Wetenschappelijke publicaties

Predictors of toxic metal exposures among US women of reproductive age

Journal of Exposure Science & Environmental Epidemiology, Published online: 24 June 2019; doi:10.1038/s41370-019-0152-3

Predictors of toxic metal exposures among US women of reproductive age

Changes in EEG signals during the cognitive activity at varying air temperature and relative humidity

Journal of Exposure Science & Environmental Epidemiology, Published online: 24 June 2019; doi:10.1038/s41370-019-0154-1

Changes in EEG signals during the cognitive activity at varying air temperature and relative humidity

Employment Quality: An Overlooked Determinant of Workers’ Health and Well-being?

AbstractIn the past four decades, high-income countries have seen a thorough socio-economic restructuring with important implications for the jobs of many workers, including health- and safety-related aspects. Much attention has been paid to psychosocial risks related to intrinsic features of contemporary work tasks, while the occupational health and safety consequences of ‘new’ conditions and relations of employment have remained neglected. This relative neglect is unjustified given the disrupting nature of many contemporary forms of employment. In this commentary, I introduce the concept of ‘employment quality’ as a novel approach towards measuring employment-related OHS risks. Employment quality involves a ‘typological approach’ towards employment arrangements, identifying five employment types in European labour markets, showing a distinct profile in terms of health-related employment characteristics. Moreover, these types align with segmented labour market theory, have a clear socio-economic profile, and show strong associations with workers’ self-reported health.

Identification of the Minimum Number of Measurements Required for Thermal Comfort Assessment in Large Workplaces

AbstractOptimization of resources is the key to improve our ability to perform multiple tasks with limited time and money. In the context of thermal comfort assessment, optimization becomes important in large rooms where tens of individuals perform similar tasks. This work focuses on the identification of the minimum number of measurement points that allows an accurate description of the thermal environment. Accuracy of description is assumed if no significant loss of information is associated to the transition from the ‘primary’ thermal map based on all available measurement points to a ‘secondary’ thermal map based on a reduced set of measurement points. The concept of ‘no significant loss’ is quantified by requiring that the difference in PMV (Predicted Mean Vote) between the two maps is kept <0.1 in the vast majority (95%) of points. PMV is a standardized synthetic index that is used worldwide for quantifying thermal comfort (ISO 7730, 2005) taking into account both environmental (thermo-hygrometric) and personal (activity, clothing) quantities.We show that the uncertainty induced by the degraded resolution of the thermal map has a limited impact on the overall uncertainty on PMV. Application of the method to a few test environments shows that the room size perpendicular to the main window and the windows orientation play the largest role in determining spatial inhomogeneity in thermal maps. A minor concurring factor is the room area.

Vertical distribution of source apportioned PM<sub>2.5</sub> using particulate-bound elements and polycyclic aromatic hydrocarbons in an urban area

Journal of Exposure Science & Environmental Epidemiology, Published online: 21 June 2019; doi:10.1038/s41370-019-0153-2

Vertical distribution of source apportioned PM2.5 using particulate-bound elements and polycyclic aromatic hydrocarbons in an urban area

Globe Temperature and Its Measurement: Requirements and Limitations

AbstractThis study addresses the measurement of the globe temperature. For this purpose, two globe thermometers with different diameters (50 and 150 mm) and a variety of thermal environmental conditions were considered. The assessments of the response times and of the influences of the globe diameter and the air velocity on the measured globe temperatures are discussed. The results of the response times clearly put in evidence that the values usually stated in the literature can be questioned and that longer measurement periods must be considered. In fact, response times >30 min were obtained in 68% of the tests performed. Moreover, differences >20ºC were obtained between the 150 and 50 mm sensors, highlighting the influence of the globe diameter. The analysis of the effect of the air velocity on the globe temperature shows mean relative differences >30% between tests in still air and with the higher air velocity considered (1.81 m s–1). On the basis of measurements carried out with the 50 mm globe, correction equations to the standard globe temperature for both natural and forced convection are proposed.

