevalence ratios (PR) were calculated for symptoms in the neck and shoulder area as reported by 303 subjects. Significant determinants for early symptoms were being a female and being an immigrant, as were repetitive movements demanding precision. High work pace, low work content and work role ambiguity were significant organizational risk factors while life style characteristics did not appear as risk factors. The results suggest that symptoms are signals not only of ergonomic deficiencies in the work situation, but in particular of work organizational conditions. Special attention should be given to the work conditions of women and immigrants in preventive interventions.
The role of smoking and air pollution in bronchial asthma in otherwise healthy adults is still unclear. We compared 79 cases of asthma, diagnosed between ages 20 and 65 years, with 304 randomly drawn population controls of similar age from the same catchment area as the cases. The comparison involved questionnaire information on smoking habits, occupational exposures, dwelling conditions, various suspect allergenic exposures, and atopy. Those who had smoked for 3 years or more, present or past, were at increased risk for bronchial asthma (odds ratio = 1.9; 95% confidence interval = 1.1-3.3). Adjustment by multiple logistic regression for age and gender as well as atopy and air pollution at work did not change the relative risk estimate. Exposure to environmental tobacco smoke, or passive smoking, at work involved a slightly greater risk.
Amyloidosis is associated with the deposition of amyloid substance in various tissues of the body. In several forms of familial amyloid polyneuropathy, mutated transthyretin is the main fibril component. The disease is inherited as an autosomal dominant trait with onset in adult life, but few carriers develop symptoms. The aim of the present investigation was to screen for additional factors that might be necessary for the development of familial amyloid polyneuropathy. We conducted a case-control study involving 51 male and 30 female cases of clinically overt familial amyloid polyneuropathy and 306 male and 317 female population controls. We considered occupational exposures, disease histories, and medical treatments as potential determinants of risk for clinically overt disease. We found an odds ratio of 5.4 for dressmakers. Low and high levels of exposure to organic solvents resulted in an odds ratio of 2.1 and 11.8, respectively. A history of prostatic hyperplasia, cholecystic disease, or appendectomy was also a risk factor, possibly as a consequence of anesthesia.
Major advances in molecular biology during recent years have helped to identify genes and enzymes that play an important role in many diseases. While not ruling out traditional forms of epidemiology, the application of epidemiologic study designs in molecular biological studies may provide possibilities of disclosing disease mechanisms at the gene level and identifying more specific indicators of disease. Data on adducts to DNA or protein usually lead to cross-sectional studies or cohorts. Genetically determined susceptibility or mutations in tumor cells might be available and possibly reflect etiologically important determinants. The case-control design is applicable and cost-effective for the analysis of such data.
OBJECTIVES: To find out whether a newly found association between diabetes mellitus and arsenic in drinking water in Taiwan could be reproduced in copper smelters with arsenic exposure. METHODS: Extended analysis of a previous case-control study from 1978 was based on death records and objective exposure information from the company. The final analysis included only those employed at the smelter. Cases were 12 people with diabetes mellitus on the death certificate and those for whom there was clinical information on this disease. Controls were 31 people without cancer, cardiovascular and cerebrovascular disease as these disease categories had been associated with arsenic exposure in the original study and elsewhere. RESULTS: The odds ratios found for diabetes mellitus with increasing arsenic exposure categories were (reference level = 1), 2.0, 4.2, and 7.0, but the 95% confidence intervals included unity. Unstratified test for trend was weakly significant, P = 0.03. CONCLUSIONS: Although based on small numbers, the findings provide some support for the suggestion that arsenic exposure could sometimes play a part in the development of diabetes mellitus.
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Exposure to radon and its decay products in mines is a well recognized risk of lung cancer in miners. A large number of epidemiologic studies from various countries are quite consistent in this respect even it the magnitude of the risk differs according to exposure levels. Indoor radon became a concern in the 1970s and about a dozen studies have been conducted since 1979, mainly of the case-control design. From first being of a simple pilot character, the designs have become increasingly sophisticated, especially with regard to exposure assessment. Crude exposure estimates based on type of house, building material and geological features have been supplemented or replaced by quite extensive measurements. Still, exposure assessment remains a difficult and uncertain issue in these studies, most of which indicate a lung cancer risk from indoor radon. Also a recent large scale study has confirmed a lung cancer risk from indoor radon. More recently there are also some studies, mainly of the correlation type, suggesting other cancers also to be related to indoor radon, especially leukemia, kidney cancer, and malignant melanoma, and some other cancers as well. The data are less consistent and much more uncertain than for indoor radon and lung cancer, however; and there is no clear support from studies of miners in this respect.
