Sleep duration and quality in permanent night work: an observational field study.

PURPOSE: Permanent night workers conceivably show better adaptation of circadian rhythms to night work than shift workers and therefore better possibilities of obtaining sufficient sleep of good quality after night shifts. We investigated the effect of night shifts including number of consecutive shifts on sleep among self-selected permanent night workers, and studied if the effect of night shifts differed between morning and evening types and compared with 3-shift workers. METHODS: The study population included 90 permanent night workers followed for 14 days (warehouse workers, 1228 observation days, 80% males). For comparison, we included 70 3-shift workers followed for 26 days (police officers, 1774 observation days, 100% men). Total sleep time (TST), primary sleep duration (PSD), and sleep efficiency were assessed by actigraphy. Measures of sleep quality and diurnal type were self-reported. RESULTS: Among permanent night workers, TST, PSD, difficulties falling asleep, disturbed sleep, and the number of awakenings decreased after night shifts compared with days without night work. Sleep efficiency, difficulties awakening, and non-refreshing sleep increased. More consecutive night shifts were associated with shorter TST and PSD. Sleep outcomes did not differ by diurnal type. Permanent night workers had fewer awakenings after night shifts than 3-shift workers, but no other differences were observed. CONCLUSION: This study does not provide evidence that supports recommendation of permanent night work to reduce adverse effects of night shifts on sleep. A limited number of consecutive night shifts is recommended to reduce accumulation of sleep debt.

Work-unit measures of psychosocial job stressors and onset of bullying: a 2-year follow-up study.

OBJECTIVES: Numerous studies have examined the health consequences of workplace bullying, but little is known about workplace antecedents of workplace bullying. This study examines whether high psychological demands, low levels of justice at work, and low decision latitude increase the occurrence of being bullied or witnessing bullying. METHODS: In 2007, 4489 Danish public employees answered a questionnaire with follow-ups in 2009 (72%) and 2011 (73% of 2009 respondents). We examined the longitudinal association between exposure to job stressors in 2007 and 2009 and bullying in 2009 and 2011, respectively, on an individual and work-unit level. For each working condition (psychological demands, decision latitude, procedural and relational justice), we calculated a mean value. Odds ratios were calculated by logistic regression. RESULTS: Low levels of individual-level relational justice, compared to high levels, were associated with a higher risk of both witnessing episodes of bullying (OR 1.66, 95% CI 1.11-2.48) and perceiving oneself as a target of bullying (OR 2.21, 95% CI 1.17-4.16). Low levels of work-unit level relational justice were associated with a higher risk of witnessing bullying (OR 1.55, 95% CI 1.04-2.30) but not perceiving oneself as a target of bullying. The other workplace characteristics exhibited no or less consistent associations across the different analytical approaches. CONCLUSION: Low levels of relational justice prospectively predicted the occurrence of workplace bullying within a 2-year period for three out of four methodological approaches, suggesting that relational justice plays a role in the prevention of workplace bullying.

Heart rate variability during sleep after two, four and seven consecutive night shifts and recovery days: a cross-over intervention study.

OBJECTIVE: Recovery after shift work is an important part reducing the health problems related to shift work. Heart rate variability (HRV) is an indicator of the balance between sympathetic and parasympathetic activity in the autonomic nervous system and can be used as a measure of recovery after night shifts. The aim of the study is to investigate autonomic recovery during sleep in response to night work in a crossover intervention study. METHODS: Seventeen male police officers working in call centres in five different police district participated in the HRV measurements. The participants were exposed to three interventions: 2 + 2: two consecutive night shifts followed by two consecutive day recovery days; 4 + 4: four consecutive night shifts followed by four consecutive recovery days; 7 + 7: seven consecutive night shifts followed by seven consecutive recovery days. On the last day with night shift and the last recovery day in each intervention the participants underwent 24 h HRV recordings. We analysed HRV during sleep. The five 5-min intervals with the lowest heart rate during each sleep period were chosen for spectral analysis of the heart interbeat interval time series. The five 5-min intervals could occur at any time during sleep. RESULTS: There were overall differences in HRV during sleep between days with night shifts and recovery days, primarily in parasympathetic activity. There was no difference in the lowest heart rate obtained, but the timing was different for the three interventions. The lowest heart rate after night shifts occurred 112 (SD 79) min, 174 (SD 115) min and 135 (SD 94) min after sleep onset for the 2 + 2 night shift, the 4 + 4 night shift and the 7 + 7 night shift, respectively. CONCLUSION: Overall sleep-related autonomic recovery had higher parasympathetic modulation of cardiac rhythm on the 2 + 2 shift system compared to the 4 + 4 and 7 + 7 shift system.

