Use, failure, and non-compliance of respiratory personal protective equipment and risk of upper respiratory tract infections-A longitudinal repeated measurement study during the COVID-19 pandemic among healthcare workers in Denmark

INTRODUCTION

Upper respiratory tract infections (URTI) are common and a common cause of sick-leave for healthcare workers, and furthermore pose a threat especially for patients susceptible to other diseases. Sufficient use of respiratory protective equipment (RPE) may protect both the workers and the patients. The COVID-19 pandemic provided a unique opportunity to study the association between use of RPE and URTI in a real-life setting. The aim of this study was to examine if failure of RPE or non-compliance with RPE guidelines increases the risk of non-COVID-19 URTI symptoms among healthcare workers.

METHODS

In a longitudinal cohort study, we collected self-reported data daily on work tasks, use of RPE, and URTI symptoms among healthcare workers with patient contact in 2 Danish Regions in 2 time periods during the COVID-19 pandemic. The association between failure of RPE or non-compliance with RPE guidelines and URTI symptoms was analyzed separately by generalized linear models. Persons tested positive for severe acute respiratory syndrome coronavirus 2 were censored from the analyses. The 2 waves of data collection were analyzed separately, as there were differences in recommendations of RPE during the 2 waves.

RESULTS

We found that for healthcare workers performing work tasks with a risk of transmission of viruses or bacteria, failure of RPE was associated with an increased risk of URTI symptoms, RR: 1.65[0.53-5.14] in wave 1 and RR: 1.30[0.56-3.03] in wave 2. Also non-compliance with RPE guidelines was associated with an increased risk of URTI symptoms compared to the use of RPE in wave 1, RR: 1.28[0.87-1.87] and wave 2, RR: 1.39[1.01-1.91]. Stratifying on high- versus low-risk tasks showed that the risk related to failure and non-compliance was primarily associated with high-risk tasks, although not statistically significant.

DISCUSSION

The study was conducted during the COVID-19 pandemic and thus may be affected by other preventive measures in society. However, this gave the opportunity to study the use of RPE in a real-life setting, also in departments that did not previously use RPE. The circumstances in the 2 time periods of data collection differed and were analyzed separately and thus the sample size was limited and affected the precision of the estimates.

CONCLUSION

Failures of RPE and non-compliance with RPE guidelines may increase the risk of URTI, compared to those who reported use of RPE as recommended. The implications of these findings are that the use of RPE to prevent URTI could be considered, especially while performing high-risk tasks where other prevention strategies are not achievable.

Validity of self-reported night shift work among women with and without breast cancer

OBJECTIVES

This study aimed to estimate the validity of self-reported information on ever-night shift work among women with and without breast cancer and illustrate the consequences for breast cancer risk estimates.

METHODS

During 2015-2016, 225 women diagnosed with breast cancer and 1800 matched controls without breast cancer employed within the Danish hospital regions during 2007-2016 participated in a questionnaire-based survey. Their reported night shift work status was linked with objective payroll register day-by-day working hour data from the Danish Working Hour Database and the Danish Cancer Registry. For the breast cancer patients and their matched controls, we estimated sensitivity and specificity for ever-working night shifts using the payroll data as the gold standard. We also used quantitative bias analysis to estimate the impact on relative risk estimates for a hypothetical population.

RESULTS

For breast cancer patients, we observed a sensitivity of ever-night shifts of 86.2% and a specificity of never-night shifts of 82.6%. For controls, the sensitivity was 80.6% and the specificity 83.7%. Odds ratio for breast cancer in a hypothetical population decreased from 1.12 [95% confidence interval (CI) 1.03-1.21] to 1.05 (95% CI 0.95-1.16) when corrected by the sensitivity and specificity estimates.

CONCLUSION

This study shows that female breast cancer patients had slightly better recall of previous night shift work than controls. Additionally, both breast cancer patients and controls recalled previous never-night shift work with low specificity. The net effect of this misclassification is a small over-estimation of the relative breast cancer risk due to night shift work.