Shift Work and Leukocyte Count Changes among Workers in Bangkok

AbstractObjectivesPrevious epidemiological evidence for the association of shift work exposure and increased leukocyte count is cross-sectional in nature, thus limiting cause-effect inference. We therefore used a longitudinal design to: (i) compare leukocyte counts at baseline between shift and day workers and (ii) examine the time trend of leukocyte counts over the follow-up period for these workers.MethodsA retrospective cohort study was conducted among 6737 workers aged <60 years at two large organizations (a humanitarian organization and a university) in Bangkok, Thailand who had participated in at least two annual health check-ups during the period 2005–2016. Shift work exposure history was assessed by a self-administered questionnaire and categorized into day, former, and current shift workers. Data on leukocyte count were collected annually as part of worksite health screening during the observation period. Association of shift work exposure and increased leukocyte count was then examined cross-sectionally and longitudinally by using multiple linear regression and multilevel analysis of repeated measures data, respectively. In addition, trends for leukocyte count over the follow-up period and work years were examined using LOWESS smooth curves.ResultsCompared to day work, the current shift work was associated with increased leukocyte counts. The magnitude of percentage increase was the highest for basophil counts, followed by eosinophil and lymphocyte counts. Both cross-sectional and longitudinal evidence revealed this association, although it was less pronounced longitudinally. For total leukocyte count, the magnitude of difference was constant across the 11-year follow-up period. However, for lymphocyte and basophil counts, these discrepancies tapered over the work years until they no longer differed (for lymphocyte count) or even differed in the opposite direction (for basophil count) in later work years.ConclusionThis study confirmed previous cross-sectional evidence that shift work exposure-increased leukocyte counts and that this was reversible. Whether this increase in immune cell count also results in an increased immune cell activity and serves as the intermediary in the association between shift work exposure and subsequent chronic disease development needs further investigation.

X2018—The 9th International Conference on the Science of Exposure Assessment

This conference, held in Manchester, UK in September 2018 was the ninth in a series of meetings on the science of exposure assessment. The first conference in the X series was held in 1988 in Woods Hole in the USA (De Vocht et al., 2013) with the most recent one being in Barcelona in 2016. X2018 brought together experts to exchange knowledge in exposure assessment sciences for human health studies. In particular, the conference offered the chance for those who measure exposures and those who model exposures to get together and compare notes. If we are to improve the quality and interpretability of research for complex, multi-stranded exposure issues then such cooperation and meetings are essential—how should we be designing our observational studies so that models can be more reflective of reality? Are the assumptions made by models (and their creators) reasonable given real-world practise? Defining the key drivers, and collecting the appropriate data to model them is vital. The opening keynote speaker, Dr Lützen Portengen (Portengen, 2018), The Netherlands, set the tone, talking about the complexities of multipollutant models and statistical means to analyse omics data but how specific exposure measurements will still be required to demonstrate causal links.

Correction to: Pesticide exposure among Bolivian farmers: associations between worker protection and exposure biomarkers

Journal of Exposure Science & Environmental Epidemiology, Published online: 14 June 2019; doi:10.1038/s41370-019-0149-y

Correction to: Pesticide exposure among Bolivian farmers: associations between worker protection and exposure biomarkers

Case-control investigation of occupational lead exposure and kidney cancer

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objectives

Lead is a suspected carcinogen that has been inconsistently associated with kidney cancer. To clarify this relationship, we conducted an analysis of occupational lead exposure within a population-based study of kidney cancer using detailed exposure assessment methods.

Methods

Study participants (1217 cases and 1235 controls), enrolled between 2002 and 2007, provided information on their occupational histories and, for selected lead-related occupations, answered questions regarding workplace tasks, and use of protective equipment. Industrial hygienists used this information to develop several estimates of occupational lead exposure, including probability, duration and cumulative exposure. Unconditional logistic regression was used to compute ORs and 95% CIs for different exposure metrics, with unexposed subjects serving as the reference group. Analyses were also conducted stratifying on several factors, including for subjects of European ancestry only, single nucleotide polymorphisms in ALAD (rs1805313, rs1800435, rs8177796, rs2761016), a gene involved in lead toxicokinetics.

Results

In our study, cumulative occupational lead exposure was not associated with kidney cancer (OR 0.9, 95% CI 0.7 to 1.3 for highest quartile vs unexposed; ptrend=0.80). Other lead exposure metrics were similarly null. We observed no evidence of effect modification for the evaluated ALAD variants (subjects of European ancestry only, 662 cases and 561 controls) and most stratifying factors, although lead exposure was associated with increased risk among never smokers.

