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1.  TRENDS IN MORTALITY FROM OCCUPATIONAL HAZARDS AMONG MEN IN ENGLAND AND WALES DURING 1979-2010 
Objectives
To monitor the impact of health and safety provisions and inform future preventive strategies, we investigated trends in mortality from established occupational hazards in England and Wales.
Methods
We analysed data from death certificates on underlying cause of death and last full-time occupation for 3,688,916 deaths among men aged 20-74 years in England and Wales during 1979-2010 (excluding 1981 when records were incomplete). Proportional mortality ratios (PMRs), standardised for age and social class, were calculated for occupations at risk of specified hazards. Observed and expected numbers of deaths for each hazard were summed across occupations, and the differences summarised as average annual excesses.
Results
Excess mortality declined substantially for most hazards. For example, the annual excess of deaths from chronic bronchitis and emphysema fell from 170.7 during 1979-90 to 36.0 in 2001-10, and that for deaths from injury and poisoning from 237.0 to 87.5. In many cases the improvements were associated with falling PMRs (suggesting safer working practices), but they also reflected reductions in the numbers of men employed in more hazardous jobs, and declining mortality from some diseases across the whole population. Notable exceptions to the general improvement were diseases caused by asbestos, especially in some construction trades and sinonasal cancer in woodworkers.
Conclusions
The highest priority for future prevention of work-related fatalities is the minority of occupational disorders for which excess mortality remains static or is increasing, in particular asbestos-related disease among certain occupations in the construction industry and sinonasal cancer in woodworkers.
doi:10.1136/oemed-2015-103336
PMCID: PMC4872835  PMID: 26976946
Occupation; mortality; trends
2.  Upper extremity musculoskeletal pain among office workers in three Spanish speaking-countries: findings from the CUPID study 
Objectives
To estimate the prevalence and incidence of upper extremity musculoskeletal pain (UEMP) and related disability among office workers in Costa Rica, Nicaragua and Spain.
Methods
Data from the multinational CUPID study on 947 (93%) participants at baseline with 90% follow-up after 12 months. logistic regression was used to estimate the associations (odds ratios [ORs] and corresponding 95% confidence intervals [95%CIs]) between country and six outcomes: baseline prevalence of (1) UEMP in past 12 months, (2) UEMP in past month, and (3) disabling UEMP in past month; (4) incidence of new UEMP at follow-up; (5) incidence of new disabling UEMP at follow-up; and (6) persistence of UEMP at follow-up, after adjustment for sociodemographic, job-related and health-related covariates.
Results
Baseline prevalence of UEMP in the past month was higher in Costa Rica (53.6%) (OR=1.89; 95% CI: 1.36-2.62), and Nicaragua (51.9%) (OR=1.74; 95% CI: 1.28-2.35) than in Spain (38.4%). Compared to Spain (33.2%), the incidence of new UEMP was 50.4% in Costa Rica (OR=2.04; 95% CI: 1.34-3.12), and 60.2% in Nicaragua (OR=3.04; 95% CI: 2.06-4.50). The incidence of disabling UEMP was higher in Nicaragua (OR=2.57; 95% CI: 1.50-4.41) and Costa Rica (OR=2.16; 95% CI: 1.22-3.84) when compared to Spain.
Conclusion
Prevalence of UEMP was approximately 2-fold higher and its incidence 2- to 3-fold higher in Costa Rica and Nicaragua as compared with Spain. Between-country differences were only partially explained by the covariates analyzed. Research is needed to explore other aspects of work and cultural attributes that might explain the residual differences in UEMP.
doi:10.1136/oemed-2015-103327
PMCID: PMC4872836  PMID: 26972870
Cross-national studies; Longitudinal; Musculoskeletal pain; Risk factors
3.  Personal exposure to static and time-varying magnetic fields during MRI procedures in clinical practice in the UK 
Background
MRI has developed into one of the most important medical diagnostic imaging modalities, but it exposes staff to static magnetic fields (SMF) when present in the vicinity of the MR system, and to radiofrequency and switched gradient electromagnetic fields if they are present during image acquisition. We measured exposure to SMF and motion-induced time-varying magnetic fields (TVMF) in MRI staff in clinical practice in the UK to enable extensive assessment of personal exposure levels and variability, which enables comparison to other countries.
Methods
8 MRI facilities across National Health Service sites in England, Wales and Scotland were included, and staff randomly selected during the days when measurements were performed were invited to wear a personal MRI-compatible dosimeter and keep a diary to record all procedures and tasks performed during the measured shift.