Risk of myocardial infarction among pigeon breeders: A follow-up study

Pigeon breeders are exposed to high levels of fine particulate organic matter in the pigeon lofts. A total of 6,704 pigeon breeders and their 1:30 sex and age-matched referents from the general Danish population were followed from 1980 or first year of membership in the Danish Racing Pigeon Association, until first event of myocardial infarction, emigration, death, or end of study, on December 31, 2013. Information on outcomes and covariates was obtained by record linkage with national registers. Stratified Cox regression models estimated the hazard ratio of myocardial infarction, adjusted for occupation and residence at the start of follow-up. Compared with referents, pigeon breeders had an adjusted hazard ratio of 1.14 (95% CI: 1.05-1.22) for myocardial infarction. Exposure to pigeon-derived organic dust may increase the risk of myocardial infarction, but this finding needs to be corroborated.

Occupational exposure to epoxy components and risk of dermatitis: A registry-based follow-up study of the wind turbine industry

BACKGROUND

Allergic contact allergy and dermatitis are frequently reported among epoxy-exposed workers.

OBJECTIVES

To determine the risk of dermatitis associated with epoxy exposure.

METHODS

We followed 825 epoxy-exposed and 1091 non-exposed blue-collar workers, and 493 white-collar workers of a Danish wind turbine blade factory during 2017-2022 with linked data from national health registers on diagnoses, patch testing, or fillings of prescriptions for topical corticosteroids. Incidence rate ratios of dermatitis or a first-time topical corticosteroid prescription were estimated with Poisson regression using non-exposed blue-collar workers as reference. We similarly estimated incidence rate ratios for the duration of epoxy exposure and current epoxy exposure.

RESULTS

Epoxy-exposed blue-collar workers showed a dermatitis incidence rate of 2.1 per 100 000 person days, a two-fold increased risk of dermatitis and a 20% increased risk of filling a prescription for topical corticosteroids. Incidence rate ratios were higher during early exposure and declined with further exposure for both outcomes. White-collar workers had generally lower risks.

CONCLUSION

We observed an increased risk of dermatitis following epoxy exposure confirming previous case reports and cross-sectional studies emphasizing the need for intensified focus on preventive efforts for this group of workers.

Night shift work characteristics and risk of incident coronary heart disease among health care workers: national cohort study

BACKGROUND

Night work has been associated with coronary heart disease. The present study examined exposure-response relations between quantitative night work characteristics and coronary heart disease (angina pectoris or myocardial infarction) with the aim to contribute to evidence-based recommendations for low-risk night work schedules.

METHODS

We followed 100 149 night workers (80% women) and 153 882 day workers (78% women), all health care workers in Denmark with day by day payroll information on night shifts from 2007 to 2015. We analysed data with Poisson regression stratified by sex and adjusted for age, calendar year, diabetes, family history of cardiovascular disease, educational level, occupation, indicators for obesity, hypercholesterolaemia, and hypertension.

RESULTS

Female and male night workers worked on average 1.7 and 1.8 night shifts per month for an average duration of less than 4 years. During follow-up, 1198 night and 2128 day workers were hospitalized with first-time coronary heart disease. When compared with day workers, the overall incidence rate ratios for female and male night workers were 1.06 [95% confidence interval (CI): 0.97, 1.17] and 1.22 (95% CI 1.07, 1.39). Highest risks were observed in top exposure categories for several night work characteristics. However, no consistent exposure-response relations by number of monthly night shifts, cumulative night shifts, years with rotating night shifts, years with any night shift and consecutive night shifts were observed among the night workers of either sex.

CONCLUSIONS

This study of a population with low exposure to night work does not indicate that reducing extent of monthly night shifts, cumulative night shifts, years with rotating night shifts, years with any night shift and consecutive night shifts would reduce the risk of coronary heart disease.

Prenatal exposure to nitrosatable drugs and timing of puberty in sons and daughters: A nationwide cohort study

BACKGROUND

N-nitroso compounds (NOCs) can be formed by endogenous reactions between nitrosatable drugs and nitrite. Animal studies have found that several NOCs are teratogenic, and epidemiological studies report associations between prenatal exposure to nitrosatable drugs and adverse birth outcomes. It is unknown whether prenatal exposure to nitrosatable drugs is harmful to the child's reproductive health, including pubertal development.

