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Author response: Coronary artery atherosclerosis associated with shift work in chemical plant workers by using coronary CT angiography We deeply appreciate the comments and suggestions from Rahman Shiri, MD, PhD. In South Korea, general health check-ups are performed by companies according to their labour management agreement. In this study, coronary artery CT angiography (CCTA) was the investigation specified by the labour management agreement. Prior to the test, the participants in this study were interviewed by a clinician. If the participants had any cardiovascular symptoms or a history of cardiovascular disease, they were transferred to specialist cardiology care and excluded from CCTA. Furthermore, the general population in South Korea can undergo self-referred CCTA evaluation as a general health examination regardless of having a clinical indication.1 We accept the fact that the study sample was small because of the limitation of using CCTA. Dr Rahman Shiri suggested that the crude OR should attenuate after adjustment for waist circumference, low-density lipoprotein-cholesterol, smoking, alcohol consumption and diabetes. Generally, these factors are known...

Shift work and coronary artery disease 1

Natural resource-based industries and prostate cancer risk in Northeastern Ontario: a case-control study ObjectiveProstate cancer continues to be the most commonly diagnosed cancer in men, and there is limited knowledge on its preventable risk factors. A number of occupational exposures in natural resource-based industries are suspected to be related to prostate cancer risk. This study investigates associations between employment in these industries and prostate cancer.MethodsData were from a population-based, case–control study previously conducted in Northeastern Ontario. Incident cases (N=760) aged 45–85 years and diagnosed with prostate cancer between 1995 and 1998 were identified from the Ontario Cancer Registry. Controls (N=1632) were recruited using telephone listings, and were frequency matched to cases by age. Lifetime occupational history was collected for all participants. Logistic regression was used to estimate ORs and their associated 95% CIs.ResultsElevated risks were observed for employment in forestry and logging industries (OR=1.87, 95% CI 1.32 to 2.73) and occupations (OR=1.71, 95% CI 1.24 to 2.35), and these risks increased with duration of employment for ≥10 years. Elevated risks were also found for employment in wood products industries (OR=1.45, 95% CI 1.07 to 1.97), and paper and allied products industries (OR=1.43, 95% CI 1.03 to 2.00), and when duration of employment was ≥10 years. There were also elevated risks in agriculture and mining-related work; however, these findings were not consistent across industry and occupation categories.ConclusionsProstate cancer risk may be associated with work in several natural resource industries, primarily in the forest industries. To further evaluate observed associations, studies should focus on natural resource-based exposures in larger populations with improved exposure assessment.

Simple benchmark for mesothelioma projection for Great Britain BackgroundIt is of considerable interest to forecast the future burden of mesothelioma mortality. Data on deaths are available, whereas no measure of asbestos exposure is available.MethodsWe compare two Poisson models: a response-only model with an age-cohort specification and a multinomial model with epidemiologically motivated frequencies.ResultsThe response-only model has 5% higher peak mortality than the dose–response model. The former performs slightly better in out-of-sample comparison.ConclusionsMortality is predicted to peak at about 2100 deaths around 2017 among males in cohorts until 1966 and below 90 years of age. The response-only model is a simple benchmark that forecasts just as well as more complicated models.

Is it still important to study if ambient air pollution triggers stillbirth? Stillbirth, or late fetal death, is defined by the WHO as a child born with no signs of life and a birth weight of 1000 g or more, a gestational age of 28 weeks or more, or a length of 35 cm or more.1 It is estimated that 2.6 million children worldwide were stillborn at 28 weeks or more in 2015, primarily in low-income and middle-income countries.2 Half of the stillbirths occur during labour and congenital abnormalities account for less than 10% of stillbirths.2 Stillbirth is an important, yet poorly understood, adverse outcomes of pregnancy. The large geographical variation suggests that the majority of stillbirths are preventable. In this issue of Occupational and Environmental Medicine, Siddika et al3 reviewed 13 original epidemiological studies that addressed the question of whether maternal exposure to ambient air pollution triggers stillbirth. They conducted a meta-analysis to summarise the existing evidence, and...

Prenatal ambient air pollution exposure and the risk of stillbirth: systematic review and meta-analysis of the empirical evidence BackgroundIndividual studies on the relations between ambient air pollution and the risk of stillbirth have provided contradictory results. We conducted a systematic review and meta-analysis to summarise the existing evidence.MethodsWe conducted a systematic search of three databases: PubMed, Scopus and Web of Science, from their time of inception to mid-April, 2015. Original studies of any epidemiological design were included. Data from eligible studies were extracted by two investigators. To calculate the summary effect estimates (EE), the random effects model was used with their corresponding 95% CI.Results13 studies met the inclusion criteria. Although not reaching statistical significance, all the summary effect estimates for the risk of stillbirth were systematically elevated in relation to mean prenatal exposure to NO2 per 10 ppb (EE=1.066, 95% CI 0.965 to 1.178, n=3), CO per 0.4 ppm (EE=1.025, 95% CI 0.985 to 1.066, n=3), SO2 per 3 ppb (EE=1.022, 95% CI 0.984 to 1.062, n=3,), PM2.5 per 4 μg/m3 (EE=1.021, 95% CI 0.996 to 1.046, n=2) and PM10 per 10 μg/m3 (EE=1.014, 95% CI 0.948 to 1.085, n=2). The effect estimates for SO2, CO, PM10 and O3 were highest for the third trimester exposure. Two time series studies used a lag term of not more than 6 days preceding stillbirth, and both found increased effect estimates for some pollutants.ConclusionsThe body of evidence suggests that exposure to ambient air pollution increases the risk of stillbirth. Further studies are needed to strengthen the evidence.

