Showing papers in "Occupational and Environmental Medicine in 2004"

An epidemiological study of the magnitude and consequences of work related violence: the Minnesota Nurses’ Study

Abstract: Aims: To identify the magnitude of and potential risk factors for violence within a major occupational population. Methods: Comprehensive surveys were sent to 6300 Minnesota licensed registered (RNs) and practical (LPNs) nurses to collect data on physical and non-physical violence for the prior 12 months. Re-weighting enabled adjustment for potential biases associated with non-response, accounting for unknown eligibility. Results: From the 78% responding, combined with non-response rate information, respective adjusted rates per 100 persons per year (95% CI) for physical and non-physical violence were 13.2 (12.2 to 14.3) and 38.8 (37.4 to 40.4); assault rates were increased, respectively, for LPNs versus RNs (16.4 and 12.0) and males versus females (19.4 and 12.9). Perpetrators of physical and non-physical events were patients/clients (97% and 67%, respectively). Consequences appeared greater for non-physical than physical violence. Multivariate modelling identified increased rates for both physical and non-physical violence for working: in a nursing home/long term care facility; in intensive care, psychiatric/behavioural or emergency departments; and with geriatric patients. Conclusions: Results show that non-fatal physical assault and non-physical forms of violence, and relevant consequences, are frequent among both RNs and LPNs; such violence is mostly perpetrated by patients or clients; and certain environmental factors appear to affect the risk of violence. This serves as the basis for further analytical studies that can enable the development of appropriate prevention and control efforts.

Increased inflammation and altered macrophage chemotactic responses caused by two ultrafine particle types

Abstract: Background: Ultrafine particles have been hypothesised to be an important contributing factor in the toxicity and adverse health effects of particulate air pollution (PM10) and nanoparticles are used increasingly in industrial processes. Aims: To compare the ability of ultrafine and fine particles of titanium dioxide and carbon black to induce inflammation, cause epithelial injury, and affect the alveolar macrophage clearance functions of phagocytosis and chemotaxis in vivo. Methods: Rats were instilled with fine and ultrafine carbon black and titanium dioxide. Inflammation was quantified by bronchoalveolar lavage; the ability of the macrophages to phagoytose indictor fluorescent beads and to migrate towards aC5a were determined. Results: Ultrafine particles induced more PMN recruitment, epithelial damage, and cytotoxicity than their fine counterparts, exposed at equal mass. Both ultrafine and fine particles significantly impaired the phagocytic ability of alveolar macrophages. Only ultrafine particle treatment significantly enhanced the sensitivity of alveolar macrophages to chemotact towards C5a. Conclusions: Ultrafine particles of two very different materials induced inflammation and epithelial damage to a greater extent than their fine counterparts. In general, the effect of ultrafine carbon black was greater than ultrafine titanium dioxide, suggesting that there are differences in the likely harmfulness of different types of ultrafine particle. Epithelial injury and toxicity were associated with the development of inflammation after exposure to ultrafines. Increased sensitivity to a C5a chemotactic gradient could make the ultrafine exposed macrophages more likely to be retained in the lungs, so allowing dose to accumulate.

Contrasting patterns of mortality and hospital admissions during hot weather and heat waves in Greater London, UK

Abstract: Background: Epidemiological research has shown that mortality increases during hot weather and heat waves, but little is known about the effect on non-fatal outcomes in the UK. Aims and Methods: The effects of hot weather and heat waves on emergency hospital admissions were investigated in Greater London, UK, for a range of causes and age groups. Time series analyses were conducted of daily emergency hospital admissions, 1 April 1994 to 31 March 2000, using autoregressive Poisson models with adjustment for long term trend, season, day of week, public holidays, the Christmas period, influenza, relative humidity, air pollution (ozone, PM 10 ), and overdispersion. The effects of heat were modelled using the average of the daily mean temperature over the index and previous two days. Results: There was no clear evidence of a relation between total emergency hospital admissions and high ambient temperatures, although there was evidence for heat related increases in emergency admissions for respiratory and renal disease, in children under 5, and for respiratory disease in the 75+ age group. During the heat wave of 29 July to 3 August 1995, hospital admissions showed a small non-significant increase: 2.6% (95% CI −2.2 to 7.6), while daily mortality rose by 10.8% (95% CI 2.8 to 19.3) after adjusting for time varying confounders. Conclusions: The impact of hot weather on mortality is not paralleled by similar magnitude increases in hospital admissions in the UK, which supports the hypothesis that many heat related deaths occur in people before they come to medical attention. This has evident implications for public health, and merits further enquiry.

