Musculoskeletal symptoms among young male workers and associations with exposure to hand–arm vibration and ergonomic stressors

Objective

The overall aim of this study was to explore the association between incident musculoskeletal symptoms in the neck and upper limbs and exposure to hand–arm vibration and ergonomic stressors.

Methods

The study has a prospective design and data at baseline and follow-up was assessed by self-administered questionnaires. The study population consisted of students that had graduated from vocational high schools in 2001–2003 in northern and western Sweden and a total of 586 men responded to both the baseline and follow-up questionnaires. The mean age was 20.7 (range 19–27) years, and the exposure information included questions regarding hand–arm vibration, postural stress, computer work, mental stress and perception of muscular tension. Musculoskeletal symptoms in the neck and upper limbs were assessed at baseline and at follow-up.

Results

Men who reported their daily vibration exposure duration (work and leisure) as more than 1 h at baseline had an increased risk of neck pain in the preceding 7 days at follow-up, when adjusting for all the other exposure variables (PR 3.29, 95% CI 1.02–14.9). Men with a calculated 8-h weighted vibration exposure level [A(8)] above 1.7 m/s² had an increased risk of developing neck pain in both the unadjusted and adjusted analyses compared to those with an exposure level below 0.5 m/s².

Conclusion

Men who reported their daily vibration exposure duration (work and leisure) to be more than 1 h at baseline had an increased risk of neck pain for the preceding 7 days at follow-up. An increased prevalence of neck pain was also observed in individuals with a calculated 8-h frequency weighted vibration exposure level above 1.7 m/s² (calculated from data assessed at follow-up) compared to those with an exposure level below 0.5 m/s². The increased risks remained when adjusting for postural and mental stress; however the results could still be confounded by other ergonomic and physical load factors not adjusted for in the analyses.

     

Changes in physical activity and heart rate variability in chronic neck–shoulder pain: monitoring during work and leisure time

Objectives

Neck–shoulder pain (NSP) is a common work-related musculoskeletal disorder with unclear mechanisms. Changes in physical activity and autonomic nervous system regulation may be involved in the pathogenesis of chronic NSP. The aim of the current study was to investigate autonomic regulation in relation to physical activity and perceived symptoms during work and leisure time among workers with chronic NSP (n = 29) as compared to a healthy control group (CON, n = 27).

Methods

Physical activity was objectively monitored for 7 days using accelerometry. Beat-to-beat heart rate was collected continuously for 72 h, with simultaneous momentary ratings of pain, stress, and fatigue. Duration of sitting/lying, standing and walking, number of steps, and energy expenditure were used as measures of physical activity. Heart rate variability (HRV) indices were extracted in time and frequency domains as reflecting autonomic regulation. Data were divided into work hours, leisure time, and sleep.

Results

The NSP group rated higher levels of stress and fatigue at work and leisure, and reduced sleep quality as compared to CON. Elevated heart rate and reduced HRV were found in NSP compared with CON, especially during sleep. The NSP group demonstrated a different pattern of physical activity than CON, with a lower activity level in leisure time. Higher physical activity was associated with increased HRV in both groups.

Conclusion

Changes in HRV reflected an autonomic imbalance in workers with chronic musculoskeletal pain. This can be explained by reduced physical activity in leisure time. Intervention studies aimed at increasing physical activity may shed further light on the association between autonomic regulation and physical activity in work-related NSP.     

The effects of neck–shoulder pain development on sensory–motor interactions among female workers in the poultry and fish industries. A prospective study

OBJECTIVES: The purpose of this prospective laboratory study was to follow newly employed workers in the fish or poultry industry for 6 months and investigate possible changes in sensory manifestations and motor performance during low load, repetitive work simulation. It was investigated whether the changes were an effect of employment duration and of development of neck-shoulder complaints. METHODS: Twelve newly employed female filleting employees without any sign of neck-shoulder tenderness/pain at the time of employment of 0 months took part in two laboratory recording sessions planned within 1 month of employment and after 6 months of employment at the plant. After 6 months, six workers out of 12 had developed pain and/or tenderness in the neck-shoulder region. The recording sessions evaluated sensory-motor aspects by measuring pressure pain threshold, work-task timing, cutting forces, surface electromyographic activity of four shoulder muscles, displacement of the centre of pressure, and 3D movements of the arm and trunk during simulation of low load, repetitive filleting. RESULTS: Effects due to the duration of employment were observed in both groups, i.e. decreased sensibility to pressure, decrease in the duration of the work cycle, increased arm starting position with respect to the upright position, and decreased range of motion of the arm and trunk (P<0.05) after 6 months. Among the workers with neck-shoulder complaints, increased sensibility to pressure, lower force level, higher electromyographic activity, decreased amplitude of arm movement, and increased trunk posture and movement amplitude (P<0.05) were observed, compared with workers without complaints. CONCLUSIONS: Differences in terms of sensory manifestations and motor control strategy were seen after 6 months of employment with or without neck-shoulder complaints. In general, changes in sensory manifestations and motor control strategy after 6 months work were most likely of importance, as they underlined a learning process as employment duration increased. Moreover, the present sensory-motor changes observed among workers with neck-shoulder complaints highlighted the potential physical risk factors associated with low load, repetitive work.     