Results
98 participants, primarily radiographers (71%) but also other healthcare staff, anaesthetists and other medical staff were included, resulting in 149 measurements. Average geometric mean peak SMF and TVMF exposures were 448 mT (range 20–2891) and 1083 mT/s (9–12 355 mT/s), and were highest for radiographers (GM=559 mT and GM=734 mT/s). Time-weighted exposures to SMF and TVMF (GM=16 mT (range 5–64) and GM=14 mT/s (range 9–105)) and exposed-time-weighted exposures to SMF and TVMF (GM=27 mT (range 11–89) and GM=17 mT/s (range 9–124)) were overall relative low—primarily because staff were not in the MRI suite for most of their shifts—and did not differ significantly between occupations.
Conclusions
These results are comparable to the few data available from the UK but they differ from recent data collected in the Netherlands, indicating that UK staff are exposed for shorter periods but to higher levels. These data indicate that exposure to SMF and TVMF from MRI scanners cannot be extrapolated across countries.
doi:10.1136/oemed-2015-103194
PMCID: PMC5116531  PMID: 26675205
4.  An observational study of shift length, crew familiarity, and occupational injury and illness in emergency medical services workers 
Objectives
Emergency medical services (EMS) clinicians are shift workers deployed in two-person teams. Extended shift duration, workplace fatigue, poor sleep, and lack of familiarity with teammates are common in the EMS workforce and may contribute to workplace injury. We sought to examine the relationship between shift length and occupational injury while controlling for relevant shift work and teamwork factors.
Methods
We obtained three years of shift schedules and occupational injury and illness reports were from 14 large EMS agencies. We abstracted shift length and additional scheduling and team characteristics from shift schedules. We matched occupational injury and illness reports to shift records and used hierarchical logistic regression models to test the relationship between shift length and occupational injury and illness while controlling for teammate familiarity.
Results
The cohort contained 966,082 shifts, 4,382 employees, and 950 outcome reports. Risk of occupational injury and illness was lower for shifts ≤8 hours in duration (RR 0.70; 95% CI 0.51–0.96) compared to shifts >8 & ≤12 hours. Relative to shifts >8 & ≤12 hours, risk of injury was 60% greater (RR 1.60; 95% CI 1.22–2.10) for employees that worked shifts >16 and ≤24 hours.
Conclusions
Shift length is associated with increased risk of occupational injury and illness in this sample of EMS shift workers.
doi:10.1136/oemed-2015-102966
PMCID: PMC4686303  PMID: 26371071
Shift work; Health and safety
5.  The Impacts of Traffic-Related and Woodsmoke Particulate Matter on Measures of Cardiovascular Health: A HEPA Filter Intervention Study 
Background
Combustion-generated fine particulate matter (PM2.5) is associated with cardiovascular morbidity. Both traffic-related air pollution and residential wood combustion may be important, but few studies have compared their impacts.
Objectives
To assess and compare effects of traffic-related and woodsmoke PM2.5 on endothelial function and systemic inflammation (C-reactive protein, interleukin-6, and band cells) among healthy adults in Vancouver, British Columbia, Canada using high efficiency particulate air (HEPA) filtration to introduce indoor PM2.5 exposure gradients.
Methods
We recruited 83 healthy adults from 44 homes in traffic- or woodsmoke-impacted areas to participate in this randomized, single-blind crossover intervention study. PM2.5 concentrations were measured during two consecutive 7-day periods, one with filtration and the other with “placebo filtration”. Endothelial function and biomarkers of systematic inflammation were measured at the end of each 7-day period.
Results
HEPA filtration was associated with a 40% decrease in indoor PM2.5 concentrations. There was no relationship between PM2.5 exposure and endothelial function. There was evidence of an association between indoor PM2.5 and C-reactive protein among those in traffic-impacted locations [42.1% increase in C-reactive protein per interquartile range increase in indoor PM2.5, 95% CI, 1.2 to 99.5] but not among those in woodsmoke-impacted locations. There were no associations with interleukin-6 or band cells.
Conclusions
Evidence of an association between C-reactive protein and indoor PM2.5 among healthy adults in traffic-impacted areas is consistent with the hypothesis that traffic-related particles, even at relatively low concentrations, play an important role in the cardiovascular effects of the urban PM mixture.
Trial registered at www.clinicaltrials.gov (NCT01570062)
doi:10.1136/oemed-2014-102696
PMCID: PMC5052064  PMID: 25896330 CAMSID: cams5976
Air pollution; particulate matter; high-efficiency air filter; cardiovascular; intervention
6.  Work schedule and physical factors in relation to fecundity in nurses 
Objectives
To evaluate the association of work schedule and physical factors with fecundity.
Methods
Women currently employed outside the home and trying to get pregnant (n=1739) in the Nurses’ Health Study 3 cohort (2010–2014) were included in this analysis. Work schedule and physical labour were self-reported on the baseline questionnaire, and every 6 months thereafter the women reported the duration of their ongoing pregnancy attempt. Multivariable accelerated failure time models were used to estimate time ratios (TR) and 95% CIs.