Climate and the prevalence of symptoms of asthma, allergic rhinitis, and atopic eczema in children

Abstract: Aims: To investigate the association between climate and atopic diseases using worldwide data from 146 centres of the International Study of Asthma and Allergies in Childhood (ISAAC). Methods: Between 1992 and 1996, each centre studied random samples of children aged 13–14 and 6–7 years (approx. 3000 per age group and centre) using standardised written and video questionnaires on symptoms of asthma, allergic rhinoconjunctivitis, and atopic eczema during the past 12 months. Data on long term climatic conditions in the centres were abstracted from one standardised source, and mixed linear regression models calculated to take the clustering of centres within countries into account. Results: In Western Europe (57 centres in 12 countries), the prevalence of asthma symptoms, assessed by written questionnaire, increased by 2.7% (95% CI 1.0% to 4.5%) with an increase in the estimated annual mean of indoor relative humidity of 10%. Similar associations were seen for the video questionnaire and the younger age group. Altitude and the annual variation of temperature and relative humidity outdoors were negatively associated with asthma symptoms. The prevalence of eczema symptoms correlated with latitude (positively) and mean annual outdoor temperature (negatively). Conclusions: Results suggest that climate may affect the prevalence of asthma and atopic eczema in children.

Sick building syndrome

Abstract: The sick building syndrome (SBS) consists of a group of mucosal, skin, and general symptoms that are temporally related to working in particular buildings It is the workers who are symptomatic, but the building or its services which are the cause The common symptoms and a method of assessment are shown in box 2 The average number of work related symptoms per occupant is known as the building symptom index It can be measured reproducibly by simple questionnaire surveys The building symptom index shows a wide variation between different buildings (fig 1); “sicker” buildings often have conditions of air temperature, humidity, and lighting levels that fully comply with current standards Some of the reproducible “facts” shown in studies in different countries are shown in box 1, and factors related to higher (sicker) building symptom indices shown in box 3 Box 4 shows the WHO standards for the management of building ventilation systems Money spent on the building services is likely to be cost effective in terms of the lost productivity in symptomatic workers Figure 1 Range of building symptom indices in a group of buildings studied with the same questionnaire with a maximum of 10 symptoms (the actual BSI is dependent on the number of possible positive answers and differs between questionnaires) ### Box 1: Reproducible observations related to sick building syndrome (?facts)

Health promotion in the workplace: framing the concept; reviewing the evidence

Abstract: The term “health promotion in the workplace” is a multidimensional concept that embraces at least two major philosophies about what health is and how it is influenced. The first philosophy sees health as largely the product of individual behaviour and as an individual responsibility. It may acknowledge the role of genetics and environment to some degree, but the type of health promotion arising from this set of beliefs focuses on individual behaviour. Consequently, the workplace is seen primarily as a venue through which various programmes can be delivered. Examples of programme areas are: fitness, stress management, smoking cessation, back care, weight reduction/nutrition, medication. The second philosophy sees health as being influenced by a number of forces, a significant number of which are outside the individual’s control. While acknowledging the individual’s responsibility for his or her own health, this set of beliefs focuses on the role of the environment. Consequently, the workplace is seen as an influence on health in its own right. The attention here tends to be on the organisation and design of work in both its physical and psychosocial dimensions. Any workplace claiming to “do” health promotion can be characterised by the subscription of its senior managers to one or other of these philosophies or, more commonly, to some blend of the two. The 1997 Luxembourg Declaration on Workplace Health Promotion in the European Union1 is an interesting document in this regard because it presents a “blended” philosophy as the ideal. Yet studies using the Luxembourg Declaration as a framework for research have revealed that by far the more common philosophy followed by organisations claiming to practice health promotion is that of focusing on the individual as opposed to the environmental.2 Be this as it may, it needs to be acknowledged that health, as we experience …

Psychosocial factors at work in relation to low back pain and consequences of low back pain; a systematic, critical review of prospective cohort studies.

Abstract: Relevant studies of low back pain (LBP) published between 1990 and 2002 were systematically retrieved via electronic databases and checking of reference lists. Forty papers fulfilled the inclusion criteria; 10 were of high quality. A wide variety of instruments had been used for collection of data on work related psychosocial factors, many of which had not undergone any form of validation. Moderate evidence was found for no association between LBP and perception of work, organisational aspects of work, and social support at work. There was insufficient evidence for a positive association between stress at work and LBP. No conclusions could be drawn regarding perception of work and consequences of LBP. There was strong evidence for no association between organisational aspects of work and moderate evidence for no association between social support at work and stress at work and consequences of LBP.