Are psychosocial factors,risk factors for symptoms and signs of the shoulder,elbow, or hand/wrist?: A review of the epidemiological literature

BACKGROUND: In 1993, an extensive review on the role of psychosocial factors in the development of musculoskeletal problems was published by Bongers et al (1993). Since then, additional reviews on this topic have been published; however, none of these focussed on upper limb problems. METHODS: In this systematic review, the methodological quality of all studies was assessed and levels of evidence were apriori defined. RESULTS: The large majority of the studies reported an association between at least one work-related psychosocial factor and adverse upper extremity symptoms or signs. High-perceived job stress was consistently associated with all upper extremity problems (UEP) in high and lower quality studies. Although not often studied, non-work-related stress was also consistently associated with UEP. In addition, there was some evidence for a relationship between high job demands and UEP, although the results did not meet the pre-set criterion for consistency. CONCLUSIONS: High job stress and non-work-related stress reactions are consistently associated with UEP. In addition, high job demands is also in most studies associated with these disorders. Firm conclusions on the role of these factors in the etiology of UEP are not possible due to the cross-sectional nature of most studies.     

Normative data for neuromuscular assessment of the hand–arm vibration syndrome and its retrospective applications in Korean male workers

Purpose

The purpose of this study was to describe normative data for the neuromuscular assessments of the hand–arm vibration syndrome (HAVS) in Korean.

Methods

Data for the vibrotactile perception threshold (VPT) at three frequencies (31.5, 125, and 250 Hz), the hand grip strength (HGS), the finger pinch strength (FPS), the finger tapping test, and the Purdue pegboard tests were collected from 120 male office workers aged 30–59 years with no prior history of regular use of handheld vibrating tools. The collected data were compared with the results of a similar study of shipbuilding workers in order to investigate the diagnostic utility of clinical test for HAVS.

Results

The mean VPT values indicate that no significant differences were observed between the dominant and non-dominant hands or between the index and little fingers. The age group of 30s was highly sensitive to vibration input with a peak in sensitivity at 125 Hz among all age groups. In neuromuscular performance, dominant hands are usually more accurate, dexterous, and functionally quicker than non-dominant hands. The index finger was superior to the little finger in the finger tapping counts (p < 0.05). Also, FPS was greater in the index finger than in the middle finger (p < 0.05). The HGS of dominant hands was significantly stronger than that of non-dominant hands (p < 0.05). When the normative data were compared with the data of shipyard workers exposed to vibration, there were statistically significant differences in VPT and neuromuscular functions.

Conclusions

The current data can be used to evaluate HAVS in Korean male workers. Age is an important factor for VPT.     

How sharp is the short QuickDASH? A refined content and validity analysis of the short form of the disabilities of the shoulder, arm and hand questionnaire in the strata of symptoms and function and specific joint conditions

Purpose  

To assess and compare content, validity, and specificity of the QuickDASH (Disability of the arm, shoulder and hand questionnaire) as compared to the full-length DASH and other instruments to give a recommendation for its use depending on a specific clinical situation.     

