Showing papers in "Scandinavian Journal of Work, Environment & Health in 2001"

Burnout and engagement at work as a function of demands and control.

Abstract: Objectives The present study was designed to test the demand-control model using indicators of both health impairment and active learning or motivation. Methods A total of 381 insurance company employees participated in the study. Discriminant analysis was used to examine the relationship between job demands and job control on one hand and health impairment and active learning on the other. Results The amount of demands and control could be predicted on the basis of employees' perceived health impairment (exhaustion and health complaints) and active learning (engagement and commitment). Each of the four combinations of demand and control differentially affected the perception of strain or active learning. Job demands were the most clearly related to health impairment, whereas job control was the most clearly associated with active learning. Conclusions These findings partly contradict the demand-control model, especially with respect to the validity of the interaction between demand and control. Job demands and job control seem to initiate two essentially independent processes, and this occurrence is consistent with the recently proposed job demands-resources model.

Consequences of workplace bullying with respect to the well-being of its targets and the observers of bullying.

Abstract: Objectives This study investigated the effects of workplace bullying and the psychological work environment on the well-being and subjective stress of the targets and observers of bullying. Methods In a questionnaire study, stress and psychological ill-health were measured, and the causes of reported stress were analyzed for municipal employees (N=949, 85% women, 15% men, mean age 41 years for the men and 40 years for the women). Results Both the targets of bullying and the observers reported more general stress and mental stress reactions than did respondents from the workplaces with no bullying. The targets also expressed feelings of low self-confidence more often than did those who had not been subjected to bullying. Being bullied, but also features of one`s work, especially haste, excessively difficult tasks and poor goal clarity, predicted the stress reactions reported. Of the single forms of bullying, judging a person`s work unjustly or in an offending manner, restricting a person`s possibilities to express his or her opinions, and assaulting one`s private life were the most clearly connected with all the stress reactions measured. Victim history was associated with feelings of low self-confidence. The targets of bullying used sleep-inducing drugs and sedatives more often than did the respondents who were not bullied. Conclusions The study shows that not only the targets of bullying, but also bystanders, suffer when someone is bullied in the workplace. Bullying must therefore be regarded as a problem for the entire work unit and not merely as a problem of the target.

Epidemiologic estimate of the proportion of fatalities related to occupational factors in Finland.

Abstract: Results The attributable fraction of work-related mortality in the relevant disease and age categories was estimated to be 7% (10% for men and 2% for women), and for all diseases and ages the fraction was 4%. For the main cause-of-death categories, the attributable fraction became 12% for circulatory system diseases, 8% for malignant neoplasms, 4% for respiratory system diseases, 4% for mental disorders, 3% for nervous system diseases, and 3% for accidents and violence. The following estimates were obtained for specific important diseases: 24% for lung cancer, 17% for ischemic heart disease, 12% for chronic obstructive pulmonary disease, and 11% for stroke. Based on these fractions, the total number of work-related deaths that occurred in Finland in 1996 was calculated to be on the order of 1800 (employed work force of 2.1 million); 86% involved men. Conclusions High-quality epidemiologic studies and national survey data are essential for obtaining reliable estimates of the proportion of deaths attributable to occupational factors. The magnitude of work-related mortality is an insufficiently recognized contributor to total mortality in Finland, especially from circulatory diseases and other diseases caused by exposure to agents other than asbestos. Key terms attributable fraction, burden of disease, epidemiologic methods, health statistics, occupational exposure.

Association between job stress and depression among Japanese employees threatened by job loss in a comparison between two complementary job-stress models.

Abstract: Objectives This study compared the separate effects produced by two complementary stress models - the job demand-control model and the effort-reward imbalance model - on depression among employees threatened by job loss. Methods A cross-sectional analysis was conducted to examine these associations among 190 male and female employees who responded to a self-administered questionnaire in a small Japanese plant with economic hardship. The employees were engaged in 2 job types - direct assembly line and indirect supportive tasks - and the latter was threatened by job loss because of downsizing. Independent variables were measured by the Japanese versions of Karasek`s demand-control questionnaire and Siegrist`s effort-reward imbalance questionnaire. Depression was assessed by the Center for Epidemiologic Studies Depression Scale. Results The employees with indirect supportive tasks (target for downsizing) were more likely to have depressive symptoms than direct assembly-line workers. Job strain, a combination of high demand and low control at work, was more frequent among the latter, while the combination of high effort and low reward was more frequent among the former. After adjustment for work environment factors, low control [odds ratio (OR) 4.7], effort reward imbalance (OR 4.1), and overcommitment (the person characteristic included in the effort-reward imbalance model) (OR 2.6) were independently related to depression. There is some indication that these effects were particularly strong in the subgroup suffering from potential job loss. Conclusions This study confirms that the 2 job stress models identify different aspects of stressful job conditions. Moreover, effort-reward imbalance and low control at work are both associated with symptoms of depression.