Aircraft noise around a large international airport and its impact on general health and medication use

Abstract: Aims: To assess the prevalence of general health status, use of sleep medication, and use of medication for cardiovascular diseases, and to study their relation to aircraft noise exposure. Methods: These health indicators were measured by a cross-sectional survey among 11 812 respondents living within a radius of 25 km around Schiphol airport (Amsterdam). Results: Adjusted odds ratios ranged from 1.02 to 2.34 per 10 dB(A) increase in Lden. The associations were statistically significant for all indicators, except for use of prescribed sleep medication or sedatives and frequent use of this medication. None of the health indicators were associated with aircraft noise exposure during the night, but use of non-prescribed sleep medication or sedatives was associated with aircraft noise exposure during the late evening (OR = 1.72). Vitality related health complaints such as tiredness and headache were associated with aircraft noise, whereas most other physical complaints were not. Odds ratios for the vitality related complaints ranged from 1.16 to 1.47 per 10 dB(A) increase in Lden. A small fraction of the prevalence of poor self rated health (0.13), medication for cardiovascular diseases or increased blood pressure (0.08), and sleep medication or sedatives (0.22) could be attributed to aircraft noise. Although the attributable fraction was highest in the governmentally noise regulated area, aircraft noise had more impact in the non-regulated area, due to the larger population. Conclusions: Results suggest associations between community exposure to aircraft noise and the health indicators poor general health status, use of sleep medication, and use of medication for cardiovascular diseases.

Work factors as predictors of intense or disabling low back pain; a prospective study of nurses' aides

Abstract: Aims: To identify the work factors that predict intense low back pain (LBP) and LBP related sick leaves in nurses' aides. Methods: The sample comprised 4266 randomly selected Norwegian nurses' aides, not bothered or only a little bothered by LBP during the previous three months, and not on sick leave when completing a mailed questionnaire in 1999. Of these, 3808 (89.3%) completed a second questionnaire 3 months later and 3651 (85.6%) completed a third questionnaire 15 months later. Intensity of low back symptoms and certified sick leaves attributed to LBP during the observation period were assessed by self reports at the follow ups. Results: After adjustments for LBP during the three months prior to baseline, baseline health complaints, demographic and familial factors, and a series of physical, psychological, and social work factors, logistic regression analyses revealed the following associations: intense low back symptoms were predicted by frequent positioning of patients in bed, perceived lack of support from immediate superior, and perceived lack of pleasant and relaxing culture in the work unit. LBP related sick leaves were predicted by frequent handling of heavy objects, medium level of work demands, perceived lack of supportive and encouraging culture in the work unit, working night shifts, and working in a nursing home. Long term LBP related sick leaves were associated with changes of work or work tasks during the observation period that resulted in a perceived reduction of support and encouragement at work. Conclusions: Not only frequent mechanical exposures, but also organisational, psychological, and social work factors, such as night shift work, perceived lack of support from superior, and perceived lack of a pleasant and relaxing or supporting and encouraging culture in the work unit, are associated with an increased risk of intense low back symptoms and LBP related sick leaves in nurses' aides.

Mortality among a cohort of garment workers exposed to formaldehyde: an update

Abstract: Aims: To evaluate the mortality experience of 11 039 workers exposed to formaldehyde for three months or more in three garment plants. The mean time weighted average formaldehyde exposure at the plants in the early 1980s was 0.15 ppm but past exposures may have been substantially higher. Methods: Vital status was updated through 1998, and life table analyses were conducted. Results: Mortality from all causes (2206 deaths, standardised mortality ratio (SMR) 0.92, 95% CI 0.88 to 0.96) and all cancers (SMR 0.89, 95% CI 0.82 to 0.97) was less than expected based on US mortality rates. A non-significant increase in mortality from myeloid leukaemia (15 deaths, SMR 1.44, 95% CI 0.80 to 2.37) was observed. Mortality from myeloid leukaemia was greatest among workers first exposed in the earliest years when exposures were presumably higher, among workers with 10 or more years of exposure, and among workers with 20 or more years since first exposure. No nasal or nasopharyngeal cancers were observed. Mortality from trachea, bronchus, and lung cancer (147 deaths, SMR 0.98, 95% CI 0.82 to 1.15) was not increased. Multiple cause mortality from leukaemia was increased almost twofold among workers with both 10 or more years of exposure and 20 years or more since first exposure (15 deaths, SMR 1.92, 95% CI 1.08 to 3.17). Multiple cause mortality from myeloid leukaemia among this group of workers was also significantly increased (8 deaths, SMR 2.55, 95% CI 1.10 to 5.03). Conclusions: Results support a possible relation between formaldehyde exposure and myeloid leukaemia mortality. Previous epidemiological studies supporting a relation between formaldehyde exposure and leukaemia mortality have been primarily of formaldehyde exposed professional groups, not formaldehyde exposed industrial workers. Limitations include limited power to detect an excess for rare cancers such as nasal and nasopharyngeal cancers and lack of individual exposure estimates.