COVID-19 risk management at the workplace, fear of infection and fear of transmission of infection among frontline employees.

OBJECTIVES: We compared COVID-19 risk management, fear of infection and fear of transmission of infection among frontline employees working within eldercare, hospital/rehabilitation, psychiatry, childcare and ambulance service and explored if group differences in fear of infection and transmission could be explained by differences in risk management. We also investigated the association of risk management with fear of infection and fear of transmission of infection among eldercare personnel. METHODS: We used cross-sectional questionnaire data collected by the Danish labour union, FOA . Data were collected 5½ weeks after the first case of COVID-19 was registered in Denmark. Data for the first aim included 2623 participants. Data for the second aim included 1680 participants. All independent variables were mutually adjusted and also adjusted for sex, age, job title and region. RESULTS: Fear of infection (49%) and fear of transmitting infection from work to the private sphere (68%) was most frequent in ambulance service. Fear of transmitting infection during work was most frequent in the eldercare (55%). Not all differences in fear of infection and transmission between the five areas of work were explained by differences in risk management. Among eldercare personnel, self-reported exposure to infection and lack of access to test was most consistently associated with fear of infection and fear of transmission, whereas lack of access to personal protective equipment was solely associated with fear of transmission. CONCLUSION: We have illustrated differences and similarities in COVID-19 risk management within five areas of work and provide new insights into factors associated with eldercare workers' fear of infection and fear of transmission of infection.

The effect of occupational physical activity on dementia: Results from the Copenhagen Male Study.

Leisure-time physical activity (LTPA) reduces the risk of dementia, while the effect of occupational physical activity (OPA) on dementia is uncertain. Therefore, the aim of this study was to investigate the effect of OPA on dementia. For comparison, also the association between LTPA and dementia was analyzed. In this longitudinal study, we used self-reported questionnaire data on OPA and LTPA collected in 1970-71 from 4721 male employees, who were 40-59 years old at baseline. Dementia was identified through national registers and participants were followed from they turned 60 years and until 2016. We estimated incidence rate ratios (IRR) and adjusted for age, socioeconomic status, marital status, and psychological stress. In additional analyses, we included health behaviors and blood pressure and mutually adjusted OPA and LTPA. We identified 697 dementia cases during 86 557 person-years. We found an IRR of 1.48 (95% CI: 1.05-2.10) among participants with high OPA compared with participants in sedentary jobs. Participants with high LTPA had a non-significantly lower IRR of dementia compared with participants with a sedentary leisure time. In conclusion, LTPA and OPA are differentially associated with dementia. Therefore, current recommendations regarding the beneficial effect of physical activity on dementia only concern LTPA, and more research on OPA and dementia is needed.

Labour market affiliation among non-bullied colleagues at work units with reported bullying.

AIM: This study investigates if non-bullied employees in Work units (WUs) where bullying occur, are more prone to leave the WUs than employees in WUs with no bullying, and if the prevalence of workplace bullying had an impact on leaving the WUs. Leaving the workplace was defined by unemployment or change of workplace at follow-up. METHODS: We had data from 8326 Danish public health invited employees from 302 WUs. Of these 3036 responded to a questionnaire on working conditions and health in 2007. WUs were classified into three categories of WUs: (1) no bullying (0% bullied), (2) moderate prevalence of bullying (< 10% bullied), and (3) high prevalence of bullying (≥ 10% bullied). Bullied respondents were used to classify the WUs and excluded in the analyses. RESULTS: We found odds ratios (ORs) for unemployment 1 year later of 1.27 [95% CI 0.69-2.37] in WUs with moderate prevalence of bullying and 1.38 [95% CI 0.85-2.23] among employed in WUs with high prevalence of bullying, adjusted for size of WUs, age, sex, and job category. For turnover 1 year later the ORs were 1.27 [95% CI 0.78-2.15] and 1.46 [95% CI 0.99-2.15] in WUs with moderate and high prevalence of bullying, respectively. CONCLUSION: We did not find that non-bullied employees leave the WUs with moderate and high prevalence of bullying more than employees in WUs with no bullying behaviour 1 year later. Leaving the workplace tended to be higher among employees in WUs with high prevalence of bullying compared to no and moderate bullying.