Health effects of occupational exposure to acrylamide using hemoglobin adducts as biomarkers of internal dose

Abstract: OBJECTIVES: This study assessed the health effects of occupational acrylamide exposure using hemoglobin (Hb) adducts as biomarkers of internal dose. METHODS: Two hundred and ten tunnel workers exposed for about 2 months to a chemical-grouting agent containing acrylamide and N-methylolacrylamide underwent a health examination. Blood samples were drawn for the analysis of Hb adducts of acrylamide. Fifty workers claiming recently developed or deteriorated symptoms of the peripheral nervous system (PNS) were referred to a neurophysiological examination. Workers with Hb-adduct levels exceeding 0.3 nmol/g globin attended follow-up examinations 6, 12, and 18 months after exposure cessation. RESULTS: Forty-seven workers had Hb-adduct levels within the normal background range (0.02-0.07 nmol/g globin), while the remaining 163 had increased levels up to a maximum of 17.7 nmol/g globin. Clear-cut dose-response associations were found between the Hb-adduct levels and PNS symptoms. Thirty-nine percent of those with Hb-adduct levels exceeding 1 nmol/g globin experienced tingling or numbness in their hands or feet. A no-observed adverse effect level of 0.51 nmol/g globin was estimated for numbness or tingling in the feet or legs. For 23 workers there was strong evidence of PNS impairment due to occupational exposure to acrylamide. All but two had recovered 18 months after the cessation of exposure. CONCLUSIONS: Occupational exposure to a grouting agent containing acrylamide resulted in PNS symptoms and signs. The use of Hb adducts of acrylamide as a biomarker of internal dose revealed strong dose-response associations. The PNS symptoms were, however, generally mild, and in almost all cases they were reversible.

Questionnaire versus direct technical measurements in assessing postures and movements of the head, upper back, arms and hands.

Abstract: OBJECTIVES: This study compares questionnaire-assessed exposure data on work postures and movements with direct technical measurements. METHODS: Inclinometers and goniometers were used to make full workday measurements of 41 office workers and 41 cleaners, stratified for such factors as musculoskeletal complaints. The subjects answered a questionnaire on work postures of the head, back, and upper arms and repeated movements of the arms and hands (3-point scales). The questionnaire had been developed on the basis of a previously validated one. For assessing worktasks and their durations, the subjects kept a 2-week worktask diary. Job exposure was individually calculated by time-weighting the task exposure measurements according to the diary. RESULTS: The agreement between the self-assessed and measured postures and movements was low (kappa = 0.06 for the mean within the occupational groups and kappa = 0.27 for the whole group). Cleaners had a higher measured workload than office workers giving the same questionnaire response. Moreover, the subjects with neck-shoulder complaints rated their exposure to movements as higher than those without complaints but with the same measured mechanical exposure. In addition, these subjects also showed a general tendency to rate their postural exposure as higher. The women rated their exposure higher than the men did. CONCLUSIONS: The questionnaire-assessed exposure data had low validity. For the various response categories the measured exposure depended on occupation. Furthermore, there was a differential misclassification due to musculoskeletal complaints and gender. Thus it seems difficult to construct valid questionnaires on mechanical exposure for establishing generic exposure-response relations in epidemiologic studies, especially cross-sectional ones. Direct technical measurements may be preferable. (Less)

Upper-limb disorders in repetitive work

Abstract: Objectives A longitudinal study was conducted to determine the predictability of personal and occupational factors with respect to the incidence of upper-limb disorders in occupations requiring repetitive work. Methods A sample of 598 workers in five activity sectors completed a self-administered questionnaire; the workers were examined by an occupational health physician in 1993-1994 and 3 years later. Three disorders were considered, carpal tunnel syndrome (CTS), lateral epicondylitis and wrist tendinitis. Results The results of this longitudinal study indicated that the following three sets of risk factors independently affect the incidence of upper-limb disorders: (i) biomechanical constraints, (ii) psychosocial factors, and (iii) personal factors. The combination of risk factors differed between CTS, lateral epicondylitis, and wrist tendinitis. The presence of psychosomatic problems was a strong predictor of wrist tendinitis. Social support at work was also associated with the incidence of wrist tendinitis. The presence of depressive symptoms and other upper-limb disorders predicted the first occurrence of lateral epicondylitis. Age was associated only with epicondylitis. The results were consistent with those concerning the role of forceful movements of the elbow for epicondylitis and confirmed the role of forceful movements for CTS. Conclusions This study considered different sets of risk factors simultaneously with a longitudinal approach, in a population with a high level of occupational exposure. The results indicate that three sets of risk factors independently affect the incidence of upper-limb disorders. In addition to biomechanical constraints, psychosocial and personal factors play a role.