Work related shoulder disorders: quantitative exposure-response relations with reference to arm posture

Abstract: Aims: To determine quantitative exposure-response relations between work with highly elevated arms and supraspinatus tendinitis, shoulder pain with disability, and shoulder pain without disability. Methods: A cross sectional study was conducted in a historical cohort of 1886 males from three occupational groups. Exposure measurements were performed for four consecutive working days in a random sample of 72 currently employed subjects. Individual work histories were obtained by questionnaire and register data. Health status was ascertained by physical examination blinded towards exposure and symptoms. Data were analysed by generalised estimating equation and multiple logistic regression with adjustment for potential confounders. Results: For current upper arm elevation above 90°, a duration increment of 1% of the daily working hours was associated with odds ratios of 1.23 (95% CI 1.10 to 1.39) for supraspinatus tendinitis, 1.16 (95% CI 1.08 to 1.24) for shoulder pain with disability, and 1.08 (95% CI 1.04 to 1.13) for shoulder pain without disability. The outcomes were not related to duration of employment in one of the three trades. Conclusions: Quantitative exposure-response relations were established between current work with highly elevated arms and clinically verified shoulder disorders. Substantial long term cumulative effects were not shown. A potential for primary prevention was revealed.

Particulate air pollution and panel studies in children: a systematic review

Abstract: Background: Panel studies have been used to investigate the short term effects of outdoor particulate air pollution across a wide range of environmental settings. Aims: To systematically review the results of such studies in children, estimate summary measures of effect, and investigate potential sources of heterogeneity. Methods: Studies were identified by searching electronic databases to June 2002, including those where outcomes and particulate level measurements were made at least daily for ⩾8 weeks, and analysed using an appropriate regression model. Study results were compared using forest plots, and fixed and random effects summary effect estimates obtained. Publication bias was considered using a funnel plot. Results: Twenty two studies were identified, all except two reporting PM 10 (24 hour mean) >50 μg.m −3 . Reported effects of PM 10 on PEF were widely spread and smaller than those for PM 2.5 (fixed effects summary: −0.012 v −0.063 l.min −1 per μg.m −3 rise). A similar pattern was evident for symptoms. Random effects models produced larger estimates. Overall, in between-study comparisons, panels of children with diagnosed asthma or pre-existing respiratory symptoms appeared less affected by PM 10 levels than those without, and effect estimates were larger where studies were conducted in higher ozone conditions. Larger PM 10 effect estimates were obtained from studies using generalised estimating equations to model autocorrelation and where results were derived by pooling subject specific regression coefficients. A funnel plot of PM 10 results for PEF was markedly asymmetrical. Conclusions: The majority of identified studies indicate an adverse effect of particulate air pollution that is greater for PM 2.5 than PM 10 . However, results show considerable heterogeneity and there is evidence consistent with publication bias, so limited confidence may be placed on summary estimates of effect. The possibility of interaction between particle and ozone effects merits further investigation, as does variability due to analytical differences that alter the interpretation of final estimates.

The psychosocial work environment and alcohol dependence: a prospective study

Abstract: Aims: To examine whether a stressful psychosocial work environment predicts alcohol dependence. Methods: Alcohol dependence of participants in the Whitehall II occupational cohort of London based civil servants (1985–88) was measured in 1991–93 using the CAGE questionnaire. The psychosocial work environment was measured by self report questions on the job demand-support-control model and on the model of effort-reward imbalance. Potential mediators including physical illness and poor mental health (GHQ) were measured at follow up in 1989. Results: Effort-reward imbalance at work was associated with alcohol dependence in men after adjustment for employment grade and other baseline factors related to alcohol dependence. Although effort-reward imbalance predicted future longstanding illness, poor mental health and negative aspects of close relationships, the association between effort-reward imbalance and alcohol dependence in men was only partially mediated through these health and social support measures. In women, low decision latitude was related to alcohol dependence to some extent, but alcohol dependence among women was more prevalent in higher occupational grades. Men with high job demands or with low work social supports had a slightly reduced risk of alcohol dependence. No association was found between objectively assessed demands, job control, and alcohol dependence in either men or women. Conclusion: A stressful psychosocial work environment in terms of effort-reward imbalance was found to be a risk factor for alcohol dependence in men. In view of the public health importance of alcohol dependence in working populations these findings call for more emphasis on psychosocial factors in occupational health research and prevention.

An incidence density sampling program for nested case-control analyses.

Abstract: Background: The nested case-control design can be a very efficient approach to an epidemiological investigation. In order to obtain unbiased estimates of relative risk, controls should be selected by incidence density sampling, which involves matching each case to a sample of those who are at risk at the time of case occurrence. Methods: This paper presents a simple computer program for incidence density sampling. This program was evaluated using data derived from a cohort study of mortality among workers employed in the nuclear weapons industry. Controls were selected for cases via incidence density sampling; an estimate of the exposure-mortality association was obtained via conditional logistic regression. After 100 iterations of this procedure, the average effect estimate was compared to the risk estimate obtained via proportional hazards regression. The same methods were used to evaluate a program for incidence density sampling that was proposed previously by Pearce in 1989.[5][1] Results: Relative risk estimates obtained from nested case-control analyses conducted using the incidence density sampling program reported in this paper are unbiased. In contrast, the program for incidence density sampling proposed by Pearce[5][1] tended to produce biased relative risk estimates; the magnitude of bias increased with increasing numbers of controls selected per case. Conclusions: The computer program described in this paper offers a simple approach to incidence density sampling for nested case-control analyses with exact matching on attained age and appropriate enumeration of the pool of eligible controls for each case. This method overcomes problems of bias inherent in a previously proposed program for incidence density sampling. [1]: #ref-5

Incidence of shoulder pain in repetitive work.