Results
Among the 1739 women (median age=33 years, 93% Caucasian) the estimated proportions of women not pregnant after 12 and 24 months were 16% and 5%, respectively. None of the various shift work patterns were associated with duration of pregnancy attempt (as a surrogate for fecundity). However, women working >40 h/week had a 20% (95% CI 7 to 35%) longer median duration of pregnancy attempt compared to women working 21–40 h/week (p-trend=0.005). Women whose work entailed heavy lifting or moving (ie, 25+ pounds) >15 times/day also had a longer median duration of pregnancy attempt (adjusted TR=1.49; 95% CI 1.20 to 1.85) compared to women who never lifted or moved heavy loads (p-trend=0.002). The association between heavy moving and lifting and duration of pregnancy attempt was more pronounced among overweight or obese women (body mass index, BMI<25: TR=1.17; 95% CI 0.88 to 1.56; BMI≥25: TR=2.03, 95% CI 1.48 to 2.79; p-interaction=0.007).
Conclusions
Working greater than 40 h per week and greater frequency of lifting or moving a heavy load were associated with reduced fecundity in a cohort of nurses planning pregnancy.
doi:10.1136/oemed-2015-103026
PMCID: PMC4609294  PMID: 26251064
7.  HEAVY MANUAL WORK THROUGHOUT THE WORKING LIFETIME AND MUSCLE STRENGTH AMONG MEN AT RETIREMENT AGE 
Introduction
Reductions in heavy manual work as a consequence of mechanisation might impact adversely on muscle strength at older ages. We investigated the association between grip strength at retirement age and lifetime occupational exposure to physically demanding activities. Grip strength is an important predictor of long-term health and physical function in older people.
Methods
Grip strength (maximum of three readings in each hand) was measured in men from the Hertfordshire Cohort Study at a single examination when their mean age was 65.8 (SD 2.9) years. Associations with lifetime occupational exposure (ascertained by questionnaire) to three activities (standing/walking ≥4 hours/day; lifting ≥25 kg; and energetic work sufficient to induce sweating) were assessed by multivariable linear regression with adjustment for various potential confounders.
Results
Complete data were available from 1,418 men who had worked for at least 20 years. After adjustment for age, height and weight, those with longer exposures to walking/standing and heavy lifting had lower grip strength, but the relationship disappeared after further adjustment for confounders. Working at physical intensity sufficient to induce sweating was not significantly associated with grip strength.
Conclusions
We found no evidence that physically demanding occupational activities increase hand grip strength at normal retirement age. Any advantages of regular physical occupational activity may have been obscured by unmeasured socio-economic confounders.
doi:10.1136/oemed-2015-103293
PMCID: PMC4817232  PMID: 26896253
Muscle strength; sarcopenia; occupation; manual work
8.  Organophosphate insecticide use and cancer incidence among spouses of pesticide applicators in the Agricultural Health Study 
Objectives
Organophosphates (OP) are among the most commonly used insecticides. OPs have been linked to cancer risk in some epidemiologic studies, which have been largely conducted in predominantly male populations. We evaluated personal use of specific OPs and cancer incidence among female spouses of pesticide applicators in the prospective Agricultural Health Study cohort.
Methods
At enrollment (1993–1997) spouses provided information about ever use of specific pesticides, including ten OPs, demographic information, reproductive health history, and other potential confounders. We used Poisson regression to estimate relative risks (RRs) and 95% confidence intervals (95% CIs) for all cancers diagnosed through 2010 for North Carolina and 2011 for Iowa.
Results
Among 30,003 women, 25.9% reported OP use, and 718 OP-exposed women were diagnosed with cancer during the follow-up period. Any OP use was associated with an elevated risk of breast cancer (RR = 1.20, 95% CI: 1.01, 1.43). Malathion, the most commonly reported OP, was associated with increased risk of thyroid cancer (RR = 2.04, 95% CI: 1.14, 3.63) and decreased risk of non-Hodgkin lymphoma (RR = 0.64, 95% CI: 0.41, 0.99). Diazinon use was associated with ovarian cancer (RR = 1.87, 95% CI: 1.02, 3.43).
Conclusions
We observed increased risk with OP use for several hormonally-related cancers, including breast, thyroid, and ovary, suggesting potential for hormonally-mediated effects. This study represents the first comprehensive analysis of OP use and cancer risk among women, and thus a need for further evaluation.
doi:10.1136/oemed-2014-102798
PMCID: PMC4909328  PMID: 26150671
“Pesticides”; “Cancer”; “Women”; “Agriculture”
9.  Risk of renal cell carcinoma following exposure to metalworking fluids among autoworkers 
Objectives
Metalworking fluids (MWF), used to cool and lubricate metal in occupational settings, are linked to several cancers but data on kidney cancer are limited. We examine how MWF influence the rate of renal cell carcinoma (RCC) in a large prospective study.