Conclusions

The findings of this study do not offer clear support for an association between occupational lead exposure and kidney cancer.

Chronic conditions as predictors of later life disability employment exit: a gendered analysis

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objectives

Increasing life expectancy has led governments to implement reforms aimed at delaying retirement. Chronic conditions are an important barrier to this given their association with pain, functional limitations, depression and ultimately lower life expectancy. Chronic diseases are gendered in terms of these characteristics, as well as their population prevalence. I examined the extent to which gender moderates the extent to which different chronic conditions lead to disability employment exit, the proportion of exits they account for and key mediators in this process.

Methods

Data from waves 1 to 8 of the English Longitudinal Study of Ageing were analysed. I followed employees aged 50–70 years until they experienced disability employment exit, or were censored. I analysed the influence of chronic conditions, functional limitations, pain, depressive symptoms and subjective life expectancy using discrete time survival analysis. All analyses were carried out separately by gender if a significant interaction was found. The mediation analysis was carried out using the Karlson/Holm/Breen method.

Results

No significant gender interactions were found for the risk of chronic conditions on disability employment exit. Lung disease (OR 4.1; 95% CI 2.8 to 5.9), cancer (OR 2.9; 95% CI 2.1 to 4.0) and arthritis (OR 2.6; 95% CI 2.1 to 3.3) were the strongest determinants. Depressive symptoms (OR 3.2; 95% CI 2.5 to 4.1) were also a strong determinant, and along with arthritis, explained a greater proportion of women than men’s exits given differences in prevalence. Pain and various types of functional limitations were important mediators of exit as well as determinants in their own right.

Conclusion

The results suggest that gender differences in the prevalence of different chronic conditions result in differences in the proportion of disability employment exits they account for in the population. Targeted and tailored interventions, for example, in the workplace might take this into account.

Home care aides experiences of verbal abuse: a survey of characteristics and risk factors

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objective

Violence from care recipients and family members, including both verbal and physical abuse, is a serious occupational hazard for healthcare and social assistance workers. Most workplace violence studies in this sector focus on hospitals and other institutional settings. This study examined verbal abuse in a large home care (HC) aide population and evaluated risk factors.

Methods

We used questionnaire survey data collected as part of a larger mixed methods study of a range of working conditions among HC aides. This paper focuses on survey responses of HC aides (n=954) who reported on verbal abuse from non-family clients and their family members. Risk factors were identified in univariate and multivariable analyses.

Results

Twenty-two per cent (n=206) of aides reported at least one incident of verbal abuse in the 12 months before the survey. Three factors were found to be important in multivariable models: clients with dementia (relative risk (RR) 1.38, 95% CI 1.07 to 1.78), homes with too little space for the aide to work (RR 1.52, 95% CI 1.17 to 1.97) and predictable work hours (RR 0.74, 95% CI 0.58 to 0.94); two additional factors were associated with verbal abuse, although not as strongly: having clients with limited mobility (RR 1.35, 95% CI 0.94 to 1.93) and an unclear plan for care delivery (RR 1.27, 95% CI 0.95 to 1.69). Aides reporting verbal abuse were 11 times as likely to also report physical abuse (RR 11.53; 95% CI 6.84 to 19.45).

Conclusions

Verbal abuse is common among HC aides. These findings suggest specific changes in work organisation and training that may help reduce verbal abuse.

Are there bidirectional relationships between psychosocial work characteristics and depressive symptoms? A fixed effects analysis of Swedish national panel survey data

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objectives

Psychosocial work characteristics have been prospectively associated with depressive symptoms. However, methodological limitations have raised questions regarding causality. It is also unclear to what extent depressive symptoms affect the experience of the psychosocial work environment. We examined contemporaneous (measured simultaneously) and lagged bidirectional relationships between psychosocial work characteristics and depressive symptoms, simultaneously controlling for time-stable individual characteristics.

Methods

We included 3947 subjects in the Swedish Longitudinal Occupational Survey of Health (SLOSH), with self-reported job demands, control, social support, work efforts, rewards, procedural justice and depressive symptoms in four waves 2010–2016. We applied dynamic panel models with fixed effects, using structural equation modelling, adjusting for all time-stable individual characteristics such as personality and pre-employment factors.