Abstract: Aims: To determine the predictiveness of personal and occupational factors for the onset of shoulder pain in occupations requiring repetitive work. Methods: A sample of 598 workers in five activity sectors completed a self administered questionnaire in 1993–94 and again three years later. Both questionnaires included questions about shoulder pain. The associations between various factors at baseline and subsequent shoulder pain were studied among subjects free from shoulder pain at baseline. Results: The incidence of shoulder pain was associated with several independent risk factors: depressive symptoms, low level of job control, and biomechanical constraints. After adjustment for other risk factors, the presence of depressive symptoms predicted occurrence of shoulder pain. A low level of job control was also associated with the onset of shoulder pain in both sexes. For men, repetitive use of a tool was a strong predictor, while the two most important biomechanical risk factors for women were use of vibrating tools and working with arms above shoulder level. Conclusion: This study used a longitudinal approach to examine different sets of risk factors for shoulder pain simultaneously. The results confirm the role of several biomechanical constraints. Psychological symptoms and a low level of job control also play a role.

Supervisory behaviour as a predictor of return to work in employees absent from work due to mental health problems

Abstract: Aims: To study supervisory behaviour as a predictive factor for return to work of employees absent due to mental health problems; and to explore the association between conditional factors and supervisory behaviour. Methods: Eighty five supervisors of employees were interviewed by telephone. Questionnaires providing information on person related factors, depressive symptoms, and sickness absence were sent to the employees at baseline, three months, six months, and after one year. Three aspects of supervisory behaviour during the period of absence were measured: communication with the employee, promoting gradual return to work, and consulting of other professionals. Results: Better communication between supervisor and employee was associated with time to full return to work in non-depressed employees. For employees with a high level of depressive symptoms, this association could not be established. Consulting other professionals more often was associated with a longer duration of the sickness absence for both full and partial return to work. If sickness absence had financial consequences for the department, the supervisor was more likely to communicate frequently with the employee. Supervisors who were responsible for return to work in their organisation were more likely to communicate better and to consult more often with other professionals. Conclusion: Supervisors should communicate more frequently with employees during sickness absence as well as hold follow up meetings more often as this is associated with a faster return to work in those employees.

Biomarkers of exposure to polycyclic aromatic hydrocarbons from environmental air pollution

Abstract: Metabolites of pyrene and DNA adducts have been used as biomarkers of high level exposure to polycyclic aromatic hydrocarbons (PAHs). A systematic review was performed to evaluate whether these biomarkers are also valid markers of low level environmental exposure to PAHs. Thirty five studies were identified with more than 10 subjects that evaluated environmental air pollution to PAHs in relation to metabolites of PAHs, mainly hydroxypyrene (1-OHP), PAH-DNA adducts, or protein adducts. PAH metabolites and, to a less extent, PAH-DNA adducts correlated well at the group level with exposure to B(a)P even at low levels of air pollution. The use of these biomarkers should be more widely implemented in combination with more traditional techniques for the assessment of general population exposure to PAHs from ambient air pollution.

Assessment of indoor air problems at work with a questionnaire.

Abstract: Results: The most common problems were dry air (35% of the respondents), stuffy air (34%), dust or dirt in the indoor environment (25%), and draught (22%). The most common work related symptoms were irritated, stuffy, or runny nose (20%), itching, burning, or irritation of the eyes (17%), and fatigue (16%). Women reported indoor air problems and work related symptoms more often than men. Allergic persons and smokers reported indoor air problems more often, and experienced work related symptoms more often than non-allergic persons and non-smokers. Conclusions: The complaints and work related symptoms associated with indoor air problems were common in office workers. The present questionnaire is a suitable tool for the occupational health personnel in investigating indoor air problems and the data of the survey can be used as a reference when the results of a survey at work are being analysed.

The effects of particulate air pollution on daily deaths: a multi-city case crossover analysis.