Methods
A cohort of Michigan autoworkers consisting of 33,421 individuals was followed 1985 through 2009. The cohort was linked to the Michigan Cancer Registry to identify new cases of RCC. We analyzed RCC in relation to cumulative exposure to each specific type of MWF (straight, soluble and synthetic) and all three types pooled into a single MWF variable, with a 15-year lag. Cox Proportional Hazards Regression with splines were used to estimate Hazard Ratios (HRs) and 95% confidence intervals (95% CIs), controlling for age, gender, race, calendar year, year hired, time since hire, plant, and other MWF types.
Results
There were 135 incident cases. A linear increase in the log-HR was observed for RCC with increasing cumulative exposure to each MWF type and total MWF exposure. At the mean of total MWF exposure (18.80 mg/m3-yr), the estimated HR was 1.11 (95% CI 1.04, 1.19).
Conclusions
Our results provide evidence for a dose-dependent association between MWF exposure and RCC. The influence of components of both oil- and water-based MWF needs further examination.
doi:10.1136/oemed-2016-103769
PMCID: PMC5045439  PMID: 27484955
Occupational autoworkers; Metalworking fluids; Kidney cancer; Renal Cell Carcinoma
10.  Authors' reply to letters from Egilman et al and Oliver et al  
doi:10.1136/oemed-2016-103870
PMCID: PMC5036213  PMID: 27466613
Lung cancer; Dose-response
11.  Cross-shift study of exposure–response relationships between bioaerosol exposure and respiratory effects in the Norwegian grain and animal feed production industry 
Objective
We have studied cross-shift respiratory responses of several individual bioaerosol components of the dust in the grain and feed industry in Norway.
Methods
Cross-shift changes in lung function and nasal congestion, as well as in respiratory and systemic symptoms of 56 exposed workers and 36 referents, were recorded on the same day as full-shift exposure to the inhalable aerosol fraction was assessed. Exposure–response associations were investigated by regression analysis.
Results
The workers were exposed on average to 1.0 mg/m3 of grain dust, 440 EU/m3 of endotoxin, 6 µg/m3 of β-1,3-glucans, 17×104/m3 of bacteria and 4×104/m3 of fungal spores during work. The exposure was associated with higher prevalence of self-reported eye and airway symptoms, which were related to the individual microbial components in a complex manner. Fatigue and nose symptoms were strongest associated with fungal spores, cough with or without phlegm was associated with grain dust and fungal spores equally strong and wheeze/tight chest/dyspnoea was strongest associated with grain dust. Bioaerosol exposure did not lead to cross-shift lung function decline, but several microbial components had influence on nose congestion.
Conclusions
Exposure to fungal spores and dust showed stronger associations with respiratory symptoms and fatigue than endotoxin exposure. The associations with dust suggest that there are other components in dust than the ones studied that induce these effects.
doi:10.1136/oemed-2015-103438
PMCID: PMC5036228  PMID: 27473330
acoustic rhinometry; gas diffusion; microbial components; spirometry
12.  Assessment of two alternative standardised tests for the vascular component of the hand–arm vibration syndrome (HAVS) 
Background
Vibration-induced white finger (VWF) is the vascular component of the hand–arm vibration syndrome (HAVS). Two tests have been standardised so as to assist the diagnosis of VWF: the measurement of finger rewarming times and the measurement of finger systolic blood pressures (FSBPs).
Objectives
This study investigates whether the two tests distinguish between fingers with and without symptoms of whiteness and compares individual results between the two test methods.
Methods
In 60 men reporting symptoms of the HAVS, the times for their fingers to rewarm by 4°C (after immersion in 15°C water for 5 min) and FSBPs at 30°C, 15°C and 10°C were measured on the same day.
Results
There were significant increases in finger rewarming times and significant reductions in FSBPs at both 15°C and 10°C in fingers reported to suffer blanching. The FSBPs had sensitivities and specificities >90%, whereas the finger rewarming test had a sensitivity of 77% and a specificity of 79%. Fingers having longer rewarming times had lower FSBPs at both temperatures.
Conclusions
The findings suggest that, when the test conditions are controlled according to the relevant standard, finger rewarming times and FSBPs can provide useful information for the diagnosis of VWF, although FSBPs are more sensitive and more specific.
doi:10.1136/oemed-2016-103688
PMCID: PMC5036229  PMID: 27535036
Vibration-induced white finger; Hand-arm vibration syndrome; Hand-transmitted vibration; Finger skin temperature; Finger systolic blood pressure
13.  Consecutive results of blood cell count and retrospective biodosimetry: useful tools of health protection regulation for radiation workers 
Background
Industrial radiography is known to be one of the most vulnerable lines of work among the range of different radiation work. According to the relevant law in Korea, every worker registered in this work should check their blood cell counts every year in addition to their thermoluminescent dosimeter (TLD) doses. Since the law was enacted, however, few follow-up studies have been carried out based on the obtained results.