OBJECTIVES

We investigated whether prenatal exposure to nitrosatable drugs was associated with timing of puberty and whether nitrate, nitrite and antioxidant intake modified any association.

METHODS

The population-based Danish National Birth Cohort (DNBC) Puberty Cohort, which includes 15,819 children, was used to investigate the association between prenatal exposure to nitrosatable drugs and timing of puberty. Around gestational week 11 and gestational week 18, mothers provided information about drug use during pregnancy. The children's self-reported information on onset of pubertal milestones was collected every six months from 11 years of age and throughout puberty. To investigate potential effect modification by nitrite, nitrate and antioxidant intake, information on these factors was obtained from a food frequency questionnaire completed by the mothers in gestational week 25, and information on nitrate concentration in maternal drinking water at her residential address was obtained from monitoring data from public waterworks. Data were analysed using a multivariable regression model for interval-censored data estimating difference in months in timing of puberty between exposure groups.

RESULTS

A total of 2,715 children were prenatally exposed to nitrosatable drugs. We did not find an association between prenatal exposure to nitrosatable drugs and timing of puberty. This finding was supported by null-findings in the following sub-analyses investigating: 1. subtypes of nitrosatable drugs (secondary and tertiary amines and amides), 2. dose-dependency (duration of drug intake), 3. effect modification by maternal intake of nitrate, nitrite, and antioxidants. 4. confounding by indication.

CONCLUSIONS

Prenatal exposure to nitrosatable drugs was not associated with timing of puberty. Nitrosatable drugs are commonly used drugs in pregnancy, and further research is needed to allow firm conclusions on the potential effect of prenatal exposure to nitrosatable drugs on the child's reproductive health.

Prenatal Exposure to Nitrate in Drinking Water and Adverse Health Outcomes in the Offspring: a Review of Current Epidemiological Research

PURPOSE OF REVIEW

Recently, several epidemiological studies have investigated whether prenatal exposure to nitrate from drinking water may be harmful to the fetus, even at nitrate levels below the current World Health Organization drinking water standard. The purpose of this review was to give an overview of the newest knowledge on potential health effects of prenatal exposure to nitrate.

RECENT FINDINGS

We included 13 epidemiological studies conducted since 2017. Nine studies investigated outcomes appearing around birth, and four studies investigated health outcomes appearing in childhood and young adulthood. The reviewed studies showed some indications of higher risk of preterm delivery, lower birth weight, birth defects, and childhood cancer related to prenatal exposure to nitrate. However, the numbers of studies for each outcome were sparse, and some of the results were conflicting. We suggest that there is a need for additional studies and particularly for studies that include information on water consumption patterns, intake of nitrate from diet, and intake of nitrosatable drugs.

Exposure levels of dust, endotoxin, and microorganisms in the Danish recycling industry

INTRODUCTION

Recycling of domestic waste and a number of employees in the recycling industry is expected to increase. This study aims to quantify current exposure levels of inhalable dust, endotoxin, and microorganisms and to identify determinants of exposure among recycling workers.

METHODS

This cross-sectional study included 170 full-shift measurements from 88 production workers and 14 administrative workers from 12 recycling companies in Denmark. The companies recycle domestic waste (sorting, shredding, and extracting materials from waste). We collected inhalable dust with personal samplers that were analysed for endotoxin (n = 170) and microorganisms (n = 101). Exposure levels of inhalable dust, endotoxin, and microorganisms and potential determinants of exposure were explored by mixed-effects models.

RESULTS

The production workers were 7-fold or higher exposed to inhalable dust, endotoxin, bacteria, and fungi than the administrative workers. Among production workers recycling domestic waste, the geometric mean exposure level was 0.6 mg/m3 for inhalable dust, 10.7 endotoxin unit (EU)/m3 for endotoxin, 1.6 × 104 colony forming units (CFU)/m³ of bacteria, 4.4 × 104 CFU/m³ of fungi (25 °C), and 1.0 × 103 CFU/m³ of fungi (37 °C). Workers handling paper or cardboard had higher exposure levels than workers handling other waste fractions. The temperature did not affect exposure levels, although there was a tendency toward increased exposure to bacteria and fungi with higher temperatures. For inhalable dust and endotoxin, exposure levels during outdoor work were low compared to indoor work. For bacteria and fungi, indoor ventilation decreased exposure. The work task, waste fraction, temperature, location, mechanical ventilation, and the company size explained around half of the variance of levels of inhalable dust, endotoxin, bacteria, and fungi.