Stress diagnoses in midlife and risk of dementia: a register-based follow-up study.

OBJECTIVES: Previous studies indicated that stress diagnoses increase the risk of dementia. However, previous results may be biased by confounding, reverse causation and misclassification. Therefore, the main aim of this study was to investigate the association between clinically diagnosed stress in midlife and later dementia risk, while addressing limitations of previous studies. METHODS: The study population was selected from all individuals in Denmark born 1935-1956. Individuals diagnosed with stress in midlife (aged 37-58 years) were matched (1:5) with individuals without stress diagnoses based on sex and birthdate (N = 103,484). Data were retrieved from national registers. Cox regression models were adjusted for socio-demographic factors and different morbidities. RESULTS: We found a 2.20 (95% CI: 1.93-2.50) times higher rate of dementia among individuals with any stress diagnosis registered in midlife compared with no stress diagnosis. Hazard rate ratios of dementia were 1.73 (95% CI: 1.13-2.65) among individuals with acute stress reactions, 2.37 (95% CI: 2.05-2.74) among individuals with adjustment disorders, and 2.20 (95% CI: 1.73-2.80) among individuals with unspecified stress reactions. Individuals with PTSD and other stress reactions had non-significantly elevated rates of dementia. Adjustment for confounding only slightly attenuated the association, and reverse causation did not appear to bias the results substantially. CONCLUSION: Our results support the hypothesis that severe stress in midlife is an important risk factor for dementia. This finding emphasizes the importance of identifying and treating severe stress in midlife to reduce potential detrimental consequences for brain health in later life.

The longitudinal association between shift work and headache: results from the Danish PRISME cohort.

PURPOSE: We investigated the effect of shift work on headache. Furthermore, we investigated whether the association between shift work and headache was explained by potential mediators in terms of perceived stress, poor sleep and health behaviors. METHODS: In this longitudinal study, we used questionnaire data (collected in 2007 and 2009) from civil servants and hospital employees from the PRISME study. 2952 individuals were available for the analyses of shift work and headache and 2272 individuals were available for the analyses of shift work and migraine. Headache was operationalized as the participants' experience of "being bothered by headache during the past 4 weeks". Migraine was operationalized as "ever being diagnosed with migraine by a medical doctor". We used binary logistic regression to compare shift workers with permanent day workers and adjusted for socio-demographic factors. In a subsequent step, we adjusted for potential mediators. RESULTS: We found higher odds of unspecific headache (OR = 1.25; 95% CI 1.02-1.54) and migraine (OR = 1.72; 95% CI 1.04-2.86) among shift workers compared with day workers. Our results suggest that the effect of shift work on headache and migraine differ between men and women. Inclusion of potential mediators in the analyses did not attenuate the associations. CONCLUSION: Shift workers have higher risk of reporting being bothered by headache as well as reporting being diagnosed with migraine. Future research is needed to disentangle the underlying mechanisms with the aim of reducing headache related to occupational exposures.

Night work and risk of ischaemic heart disease and anti-hypertensive drug use: a cohort study of 145 861 Danish employees.

BACKGROUND: Ischaemic heart disease (IHD) and hypertension are leading causes of mortality and night work has been suspected as a risk factor. Meta-analyses and previous studies are often limited by power and various definitions of exposure and outcomes. This study aimed to investigate if night work increases the risk of IHD or anti-hypertensive drug usage in a large cohort of Danish employees. METHODS: Individual participant data on night work were drawn from the Danish Labour Force Survey (1999-2013). We included 145 861 participants (53% men) 21-59 years of age working 32 h or more per week. Participants with diagnosis or drug use in the year prior to baseline were excluded. Data on outcomes were obtained from nationwide health registers. Using Poisson regression we analyzed incidence rates of the outcomes as functions of night work adjusted for relevant covariates. RESULTS: We observed 3635 cases of IHD and 20 648 cases used anti-hypertensive drugs. When examining main effects the association of night work with drug use was estimated at rate ratio (RR): 1.05 (95% CI: 1.01-1.09). A sensitivity analysis suggested a dose-response association. The association of night work with IHD was estimated at RR: 1.08 (95% CI: 0.98-1.19). Overall likelihood ratio test showed no statistically significant associations between night work and IHD or drug use when including interactions with sex and socioeconomic status. CONCLUSIONS: Night work was associated with an increased risk of anti-hypertensive drug use. Small estimates suggested a dose-response association. No statistically significant association between night work and IHD were found.