Objectives
To ascertain the clinical usefulness of complete blood cell count (CBC) results and suggest a proper protocol of health protection for radiation workers.
Methods
After reviewing all the consecutive results of CBC and TLD doses from radiation workers registered nationwide, we selected two groups of high-risk radiation workers, CBC-high risk (CBC-HR) and TLD-high risk (TLD-HR) groups. A control group of unexposed healthy adults was also included. We compared the absorbed doses calculated by cytogenetic biodosimetry among those three groups, and examined possible confounding factors for each group.
Results
Both groups of high-risk radiation workers, CBC-HR and TLD-HR, showed higher chromosome aberrations than the control group. In the control group, previous medical history of a CT scan increased the frequency of chromosome aberrations. In contrast, the frequency of chromosome aberrations in the high-risk radiation workers was affected not by the previous CT history but only by the duration of their work.
Conclusions
We ascertain that reviewing consecutive results of blood cell counts and cytogenetic biodosimetry are useful complementary tools to TLD doses for health protection regulation. Several confounding factors including work duration and previous medical history need to be considered for the interpretation of biodosimetry results.
doi:10.1136/oemed-2016-103775
PMCID: PMC5036271  PMID: 27466611
Radiation workers; Complete blood count; Cytogenetic dosimetry; Retrospective dosimetry; Thermoluminescent dosimeter
14.  Breath-taking jobs: a case–control study of respiratory work disability by occupation in Norway 
Background
The current knowledge on respiratory work disability is based on studies that used crude categories of exposure. This may lead to a loss of power, and does not provide sufficient information to allow targeted workplace interventions and follow-up of patients with respiratory symptoms.
Objectives
The aim of this study was to identify occupations and specific exposures associated with respiratory work disability.
Methods
In 2013, a self-administered questionnaire was mailed to a random sample of the general population, aged 16–50, in Telemark County, Norway. We defined respiratory work disability as a positive response to the survey question: ‘Have you ever had to change or leave your job because it affected your breathing?’ Occupational exposures were assessed using an asthma-specific job-exposure matrix, and comparison of risks was made for cases and a median of 50 controls per case.
Results
247 workers had changed their work because of respiratory symptoms, accounting for 1.7% of the respondents ever employed. The ‘breath-taking jobs’ were cooks/chefs: adjusted OR 3.6 (95% CI 1.6 to 8.0); welders: 5.2 (2.0 to 14); gardeners: 4.5 (1.3 to 15); sheet metal workers: 5.4 (2.0 to 14); cleaners: 5.0 (2.2 to 11); hairdressers: 6.4 (2.5 to 17); and agricultural labourers: 7.4 (2.5 to 22). Job changes were also associated with a variety of occupational exposures, with some differences between men and women.
Conclusions
Self-report and job-exposure matrix data showed similar findings. For the occupations and exposures associated with job change, preventive measures should be implemented.
doi:10.1136/oemed-2015-103488
PMCID: PMC5013093  PMID: 27365181
respiratory work disability; occupation; respiratory symptoms; exposures; job-exposure matrix
15.  Lighting and marking policies are associated with reduced farm equipment-related crash rates: a policy analysis of nine Midwestern US states 
Objective
To evaluate the effectiveness of roadway policies for lighting and marking of farm equipment in reducing crashes in Illinois, Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota and Wisconsin.
Methods
In this ecological study, state policies on lighting and marking of farm equipment were scored for compliance with standards of the American Society of Agricultural and Biological Engineers (ASABE). Using generalized estimating equations negative binomial models, we estimated the relationships between lighting and marking scores, and farm equipment crash rates, per 100 000 farm operations.
Results
A total of 7083 crashes involving farm equipment was reported from 2005 to 2010 in the Upper Midwest and Great Plains. As the state lighting and marking score increased by 5 units, crash rates reduced by 17% (rate ratio=0.83; 95% CI 0.78 to 0.88). Lighting-only (rate ratio=0.48; 95% CI 0.45 to 0.51) and marking-only policies (rate ratio=0.89; 95% CI 0.83 to 0.96) were each associated with reduced crash rates.
Conclusions
Aligning lighting and marking policies with ASABE standards may effectively reduce crash rates involving farm equipment.
doi:10.1136/oemed-2016-103672
PMCID: PMC5013097  PMID: 27405602
16.  Incidence of mesothelioma in Lombardy, Italy: exposure to asbestos, time patterns and future projections 
Objectives
In Italy, asbestos has been extensively used from 1945 to 1992. We evaluated the impact of exposure to asbestos on occurrence of malignant mesothelioma (MM) in the Lombardy Region, Northwest Italy, the most populated and industrialised Italian region.
Methods
From the Lombardy Mesothelioma Registry, we selected all incident cases of MM diagnosed between 2000 and 2012. We described sources of exposure to asbestos and examined time trends of MM rates. Using Poisson age-cohort models, we derived projections of burden of MM in the Lombardy population for the period 2013–2029.