Prevalence and occupational associations of neck pain in the British population

Abstract: Objectives This study determined the prevalence of neck pain and its relation to occupation and occupational activities in the general population. Methods A questionnaire was mailed to 21 201 subjects aged 16-64 years, randomly selected from the patient registers of general practices in England, Scotland, and Wales, and to 993 subjects randomly selected from pay records of the armed services. Information was collected on occupation, workplace physical activities, neck pain in the past week and year, headaches, and feelings of tiredness or stress. Associations were explored by logistic regression, the resultant odds ratios being converted to prevalence ratios (PR). Results Among 12 907 respondents, 4348 and 2528 reported neck pain in past year (1421 with pain interfering with normal activities) and week, respectively. Symptoms were the most prevalent among male construction workers [past week and year 24% and 38% (pain interfering with activities 11%), respectively], followed by nurses, armed services members, and the unemployed. Generally the age-standardized prevalence of neck pain varied little by occupation. Work with arms above the shoulders for >1 hours/day was associated with a significant excess of symptoms [PR 1.3-1.7 (women) and 1.2-1.4 (men)], but no associations existed for typing, lifting, vibratory tool use, or professional driving. Stronger neck-pain associations were found with frequent headaches (PR 2.3-2.8) and frequent tiredness or stress (PR 2.2-2.5) than with occupational activities. Conclusions The data provide evidence against a strong association between neck pain and the examined occupational physical activities. They suggest that psychosocial factors may be more important.

Psychosocial work characteristics and psychological strain in relation to low-back pain

Abstract: Objectives This study investigated the relationship between psychosocial work characteristics and low-back pain and the potential intermediate role of psychological strain variables in this relationship. Methods The research was part of a prospective cohort study of risk factors for musculoskeletal symptoms. The study population consisted of 861 workers from 34 companies in The Netherlands who had no low-back pain at baseline and for whom data on the occurrence of low-back pain were obtained with annual questionnaires during a 3-year follow-up period. Information on psychosocial work characteristics and psychological strain variables was collected using a questionnaire at baseline. Cases of low-back pain were defined as workers who reported, in at least one of the annual follow-up questionnaires, that they had had regular or prolonged low-back pain in the previous 12 months. Results After adjustment for individual factors and quantified physical load at work, nonsignificant relative risks ranging from 1.3 to 1.6 were observed for high quantitative job demands, high conflicting demands, low supervisory support, and low co-worker support. Decision authority and skill discretion showed no relationship with low-back pain. In general, the estimated relative risks for the psychosocial work characteristics were scarcely influenced by additional adjustment for job satisfaction, emotional exhaustion, and sleeping difficulties. Conclusions It can be concluded that low social support, from either supervisors or co-workers, appears to be a risk factor for low-back pain. Some indications of a relationship between high quantitative job demands and high conflicting demands and low-back pain were also found. Little evidence was found for an intermediate role for the psychological strain variables under study.

Asthma risk, cleaning activities and use of specific cleaning products among Spanish indoor cleaners.

Abstract: Objectives Recent studies have shown an excess risk of asthma for cleaners, but it is not clear which cleaning-related exposures induce or aggravate asthma. Methods Risk factors for asthma were studied among indoor cleaners participating in the Spanish part of the European Community Respiratory Health Survey in 1992. In 1998, 78 of the 91 subjects reporting cleaning-related jobs in 1992 were identified. Of these, 67 indoor cleaners were interviewed by telephone about their cleaning activities and their use of cleaning products in 1992. These data were related to asthma prevalence in 1992, and the cleaners were compared with a reference group of office workers. Results Asthma prevalence was 1.7 times higher [95% confidence interval (95% CI) 1.1-2.6] among the cleaners than among the referents, being highest among private home cleaners (3.3, 95% CI 1.9-5.8). The prevalence of housedust mite sensitization amounted to 28% for the home cleaners and was significantly (P<0.01) higher than for other indoor cleaners (3%), but similar to the corresponding prevalence of office workers (22%). More than half of the cleaners reported work-related respiratory symptoms. The asthma risk of the home cleaners was mainly associated with kitchen cleaning and furniture polishing, with the use of oven sprays and polishes. Conclusions The asthma risk of Spanish cleaners is primarily related to the cleaning of private homes. This relationship may be explained by the use of sprays and other products in kitchen cleaning and furniture polishing.

Work environment of Danish shift and day workers.

Abstract: Objectives Both shift work and other work environment factors have been shown to be related to heart disease. This study examined whether shift work is associated with other work environment factors related to heart disease in a random sample of the population. If so, shift work could be acting as a proxy for work environment differences. Methods Data on 5940 employees in the Danish Work Environment Cohort Study from 1990 were reanalyzed. The information included work schedules [permanent day work, irregular workhours (including morning work), 2-shift or fixed evening and 3-shift or fixed night], length of workweek, physical factors (noise, heat, dust, passive smoking, walking, standing and monotonous repetitive tasks), and psychosocial factors (including demands and control dimensions, social support, conflicts and job insecurity). Results At least 1 group of shift workers had a higher prevalence of nearly every unfavorable work environment factor investigated. Exceptions were dust exposure and quantitative demands. Especially conflicts at work and low decision latitude were higher among all the groups of shift workers, and all-day walking or standing work and part-time jobs were more often found among female shift workers. The 3 different shiftwork groups were exposed to different parts of the work environment, and also men and women in shift work differed in relation to the work environment. Age and social class influenced the relationship, but not in any particular pattern. Conclusions In a heterogenous population shift work was found to be associated with other work environment factors suspected to cause heart disease.