Perceived stress and dementia: Results from the Copenhagen city heart study.

Objectives: We investigated if perceived stress in midlife increased the risk of dementia. Furthermore, we explored differences between subgroups related to sex, age and employment status when reporting stress.Methods: In this longitudinal study, we used information on perceived stress from 10,814 participants (mean age 56.7 years). Participants were followed through Danish national registers for development of dementia. Participants were considered at risk of dementia from the date they turned 60 years. Perceived stress was assessed as a combination of self-reported intensity and frequency of stress, and categorized into low (score 0-1), medium (score 2-4), and high stress (score 5-6). We used Poisson regression to estimate incidence rate ratios (IRR) and their 95% confidence intervals (CI) and adjusted for sociodemographic factors and psychiatric morbidity at baseline (main model) as well as cardio/cerebrovascular diseases and health behaviors at baseline (additional model).Results: The mean follow-up time was 13.8 years, and 1,519 participants were registered with dementia. Dementia risk was higher in participants reporting medium stress (IRR = 1.11, 95% CI: 0.99-1.24) and high stress (IRR = 1.36, 95% CI: 1.13-1.65). Adjustment for cardio/cerebrovascular diseases and health behaviors did not alter the results. We did not find strong support for differences between subgroups, although the association between stress and dementia was stronger for those who were employed at the time of reporting high stress.Conclusion: Our results provide empirical support for an effect of perceived stress on the risk of dementia in old age.

Mid- to late-life migraine diagnoses and risk of dementia: a national register-based follow-up study.

BACKGROUND: Previous studies found an association between migraine and dementia, which are two leading causes of disability. However, these studies did not differentiate between migraine types and did not investigate all prevalent dementia subtypes. The main objective of this national register-based study was to investigate whether migraine was a risk factor for dementia. Additionally, we explored potential differences in dementia risk for migraine with and without aura. METHODS: We obtained data on birth cohorts born between 1935 and 1956 (n = 1,657,890) from Danish national registers. Individuals registered with migraine before age 59 (n = 18,135) were matched (1:5) on sex and birthdate with individuals without migraine (n = 1,378,346). Migraine was defined by International Classification of Diseases (ICD) diagnoses and dementia was defined by ICD diagnoses and anti-dementia medication. After matching, 62,578 individuals were eligible for analysis. For the statistical analyses, we used Cox regression models and adjusted for socio-demographic factors and several psychiatric and somatic morbidities. RESULTS: During a median follow-up time of 6.9 (IQR: 3.6-11.2) years, 207 individuals with migraine developed dementia. Compared with individuals without migraine, we found a 50% higher rate of dementia among individuals with migraine (HR = 1.50; 95% CI: 1.28-1.76). Individuals without aura had a 19% higher rate of dementia (HR = 1.19; 95% CI: 0.84-1.70), and individuals with aura had a two times higher rate of dementia (HR = 2.11; 95% CI: 1.48-3.00). CONCLUSIONS: Our findings support the hypothesis that migraine is a midlife risk factor for dementia in later life. The higher rate of dementia in individuals with a hospital-based diagnosis of migraine with aura emphasizes the need for studies on pathological mechanisms and potential preventative measures. Furthermore, given that only hospital-based migraine diagnoses were included in this study, future research should also investigate migraine cases derived from the primary healthcare system to include less severe migraine cases.

Midlife Forgetfulness and Risk of Dementia in Old Age: Results from the Danish Working Environment Cohort Study.

BACKGROUND: Despite the current evidence of a high prevalence of forgetfulness in middle-aged individuals, and the evidence of a link between midlife memory complaints and biological changes in the brain, no previous study has yet investigated midlife forgetfulness in relation to risk of dementia in old age. AIMS: We investigated whether midlife forgetfulness was an indicator of an increased risk of dementia in old age. METHODS: We used data from 3,136 employed men and women who participated in the Danish Work Environment Cohort Study in 1990. These data were linked to Danish national registers. Participants were asked whether their closest relative had ever told them that they were forgetful. Incidence rate ratios (IRR) were estimated using Poisson regression analysis. RESULTS: At baseline, 749 (24%) study participants were categorized as forgetful, and 86 (2.7%) participants were diagnosed with dementia during a total of 31,724 person-years at risk. After adjusting for sociodemographic factors, comorbidities, and work-related factors, midlife forgetfulness was associated with a higher risk of dementia (IRR = 1.82; 95% CI: 1.12-2.97). CONCLUSIONS: This study is the first to investigate midlife forgetfulness and dementia, and the results suggest that midlife forgetfulness is an early indicator of an increased risk of dementia in old age.