Results
In 2000–2012, we recorded 4442 cases of MM (2850 men, 1592 women). Occupational exposure to asbestos was more frequent in men (73.6%) than in women (38.2%). Non-occupational exposure was found for 13.6% of women and 3.6% of men. The average number of cases of MM per year was still increasing (+3.6% in men, +3.3% in women). Incidence rates were still increasing in individuals aged 65+ years and declining in younger people. A maximum of 417 cases of MM (267 men, 150 women) are expected in 2019. We forecast there will be 6832 more cases (4397 in men, 2435 in women) in the period 2013–2029, for a total of 11 274 cases of MM (7247 in men, 4027 in women) in 30 years.
Conclusions
This study documented a high burden of MM in both genders in the Lombardy Region, reflecting extensive occupational (mainly in men) and non-occupational (mainly in women) exposure to asbestos in the past. Incidence rates are still increasing; a downturn in occurrence of MM is expected to occur after 2019.
doi:10.1136/oemed-2016-103652
PMCID: PMC5013098  PMID: 27312399
Mesothelioma incidence; Asbestos exposure; Mesothelioma projections; Age-cohort model; Cancer registry
17.  Mortality differences between self-employed and paid employees: a 5-year follow-up study of the working population in Sweden 
Objectives
Analyse mortality differences between self-employed and paid employees with a focus on industrial sector, educational level and gender using Swedish register data.
Methods
A cohort of the total working population (4 776 135 individuals; 7.2% self-employed; 18–100 years of age at baseline 2003) in Sweden with a 5-year follow-up (2004–2008) for all-cause and cause-specific mortality (57 743 deaths). Self-employed individuals were categorised as sole proprietors or limited liability company (LLC) owners according to their enterprise's legal form. Cox proportional hazards models were applied to compare mortality rates between sole proprietors, LLC owners and paid employees, adjusted for sociodemographic confounders.
Results
Mortality from cardiovascular diseases was 16% lower and from suicide 26% lower among LLC owners than among paid employees, adjusted for confounders. Within the industrial category, all-cause mortality was 13–15% lower among sole proprietors and LLC owners compared with employees in manufacturing and mining (MM) as well as personal and cultural services (PCS), and 11–20% higher in sole proprietors in trade, transport and communication and the welfare industry (W). A significant three-way interaction indicated 17–23% lower all-cause mortality among male LLC owners in MM and female sole proprietors in PCS, and 50% higher mortality in female sole proprietors in W than in employees in the same industries.
Conclusions
Mortality differences between self-employed individuals and paid employees vary by the legal form of self-employment, across industries, and by gender. Differences in work environment exposures and working conditions, varying market competition across industries and gender segregation in the labour market are potential mechanisms underlying these findings.
doi:10.1136/oemed-2015-103472
PMCID: PMC5013135  PMID: 27443155
self-employed; mortality; cohort; industry; Sweden
18.  Occupational Exposures and Lung Cancer Risk among Minnesota Taconite Mining Workers 
Objective
To examine the association between employment duration, elongate mineral particle (EMP) exposure, and silica exposure and the risk of lung cancer in the taconite mining industry.
Methods
We conducted a nested case control study of lung cancer within a cohort of Minnesota taconite iron mining workers employed by any of the mining companies in operation in 1983. Lung cancer cases were identified by vital records and cancer registry data through 2010. Two age-matched controls were selected from risk sets of cohort members alive and lung cancer free at the time of case diagnosis. Calendar time-specific exposure estimates were made for every job and were used to estimate workers’ cumulative exposures. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression. We evaluated total lung cancer risk and risk of histological subtype by total work duration and by cumulative EMP and silica exposure by quartile of the exposure distribution.
Results
A total of 1,706 cases and 3,381 controls were included in the analysis. After adjusting for work in hematite mining, asbestos exposure, and sex, the OR for total duration of employment was 0.99 (95% CI: 0.96–1.01). The ORs for quartile 4 versus 1 of EMP and silica exposure were 0.82 (95% CI: 0.57–1.19) and 0.97 (95% CI: 0.70–1.35) respectively. The risk of each histological subtype of lung cancer did not change with increasing exposure.
Conclusions
This study suggests that the estimated taconite mining exposures do not increase the risk for the development of lung cancer.
doi:10.1136/oemed-2015-102825
PMCID: PMC4537827  PMID: 25977445
Occupational exposure; Lung cancer; Epidemiology; Non-asbestiform exposure
19.  Endotoxin and gender modify lung function recovery after occupational organic dust exposure: a 30 year study 
OBJECTIVES
The purpose of this study is to determine the trajectory of lung function change after exposure cessation to occupational organic dust exposure, and to identify factors that modify improvement.