Interethnic differences at the thermometric response to cold test: functional disorders of blood circulation in hand fingers and exposure to hand–arm vibration

Objectives To report some notable aspects regarding thermometric response to cold test in black African subjects compared with Caucasians: both groups comprised persons exposed to hand–arm vibration and controls. Methods An overall sample of 48 workers was examined in order to study their blood circulation in hand fingers: a control group of 12 healthy Caucasian workers never exposed before to hand–arm vibration; 12 Caucasian workers exposed for several years to vibrating tools and affected by occupational Raynaud’s phenomenon; 12 healthy black African workers exposed to hand–arm vibration for almost 3 years; and 12 healthy black African workers never exposed to hand–arm vibration. Computerized skin thermometry was performed and thermometric curves were analyzed according to thermometric interpretation criteria such as the area-over-curve (AOC), the fifth minute of recovery/baseline temperature ratio (5REC/BT) and the temperature at the tenth minute of recovery (10REC) after cold test. Results Thermometric parameters in Caucasian subjects confirmed the basis of the existing literature in controls (basal finger temperature higher than 32°C and complete recovery to the initial temperature after the cold test) and also in patients with Raynaud’s phenomenon (basal temperature often lower than control subjects and slow recovery of finger temperature after cold test). Statistically significant difference was found between healthy Caucasians and healthy black subjects in all the parameters tested: healthy black subjects showed values of AOC and 10REC suggesting almost constantly lower finger temperatures during the thermometry test. Black people, both exposed and non-exposed to hand–arm vibration showed thermometric parameters suggesting poor blood microcirculation, which seems even poorer than in Caucasian people complaining Raynaud’s phenomenon. Conclusions Our chronothermometric tests suggest some significant interethnic differences in peripheral microcirculation, which seems rather poor in black African subjects in comparison with Caucasians.     

The effect of different warming methods on sensory nerve conduction velocity in shipyard workers occupationally exposed to hand–arm vibration

OBJECTIVES: Segmental sensory nerve conduction velocity (SNCV) was measured from the wrists to the hands and digits in a population of 134 (126 men and 8 women) vibration-exposed shipyard workers following systemic warming using a bicycle ergometer. Results were compared to earlier nerve conduction tests, identical in execution, except that the warming process was segmental and cutaneous. The study was designed to investigate whether SNCVs, which were selectively slow in the fingers after segmental cutaneous (skin surface) warming, would be affected differently by systemic warming. METHODS: Wrist-palm, palm-proximal digit, and digital sensory nerve segments were assessed antidromically by stimulating at the wrist with recording electrodes placed distally. The same subjects were cutaneously warmed in 2001 to >/=31 degrees C and were systemically warmed 28 months later in 2004 by ramped sustained exercise to 100 W for 12 min. Skin temperatures were measured by traditional thermistry and by infrared thermal images taken over the hand and wrist surfaces. RESULTS: When systemic warming was compared to segmental cutaneous warming, SNCVs were increased by 15.1% in the third digit and 20.4% in the fifth digit of the dominant hand. Respective increases in the non-dominant hand were 11.0% and 19.4%. A strong association between increased surface skin temperature and faster SNCV, which had been observed after segmental cutaneous warming, was largely eliminated for both digit and palmar anatomic segments after systemic warming. Significant differences in SNCV between vibration-exposed and non-exposed workers, which had been observed after segmental cutaneous warming, were eliminated after systemic warming. Systemic warming had only a small effect on the wrist-palm (transcarpal) segmental SNCVs. CONCLUSIONS: Reduced SNCV in the digits was observed in vibration-exposed and non-exposed workers. Substituting exercise-induced systemic warming for segmental cutaneous warming significantly increased SNCV in the digits and appeared to reduce differences in SNCV between vibration-exposed and non-exposed workers. These findings persisted despite a substantial time interval between tests, during which the subjects continued to work. There may be more general implications for diagnosing clinical conditions in industrial workers, such as the carpal tunnel syndrome and the hand-arm vibration syndrome.     

Incidence of shoulder and neck pain in a working population: effect modification between mechanical and psychosocial exposures at work? Results from a one year follow up of the Malm? shoulder and neck study cohort

STUDY OBJECTIVE: To assess the impact of mechanical exposure and work related psychosocial factors on shoulder and neck pain. DESIGN: A prospective cohort study. PARTICIPANTS: 4919 randomly chosen, vocationally active men and women ages 45-65 residing in a Swedish city. Neck and shoulder pain were determined by the standardised Nordic questionnaire. Mechanical exposure was assessed by an index based on 11 items designed and evaluated for shoulder and neck disorders. Work related psychosocial factors were measured by the Karasek and Theorell demand-control instrument. MAIN RESULTS: High mechanical exposure was associated with heightened risk for shoulder and neck pain among men and women during follow up. Age adjusted odds ratios (OR) were 2.17 (95% confidence intervals (CI): 1.65, 2.85) and 1.59 (95% CI: 1.22, 2.06), respectively. In women, job strain (high psychological job demands and low job decision latitude) correlated with heightened risk (OR = 1.73, 95% CI: 1.29, 2.31). These risk estimates remained statistically significant when controlled for high mechanical exposure regarding job strain (and vice versa), and for sociodemographic factors. Testing for effect modification between high mechanical exposure and job strain showed them acting synergistically only in women. CONCLUSION: Job related mechanical exposure in both sexes, and psychosocial factors in women, seem independently of each other to play a part for development of shoulder and neck pain in vocationally active people. The effect of psychosocial factors was more prominent in women, which could be the result of biological factors as well as gender issues. These results suggest that interventions aiming at reducing the occurrence of shoulder and neck pain should include both mechanical and psychosocial factors.     