Contingent employment, health and sickness absence

Abstract: OBJECTIVES: This study explored the health and sickness absences of contingent employees. METHODS: Analyses of self-reported health and recorded spells of sickness absence were based on a cohort of 5650 employees (674 men, 4976 women) in 10 Finnish hospitals. RESULTS: After adjustment for demographic and work-related characteristics, contingent employees had a better self-rated health status [odds ratio 0.76, 95% confidence interval (95% CI) 0.62-0.94 of poor or average health status]. There were no differences in the prevalence of diagnosed chronic diseases and minor psychiatric morbidity between the groups. After adjustment for self-rated health and confounding, female, but not male, contingent employees had a lower rate of self-certified (1-3 days) sickness absences than permanent employees (rate ratio 0.90, 95% CI 0.85-0.95). Contingent employees, irrespective of gender, had a 0.77 (95% CI 0.71-0.84) times lower rate of medically certified (>3 days) sickness absence than permanent employees. Poor self-rated health status, reported diagnosed chronic diseases, and minor psychiatric morbidity were associated with medically certified absences to a less extent among contingent employees than among permanent employees. CONCLUSIONS: These findings suggest better self-rated health and a lower sickness absence rate for contingent employees than for permanent employees. The difference in sickness absence between the groups seems not only to be associated with actual differences in health, but also with different thresholds of taking sick leave or working while ill.

Hearing loss among workers exposed to moderate concentrations of solvents

Abstract: Objectives It is known that some industrial organic solvents are ototoxic. This study was aimed at evaluating the hearing effects of a mixture of organic solvents alone or in combination with noise on employees in paint and lacquer enterprises. The concentration of solvents was below the occupational exposure limits (OEL) for most of the subjects. Methods Altogether 517 subjects were divided into the following three groups: persons with no risk due to noise or organic solvent exposure at the workplace, workers exposed to organic solvents only, and workers exposed to both organic solvents and noise. Results The relative risk (RR) of hearing loss in the solvent-only exposure group was significantly increased (RR 4.4 and RR 2.8 for noise exposure of <80 dB-A and <85 dB-A, respectively) in a wide range of frequencies (2-8 kHz). No additional risk in the solvent + noise exposure group was found (RR 2.8). Hearing thresholds were significantly poorer in a wide range of frequencies (1-8 kHz) for both groups exposed to solvents, when compared with the reference group. The mean hearing thresholds at frequencies of 2-4 kHz were poorer for workers exposed to solvents + noise than for the solvent-only group; this finding suggests an additional effect for noise. However, there was no correlation between hearing loss and the extent of solvent exposure. Conclusions The results indicate that occupational organic solvent exposure at moderate concentrations increases the risk of hearing loss, and the ototoxic effects should be considered when the health effects of exposed workers are monitored.

Questionnaire-based mechanical exposure indices for large population studies--reliability, internal consistency and predictive validity

Abstract: Objectives This study attempts to construct valid indices for mechanical exposure of the shoulder-neck region with relation to the development of shoulder-neck pain in a 1-year perspective study of a general population. Methods A comprehensive questionnaire was presented to 14 556 subjects aged 45 or 65 years and repeated after 12 months. Twenty-four questions concerning positions, movements, and manual materials handling were registered on a 3-point impact scale. Musculoskeletal problems were reported on a slightly modified version of the Standardized Nordic Questionnaire for the Analysis of Musculoskeletal Symptoms. Test-retest stability after 2 weeks was calculated for 232 consecutive participants. Based on mechanistic theories, 4 exposure indices were formed. Another 5 constructs were obtained by factor analysis. Results All the indices showed good test-retest stability, and 5 of them had very good internal consistency. Due to overlaps between the indices, 2 indices stood out as having unique properties. One of them concerned mainly postures and the other dealt primarily with measured lifting. However, the latter was not related to the shoulder-neck pain outcome when adjusted for the posture index. The posture index showed an exposure-effect relationship with the outcome. The job titles implied a large degree of exposure misclassification. Conclusions The posture index is recommended as a mechanical exposure index for analyses of interaction with other possible determinants of shoulder-neck pain (ie, psychosocial factors). The use of such an index instead of job titles in large population studies will reduce the risk of misclassification.