METHODS
The Shanghai Textile Worker Study is a longitudinal study of 447 cotton workers exposed to endotoxin-containing dust and 472 silk workers exposed to non-endotoxin-containing dust. Spirometry was performed at 5 year intervals. Air sampling was performed to estimate individual cumulative exposures. The effect of work cessation on FEV1 was modeled using generalized additive mixed effects models to identify the trajectory of FEV1 recovery. Linear mixed effects models incorporating interaction terms were used to identify modifiers of FEV1 recovery. Loss to follow-up was accounted for with inverse probability of censoring weights.
RESULTS
74.2% of the original cohort still alive participated in 2011. Generalized additive mixed models identified a non-linear improvement in FEV1 for all workers after exposure cessation, with no plateau noted 25 years after retirement. Linear mixed effects models incorporating interaction terms identified prior endotoxin exposure (p=0.01) and male gender (p=0.002) as risk factors for impaired FEV1 improvement after exposure cessation. After adjusting for gender, smoking delayed the onset of FEV1 gain but did not affect the overall magnitude of change.
CONCLUSIONS
Lung function improvement after cessation of exposure to organic dust is sustained. Endotoxin exposure and male gender are risk factors for less FEV1 improvement.
doi:10.1136/oemed-2014-102579
PMCID: PMC4506722  PMID: 25666844
cotton; endotoxin; FEV1; recovery of function; occupational diseases; gender
20.  Assessed occupational exposure to chlorinated, aromatic and Stoddard solvents during pregnancy and risk of fetal growth restriction 
Objectives
Previous experimental and epidemiological research suggests that maternal exposure to some organic solvents during pregnancy may increase the risk of fetal growth restriction (FGR). We evaluated the association between expert-assessed occupational solvent exposure and risk of small for gestational age (SGA) infants in a population-based sample of women in the National Birth Defects Prevention Study.
Methods
We analysed data from 2886 mothers and their infants born between 1997 and 2002. Job histories were self-reported. Probability of exposure to six chlorinated, three aromatic and one petroleum solvent was assessed by industrial hygienists. SGA was defined as birthweight<10th centile of birthweight-by-gestational age in a national reference. Logistic regression was used to estimate ORs and 95% CIs to assess the association between SGA and exposure to any solvent(s) or specific solvent classes, adjusting for maternal age and education.
Results
Approximately 8% of infants were SGA. Exposure prevalence to any solvent was 10% and 8% among mothers of SGA and non-SGA infants, respectively. Among women with ≥50% probability of exposure, we observed elevated but imprecise associations between SGA and exposure to any solvent(s) (1.71; 0.86 to 3.40), chlorinated solvents (1.70; 0.69 to 4.01) and aromatic solvents (1.87; 0.78 to 4.50).
Conclusions
This is the first population-based study in the USA to investigate the potential association between FGR and assessed maternal occupational exposure to distinct classes of organic solvents during pregnancy. The potential associations observed between SGA and exposure to chlorinated and aromatic solvents are based on small numbers and merit further investigation.
doi:10.1136/oemed-2015-102835
PMCID: PMC4572733  PMID: 26076683
21.  Heavy lifting at work and risk of retinal detachment: a population-based register study in Denmark 
Objectives
To investigate the relationship between rhegmatogenous retinal detachment (RRD) and frequent heavy lifting in a Danish working population through national register data.
Methods
A dynamic cohort of all men aged 20–59 years in Denmark was followed through the Danish Occupational Hospitalisation Register from 1995 to 2010 for diagnosed RRD. Occupational categories were classified according to their potential for heavy lifting in 4 main groups: heavy lifters, manual workers unlikely to be heavy lifters, other manual workers and non-manual workers unlikely to be heavy lifters. The age-standardised rate of diagnosed RRD for heavy lifting occupations was compared with that experienced by the other 3 occupational categories. Rate ratios (RRs) and 95% CIs were estimated through a Poisson regression model adjusted for calendar period and age group.
Results
The highest age-standardised rate of diagnosed RRD was recorded among non-manual workers performing occupational activities unlikely to be associated with heavy lifting (18.0 cases per 100 000 person-years). The RR for workers in jobs expected to entail a high frequency of heavy lifting compared with manual workers whose occupation was unlikely to be associated with heavy lifting was 0.91 (95% CI 0.73 to 1.14), while in comparison with other manual workers, it was 0.93 (95% CI 0.78 to 1.11). The RR compared with non-manual workers in occupations unlikely to entail heavy lifting was 0.51 (95% CI 0.43 to 0.60).
Conclusions
These findings do not support an association of occupational heavy lifting with diagnosed RRD. The epidemiological evidence for this association is still inconclusive. Future studies should use a more specific measure of exposure to resolve the outstanding uncertainties.
doi:10.1136/oemed-2015-102979
PMCID: PMC4759926  PMID: 26561504
22.  Erratum: Mortality rates by occupation in Korea: a nationwide, 13-year follow up study 
doi:10.1136/oemed-2015-103192corr1
PMCID: PMC4941137  PMID: 27165810
23.  International perspective on common core competencies for occupational physicians: a modified Delphi study 
Objectives
The competencies required of occupational physicians (OPs) have been the subject of peer-reviewed research in Europe and individual countries around the world. In the European Union (EU), there has been development of guidance on training and common competencies, but little research has extended beyond this. The aim of this study was to obtain consensus on and identify the common core competencies required of OPs around the world.