Environmental factors associated with baseline and serial changes in fractional exhaled nitric oxide (FeNO) in spice mill workers BackgroundThis study evaluated the determinants of high fractional exhaled nitric oxide (FeNO; >50 ppb) and serial changes in FeNO over a 24-hour period in spice mill workers at risk of work-related allergic respiratory disease and asthma.MethodsA cross-sectional study of 150 workers used European Community Respiratory Health Survey (ECRHS) questionnaires, Phadiatop, serum-specific IgE (garlic, chilli pepper, wheat; Phadia, ImmunoCAP), spirometry and FeNO. A hand-held portable nitric oxide sampling device (NIOX MINO, Aerocrine AB) measured FeNO before and after the 8-hour shift and after 24 hours from baseline.ResultsThe mean age of workers was 33 years; 71% were male, 46% current smokers and 45% atopic. Among workers with garlic sensitisation, 13% were monosensitised and 6% were co-sensitised to chilli pepper. Baseline preshift FeNO geometric mean (GM=14.9 ppb) was similar to the mean change across shift (GM=15.4 ppb) and across the 24-hour period (GM=15.8 ppb). In multivariate linear models, smoking (β=–0.507) and atopy (β=0.433) were strongly associated with FeNO. High FeNO (>50 ppb) was significantly associated with asthma-like symptoms due to spice dust (OR=5.38, CI 1.01 to 28.95). Sensitisation to chilli pepper was more strongly correlated with FeNO (r=0.32) and FeNO>50 ppb (OR=17.04, p=0.005) than garlic. FeNO increase (>12%) across 24 hours demonstrated a strong association with elevated exposures to spice dust particulate (OR=3.77, CI 1.01 to 14.24).ConclusionsThis study suggests that chilli pepper sensitisation is associated with high FeNO (>50 ppb), more strongly compared with garlic, despite the low prevalence of sensitisation to chilli. Elevated inhalant spice dust particulate is associated with a delayed elevation of FeNO across the 24-hour period.

Commentary: Pleural mesothelioma, and occupational and non-occupational asbestos exposure: a case-control study with quantitative risk assessment. In their publication based on a case–control study of pleural mesothelioma in Casale Monferrato, Ferrante et al1 reported associations with occupational and non-occupational (household and residential) exposure to asbestos. From a qualitative point of view, these results are hardly surprising since similar findings have been reported in several other populations with heavy asbestos exposure (for review see ref. 2). The main emphasis of the publication, however, rests on quantitative estimates of these associations. However, the results suffer from important limitations, and these limit their interpretation. Response rate was 89% among cases and 63% among controls, and the proportion of interviews with proxies was 46% for cases and 93% for controls. These differences represent potential sources of selection and information bias;3 report bias (from participants and proxies) is a particular reason of concern given the widespread knowledge in the local community of the carcinogenic effects of asbestos...

Domains of cognitive function in early old age: which ones are predicted by pre-retirement psychosocial work characteristics? BackgroundPsychosocial work characteristics may predict cognitive functioning after retirement. However, little research has explored specific cognitive domains associated with psychosocial work environments. Our study tested whether exposure to job demands, job control and their combination during working life predicted post-retirement performance on eight cognitive tests.MethodsWe used data from French GAZEL cohort members who had undergone post-retirement cognitive testing (n=2149). Psychosocial job characteristics were measured on average for 4 years before retirement using Karasek's Job Content Questionnaire (job demands, job control and demand–control combinations). We tested associations between these exposures and post-retirement performance on tests for executive function, visual-motor speed, psychomotor speed, verbal memory, and verbal fluency using ordinary least squares regression.ResultsLow job control during working life was negatively associated with executive function, psychomotor speed, phonemic fluency and semantic fluency after retirement (p's<0.05), even after adjustment for demographics, socioeconomic status, health and social behaviours and vascular risk factors. Both passive (low-demand, low-control) and high-strain (high-demand, low-control) jobs were associated with lower scores on phonemic and semantic fluency when compared to low-strain (low-demand, high-control) jobs.ConclusionsLow job control, in combination with both high and low-job demands, is associated with post-retirement deficits in some, but not all, cognitive domains. In addition to work stress, associations between passive work and subsequent cognitive function may implicate lack of cognitive engagement at work as a risk factor for future cognitive difficulties.

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.