Results

Higher levels of job demands, job demands in relation to control, work efforts and efforts in relation to rewards were contemporaneously associated with more depressive symptoms (standardised β: 0.18–0.25, p<0.001), while higher levels of workplace social support, rewards at work and procedural justice were associated with less depressive symptoms (β: –0.18, p<0.001,β: –0.16, p<0.001 and β: –0.09, p<0.01, respectively). In contrast, only work efforts predicted higher levels of depressive symptoms 2 years later (β: 0.05, p<0.05). No other lagged associations were found in any direction.

Conclusions

After controlling for all time-invariant confounding, our results suggest that psychosocial work characteristics predominantly affect depressive symptoms immediately or with only a short time lag. Furthermore, we found no evidence of reverse causation. This indicates short-term causal associations, although the temporal precedence of psychosocial work characteristics remains uncertain.

Melanoma incidence in Australian commercial pilots, 2011-2016

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objectives

Occupational exposure to cosmic and ultraviolet radiation may increase airline pilots’ risk of cutaneous melanoma. Meta-analyses of available data show a higher than average incidence of melanoma in airline pilots, but the most recent systematic review revealed that few contemporary data are available. Moreover, all relevant studies have been conducted in Northern Hemisphere populations. We therefore aimed to examine if Australian commercial pilots have a raised incidence of melanoma compared with the general population.

Methods

We examined all melanoma histologically diagnosed among Australian-licensed commercial pilots in the period 2011–2016 by manually reviewing de-identified data in the medical records system of the Australian Civil Aviation Safety Authority. We estimated age-specific incidence rates and compared these with corresponding population rates using standardised incidence ratios (SIRs) as measures of relative risk. Expected numbers were calculated by multiplying age- and calendar period-specific person-years (PYs) with corresponding rates from the entire Australian population; 95% CI were calculated assuming a Poisson distribution of the observed cases.

Results

In this cohort of Australian-licensed commercial pilots observed for 91 370 PYs, 114 developed a melanoma (51 invasive, 63 in situ). More than 50% of melanomas occurred on the trunk, and the predominant subtype was superficial spreading melanoma. The SIR for invasive melanoma was 1.20 (95% CI 0.89 to 1.55) and for melanoma in situ, 1.39 (95% CI 1.08 to 1.78).

Conclusion

Australian-licensed commercial pilots have a modestly raised risk of in situ melanoma but no elevation of invasive melanoma compared with the general population.

Longitudinal investigation of haematological alterations among permethrin-exposed pesticide applicators in the Biomarkers of Exposure and Effect in Agriculture study

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objectives

Permethrin use has been associated with an increased risk of multiple myeloma (MM) among pesticide applicators. However, the biological plausibility and mechanisms underlying this association are not fully understood. The aim of this study was to assess whether exposure to permethrin is related to haematological alterations among occupationally exposed pesticide applicators.

Methods

We conducted a longitudinal study among 33 pesticide applicators in the Biomarkers of Exposure and Effect in Agriculture study comparing haematological parameters in the offseason with the day after permethrin exposure and, for 27 participants, approximately 3 weeks postexposure. Complete blood counts with white blood cell differential and lymphocyte subsets were measured at each visit. Multivariate linear mixed effects models were used to assess the relationship between natural log-transformed haematological parameters and exposure to permethrin.

Results

The adjusted geometric mean immature granulocyte count was elevated among pesticide applicators following permethrin exposure compared with their offseason levels (37% increase, 95% CI 6% to 76%). Modest but statistically significant (p<0.05) alterations in red blood cell (RBC) parameters (eg, decreased RBC count and haemoglobin and increased mean corpuscular volume and RBC distribution width-SD) were also observed the day after permethrin use compared with offseason levels; decreases in RBC count and haemoglobin and increases in RBC distribution width-SD persisted approximately 3 weeks after permethrin use.

Conclusions

Altered haematological parameters could be indicative of disrupted haematopoiesis, providing insights into the biological plausibility of the observed association between permethrin use and MM risk among pesticide applicators.

Assault predicts time away from work after claims for work-related mild traumatic brain injury

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Introduction

Workplace violence carries a substantial economic loss burden. Up to 10% of all traumatic brain injury (TBI) admissions result from physical assault. There remains a paucity of research on assault as a mechanism of injury, taking into account sex, and its association with work re-entry.