Abstract: Background: Numerous studies have reported that day-to-day changes in particulate air pollution are associated with day-to-day changes in deaths. Recently, several reports have indicated that the software used to control for season and weather in some of these studies had deficiencies. Aims: To investigate the use of the case-crossover design as an alternative. Methods: This approach compares the exposure of each case to their exposure on a nearby day, when they did not die. Hence it controls for seasonal patterns and for all slowly varying covariates (age, smoking, etc) by matching rather than complex modelling. A key feature is that temperature can also be controlled by matching. This approach was applied to a study of 14 US cities. Weather and day of the week were controlled for in the regression. Results: A 10 µg/m3 increase in PM10 was associated with a 0.36% increase in daily deaths from internal causes (95% CI 0.22% to 0.50%). Results were little changed if, instead of symmetrical sampling of control days the time stratified method was applied, when control days were matched on temperature, or when more lags of winter time temperatures were used. Similar results were found using a Poisson regression, but the case-crossover method has the advantage of simplicity in modelling, and of combining matched strata across multiple locations in a single stage analysis. Conclusions: Despite the considerable differences in analytical design, the previously reported associations of particles with mortality persisted in this study. The association appeared quite linear. Case-crossover designs represent an attractive method to control for season and weather by matching.

Perceived muscular tension, job strain, physical exposure, and associations with neck pain among VDU users; a prospective cohort study.

Abstract: Aims: To determine whether perceived muscular tension, job strain, or physical exposure are associated with increased risk of developing neck pain among VDU users. Methods: A baseline questionnaire was answered by 1283 respondents, of whom 671 were free from neck pain at baseline. Perceived muscular tension, job strain, and physical exposure were assessed at baseline. Information about newly developed neck pain was collected in 10 follow up questionnaires and the case definition was the first report of such pain in any of the follow up questionnaires. Median follow up time was 10.9 months. Results: Both men and women who perceived muscular tension at least a few times per week, compared to those who had not perceived muscular tension the preceding month, had an incidence rate ratio (IRR) of 1.9 (95% CI 1.25 to 2.93) for developing neck pain, when stratifying for sex. High perceived muscular tension was associated with an increased risk (IRR 1.6, 95% CI 1.02 to 1.91), even when controlling for job strain, physical exposure, and age in the model stratified by sex. Conclusions: Perceived muscular tension was associated with an increased risk of developing neck pain among VDU users. The combination of high job strain and high perceived muscular tension was associated with higher risk of developing neck pain than the combination of high physical exposure and high perceived muscular tension. There was an indication of an excess risk due to interaction between high physical exposure and high job strain.

Acute childhood leukaemia and environmental exposure to potential sources of benzene and other hydrocarbons; a case-control study

Abstract: Aim: To analyse the association between potential environmental exposure to hydrocarbons and the risk of acute childhood leukaemia. Methods: A hospital based multicentre case control study, stratified on centre, age, and sex, with 280 leukaemia cases and 285 controls was carried out. Data were collected by a standardised interview of the mothers. Results: No clear association was seen between maternal occupational exposure to hydrocarbons during pregnancy and leukaemia, or between residential traffic density and leukaemia. There was an association between dwellings neighbouring a petrol station or a repair garage during childhood and the risk of childhood leukaemia (OR 4.0, 95% CI 1.5 to 10.3), with a duration trend. The association, which appeared particularly strong for acute non-lymphocytic leukaemia (OR 7.7, 95% CI 1.7 to 34.3), was not altered by adjustment for potential confounding factors. Conclusions: Results showed an association between acute childhood leukaemia and dwellings neighbouring auto repair garages and petrol stations, which are benzene emitting sources. These findings could be due to chance, although the strength of the association and the duration trend are arguments for a causal association.

Stress and dysmenorrhoea: a population based prospective study

Abstract: Background: Dysmenorrhoea is the most common gynaecological disorder in women of reproductive age. Despite the association between stress and pregnancy outcomes, few studies have examined the possible link between stress and dysmenorrhoea. Aims and Methods: Using a population based cohort of Chinese women, the independent effect of women's perceived stress in the preceding menstrual cycle on the incidence of dysmenorrhoea in the subsequent cycle was investigated prospectively. The analysis included 1160 prospectively observed menstrual cycles from 388 healthy, nulliparous, newly married women who intended to conceive. The perception of stress and the occurrence of dysmenorrhoea in each menstrual cycle were determined from daily diaries recorded by the women. Results: After adjustment for important covariates, the risk of dysmenorrhoea was more than twice as great among women with high stress compared to those with low stress in the preceding cycle (OR = 2.4; 95% CI 1.4 to 4.3). The risk of dysmenorrhoea was greatest among women with both high stress and a history of dysmenorrhoea compared to women with low stress and no history of dysmenorrhoea (OR = 10.4, 95% CI 4.9 to 22.3). Stress in the follicular phase of the preceding cycles had a stronger association with dysmenorrhoea than stress in the luteal phase of the preceding cycles. Conclusion: This study shows a significant association between stress and the incidence of dysmenorrhoea, which is even stronger among women with a history of dysmenorrhoea.