Night work and miscarriage: a Danish nationwide register-based cohort study.

OBJECTIVE: Observational studies indicate an association between working nights and miscarriage, but inaccurate exposure assessment precludes causal inference. Using payroll data with exact and prospective measurement of night work, the objective was to investigate whether working night shifts during pregnancy increases the risk of miscarriage. METHODS: A cohort of 22 744 pregnant women was identified by linking the Danish Working Hour Database (DWHD), which holds payroll data on all Danish public hospital employees, with Danish national registers on births and admissions to hospitals (miscarriage). The risk of miscarriage during pregnancy weeks 4-22 according to measures of night work was analysed using Cox regression with time-varying exposure adjusted for a fixed set of potential confounders. RESULTS: In total 377 896 pregnancy weeks (average 19.7) were available for follow-up. Women who had two or more night shifts the previous week had an increased risk of miscarriage after pregnancy week 8 (HR 1.32 (95% CI 1.07 to 1.62) compared with women, who did not work night shifts. The cumulated number of night shifts during pregnancy weeks 3-21 increased the risk of miscarriages in a dose-dependent pattern. CONCLUSIONS: The study corroborates earlier findings that night work during pregnancy may confer an increased risk of miscarriage and indicates a lowest observed threshold level of two night shifts per week.

Night work and sick leave during pregnancy: a national register-based within-worker cohort study.

OBJECTIVE: The aim of our study was to investigate the acute effect of night work during pregnancy on the risk of calling in sick the following day using register-based information and the workers as their own controls. METHODS: Using the payroll-based national Danish Working Hour Database, including all public hospital employees in Denmark, we identified 9799 pregnant women with ≥1 day shift and ≥1 night shift and ≥1 day of sick leave during the first 32 pregnancy weeks from January 2007 to December 2013. We performed fixed effects logistic regression, that is, within-worker comparisons, of the risk of sick leave of any duration starting within 24 hours after night shifts of different length versus day shifts. RESULTS: Most of the participants were nurses (64%) or physicians (16%). We found an increased relative risk of sick leave following night shifts compared with day shifts during all pregnancy trimesters. The risk was highest for night shifts lasting >12 hours (OR 1.37, 95% CI 1.15 to 1.63 for nurses; OR 1.87, 95% CI 1.69 to 2.08 for physicians) and among women aged >35 years (OR 1.42, 95% CI 1.24 to 1.63). CONCLUSION: Among Danish public hospital employees night shifts during pregnancy, especially shifts longer than 12 hours, increased the risk of calling in sick the following day independent of personal factors and time-invariant confounders in all pregnancy trimesters.

Does leadership support buffer the effect of workplace bullying on the risk of disability pensioning? An analysis of register-based outcomes using pooled survey data from 24,538 employees.

PURPOSE: To investigate whether self-reported exposure to workplace bullying predicts the risk of disability pensioning among employees in two occupational groups-(1) employees working with clients or customers and (2) office workers and manual workers-and whether leadership support and occupational group moderates that association. METHODS: Survey data from 24,538 employees (112,889 person years) were fitted to a national register containing information on disability-pension payments. Using multi-adjusted Cox-regression analysis, observations were followed in the register to assess the risk of disability pensioning. The average follow-up time was 4.6 years (standard deviation [SD] = 1.5). RESULTS: Self-reported exposure to workplace bullying predicted an increased risk of disability pensioning (hazard ratio [HR] = 1.46; 95% confidence interval [CI]: 1.15-1.86). This association was moderated by leadership support: the association between workplace bullying and disability pensioning was significantly different for respondents who reported low leadership support (HR = 1.97; 95% CI: 1.38-2.80) compared to respondents who reported medium (HR = 1.03; 95% CI: 0.60-1.76) or high leadership support (HR = 1.08; 95% CI: 0.60-1.95). Further analyses showed similar associations between workplace bullying and the risk of disability pensioning among the two occupational groups. CONCLUSIONS: Self-reported workplace bullying increases the risk of disability pensioning, and this association is buffered by leadership support. Workplace bullying should be considered an important workplace stressor. This study indicates that workplaces may enhance worker retention by actively promoting measures to eliminate the occurrence of workplace bullying and to enhance leadership support.