Objectives

The aim of this study was to characterise, by sex, the sample of workers who had sustained a work-related mild TBI (wr-mTBI) and to assess the independent influence of assault, as a mechanism of injury, on time away from work.

Methods

A population-based retrospective cohort of workers’ compensation claimants in Australia (n=3129) who had sustained a wr-mTBI was used for this study. A multivariable logistic regression analysis assessed whether workers who had sustained wr-mTBI as a result of assault (wr-mTBI-assault) were more likely to claim time off work compared with workers who had sustained a wr-mTBI due to other mechanisms.

Results

Among claimants who sustained a wr-mTBI, 9% were as a result of assault. The distribution of demographic and vocational variables differed between the wr-mTBI-assault, and not due to assault, both in the full sample, and separately for men and women. After controlling for potential confounding factors, workers who sustained wr-mTBI-assault, compared with other mechanisms, were more likely to take days off work (OR 2.14, 95% CI 1.53 to 2.99) within a 3-month timeframe.

Conclusion

The results have policy-related implications. Sex-specific and workplace-specific prevention strategies need to be considered and provisions to support return-to-work and well-being within this vulnerable cohort should be examined.

Continued increase in prevalence of r-type opacities among underground coal miners in the USA

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Introduction

Respirable crystalline silica exposure has been implicated in the resurgence of coal workers’ pneumoconiosis (CWP) in the USA. A 2010 report found an increasing prevalence of r-type opacities, which are associated with silicosis lung pathology, on the radiographs of working underground coal miners in central Appalachia. This analysis updates that report by assessing the prevalence of r-type opacities during 2010–2018 compared with earlier decades.

Methods

Data from the Coal Workers’ Health Surveillance Program were used to calculate the prevalence of r-type opacities on radiographs of working underground coal miners. The data were restricted to radiographs taken during 1 January 1980 to 15 September 2018. The presence of r-type opacities was defined as an r-type classification for either the primary or secondary shape/size of small opacities. Prevalence ratios for r-type opacities were calculated using log binomial regression.

Results

Radiograph classifications for 106 506 miners were included in analysis. For the USA overall, the prevalence of r-type opacities among miners with radiographs taken during 2010–2018 compared with 1980–1989 has increased (PR 2.4; 95% CI 1.9 to 3.0). For central Appalachia, the proportion of r-type opacities observed increased when comparing 1980–1989 to 2010–2018 (PR 6.0; 95% CI 4.6 to 7.9).

Conclusions

The prevalence of r-type opacities on the radiographs of Appalachian underground coal miners continues to increase, implicating exposure to crystalline silica in respirable coal mine dust. The current findings underscore the importance of monitoring and controlling exposure to silica in coal mines.

Down-regulation of the inflammatory response after short-term exposure to low levels of chemical vapours

http://oem.bmj.com/rss/current.xml - do, 06/13/2019 - 11:30
Objective

To investigate the relation between signs and symptoms of irritation and biomarkers of inflammatory markers in blood in healthy volunteers exposed to different chemical vapours for 2 or 4 hours in an exposure chamber.

Methods

The investigated chemicals were: acetic acid (5 and 10 ppm), acrolein (0.05 and 0.1 ppm), 1,4-dioxane (20 ppm), n-hexanal (2 and 10 ppm), hydrogen peroxide (0.5 and 2.2 ppm), 2-propanol (150 ppm), m-xylene (50 ppm), standard and dearomatised white spirit (100 and 300 mg/m3). C reactive protein (CRP), serum amyloid A protein and interleukin 6 were measured in plasma immediately before and 2 or 4 hours after the exposures. Symptoms were rated from 0 to 100 mm in Visual Analogue Scales and covered 10 questions whereof four related to irritation: discomfort in the eyes, nose and throat and dyspnoea. The effect measurements included blink frequency by electromyography, nasal swelling by acoustic rhinometry and lung function by spirometry.

Results

Logistic quantile regression analyses revealed no significant associations except a negative relation between ratings of irritation and CRP.

Conclusion

The results suggest a down-regulation of CRP after short-term exposure to low levels of vapours of irritating chemicals. This response might be mediated by the cholinergic anti-inflammatory pathway and further studies are recommended in order to refute or confirm this hypothesis.

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