Methods
A modified Delphi study was carried out among representative organisations and networks of OPs in a range of countries around the world. It was conducted in 2 rounds using a questionnaire based on the specialist training syllabus of a number of countries, expert panel reviews and conference discussions.
Results
Responses were received from 51 countries around the world, with the majority from Europe (60%; 59%) and North and South America (24%; 32%) in rounds 1 and 2, respectively. General principles of assessment and management of occupational hazards to health and good clinical care were jointly considered most important in ranking when compared with the other topic areas. Assessment of disability and fitness for work, communication skills and legal and ethical issues completed the top five. In both rounds, research methods and teaching and educational supervision were considered least important.
Conclusions
This study has established the current priorities among OPs across 51 countries of the common competencies required for occupational health (OH) practice. These findings can serve as a platform for the development of common core competencies/qualifications within specific geographical regions or internationally. This is particularly pertinent with globalisation of commerce and free movement within the EU.
doi:10.1136/oemed-2015-103285
PMCID: PMC4941142  PMID: 27076063
competencies; occupational physician training; Delphi study; occupational medicine
24.  Can psychosocial work conditions protect against age-related cognitive decline? Results from a systematic review 
According to the use it or lose it hypothesis, intellectually stimulating activities postpone age-related cognitive decline. A previous systematic review concluded that a high level of mental work demands and job control protected against cognitive decline. However, it did not distinguish between outcomes that were measured as cognitive function at one point in time or as cognitive decline. Our study aimed to systematically review which psychosocial working conditions were prospectively associated with high levels of cognitive function and/or changes in cognitive function over time. Articles were identified by a systematic literature search (MEDLINE, Web of Science (WOS), PsycNET, Occupational Safety and Health (OSH)). We included only studies with longitudinal designs examining the impact of psychosocial work conditions on outcomes defined as cognitive function or changes in cognitive function. Two independent reviewers compared title-abstract screenings, full-text screenings and quality assessment ratings. Eleven studies were included in the final synthesis and showed that high levels of mental work demands, occupational complexity or job control at one point in time were prospectively associated with higher levels of cognitive function in midlife or late life. However, the evidence to clarify whether these psychosocial factors also affected cognitive decline was insufficient, conflicting or weak. It remains speculative whether job control, job demands or occupational complexity can protect against cognitive decline. Future studies using methodological advancements can reveal whether workers gain more cognitive reserve in midlife and late life than the available evidence currently suggests. The public health implications of a previous review should thereby be redefined accordingly.
doi:10.1136/oemed-2016-103550
PMCID: PMC4941143  PMID: 27178844
25.  Asthma history, job type, and job changes among U.S. nurses 
Objectives
Nurses are at increased risk of occupational asthma, an observation that may be related to disinfectants exposure. Whether asthma history influences job type or job changes among nurses is unknown. We investigated this issue in a large cohort of nurses.
Methods
The Nurses' Health Study II is a prospective study of U.S. female nurses enrolled in 1989 (ages 24-44 years). Job status and asthma were assessed in biennial (1989-2011) and asthma-specific questionnaires (1998, 2003). Associations between asthma history at baseline (diagnosis before 1989, n=5, 311) and job type at baseline were evaluated by multinomial logistic regression. The relations of asthma history and severity during follow-up to subsequent job changes were evaluated by Cox models.
Results
The analytic cohort included 98,048 nurses. Compared to nurses in education/administration (likely low disinfectant exposure jobs), women with asthma history at baseline were less often employed in jobs with likely high disinfectant exposure, such as operating rooms (odds ratio: 0.73[95%CI, 0.63-0.86]) and ER/inpatient units (0.89[0.82-0.97]). During 22-year follow-up, nurses with a baseline history of asthma were more likely to move to jobs with lower exposure to disinfectants (hazard ratio: 1.13[1.07-1.18]), especially among those with more severe asthma (hazard ratio for mild persistent: 1.13; moderate persistent 1.26; severe persistent: 1.50, compared to intermittent asthma, P trend: 0.004).
Conclusion
Asthma history was associated with baseline job type and subsequent job changes among nurses. This may partly reflect avoidance of tasks involving disinfectant use, and may introduce bias in cross-sectional studies on disinfectant exposure and asthma in nurses.
doi:10.1136/oemed-2014-102547
PMCID: PMC4472505  PMID: 25713153
Asthma; Occupational; Nurses; Healthy worker effect; Disinfectants; Occupational exposure

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