Emotional demands and exhaustion: cross-sectional and longitudinal associations in a cohort of Danish public sector employees.

PURPOSE: To examine cross-sectional and longitudinal associations between content-related emotional demands at work and exhaustion, and to investigate if these associations were modified by other psychosocial work characteristics. METHODS: In 2007, 4489 Danish public service employees participated in the PRISME study by completing postal questionnaires, and 3224 participated in the follow-up in 2009. Content-related emotional demands were measured by a scale (scored 1 to 5) based on five work-content-related items, and exhaustion was measured with the general exhaustion scale from the Copenhagen Burnout Inventory (CBI) (scored 1 to 5). The cross-sectional and longitudinal associations with exhaustion were analysed in the same model and adjusted for effects of potential confounders. Effect modifications were examined separately for self-reported emotional enrichment, meaningful work, job control, social support at work and quantitative demands. RESULTS: Exhaustion increased with increasing emotional demands, both cross-sectionally and longitudinally. However, although statistically significant, the effect was small. In the longitudinal analysis, a one unit increase in emotional demands was associated with a 0.03 unit (95% CI: 0.01-0.06) increase in exhaustion. We found statistically significant effect modification for three of six potentially modifying work characteristics. The effect of emotional demands on exhaustion was lower for participants with high levels of emotional enrichment (cross-sectionally and longitudinally), high levels of meaningful work (longitudinally), and higher for high levels of quantitative demands (cross-sectionally). CONCLUSIONS: Increasing content-related emotional demands were associated with increasing levels of exhaustion, cross-sectionally and longitudinally. This effect was reduced if the work was experienced as emotionally enriching and meaningful.

Prolonged or serious conflicts at work and incident dementia: a 23-year follow-up of the Copenhagen City Heart Study.

PURPOSE: Only a few studies have investigated the impact of negative aspects of social relations on cognitive function, and they have shown mixed results. Conflicts at work are part of the negative aspects of social relations, but the impact of experiencing conflicts at work has not yet been investigated as a risk factor for dementia. Therefore, we investigated whether experiencing prolonged or serious conflicts with a supervisor or colleagues at work was associated with incident dementia in old age. METHODS: We analyzed data of 6,436 men and women from the third survey of the Copenhagen City Heart Study. At baseline in 1991-1994, the participants reported whether they had ever had a prolonged or serious conflict at work. The participants were followed until 2014. We used Poisson regression to estimate incidence rate ratios (IRR) and their 95% confidence intervals (CI). RESULTS: After adjusting for potential confounders, the IRR for dementia was 1.53 (95% CI 0.77-3.03) among participants who had reported having prolonged or serious conflicts both with a supervisor and colleagues compared with participants who had never had such conflicts. In separate analyses stratified by sex, the IRRs were 2.14 (95% Cl 0.97-4.71) for men and 0.98 (95% Cl 0.29-3.32) for women. CONCLUSIONS: Our findings did not support an overall association between experiencing prolonged or serious conflicts at work and incident dementia. However, because of the large differences in the point estimates for men and women, future research could aim at investigating potential sex differences regarding the association between conflicts at work and dementia.

Working hour characteristics and schedules among nurses in three Nordic countries - a comparative study using payroll data.