Physical Exposure Assessment in Monotonous Repetitive work-the PRIM Study

Abstract: Objectives A program called the Project on Research and Intervention in Monotonous Work (PRIM) was initiated in 1994 as a prospective cohort study of work-related musculoskeletal disorders. The group-based exposure assessment strategy, focusing on task-related exposure and used to obtain baseline measures of physical exposures, is reported in this paper. Methods Monotonous, repetitive worktasks were evaluated at 19 factories. Tasks with an estimated similarity in physical exposure were aggregated before 103 exposure groups were formed. Subjects from the exposure groups were randomly sampled for measurements, and task-related exposure levels were quantified by 43 single exposure items using a real-time video-based observation method that allowed computerized estimates of repetitiveness, body postures, force, and velocity. In combination with questionnaire-based data on task distribution, the duration of exposure was calculated at the individual level. Results The video-based observational method and the large number of exposure variables enabled the establishment of detailed quantitative exposure profiles in 103 task-based exposure groups. However, methodological problems associated with the use of grouped exposure assessment were revealed. Despite efforts to optimize group homogeneity, the within-group variance was larger than the between-group variance for several shoulder postural variables. Conclusions A task-based exposure-assessment strategy can be successful in solving some of the main problems associated with the assessment of physical workplace exposures. The large within-group variance in exposure to nonneutral shoulder postures may eventually require individual assessment or the inclusion of groups with maximal contrast in exposure or both.

Life-style intervention at the worksite--reduction of cardiovascular risk factors in a randomized study.

Abstract: Objectives This study tested a feasible method for screening for cardiovascular risk at the worksite and investigated the effects of a long-term comprehensive program of life-style intervention to prevent cardiovascular disease. Methods Employees in the public sector filled out a self-administered questionnaire with questions on social, medical, and work-related factors. The respondents numbered 454 (80%). A score sum for cardiovascular risk was calculated (range 1-20, median 7.0), and the 128 subjects with a sum above 8 were invited to a health examination including blood sampling. Thereafter the subjects were invited to participate, following randomization, in a comprehensive, 18-month, life-style intervention program to improve cardiovascular risk or in a control group. Results The intervention group significantly decreased body mass index, diastolic blood pressure, heart rate, low-density lipoprotein (LDL) cholesterol, and smoking habits during the intervention. The initially elevated serum cortisol, as a marker of stress reaction, normalized in the intervention group. In the control group LDL cholesterol also decreased, but the glucose and triglyceride levels increased, and smoking habits were unchanged. Sick days for a given period decreased after 1 year in the intervention group but not in the control group. Conclusions Several cardiovascular risk factors can be improved and morning serum cortisol normalized during a long-term life-style intervention program with a randomized design using a worksite population of middle-aged subjects. The use of a 2-step screening program, with an initial questionnaire followed by a health check of subjects with elevated risk, is feasible for worksite settings.

Exposure-response Models Based on Extended follow-up of a Cohort Mortality Study in the Automobile Industry

Abstract: Objectives This report describes the extended follow-up of a cohort of 46 399 automobile manufacturing workers with potential exposure to metalworking fluids (MWF) The outcomes of interest were cancers of the esophagus, stomach, colon, rectum, liver, pancreas, larynx, skin, prostate, and brain, as well as leukemia Additional follow-up increased the power to detect modest elevations in mortality rates in association with specific types of MWF, including synthetic fluids not in widespread use until the 1970s Methods Standardized mortality ratios (SMR) were computed for the most recent 10 years of follow-up, as well as for the entire study period Adjusted relative risks (RR) were estimated in Poisson regression models with categorical variables for cumulative exposure to each type of MWF and in proportional hazards models with continuous exposure variables Results Associations were found between straight MWF and esophageal, laryngeal and rectal cancer; soluble MWF and cancer of the esophagus, larynx, skin, and brain; synthetic MWF and cancer of the esophagus, liver, and prostate The elevated RR values were modest in magnitude (15 to 20) SMR values were increased for stomach, liver, and pancreatic cancer and also for leukemia in the last 10 years of follow-up The SMR values were also elevated for stomach and liver cancer among the persons recently hired Conclusions The results provide further evidence that exposure to metalworking fluids causes cancer among workers in automobile manufacturing Although airborne exposures declined over the study period, this study suggests that modest risk of several digestive cancers, as well as prostatic cancer and leukemia, may persist at current levels of exposure to water-based metalworking fluids

Evaluation of physical workload standards and guidelines from a Nordic perspective.