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BACKGROUND: Residential radon is the principal source of exposure to ionizing radiation in most countries. To determine the implications for the risk of lung cancer, we performed a nationwide case-control study in Sweden. METHODS: The study included 586 women and 774 men 35 to 74 years of age with lung cancer that was diagnosed between 1980 and 1984. For comparison, 1380 female and 1467 male controls were studied. Radon was measured in 8992 dwellings occupied by the study subjects at some time since 1947. Information on smoking habits and other risk factors for lung cancer was obtained from questionnaires. RESULTS: Radon levels followed a log-normal distribution, with geometric and arithmetic means of 1.6 and 2.9 pCi per liter (60.5 and 106.5 Bq per cubic meter), respectively. The risk of lung cancer increased in relation to both estimated cumulative and time-weighted exposure to radon. In comparison with time-weighted average radon concentrations up to 1.4 pCi per liter (50 Bq per cubic meter), the relative risk was 1.3 (95 percent confidence interval, 1.1 to 1.6) for average radon concentrations of 3.8 to 10.8 pCi per liter (140 to 400 Bq per cubic meter), and it was 1.8 (95 percent confidence interval, 1.1 to 2.9) at concentrations exceeding 10.8 pCi per liter. The estimates of risk were in the same range as those projected from data in miners. The interaction between radon exposure and smoking with regard to lung cancer exceeded additivity and was closer to a multiplicative effect. CONCLUSIONS: Residential exposure to radon is an important cause of lung cancer in the general population. The risks appear consistent with earlier estimates based on data in miners.
The mortality pattern of taxi drivers in Rome as possibly exposed mainly to gasoline engine exhausts was evaluated by means of a historical cohort study. A total of 2,311 male subjects registered as taxi drivers between 1950 and 1975 was followed from 1965 through 1988. The overall mortality was lower than expected on the basis of regional (Latium) reference rates (692 deaths, standardized mortality ratio [SMR] = 0.89, 95% confidence interval [CI] 0.82-0.96), whereas the number of recorded deaths for malignant neoplasms was about the expected (205 deaths, SMR = 0.99, 95% CI 0.86-1.13). Mortality from circulatory and respiratory diseases was lower than expected. Diabetes was significantly increased (42 deaths, SMR = 1.73, 95% CI = 1.25-2.34). An increased SMR appeared for respiratory cancer (SMR = 1.23, 95% CI = 0.98-1.50), mainly due to lung cancer (observed [O] = 76, SMR = 1.23, 95% CI = 0.97-1.54); two pleural cancers were also recorded. The excess of lung cancer deaths was present only among those enrolled in the most recent period (1965-1975) (45 deaths, SMR = 1.40, 95% CI = 1.02-1.87), especially among those of younger age (< 65 years) (SMR = 1.86); there was no relation between lung cancer mortality and latency since first enrollment in the cooperatives or duration of membership. There are difficulties in interpreting the excess of lung cancer on the basis of occupational exposures; however, the increased risk observed among workers employed in more recent calendar periods may be due to heavier exposure in the last decades; further follow-up of the cohort may elucidate whether there is an increasing lung cancer risk among taxi drivers.
