Job strain and neck-shoulder symptoms: a prevalence study of women and men white-collar workers

BACKGROUND: Neck-shoulder symptoms are frequent among workers. Psychosocial factors at work have been associated with neck-shoulder symptoms, but few studies have examined job strain, the combined effect of high psychological demands (PD) and low decision latitude (DL). AIMS: To examine the association between psychosocial factors at work and the prevalence of self-reported neck-shoulder symptoms among white-collar workers. METHODS: In a cross-sectional study of 1543 white-collar workers, PD and DL at work were measured with Karasek's questionnaire. Prevalent cases were workers for whom neck-shoulder symptoms were present for >or=3 days during the previous 7 days and for whom pain intensity was greater than half the visual analogue scale. Gender and social support at work were evaluated as potential effect modifiers. RESULTS: Workers exposed to high job strain had a higher prevalence of neck-shoulder symptoms [adjusted prevalence ratio (PR): 1.54, 95% confidence interval (CI): 1.00-2.37]. No modifying effect of gender was observed in this association. The effect of job strain was stronger in workers with low social support (adjusted PR: 1.84, 95% CI: 0.92-3.68). These associations tended to be stronger and/or more precise when using alternative exposures and case definition. Namely, a stronger job strain effect was observed when a tertile cut-off was used to classify exposure (adjusted PR: 2.47, 95% CI: 1.15-5.32). CONCLUSION: These results suggest that primary prevention of neck-shoulder symptoms among white-collar workers should consider the exposure to job strain, especially when workers are exposed to low social support at work.     

Active or passive treatment for neck-shoulder pain in occupational health care? A randomized controlled trial

AIMS: To compare the effectiveness of thoracic manipulations with instructions for physiotherapeutic exercises for the treatment of neck pain in occupational health care. METHODS: Seventy-five subjects aged 30-55 years from a random sample of 241 employees of the Finnish Broadcasting Company were randomly allocated to treatment in the form of four thoracic manipulations (n = 43), or instructions for physiotherapeutic exercises (n = 32). The subjects reported neck-shoulder pain on a structured pain questionnaire using a visual analogue scale (VAS, 0-10). Muscle tenderness and tender thoracic levels were evaluated by a blinded investigator (A.S.) at 6- and 12 month follow-ups. RESULTS: A statistically significant difference was found in self-reported worst pain by VAS at the 12 month follow-up in favour of the thoracic manipulation group. CONCLUSIONS: The natural course of the neck-shoulder pain in this study appears benign; pain was also reduced in the drop-out group. Both treatments were found effective at the 12 month follow-up. The effect of four manipulations was more favourable than the personal exercise program in treating the more intense phase of pain.     

A case-control study of the relationship between the risk of colon cancer in men and exposures to occupational agents

BACKGROUND: We conducted a population-based case-control study in Montreal, Canada, to explore associations between hundreds of occupational circumstances and several cancer sites, including colon. METHODS: We interviewed 497 male patients with a pathologically confirmed diagnosis of colon cancer, 1514 controls with cancers at other sites, and 533 population-based controls. Detailed job histories and relevant potential confounding variables were obtained, and the job histories were translated by a team of chemists and industrial hygienists into a history of occupational exposures. RESULTS: We found that there was reasonable evidence of associations for men employed in nine industry groups (adjusted odds ranging from 1.1 to 1.6 per a 10-year increase in duration of employment), and in 12 job groups (OR varying from 1.1 to 1.7). In addition, we found evidence of increased risks by increasing level of exposures to 21 occupational agents, including polystyrene (OR for "substantial" exposure (OR(subst)) = 10.7), polyurethanes (OR(subst) = 8.4), coke dust (OR(subst) = 5.6), mineral oils (OR(subst) = 3.3), polyacrylates (OR(subst) = 2.8), cellulose nitrate (OR(subst) = 2.6), alkyds (OR(subst) = 2.5), inorganic insulation dust (OR(subst) = 2.3), plastic dusts (OR(subst) = 2.3), asbestos (OR(subst) = 2.1), mineral wool fibers (OR(subst) = 2.1), glass fibers (OR(subst) = 2.0), iron oxides (OR(subst) = 1.9), aliphatic ketones (OR(subst) = 1.9), benzene (OR(subst) = 1.9), xylene (OR(subst) = 1.9), inorganic acid solutions (OR(subst) = 1.8), waxes, polishes (OR(subst) = 1.8), mononuclear aromatic hydrocarbons (OR(subst) = 1.6), toluene (OR(subst) = 1.6), and diesel engine emissions (OR(subst) = 1.5). Not all of these effects are independent because some exposures occurred contemporaneously with others or because they referred to a group of substances. CONCLUSIONS: We have uncovered a number of occupational associations with colon cancer. For most of these agents, there are no published data to support or refute our observations. As there are few accepted risk factors for colon cancer, we suggest that new occupational and toxicologic studies be undertaken focusing on the more prevalent substances reported herein.     