Abstract: In 1997 the Nordic Council of Ministers decided to initiate a project with the aim of evaluating existing physical workload standards from a Nordic perspective as a background for possible future initiatives and needs. The decision reflects Nordic interest in critically validating the rapidly increasing number of European and American standards and guidelines being developed for physical workload. A working group was appointed consisting of representatives of the Danish, Finnish, Norwegian, and Swedish institutes of occupational health. This report presents the results of the group's considerations and its main conclusions. In general, the project aimed at providing a thorough review of the different standards, a description of their legal status, and a judgment of their scientific and practical value. Following a brief account of the history of physical workload standards and a theoretical account of the problems involved, 26 standards or guidelines are grouped and reviewed in the following seven categories: (i) general ergonomics standards, (ii) guidelines for manual materials handling, (iii) guidelines for repetition, force, and posture in monotonous, repetitive work, (iv) vibration standards, (v) guidelines for energy consumption, (vi) guidelines for specific industries, and (vii) acute overload guidelines. The standards and guidelines represent a variety of issuing bodies and organizations, for example, the European Committee for Standardization (CEN), the International Organization for Standardization (ISO), the American National Standards Institute (ANSI), the International Ergonomics Association (IEA), the (United States) National Institute for Occupational Safety and Health (NIOSH), and the (United States) Occupational Safety and Health Administration (OSHA). As a means of promoting a "code of practice" for the evaluation of physical workload standards, a framework of criteria for identifying scientifically "good" and practically efficient standards was established, and the following three key areas were identified in the evaluation procedure: (i) scientific coherency, (ii) effectiveness, and (iii) usability. [Scientific coherency considers the degree to which standards are related to scientific knowledge on the causes of the injuries or diseases in question. The effectiveness of an occupational safety and health standard describes the impact of the standard with regard to the prevention of occupational disease and injury. And the usability criterion evaluates the potential for implementing the standard.] Prior to the evaluation, the standards were divided into the following two groups according to their level of accuracy: (i) standards presenting quantitative guidelines for specific exposures with precise and numerical acceptance criteria and (ii) process-type standards presenting mainly qualitative guidelines and focusing on a program approach. The two groups were evaluated separately, and the results have been presented in two different sections. In general the evaluation was the most favorable for process-type standards. The most conspicuous difference between process-type and quantitative-type standards was found for the "scientific coherency" criteria.

High-resolution computed tomography classification of lung fibrosis for patients with asbestos-related disease.

Abstract: Objectives This study tested a new high-resolution computed tomography (HRCT) scoring method for asbestos-induced parenchymal changes in the lung. Methods HRCT scans of 602 asbestos-exposed workers and 49 referents were reviewed by 3 radiologists. Structured forms were filled out for a semiquantitative HRCT fibrosis score based on several specified parenchymal abnormalities scored separately. Observer agreement was studied with the use of the quadratic-weighted kappa (kappa qw ). The HRCT fibrosis score (from 0 to V with definitions and index images given retrospectively) was compared with the radiographic classification of the International Labour Office (ILO) for the same patients. Receiver-operating characteristic (ROC) curves were computed to compare the tests for diagnosing asbestosis. Results Good inter- and intraobserver agreements were achieved (kappa qw = 0.64 and 0.72, respectively) as regards the HRCT fibrosis score. All the specified computed tomography findings explained 86% of the variance in the HRCT fibrosis score. Age and occupational group were significant predictors of fibrosis. The area under the ROC curve was significantly greater for the HRCT fibrosis score (0.89) than for the ILO radiographic classification (0.76). The sensitivity (70%) and specificity (91%) of the HRCT fibrosis score (classes I/II-V representing asbestosis) were better than those of the classification published by the International Labour Office (51% and 89%, respectively, score ≥1/0 representing asbestosis). Conclusions The examined HRCT scoring method proved to be a simple, reliable, and reproducible method for classifying lung fibrosis and diagnosing asbestosis also in large populations with occupational disease, and it would be possible to use it as a part of an international classification.

Exposure to titanium dioxide and risk of lung cancer in a population-based study from Montreal.

Abstract: Objectives This study assessed the lung cancer risk from exposure to titanium dioxide, an important pigment with limited evidence of carcinogenicity in experimental animals but sparse data for humans. Methods The risk of lung cancer among residents in Montreal, Canada, was analyzed, including 857 histologically confirmed cases of lung cancer diagnosed during 1979-1985 among men aged 35-70 years and a group of referents comprising 533 randomly selected, healthy residents and 533 persons with cancer in organs other than the lung. Exposure to titanium dioxide and other titanium compounds was assessed by a team of industrial hygienists on the basis of a detailed occupational questionnaire. Results Thirty-three cases and 43 referents were classified as exposed to titanium dioxide. The odds ratio was 0.9 [95% confidence interval (95% CI) 0.5-1.5]. No trend was apparent according to the estimated frequency, level, or duration of exposure. The odds ratio was 1.0 (95% CI 0.3-2.7) for medium or high exposure for at least 5 years. Few subjects were classified as exposed to titanium dioxide fumes or to other titanium compounds, but the risk of lung cancer was nonsignificantly increased for exposure to these agents. Conclusions Although misclassification of exposure and low exposure prevalence might have resulted in false negative results, this study does not suggest that occupational exposure to titanium dioxide increases the risk of lung cancer.

Intervention in shift scheduling and changes in biomarkers of heart disease in hospital wards.