Spatial clustering and space–time clusters of leukemia among children in Germany, 1987–2007

Leukemia is the most frequent malignancy in children under the age of 15 years. The question of whether childhood leukemia has a tendency for clustering or forms clusters has been studied for several decades. The environmental risk factor discussed most often is infection, which might result in spatial clustering and space–time clusters. The German Childhood Cancer Registry provided data on 11,946 children with leukemia diagnosed during 1987–2007, as classified in the International Classification for Childhood Cancer (third edition), aggregated by municipality. We used the Potthoff–Whittinghill model to test for a general trend for clustering and the spatial scan statistic to search for localized clusters. No evidence of global clustering was found, neither for the whole study population nor in sub-groups by age, period or population density, or for different types of leukemia. A similar result was found for localized clusters. The analysis shows no evidence of a tendency to clustering, however, aggregation of data at the municipality level might have diluted small localized clusters. The results of this study do not provide support for the hypothesis of an infectious or a spatial environmental etiology of childhood leukemia.     

Substance or space? The relative importance of substance properties and environmental characteristics in modeling the fate of chemicals in Europe

The relative influence of substance properties and of environmental characteristics on the variation in the environmental fate of chemicals was studied systematically and comprehensively. This was done by modeling environmental concentrations for 200 sets of substance properties, representative of organic chemicals used, and 137 sets of environmental characteristics, representative of regions in Europe of 250 x 250 km. Since it was expected that the model scale has an influence on the predicted concentration variations, the calculations were repeated for regions with a 100 x 100 km and 50 x 50 km area. Stepwise multiple regression analysis was performed to determine the contribution of each of the individual input parameters on the total concentration variation. Depending on the scenario, the range in predicted environmental concentrations spreads from two up to nine orders of magnitude. In accord with earlier studies, variation in the fate of chemicals in the environment appeared to depend mainly on substance-specific partition coefficients and degradation rates. For the estimation of soil and water concentrations with direct emissions to these compartments, however, the influence of spatial variation in environmental characteristics can mount up to two orders of magnitude, a range that can be significant to account for in certain model applications. Concentration differences in water and soil are predicted to be larger if a smaller region is applied in the model calculations, and the relative influence of environmental characteristics on the total variation increases on a more detailed spatial scale. It is argued that the influence of environmental characteristics as predictors of exposure concentrations of chemicals deserves better attention in comparative risk assessment with conventional nonspatial multimedia box models.     

Letter to the Editor: Prevalence of HIV, HTLV-I and HTLV-II among female sex workers in Spain, 2000–2001

Using an unlinked anonymous survey the seroprevalence of HIV, HTLV-I and HTLV-II was analysed among female sex workers. They were surveyed when they attended sexually transmitted disease clinics in six Spanish cities during the period 2000-2001. Fifty-eight percent of the 3149 women analysed came from Latin America or sub-Saharan Africa. The total prevalence of HIV was 0.7%, rising to 15.9% amongst injecting drug users (IDUs). When this group was not included, the prevalence amongst the Latin-Americans or sub-Saharan Africans was 0.8% and amongst the women from other origins 0.3% (p = 0.148). 33.3% of the women infected with HIV already knew about their infection. The prevalences of HTLV-I and HTLV-II were 0.3% and 0.2%, respectively. The prevalences of these three infections in this collective were low if evaluated without the IDUs.     