Parental occupational exposures and risk of childhood cancer: a review

We reviewed the literature in order to summarize the present knowledge on the association between parental occupational exposures to chemicals and the risk of childhood malignancy. The 32 studies pertaining to this topic were evaluated by considering various study qualities such as sample size, specificity of outcome, confounding, exposure specificity, and control selection. When evaluating the findings from any epidemiologic study, the potential sources of bias have to be considered. The selection of subjects, misclassification of exposure or outcome, and confounding from extraneous factors can contribute to a biased estimate of effect. Studies done to minimize these potential biases will be more valid, and these studies should be given the most weight when parental occupational exposures are evaluated as risk factors for childhood malignancy. We conclude that the preponderance of evidence supports the hypothesis that occupational exposure of parents to chemicals increases the risk of childhood malignancy. The parental occupational exposures implicated in childhood malignancy risk are exposure to chemicals including paints, petroleum products, solvents (especially chlorinated hydrocarbons) and pesticides, and exposure to metals. The available data do not allow the identification of specific etiologic agents within these categories of compounds. Future epidemiologic and toxicologic studies should be designed to pursue these leads.     

Are occupational factors important determinants of socioeconomic inequalities in musculoskeletal pain?

OBJECTIVES: The aim of this study was to quantify socioeconomic inequalities in low-back pain, neck-shoulder pain, and arm pain in the general working population in Oslo and to examine the impact of job characteristics on these inequalities. METHODS: All economically active 30-, 40-, and 45-year-old persons who attended the Oslo health study in 2000-2001 and answered questions on physical job demands, job autonomy, and musculoskeletal pain were included (N=7293). Occupational class was used as an indicator of socioeconomic status. The lower occupational classes were compared with higher grade professionals, and prevalences, prevalence ratios, prevalence differences, and population attributable fractions were calculated. RESULTS: There were marked, stepwise socioeconomic gradients for musculoskeletal pain, steeper for the men than for the women. The relative differences (prevalence ratios) were larger for low-back pain and arm pain than for neck-shoulder pain. The absolute differences (prevalence differences) were the largest for low-back pain. Physical job demands explained a substantial proportion of the absolute occupational class inequalities in low-back pain, while job autonomy was more important in explaining the inequalities in neck-shoulder pain and arm pain. The estimated population attributable fractions supported the impact of job characteristics at the working population level, especially for low-back pain. CONCLUSIONS: In this cross-sectional study, physical job demands and job autonomy explained a substantial proportion of occupational class inequalities in self-reported musculoskeletal pain in the working population in Oslo. This finding indicates that the workplace may be an important arena for preventive efforts to reduce socioeconomic inequalities in musculoskeletal pain.     

Smoking behavior in trucking industry workers

BACKGROUND: In retrospective occupational studies, the degree of confounding by smoking depends on variation in smoking among job-related exposure groups. We assessed the relationship between job title and smoking behavior as part of a study on occupational exposures and lung cancer. METHODS: A questionnaire on smoking was mailed to a sample of 11,986 trucking industry workers. Company records were used to gather other relevant information. RESULTS: The response rate was 40.5%. Among white males, the age-adjusted prevalence of ever smoking was highest among longhaul truck drivers (67%) and lowest among clerks (44%). Smoking rates among workers with other job titles were similar. CONCLUSIONS: Our results will be used to adjust for the differences in smoking among job-related exposure groups when assessing the association between particulate matter exposure and lung cancer mortality. Our study also suggests that an assessment of methods to control for smoking should be considered in the design of retrospective occupational health studies.     