Abstract: Objectives The effect of introducing regularity, few consecutive night shifts, more weekends off, and only 2 different types of shifts (day-evening or day-night) into shift scheduling on biomarkers of heart disease was studied. Methods Ergonomic shift criteria were introduced in a quasi-experimental controlled intervention in 4 hospital wards. Six wards participated as controls. Altogether 101 nurses and nurses` aides were followed for 6 months with measurements of cholesterol and triglycerides. The intervention led to more regular schedules and more staff having 2 shifts in 2 of the intervention wards 1 year after the intervention. The schedules among the controls became less regular and less predictable. The number of consecutive night shifts remained unchanged. Results After 6 months the high-density lipoprotein (HDL) cholesterol level had increased in the intervention group, and the total cholesterol and low-density lipoprotein (LDL) cholesterol levels and the total:HDL cholesterol ratio had decreased. Regardless of the intervention, changes in regularity were associated with the triglyceride and HDL cholesterol levels and also with the total:HDL cholesterol ratio. More ergonomic changes were associated with lower LDL cholesterol levels, a lower total:HDL cholesterol ratio, and higher HDL cholesterol levels. Conclusions Increased ergonomic scheduling was possible. Lipids and lipoproteins changed as predicted, both when the changes were assessed in respect to the changes in schedules that resulted from the intervention and the changes that occurred regardless of the intervention. The study suggests that scheduling based on ergonomic criteria is a possible means for reducing the risk of heart disease among shift workers.

Group-based measurement strategies in exposure assessment explored by bootstrapping

Abstract: Objectives The precision of mean exposure to pushing was examined in 2 occupational groups using various combinations of the number of workers and measurements per worker. Methods The frequency and duration of pushing of the 2 occupational groups was assessed using onsite observation. All data were divided into successive periods of 30 minutes of observation. The precision of the group mean exposure to pushing was expressed by 90% confidence intervals obtained by bootstrapping. The effect on the confidence interval of varying numbers of workers and numbers of periods per worker was examined. Results For both occupational groups there was little precision to be gained when >10 workers were observed. Within the maximum number of workers used in the bootstrap simulations, it appeared that, beyond 10 workers, the confidence intervals decreased by <5% for every worker that was added, when each worker was observed at least 8 periods of 30 minutes. If workers were observed exactly 4 periods of 30 minutes per worker, an additional 4 workers were required to compensate for the loss of precision. An unbalanced strategy with approximately 8 periods of 30 minutes per worker hardly decreased the precision of the group mean, however. Conclusions The precision of the group-based mean exposure to pushing is influenced by the number of workers observed and by the number of repeated measurements per worker. In the planning of measurement strategies, it is advisable to account for possible sources of variance in advance and to assess the exposure variability.

Excessive fatigue and weight gain among cleanroom workers after changing from an 8-hour to a 12-hour shift

Abstract: Objectives This study attempted to clarify the health effects of implementing a 12-hour shift in place of the traditional 8-hour shift in work in a clean room in an electronic parts producing factory. Methods Health-check records during a year or longer before and after the shift change were reviewed regarding subjective symptoms, height, body weight, and blood pressure for 189 male workers who had moved to a 12-hour shift and for 16 male workers who remained on an 8-hour shift. Results The workers changing to a 12-hour shift showed significant increases in subjective symptoms, particularly psychological symptoms defined as related to fatigue and bodyweight gain, 1 kg on average, in the year after the shift change. Increased symptoms and body weight remained high even another year later. The workers remaining in the 8-hour shift did not show significant changes in symptoms or body weight during the observation. No changes in blood pressure were observed in relation to the shift move. Conclusions The results suggested that implementing a 12-hour shift caused marked psychological fatigue and unhealthy weight gain among some cleanroom workers and that the adaptation to the new work shift did not seem easy for these workers. Working in a clean room can be considered a job in which special caution is needed regarding increased fatigue when a compressed working schedule is implemented. Attention should also be paid to possible weight gain among persons working 12-hour shifts.

A novel approach for evaluating level, frequency and duration of lumbar posture simultaneously during work.

Abstract: Objectives Electrogoniometers are used to collect continuous information on postural distributions among workers. Enormous quantities of data are generated that have to be reduced to meaningful parameters (angle, frequency, and duration). In this study we propose statistical models to determine these essential characteristics of postural load on nurses, housekeepers, and office workers. Methods A direct registration of the lumbar posture was made over a workday with an inclinometer. An exposure variation analysis was used to summarize information on the angle of trunk flexion, the time period of maintained postures, and the percentage of worktime in a data matrix. A hierarchical regression analysis was used to compare these characteristics among nurses (N=64), housekeepers (N=16), and office workers (N=27). Results The occupational groups did not differ for either frequency or duration of trunk flexion over 30 degrees since frequency and duration were inversely related. Nurses experienced longer worktimes than the office workers did for trunk flexion between 30 and 70 degrees maintained < 5 seconds, whereas office workers experienced longer worktimes in smaller angles (<30 degrees) for longer periods. Comparable differences in the distributions of postural load were found between housekeepers and office workers. Conclusions This study describes the use of hierarchical models in analyses of the exposure level, frequency, and duration of postural load simultaneously and offers an alternative to conventional ergonomic analysis in which the dynamics of exposure are often ignored. The distinction in postural load between nurses or housekeepers and office workers is best determined by the combination of trunk angle and time period.

Exposure to hexahydrophthalic and methylhexahydrophthalic anhydrides--dose-response for sensitization and airway effects.