Minimum health and safety requirements for workers exposed to hand-transmitted vibration and whole-body vibration in the European Union; a review

Abstract: In 2002, the Parliament and Commission of the European Community agreed "minimum health and safety requirements" for the exposure of workers to the risks arising from vibration. The Directive defines qualitative requirements and also quantitative requirements in the form of "exposure action values" and "exposure limit values". The quantitative guidance is based on, but appears to conflict with, the guidance in International Standards for hand-transmitted vibration (ISO 5349) and whole-body vibration (ISO 2631). There is a large internal inconsistency within the Directive for short duration exposures to whole-body vibration: the two alternative methods give very different values. It would appear prudent to base actions on the qualitative guidance (i.e. reducing risk to a minimum) and only refer to the quantitative guidance where there is no other reasonable basis for the identification of risk (i.e. similar exposures are not a suspected cause of injury). Health surveillance and other precautions will be appropriate wherever there is reason to suspect a risk and will not be restricted to conditions where the exposure action value is exceeded.

The effectiveness of ergonomic interventions on return-to-work after low back pain; a prospective two year cohort study in six countries on low back pain patients sicklisted for 3–4 months

Abstract: Aims: To study occurrence and effectiveness of ergonomic interventions on return-to-work applied for workers with low back pain (LBP). Methods: A multinational cohort of 1631 workers fully sicklisted 3–4 months due to LBP (ICD-9 codes 721, 722, 724) was recruited from sickness benefit claimants databases in Denmark, Germany, Israel, Sweden, the Netherlands, and the United States. Medical, ergonomic, and other interventions, working status, and return-to-work were measured using questionnaires and interviews at three months, one and two years after the start of sickleave. Main outcome measure was time to return-to-work. Cox’s proportional hazards model was used to calculate hazard ratios regarding the time to return-to-work, adjusted for prognostic factors. Results: Ergonomic interventions varied considerably in occurrence between the national cohorts: 23.4% (mean) of the participants reported adaptation of the workplace, ranging from 15.0% to 30.5%. Adaptation of job tasks and adaptation of working hours was applied for 44.8% (range 41.0–59.2%) and 46.0% (range 19.9–62.9%) of the participants, respectively. Adaptation of the workplace was effective on return-to-work rate with an adjusted hazard ratio (HR) of 1.47 (95% CI 1.25 to 1.72; p Conclusions: Results suggest that ergonomic interventions are effective on return-to-work of workers long term sicklisted due to LBP.

Study on the relation between occupational fenvalerate exposure and spermatozoa DNA damage of pesticide factory workers

Abstract: Aims: To determine sperm nuclear DNA integrity and to investigate the relation between fenvalerate (FE) exposure and spermatozoa DNA damage. Methods: Sperm DNA fragmentation was detected by a modified alkaline single cell gel electrophoresis (Comet) assay and a terminal deoxynucleotidyl transferase mediated dUTP nick end labelling (TUNEL) assay. The olive tail moment (OTM) and percentage tail DNA were measured by the Comet assay, and cell positive percentage was measured by the TUNEL assay for DNA damage evaluation. Results: The DNA integrity of spermatozoa of external and internal control groups were both significantly greater than that of the FE exposed group. The median value of tail DNA percentage in the exposure group was 11.30, which was significantly higher than 5.60 in the internal control group and 5.10 in the external control group. The median value of OTM was 3.80 in the exposure group, significantly higher than 1.50 in the internal control group and 2.00 in the external control group. Mean cell positive was 31.2% in the exposure group, significantly higher than 17.4% in the internal control and 19.6% in the external control groups. Cell positive (%) was significantly correlated with tail DNA percentage and with OTM of whole subjects (n = 63). Conclusions: Results showed that occupational FE exposure is associated with an increase in sperm DNA damage. A combination of the Comet and TUNEL assays would offer more comprehensive information for a better understanding of sperm DNA damage, and the biological significance of sperm DNA damage in sperm function and male infertility.

Distribution of sickness absence in the European Union countries

Abstract: Aims: To determine the sickness absence frequency in European Union (EU) countries. Methods: Sickness absence was measured by questionnaire using the Third European Survey on Working Conditions. Employees were considered to have sickness absence if they reported to be absent at least one day in the past 12 months because of an accident at work, work related problems, or by other health problems. Results: Sickness absence percentages were lower in Southern European countries compared with Central and Northern European countries, and, in general, slightly higher in men than in women. Conclusion: This is the first description of sickness absence in each of the 15 EU countries. Examination of the sickness absence patterning between EU countries could indicate countries where important lessons to reduce sickness absence are to be learned and diffused across the EU.