Longitudinal evidence for the association between work-related physical exposures and neck and/or shoulder complaints: a systematic review

Background

Most existing reviews focus on evidence for the association between neck and/or shoulder complaints and physical exposures at the workplace gathered from cross-sectional studies. In comparison, this review summarizes existing evidence from longitudinal studies only.

Methods

A systematic literature research was conducted in Medline and EMBASE (1975–2009), and all studies were scanned by at least two researchers according to strict inclusion criteria. Levels of evidence were assigned according to the number of studies reporting similar findings, and according to the methodological quality of the included studies.

Results

Altogether 21 longitudinal studies (19 high-quality studies) met the inclusion criteria and were included in this review. In comparison with former reviews, we found strong evidence for an association between shoulder complaints and manual material handling (MMH) (range between Odds Ratio (OR) 1.4 and 4.9), vibration (range between OR 1.6 and OR 2.5), trunk flexion or rotation (range between OR 1.8 and OR 5.1), and working with hands above shoulder level (range between OR 1.1 and OR 1.8). Apart from that, the included studies confirmed existing knowledge on the association between physical exposures at the workplace and neck and/or shoulder complaints.

Conclusions

This analysis of longitudinal studies allowed for new evidence with regard to four cause-effect chains between physical exposures at work and the development of shoulder, neck and neck/shoulder complaints. As outcome variables varied greatly among the included studies, harmonization in studies on musculoskeletal research is desirable.     

Comparison of first, last, and longest-held jobs as surrogates for all jobs in estimating cumulative exposure in cross-sectional studies of work-related asthma

BACKGROUND: Previous occupational studies have used exposure in most recent job as a surrogate for all jobs or "total work history" exposure. This method may not be valid for diseases in which disability brought on by one job may influence later work history, such as asthma. We investigated different surrogates for total work history for the outcome of asthma symptoms. METHODS: In a cross-sectional study, we quantitatively compared three exposure surrogates (last job, first job, and longest-held job) with the total cumulative work exposure (all jobs) in a cohort of 1778 aluminium industry workers. The chemical exposures we compared were total fluoride dust, inspirable dust, and sulfur dioxide with the respiratory symptoms of wheeze, chest tightness, and rhinitis. RESULTS: When extrapolated over time, all surrogates quantitatively overestimated the gold standard "all jobs" for all three exposures investigated. For the symptom of wheeze, last job was found to be the worst surrogate for all jobs for the three exposure types investigated. Prevalence ratios for fluoride exposure and the symptom of occupational wheeze were last job 1.07 (95% confidence interval, 0.92-1.26), longest job 1.10 (0.94-1.30), first job 1.14 (0.97-1.35), and all jobs 1.27 (1.05-1.53). CONCLUSIONS: Although last job has been found to be a satisfactory surrogate for all jobs in cancer studies, we do not recommend the use of this metric in studies of chronic diseases where development of disability may occur with early exposure. We found that both first job and longest job held were better metrics in studies where the adverse health effect may influence the job history of subject.     

Measurement properties of a self-report index of ergonomic exposures for use in an office work environment.

Office work-related upper extremity symptoms and disorders have been associated with static work posture, repetition, and inadequate recovery in the anatomic structures of the neck and upper extremities. Despite these associations, relatively little research has been conducted on the development of practical measures of these ergonomic exposures. The present study examines the measurement properties of an upper-extremity-specific self-report index of ergonomic exposures. Ninety-two symptomatic office workers completed a Web-based questionnaire measuring demographic variables, ergonomic exposures, pain, job stress, and functional limitations. Comparisons of internal consistency, construct validity, and discriminative and predictive abilities were made between the self-report index and an observational exposure assessment checklist. Results indicated that the self-report index had acceptable measurement properties. Furthermore, higher levels of self-reported ergonomic exposures were associated with upper extremity pain, symptom severity, and functional limitations. In contrast, higher levels of observed exposure were related only to lower levels of general physical function. The self-report measure has potential for use in occupational health surveillance programs for office work environments and as an outcome measure of ergonomic exposure in intervention trials. These results also suggest the need for using multiple methods when assessing ergonomic exposures.     