Abstract: OBJECTIVES: This study clarified the exposure-response relationships for the organic acid anhydrides (OAA) hexahydrophthalic (HHPA) and methylhexahydrophthalic (MHHPA) anhydrides and the development of specific immunoglobulin (IG) E and G antibodies and work-related symptoms. METHODS: In an epoxy resin-using factory, air levels of OAA were determined by gas chromatography-mass spectrometry. Occupational, smoking, and medical histories (questionnaire) were obtained for 154 exposed workers and 57 referents. Work-related symptoms of the eyes and airways were recorded, and OAA metabolites were analyzed in urine. A skin-prick test with common allergens and conjugates of OAA were performed. Specific IgE (radioallergosorbent test) and IgG (enzyme-linked immumosorbent assay) antibodies were determined in serum, and spirometry was performed. RESULTS: Air levels of the OAA were low (HHPA < 1 to 94, MHHPA < 3 to 77 microg/m3) and associated with the concentrations of the OAA metabolites in urine. Furthermore, for the exposed workers, there were high prevalences of sensitization (IgE 22%, IgG 21%), which correlated with the exposure. Neither atopy nor smoking increased this risk significantly. Furthermore, work-related symptoms were more prevalent among the exposed workers than among the referents (eyes 23% versus 14%, nose 28% versus 16%, nose bleeding 8% versus 0%, lower airways 10% versus 4%), and they were related to the exposure (adjusted prevalence odds ratios (POR) in the highest group 7.7, 3.6 and 17, respectively) and the IgE levels (POR 4.9, 3.1 and 5.6, respectively). CONCLUSIONS: In spite of the very low OAA levels in the air and metabolites in the urine, there were high and exposure-related risks of specific IgE and IgG sensitization and of work-related symptoms for the eyes, nose (especially bleeding), and lower airways.

Do psychosocial strain and physical exertion predict onset of low-back pain among nursing aides?

Abstract: Objectives The aim of this study was to investigate psychosocial factors and physical exertion at work in relation to the onset of low-back pain. Methods The study was carried out as a case-crossover investigation of nursing aides caring for the elderly. Cases were identified among 157 nursing aides over a period of 2 years. Psychosocial factors, physical exertion, and low-back pain were reported daily in diary questionnaires over three consecutive days at work, repeated in six periods of 3 days. For each subject, case observations were identified as pain onset from one day to the next and matched with reference observations with no pain onset from the same person. Prospective data collection allowed analyses to be conducted with and without a lag in time between exposure and pain onset. Results The results of the analyses with time lag (longitudinal) did not support the hypothesis that psychosocial and physical strain from 1 day of work predicts pain onset the following day. However, physical exertion, stress, and, to some extent, time pressure were associated with pain on the day of onset. Conclusion The effect period, if any, of exposure to physical exertion, stress, and time pressure on the onset of acute low-back pain is considered to be less than 24 hours.

A training exercise in subjectively estimating inhalation exposures.

Abstract: Objectives This study examined whether it is possible to train occupational hygienists to estimate inhalation exposures reliably from limited occupational information using a new method and assessed improvements in the quality of the estimate using the aggregate from multiple assessors. Methods Five occupational hygienists estimated inhalation exposure for 40 tasks covering a range of chemical hazards using a recently developed subjective modeling technique supplemented by detailed guidance notes. The measured exposure levels were used to determine the validity of the method. The correlation coefficients of the log-transformed data were used to assess the discriminative power of the method, and the ratio of the mean estimate to measured values was used to measure accuracy. Results There was good-to-excellent agreement between the assessors` estimates and the measured data, the correlation coefficients ranging from 0.73 to 0.85. There was a tendency for assessors to overestimate the exposure levels by, on the average, two- to fourfold. Aggregating the assessors` estimates helped to improve the correlation coefficient to 0.88, the overestimation being 2.6-fold. Using more than three assessors for aggregate estimates did not improve the reliability of the method. Conclusions Overall, the assessors found the method to be useful in generating exposure estimates that correlate well with measured levels. The provision of high-quality guidance information is likely to be important in the generation of reliable exposure estimates. The method is likely to be of use in epidemiologic studies in which limited exposure data are available.

Conservative treatment for repetitive strain injury.

Abstract: Various conservative treatment options for repetitive strain injury are widely used, despite questionable evidence of their effectiveness. This systematic review evaluates the effectiveness of these treatment options for relieving symptoms of repetitive strain injury and improving activities of daily living. Searches in Medline and Embase, with additional reference checking resulted in 15 eligible trials for this review. Methodological quality was assessed, and data-extraction was performed. With the use of a "best-evidence synthesis", no strong evidence was found for the effectiveness of any of the treatment options. There is limited evidence that multidisciplinary rehabilitation, ergonomic intervention measures, exercises, and spinal manipulation combined with soft tissue therapy are effective in providing symptom relief or improving activities of daily living. There is conflicting evidence for the effectiveness of behavioral therapy. In conclusion, little is known about the effectiveness of conservative treatment options for repetitive strain injury. To establish strong evidence, more high-quality trials are needed.