Changing trends in US mesothelioma incidence

Abstract: Aims: To report the temporal pattern and change in trend of mesothelioma incidence in the United States since 1973. Methods: The Surveillance, Epidemiology, and End Results (SEER) programme of the National Cancer Institute has since 1973 provided annual age adjusted incidence for mesothelioma in representative cancer registries dispersed throughout the USA. SEER data are analysed to describe the trend of male mesothelioma incidence in the USA. Results: The US male mesothelioma incidence data indicate that after two decades of increasing incidence, a likely decline has been observed since the early 1990s, when a highly significant change in the upward course occurred. Conclusions: Increasing male mesothelioma incidence for many years was undoubtedly the result of exposure to asbestos. The high mesothelioma risk was prominently influenced by exposure to amphibole asbestos (crocidolite and amosite), which reached its peak usage in the 1960s and thereafter declined. A differing pattern in some other countries (continuing rise in incidence) may be related to their greater and later amphibole use, particularly crocidolite. The known latency period for the development of this tumour provides biological plausibility for the recent decline in mesothelioma incidence in the USA. This favourable finding is contrary to a widespread fear that asbestos related health effects will show an inevitable increase in coming years, or even decades.

Dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain

Abstract: Aims: To assess dose-response relations between occupational exposures to physical and psychosocial factors and the risk of low back pain. Methods: A cohort of 523 subjects, working in nursing homes and homes for the elderly, was followed prospectively for one year. Physical load for different occupations was assessed by quantitative observations at the workplace. Information on low back pain and other factors was gathered with questionnaires administered at baseline and at one year. Two outcome measures of low back pain incidence were used: any new episode of pain lasting for at least a few hours during follow up (LBP); and any new episode of disabling pain that interfered with daily activities during follow up (LBP/D). Hierarchical regression analysis with a spline function was used to estimate dose-response relations. Results: The risk of LBP was not associated with physical factors, controlling for confounders; but this outcome was inversely associated with age and weakly, though imprecisely, associated with two psychosocial factors—low decision authority and high work demands. In contrast, the risk of LBP/D was positively associated with age and not associated with the psychosocial factors. Trunk flexion over 45 degrees was monotonically associated with the risk of LBP/D; the estimated relative risk was 3.18 (95% CI 1.13 to 9.00) for 1 hour and 45 minutes of bending per week (90th centile), relative to 30 minutes per week. The hierarchical estimates of effect were more stable than were the maximum likelihood estimates. Conclusion: Occupational exposure to trunk flexion over 45 degrees appears to be a risk factor for low back pain with disability among persons employed in nursing homes and homes for the elderly in the Netherlands.

Output power levels from mobile phones in different geographical areas; implications for exposure assessment

Abstract: Background: The power level used by the mobile phone is one of the most important factors determining the intensity of the radiofrequency exposure during a call. Mobile phone calls made in areas where base stations are densely situated (normally urban areas) should theoretically on average use lower output power levels than mobile phone calls made in areas with larger distances between base stations (rural areas). Aims: To analyse the distribution of power levels from mobile phones in four geographical areas with different population densities. Methods: The output power for all mobile phone calls managed by the GSM operator Telia Mobile was recorded during one week in four defined areas (rural, small urban, suburban, and city area) in Sweden. The recording included output power for the 900 MHz and the 1800 MHz frequency band. Results: In the rural area, the highest power level was used about 50% of the time, while the lowest power was used only 3% of the time. The corresponding numbers for the city area were approximately 25% and 22%. The output power distribution in all defined urban areas was similar. Conclusion: In rural areas where base stations are sparse, the output power level used by mobile phones are on average considerably higher than in more densely populated areas. A quantitative assessment of individual exposure to radiofrequency fields is important for epidemiological studies of possible health effects for many reasons. Degree of urbanisation may be an important parameter to consider in the assessment of radiofrequency exposure from mobile phone use.

Effect of employee worktime control on health: a prospective cohort study.

Abstract: Aims: To investigate the health effects of employee worktime control. Methods: Prospective cohort study among 4218 permanent full time municipal employees linking questionnaire data from 1997 and 2000 with sickness absence records from 1997 and 2001. Worktime control was considered high for the highest tertile in both 1997 and 2000, low for the lowest tertile for both years, and intermediate for all other combinations. Self rated health status, psychological distress, and medically certified periods of sickness absence were used as the health outcomes. Adjustments were made for age, baseline health status, occupational status, marital status, dependent children, and behavioural health risks. Results: In the follow up, women with a low level of worktime control had a 1.9 times (95% CI 1.4 to 2.5) higher odds ratio for poor self rated health, a 1.4 times (95% CI 1.1 to 1.8) higher odds ratio for psychological distress, and a 1.5 times (95% CI 1.3 to 1.7) higher risk of medically certified sickness absences than women with a high level of worktime control. The health effects of worktime control were particularly evident among women with families. Among men, worktime control was not associated with self rated health or distress, but it predicted sickness absences in two subgroups: those with dependent children and those with manual occupations. Conclusions: A low level of worktime control increases the risk of future health problems. The risk is highest among women, especially those with families, and among manual workers. The results suggest that worktime control can help workers integrate their work and private lives successfully.