High physical and psychosocial load at work and sickness absence due to neck pain

OBJECTIVES: This study investigates the relationship between physical and psychosocial load at work and sickness absence due to neck pain. METHODS: A prospective cohort study with a follow-up period of 3 years (1994-1998) was performed among a working population. At the beginning of the study, physical load at work was quantified by means of video recordings. Work-related psychosocial variables were measured by means of the Job Content Questionnaire. The frequency of sickness absence due to neck pain with a minimal duration of 3 days was assessed on the basis of company registrations during the follow-up period. Altogether 758 workers were included in the analyses. Possible confounding by individual characteristics, physical load, and psychosocial load was studied. RESULTS: Work-related neck flexion and neck rotation, low decision authority, and medium skill discretion showed statistically significant increased risks for sickness absence due to neck pain (adjusted rate ratios ranging from 1.6 to 4.2). High quantitative job demands, low skill discretion, and low job security showed nonsignificant increased risks for sickness absence due to neck pain (adjusted rate ratios of 2.0, 1.6 and 1.7, respectively). Work-related sitting, conflicting job demands, supervisor support, and co-worker support did not increase sickness absence due to neck pain. CONCLUSION: Work-related neck flexion, neck rotation, low decision authority, and medium skill discretion are risk factors for sickness absence due to neck pain. There are indications that high job demands, low skill discretion, and low job security are also risk factors for sickness absence due to neck pain.     

Social disparities in the burden of occupational exposures: results of a cross-sectional study

BACKGROUND: Most occupational studies evaluate a single exposure in relation to a particular disease. However, workers typically experience multiple exposures simultaneously. There is also increasing evidence of disparities in health by sociodemographic characteristics, mostly related to social position such as gender, race/ethnicity, immigration status, income, and education. Little information exists on the worker experience of multiple occupational exposures as they vary among social groups. The objectives of this article were to: assess the burden of exposures reported within 1 year by a socially diverse population working in a range of industries; and evaluate whether sociodemographic characteristics affected the patterns of these exposures. METHODS: Study participants were from 14 unionized worksites in meat processing, electrical lighting manufacturing, retail grocery stores, and school bus driving. A cross-sectional study design used a self-administered, computer-assisted questionnaire (English and Spanish) to assess sociodemographic characteristics and nine workplace exposures, within the past year. An interviewer-administered job history also was collected. RESULTS: Twelve hundred eighty-two workers (72%) completed the survey: 36% women, 23% Latino, 39% black, 24% white, and 48% born outside the US. The prevalence of high exposures ranged from 21% (chemicals) to 39% (neck strain). Forty-six percent reported three or more high exposures. Exposure reporting varied among sociodemographic groups. Some of the disparities were explained by the jobs held by different groups, but after statistically controlling for job, many disparities remained. CONCLUSIONS: Sociodemographic characteristics should be considered when conducting exposure assessments using questionnaires. More research is needed to understand how social characteristics may influence exposures.     

Occupational musculoskeletal stress and disorders of the neck and shoulder: a review of possible pathophysiology

Summary Disorders and complaints in the neck and shoulder regions are common among industrial workers and are often attributed to occupational musculoskeletal stress. The possible pathophysiological mechanism of occupational stress on the neck and shoulders is reviewed. A mechanical origin for cervical disc degeneration and osteoarthrosis is reported for a few occupational groups. However, a mechanical origin for osteoarthrosis is debatable. A work posture involving elevated arms may accelerate degeneration of shoulder tendons through impairment of circulation due to static tension and humeral compression against the coracoacromial arch. Furthermore, work tasks with repetitive arm movements may evoke shoulder tendinitis or tendovaginitis, probably due to friction. Three possible routes to neck-shoulder muscular pain are discussed; mechanical failure, local ischemia and energy metabolism disturbance.     