The role of personal characteristics in the relationship between health and psychological distress among kidney transplant recipients

Although kidney transplantation improves overall quality of life and physical functioning, improvements of psychological distress are often modest. However, apparent stressors such as comorbidity are only weakly associated with psychological distress and their impact differs considerably between patients. Wilson and Cleary proposed a theoretical model to explain these relationships. This model has been supported by research, but has never been applied in a population of kidney transplant recipients. Findings of the current study are based on a cross-sectional study carried out in 2008 in the northern Netherlands. An elaborated version of Wilson and Cleary's model specifying hypothesized relationships of objective health, functional status, subjective health, personal characteristics and psychological distress was evaluated with structural equation modelling. After elimination of non-significant paths the final model provided a good fit for the data, X(2) (2)=4.23, p=0.12; RMSEA=0.047, CI(RMSEA) (0; 0.11); ECVI=0.060, ECVI(sat)=0.059. Results suggest that objective health has an indirect effect on psychological distress, in size comparable to the effects exerted by functional status and subjective health. Personal characteristics are the strongest determinant of psychological distress, but are directly and indirectly affected by objective health. Results indicate that poor health might cause psychological distress by increasing coping demands while simultaneously decreasing coping resources.     

Correlation between work process-related exposure to polycyclic aromatic hydrocarbons and urinary levels of α-naphthol, β-naphthylamine and 1-hydroxypyrene in iron foundry workers

Summary In two Danish iron foundries the concentration of polycyclic aromatic hydrocarbons (PAH) in 24 personal air samples of workers employed in selected processes, i.e. melters, melted iron transporters, casters, machine molders, hand molders, shake-out workers and finishing workers, were measured and correlated to levels of 1-hydroxypyrene, -naphthol and -naphthylamine in the urine of exposed workers. The highest total airborne PAH concentrations (sum of 15 selected PAH compounds: 9.6–11.2 g/m³) were associated with casting, machine molding, and shake-out. The highest concentrations of the sum of six selected airborne carcinogenic PAH compounds were found for melting, casting and machine and hand molding. As seen in other working environments involving low-level PAH exposure, the content of naphthalene was high, in general exceeding 85% of the total content of PAH compounds. The present study demonstrates that 1-hydroxypyrene is a useful and direct biomarker of low-dose occupational exposure to PAH compounds. Molding and casting had the highest pyrene levels in iron foundries. Furthermore, the data shows that levels of -naphthylamine in urine are significantly elevated in iron foundry workers. Hand molders, finishing workers and truck drivers tended to have the highest levels. Concerning -naphthol the highest concentrations were measured in urine from casters and shake-out workers. With regard to epidemiologic studies demonstrating that molders and casters have a higher risk of lung cancer, the present study suggests that the elevated risk may be due to exposure to carcinogenic PAH compounds in iron foundries, particularly in some high-risk work processes, e.g. casting and molding. In addition, the present study suggests that biological monitoring of 1-hydroxypyrene and -naphthylamine may be used to estimate the individual exposure, which seems to be correlated with exposure during individual work processes.     

The Epidemiology of Human Immunodeficiency Virus Infection and Care among Adult and Adolescent Females in the United States, 2008–2012

ObjectiveWe sought to determine epidemiological patterns in diagnoses of human immunodeficiency virus (HIV) infection and prevalence among females by age, race/ethnicity and transmission category, and essential steps in the continuum of HIV care.MethodsUsing data from the National HIV Surveillance System, we estimated the number of females aged 13 years or older diagnosed with HIV infection in 2008 through 2012 and living with HIV at the end of 2011 in the United States. We determined percentages of females linked to care, retained in care, and virally suppressed in 18 jurisdictions with complete reporting of CD4 and viral load test results.ResultsFrom 2008 to 2012, the estimated rate of HIV diagnoses among females decreased from 9.3 to 6.9 per 100,000 (−7.1% per year; 95% confidence interval [CI], −7.9, −6.3). In 2012, the diagnosis rate was highest among Blacks/African Americans (35.7), followed by Hispanics or Latinos (6.4), and Native Hawaiian Other Pacific Islander (5.1), and lowest among Whites (1.8). Most females diagnosed in 2012 were linked to care within 3 months of diagnosis (82.5%). About one-half (52.4%) of females living with HIV in 2011 received ongoing care in 2011 and 44.3% had a suppressed viral load. Viral suppression was lower among American Indian/Alaska Native (29.7%) and Black/African American (41.6%) compared with White females (46.5%). The percentage in care and with viral suppression was lower among younger compared with older females.ConclusionHIV diagnoses continue to decrease among females; however, disparities exist in HIV burden and viral suppression. Improvements in care and treatment outcomes are needed for all women with particular emphasis on younger women.