CONCLUSION

The production workers of the Danish recycling industry participating in this study had higher exposure levels of inhalable dust, endotoxin, bacteria, and fungi than the administrative workers. Exposure levels of inhalable dust and endotoxin among recycling workers in Denmark were generally below established or suggested occupational exposure limits (OEL). However, 43% to 58% of the individual measurements of bacteria and fungi were above the suggested OEL. The waste fraction was the most influential determinant for exposure, and the highest exposure levels were seen during handling paper or cardboard. Future studies should examine the relationship between exposure levels and health effects among workers recycling domestic waste.

Night and evening shifts and risk of calling in sick within the next two days - a case-crossover study design based on day-to-day payroll data

OBJECTIVE

Night and evening work is associated with risk of sickness absence, but little is known about the acute effects of these types of shifts on sickness absence. The aim of the current study is therefore to examine the risk of calling in sick within two days after a night or an evening shift.

METHODS

By use of a case-crossover design, odds of calling in sick within two days after a night or an evening shift compared to day shifts were analyzed within the same person. Day-to-day information on shifts and sickness absence were derived from the Danish Working Hour Database on 44 767 cases. Data were analyzed using conditional logistic regression. The analyses were supplemented by extensive testing of methodological choices.

RESULTS

Analyses showed higher odds of calling in sick after a night shift [odds ratio (OR) 1.22, 95% confidence intervak (CI) 1.14-1.30] and lower odds after an evening shift (OR 0.89, 95% CI 0.84-0.93) compared to day shifts within the same person. Testing of methodological choices suggested that in particular the duration of case and control periods, time between these periods along with the number of control periods affected the results.

CONCLUSION

This large and unique within-person study among Danish hospital employees indicate that the risk of calling in sick is affected by the types of shifts, independently of sex, age, and time-invariant confounding. Extensive testing identified important methodological choices eg, length and number of included periods to consider when choosing the case-crossover design.

The Relationship Between Potential Occupational Sensitizing Exposures and Asthma: An Overview of Systematic Reviews

OBJECTIVES

The aim was to identify, appraise, and synthesize the scientific evidence of the relationship between potential occupational sensitizing exposures and the development of asthma based on systematic reviews.

METHODS

The study was conducted as an overview of systematic reviews. A systematic literature search was conducted for systematic reviews published up to 9 February 2020. Eligibility study criteria included persons in or above the working age, potential occupational sensitizing exposures, and outcomes defined as asthma. Potential occupational sensitizing exposures were divided into 23 main groups comprising both subgroups and specific exposures. Two reviewers independently selected studies, extracted study data, assessed study quality, and evaluated confidence in study results and level of evidence of the relationship between potential occupational sensitizing exposures and asthma.

RESULTS

Twenty-seven systematic reviews were included covering 1242 studies and 486 potential occupational sensitizing exposures. Overall confidence in study results was rated high in three systematic reviews, moderate in seven reviews, and low in 17 reviews. Strong evidence for the main group of wood dusts and moderate evidence for main groups of mites and fish was found. For subgroups/specific exposures, strong evidence was found for toluene diisocyanates, Aspergillus, Cladosporium, Penicillium, and work tasks involving exposure to laboratory animals, whereas moderate evidence was found for 52 subgroups/specific exposures.

CONCLUSIONS

This overview identified hundreds of potential occupational sensitizing exposures suspected to cause asthma and evaluated the level of evidence for each exposure. Strong evidence was found for wood dust in general and for toluene diisocyanates, Aspergillus, Cladosporium, Penicillium, and work tasks involving exposure to laboratory animals.

Prenatal nitrate exposure from diet and drinking water and timing of puberty in sons and daughters: A nationwide cohort study

BACKGROUND

In Western countries, age at pubertal development has declined during the last century in girls, and probably also in boys. No studies have investigated whether nitrate, a widespread environmental exposure with teratogenic and hormone disrupting properties, might affect timing of puberty.

OBJECTIVES

We investigated if prenatal exposure to nitrate from drinking water and diet was associated with timing of puberty.