Risk of pancreatic cancer in workers exposed to chlorinated hydrocarbon solvents and related compounds: a meta-analysis

This is a meta-analysis of occupational exposures to chlorinated hydrocarbon (CHC) solvents and pancreatic cancer, based primarily on studies that addressed exposure directly (agent studies) and secondarily on studies that reported data without verification of individual CHC exposures (job title studies), all of which were listed in databases for the period January 1969 to May 1998. Standardized extraction of data and double-checking of consistency of data extraction by five extractors were done. Simple random models estimated meta-relative risks. Suggestive weak excesses were found for trichloroethylene (meta-relative risk (MRR) = 1.24, 95% confidence interval (CI): 0.79, 1.97), polychlorinated biphenyls (MRR = 1.37, 95% CI: 0.56, 3.31), methylene chloride (MRR = 1.42, 95% CI: 0.80, 2.53), and vinyl chloride (MRR = 1.17, 95% CI: 0.71, 1.91) but not for carbon tetrachloride. One study addressed tetrachloroethylene (MRR = 3.08, 95% CI: 0.63, 8.99); another investigated chlorohydrin production (MRR = 4.92, 95% CI: 1.58, 11.4). Exposure-response meta-analyses for trichloroethylene and methylene chloride failed to reveal trends. Job title studies on metal degreasing and dry cleaning revealed significant MRRs (2.0 and 1.4, respectively). Publication bias was unlikely. Confounding may have remained insufficiently controlled. Unless the results are seriously biased by exposure or endpoint misclassification or by confounding, strong causal associations between CHC compounds and pancreatic cancer can be judged unlikely. Interactions between environmental and occupational agents, lifestyle factors, and genetic susceptibility remain a possibility, but the data for this meta-analysis did not address interactions.     

Cancer risks associated with 10 inorganic dusts: results from a case-control study in Montreal

A multicancer site, multifactor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with eligible cases, comprising all incident cases of 20 types of cancer who were male, aged 35-70 years, and a resident in Montreal. The interview was designed to obtain detailed lifetime job histories and information on potential confounders. Each job history was reviewed by a team of chemists and industrial hygienists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included; 3,726 cases were interviewed. For each site of cancer analyzed, controls were selected from among the other sites in the study. This report concerns the associations between the 12 main types of cancer in our series and 10 inorganic dusts that are found mainly in construction and metal industries. All site-exposure combinations were investigated. After intensive control for confounding, nonadenocarcinoma (NAC) of the lung was associated with long duration-high level exposure to silica (odds ratio [OR] = 1.4), excavation dust (OR = 1.9), concrete dust (OR = 2.5), abrasives dust (OR = 1.4), and alumina (OR = 1.5). It was difficult to disentangle the relative effects of those substances, and confounding among them was a distinct possibility. Although residual confounding by some uncontrolled factors may explain the elevated ORs, the results were compatible with the hypothesis of a nonspecific relation between NAC of the lung and respirable inorganic dusts as a class. Other associations that remained suggestive after in-depth analysis were silica and stomach cancer (OR = 1.2) and concrete dust and lymphoma (OR = 2.9).     

Estimating the relative risk of pancreatic cancer associated with exposure agents in job title data in a hierarchical Bayesian meta-analysis

OBJECTIVES: The study demonstrates the application of a hierarchical Bayesian meta-analysis of epidemiologic studies that show an association between pancreatic cancer risk and job titles, using a job-exposure matrix to estimate risks for occupational exposure agents. METHODS: Altogether 261 studies published from 1969 through 1998 on pancreatic cancer and job titles were identified. When proportional studies are excluded, 77 studies were informative for 9 selected occupational agents. These studies included more than 3799 observed pancreatic cancer cases. Hierarchical Bayesian models were used for job titles (lower-level data) and agents (higher-level data), the latter from a Finnish job-exposure matrix. Non-Bayesian random effects models were applied for job titles to check consistency with the Bayesian results. RESULTS: The results suggest that occupational exposures to chlorinated hydrocarbon compounds may increase the risk of pancreatic cancer; the meta-relative risk (MRR) was 2.21 [95% credible interval (CrI) 1.31-3.68]. A suggestive weak excess was found for exposure to insecticides (MRR 1.95, 95% CrI 0.51-7.41). CONCLUSIONS: Hierarchical models are applicable in meta-analyses when studies addressing the agent(s) under study are lacking or are very few, but several studies address job titles with potential exposure to these agents. Hierarchical meta-analytic models involving durations and intensities of exposure to occupational agents from a job-exposure matrix should be developed.     

Risk of spontaneous abortion in women occupationally exposed to anaesthetic gases: a meta-analysis.