BACKGROUND: Organisation of working hour schedules in the Northern European countries are rather similar. EU countries are obliged to adopt national legislation regarding duration of weekly working hours and rest periods. Yet, working hour characteristics and schedules are likely to differ with respect to starting times and duration depending e.g. on culture and tradition. Yet, very little is known about potential differences between shifts and schedules across countries among nursing personel. This knowledge is relevant, since the potential differences in working hour characteristics may influence and possibly explain some of the differences observed in studies of health and safety.The aim of the study was to compare characteristics of working hours and work schedules among nursing personel in three Nordic countries: Denmark, Finland and Norway. METHODS: The study populations included nursing personnel holding a ≥ 50% position at public hospitals in Denmark (n = 63,678), Finland (n = 18,257) or Norway (n = 1538) in 2013. Objective payroll based registry data with information on daily starting and ending times were used to compare working hour characteristics e.g. starting time, duration of shift, and quick returns (< 11 h between two shifts), as well as work schedules e.g. permanent or 3-shift work between the three countries. RESULTS: Night shifts generally started earlier and lasted longer in Finland (10-11 h starting at 20:00-22:59) than in Norway (10 h starting at 21:00-21:59) and in Denmark (8 h starting at 23:00-23:59). Very long shifts (≥12 h) were more common in Denmark (12%) compared to Finland (8%) and Norway (3%). More employees had many (> 13/year) quick returns in Norway (64%) and Finland (47%) compared to Denmark (16%). The frequency of 3-shift rotation workers was highest in Norway (41%) and lower in Denmark (22%) and Finland (22%). There were few differences across the countries in terms of early morning shifts and (very) long weekly working hours. CONCLUSION: Despite similar distribution of operational hours among nurses in the three countries, there were differences in working hour characteristics and the use of different types of work schedules. The observed differences may affect health and safety.

Association between polycyclic aromatic hydrocarbon exposure and peripheral blood mononuclear cell DNA damage in human volunteers during fire extinction exercises.

This study investigated a number of biomarkers, associated with systemic inflammation as well as genotoxicity, in 53 young and healthy subjects participating in a course to become firefighters, while wearing personal protective equipment (PPE). The exposure period consisted of a 3-day training course where the subjects participated in various live-fire training exercises. The subjects were instructed to extinguish fires of either wood or wood with electrical cords and mattresses. The personal exposure was measured as dermal polycyclic aromatic hydrocarbon (PAH) concentrations and urinary excretion of 1-hydroxypyrene (1-OHP). The subjects were primarily exposed to particulate matter (PM) in by-stander positions, since the self-contained breathing apparatus effectively prevented pulmonary exposure. There was increased dermal exposure to pyrene (68.1%, 95% CI: 52.5%, 83.8%) and sum of 16 polycyclic aromatic hydrocarbons (Æ©PAH; 79.5%, 95% CI: 52.5%, 106.6%), and increased urinary excretion of 1-OHP (70.4%, 95% CI: 52.5%; 106.6%) after the firefighting exercise compared with the mean of two control measurements performed 2 weeks before and 2 weeks after the firefighting course, respectively. The level of Fpg-sensitive sites in peripheral blood mononuclear cells (PBMCs) was increased by 8.0% (95% CI: 0.02%, 15.9%) compared with control measurements. The level of DNA strand breaks was positively associated with dermal exposure to pyrene and Æ©PAHs, and urinary excretion of 1-OHP. Fpg-sensitive sites were only associated positively with PAHs. Biomarkers of inflammation and lung function showed no consistent response. In summary, the study demonstrated that PAH exposure during firefighting activity was associated with genotoxicity in PBMCs.

Retrospectively assessed physical work environment during working life and risk of sickness absence and labour market exit among older workers.

OBJECTIVE: To determine the prospective association between retrospectively assessed physical work environment during working life and prospectively assessed sickness absence and labour market exit among older workers. METHODS: Using Cox regression analyses we estimated the 4-year to 6-year prospective risk of register-based long-term sickness absence (LTSA), disability pension, early retirement and unemployment from exposure to different physical work environmental factors during working life among 5076 older workers (age 49-63 at baseline) from the Copenhagen Aging and Midlife Biobank cohort. RESULTS: Very hard physical work throughout working life was a risk factor for LTSA (HR 1.66,95% CI 1.32 to 2.07), disability pension (HR 2.21,95% CI 1.04 to 4.72) and early retirement (HR 1.57,95% CI 1.13 to 2.17). Both short-term (<10 years) and long-term (≥20 years) exposures to lifting or carrying of heavy burdens predicted the risk of LTSA (HRs 1.49-1.56) and disability pension (HRs 2.26-3.29). In contrast, exposure to dust was associated with LTSA and disability pension only following 20 or more exposure years. CONCLUSIONS: Retrospectively assessed hard physical work during working life and exposure to several factors in the physical work environment, especially heavy lifting, were important for labour market exit and sickness absence. This study underscores the importance of reducing physical work exposures throughout the working life course for preventing sickness absence and premature exit from the labour market.