OBJECTIVES: Benzene is an established animal and human carcinogen. The mechanism of benzene toxicity, particularly its leukaemogenic effect, is not fully understood. The modified base 8-hydroxy-deoxyguanosine (8-OHdG) is a sensitive marker of the DNA damage due to hydroxyl radical attack at the C8 of guanine. This damage, if left unrepaired, has been proposed to contribute to mutagenicity and cancer promotion. We conducted this biomonitoring study with the aim of evaluating the association between excretion of 8-OHdG and level of exposure to benzene and other aromatic compounds among occupationally exposed people. METHODS: A random sample of 65 filling station attendants from Rome, Italy was studied for personal exposure to benzene, toluene, and xylenes, and excretion of 8-OHdG. Information about age, length of employment, smoking habits, and diagnostic exposure to x rays was collected by questionnaire. An average yearly level of exposure to benzene and methylbenzenes was calculated for each filling station attendant on the basis of about seven repeated personal samples collected during one year. A spot sample of 20 ml of urine was collected from each worker. Concentrations of 8-OHdG were determined by high performance liquid chromatography (HPLC) with coupled columns. RESULTS: A mean (SD) concentration of 1.36 (0.49) mumol of 8-OHdG/mol of creatinine was measured. A significant correlation was found between urinary 8-OHdG and exposure to benzene (r = 0.34). In a multiple regression analysis relating the concentration of urinary 8-OHdG with the age, length of employment, smoking, diagnostic exposure to x rays and personal exposure to benzene, an increase of 0.15 mumol/mol creatinine in urinary 8-OHdG/unit increase in the natural logarithm of the average yearly benzene concentration was estimated. CONCLUSION: This study shows a dose-response effect between personal exposure to benzene and urinary 8-OHdG concentration; further studies are needed to clarify the biological significance of 8-OHdG as a marker of cancer risk.
OBJECTIVE: To evaluate the effects of an early, active, and multidisciplinary rehabilitation programme for neck and shoulder disorders. METHODS: Primary health care and industrial health care of a nonrandomised, controlled, cohort was followed up over two years in a geographically defined area. The cohort consisted of working people who consulted a physician about disorders of the neck or shoulders from 1 August 1988 to 31 October 1989. Criteria for acceptance; not chronic symptoms, patients had sick leave of no more than four weeks. Disorders were not caused by trauma, infections, malignancy, rheumatic diseases, abuse, or pregnancy. 107 people qualified for the study, 87% were followed up for two years. They were divided into two groups. One group obtained active, multidisciplinary rehabilitation for eight weeks that comprised physical training, information, education, social interaction, and work place visits. Controls were given traditional treatment; physiotherapy, medication, rest, and sick leave. The main outcome measures were: average number of days of sick leave for the two years after rehabilitation, subjective pain on a visual analogue scale, and ratings on seven subscales of the sickness impact profile. RESULTS: At 12 and 24 months of follow up effects of the active rehabilitation programme did not differ from traditional treatment in any of the outcome measures. New work task (P < 0.05) or changed work place (P < 0.001) during the follow up period were associated with decreased sick leave, independent of treatment. CONCLUSIONS: Active, multidisciplinary rehabilitation of neck and shoulder disorders was not more effective than traditional treatment. Changed work conditions were associated with decreased sick leave, independent of type of treatment provided.
A case-control study was performed to elucidate the strength of the relation between musculoskeletal disorders in the neck and shoulders and physical, organisational, and psychosocial aspects of the work environment. Cases were identified as those persons who consulted a physician in a community in southern Sweden for new musculoskeletal disorders in the neck and shoulders during a study period from August 1988 to the end of October 1989. One hundred and nine cases were collected and clinically examined. The cases also answered the Nordic questionnaire on symptoms as well as a questionnaire on work conditions and background factors. Controls were drawn as a random sample of the working population in the community where the cases appeared. A total of 637 controls answered the same questionnaires as the cases. Odds ratios (ORs) were calculated by logistic regression. The odds ratios were 11.4 for women, 4.9 for immigrant background, and 3.7 for current smoking. To exercise rarely, compared with often, appeared as a preventive factor with an OR of 0.3. The ORs for various determinants of physical work load were 7.5 for repetitive movements demanding precision, 13.6 for light lifting, 3.6 for uncomfortable sitting positions, 4.8 for work with lifted arms, and 3.5 for a rushed work pace. Regarding work organisational determinants, the ORs were 16.5 for ambiguity of work role (uncertainty whether the person could manage the work) 2.6 for low quality work, and 3.8 for high demands on attention. Several of the determinants showed a significant dose-response relation with disease. It seems that work organisation and psychosocial work conditions are as important determinants for disease in the neck and shoulders as are the physical work conditions.