OBJECTIVES: To determine the association between maternal occupational exposure to anaesthetic gases and risk of spontaneous abortion. METHODS: A meta-analysis was performed of published epidemiological studies identified from literature reviews, unsystematic perusal of reference lists of relevant publications, and two Medline searches (1984-92, keywords: anaesthetic gases; anaesthetics; anaesthetics, local; operating rooms; operating room nursing; pregnancy; abortion; 1985-92, keywords: anaesthetics; adverse effects; occupational exposure; anaesthesia, inhalation; operating room nursing; pregnancy; abortion). All peer reviewed studies were retained. Student theses were excluded, as were conference abstracts, unpublished material, and two studies in which data on paternal and maternal occupational exposures were pooled. The relative risk of spontaneous abortion was estimated. RESULTS: One study found no increase in risk of abortion when gases were scavenged or when the exposure to unscavenged gases was low. None of the studies included ambient gas sampling. 24 comparisons between exposed and unexposed women, obtained from 19 reports, were included. The overall relative risk was 1.48 (95% confidence interval (95% CI), 1.4 to 1.58). To test whether this result was influenced by the quality of the studies, the validity of the reviewed papers was rated on the basis of three criteria: appropriateness of the unexposed comparison group, control for non-occupational confounding variables, and response rate. The estimate of risk increased to 1.9 (95% CI, 1.72 to 2.09) when analysis was restricted to the six comparisons which were rated the most rigorous. CONCLUSIONS: Epidemiological studies based on data obtained in the prescavenging era indicate an increased risk of spontaneous abortion. The estimated increased risk was not diminished but rather increased by exclusion of the more methodologically flawed studies.     

Mortality and cancer incidence in a cohort of meatworkers

Methods: In a retrospective cohort study, a list of members of a meatworkers union in Australia was matched with the national death and cancer registries. Standardised mortality ratios (SMR) and standardised incidence ratios (SIR) were calculated using Australian population rates. Exposure to animal viruses, animal blood, animal faeces, and plastic pyrolysis products was assigned according to job title. A nested case control analysis examined the risk of mortality and cancer incidence by each exposure.

Results: There were approximately 20 000 subjects available for analysis. Male workers had increased risk of mortality from all causes (SMR 116, 95% CI 105 to 128) and from injury (SMR 131, 95% CI 108 to 157). Risk of incident lung cancer in males was non-significantly increased (SIR 164, 95% CI 97 to 259) and males had a raised risk of head and neck cancer (SIR 188, 95% CI 103 to 315). There were no significant associations with specific exposures.

Conclusions: Compared to the general Australian population, meatworkers have increased risk of death from all causes, death from injury, and incident lung and head and neck cancer. Analysis by occupational exposures did not disclose any strong evidence of specific occupational risk factors, although this analysis was limited by small numbers of some outcomes and exposure assessment which was based on job titles only.

     

Occupational risk factors for renal cell carcinoma in Montreal

BACKGROUND: Little is known about the role of workplace exposures on the risk of renal cell cancer. METHODS: A population-based case-control study was undertaken in Montreal to assess the association between hundreds of occupational circumstances and several cancer sites, including the kidney. A total of 142 male patients with pathologically confirmed renal cell carcinoma, 1900 controls with cancer at other sites and 533 population-based controls were interviewed. Detailed job histories and relevant data on potential confounders were obtained. A group of chemists-hygienists evaluated each job reported and translated them into a history of occupational exposures using a checklist of 294 substances. Multivariate logistic regression models using either population, cancer controls, or a pool of both groups were used to estimate odds ratios. RESULTS: There were some indications of excess risks among printers, nursery workers (gardening), aircraft mechanics, farmers, and horticulturists, as well as in the following industries: printing-related services, defense services, wholesale trade, and retail trade. Notwithstanding the low precision of many of the odds ratio estimates, the following workplace exposures showed some evidence of excess risk: chromium compounds, chromium (VI) compounds, inorganic acid solutions, styrene-butadiene rubber, ozone, hydrogen sulphide, ultraviolet radiation, hair dust, felt dust, jet fuel engine emissions, jet fuel, aviation gasoline, phosphoric acid and inks. CONCLUSIONS: For most of these associations there exist no, or very little, previous data. Some associations provide suggestive evidence for further studies.