METHODS

This cohort study included 15,819 children born from 2000 to 2003 within the Danish National Birth Cohort. Self-reported information on current status of various pubertal milestones was provided every six months by a questionnaire from 11 years of age until 18 years or full maturity, whichever came first. Maternal nitrate intake from diet (mg/day) was derived from a mid-pregnancy food frequency questionnaire and individual level nitrate exposure from drinking water (mg/L) was derived using measurements from Danish public waterworks. Adjusted average differences in months in age at attaining several pubertal milestones as well as the average age difference in age at attaining all the milestones were estimated separately for diet and water using a regression model for interval-censored data. C- and E-vitamin, red meat and processed meat intake were explored as potential effect modifiers in sub-analyses.

RESULTS

No strong associations were observed between prenatal exposure to nitrate and timing of puberty in children. However, sons born of mothers with a nitrate concentration in drinking water at their residential address of > 25 mg/L (half of the World Health Organisation (WHO) guideline value) compared with ≤ 1 mg/L showed a tendency towards earlier age at pubertal development with an average age difference of -1.2 months (95 % confidence interval,-3.0;0.6) for all the pubertal milestones combined.

DISCUSSION

Studies including more highly exposed children are needed before the current WHO drinking water guideline value for nitrate can be considered safe concerning pubertal development.

Nitrate in Maternal Drinking Water during Pregnancy and Measures of Male Fecundity in Adult Sons

Animal studies indicate deleterious effects of nitrate exposure on fecundity, but effects in humans are unknown, both for the prenatal and postnatal periods. We aimed to investigate if exposure to nitrate in maternal drinking water during the sensitive period of fetal life is associated with measures of fecundity in the adult sons. In a sub-analysis, the potential effects of nitrate exposure in adulthood were investigated. This cohort included 985 young adult men enrolled in The Fetal Programming of Semen Quality Cohort (FEPOS). Semen characteristics, testes volume and reproductive hormones were analyzed in relation to nitrate concentration in maternal drinking water, using a negative binomial regression model. The nitrate concentration in drinking water was obtained from monitoring data from Danish waterworks that were linked with the mothers' residential address during pregnancy. The median nitrate concentration in maternal drinking water was 2 mg/L. At these low exposure levels, which are far below the World Health Organization's (WHO) guideline value of 50 mg/L, we did not find indications of harmful effects of nitrate on the investigated measures of male fecundity.

Healthcare workers' SARS-CoV-2 infection rates during the second wave of the pandemic: follow-up study

OBJECTIVES

This study aimed to assess if, during the second wave of the COVID-19 pandemic, healthcare workers had increased severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rates, following close contact with patients, co-workers and persons outside work with COVID-19.

METHODS

A follow-up study of 5985 healthcare workers from Denmark was conducted between November 2020 and April 2021 and provided day-to-day information on COVID-19 contacts. SARS-CoV-2 infection was defined by the first positive polymerase chain reaction (PCR) test ever. Data was analyzed in multivariable Poisson regression models.

RESULTS

The SARS-CoV-2 infection rates following close contact 3-7 days earlier with patients, co-workers and persons outside work with COVID-19 were 153.7, 240.8, and 728.1 per 100 000 person-days, respectively. This corresponded with age, sex, month, number of PCR tests and mutually adjusted incidence rate ratios of 3.17 [40 cases, 95% confidence interval (CI) 2.15-4.66], 2.54 (10 cases, 95% CI 1.30-4.96) and 17.79 (35 cases, 95% CI 12.05-26.28). The risk of SARS-CoV-2 infection was thus lower, but the absolute numbers affected was higher following COVID-19 contact at work than COVID-19 contact off work.

CONCLUSIONS

Despite strong focus on preventive measures during the second wave of the pandemic, healthcare workers were still at increased risk of SARS-CoV-2 infection when in close contact with patients or co-workers with COVID-19. There is a need for increased focus on infection control measures in order to secure healthcare workers' health and reduce transmission into the community during ongoing and future waves of SARS-CoV-2 and other infections.

Use of Personal Protective Equipment Among Healthcare Workers During the First and the Second Wave of the COVID-19 Pandemic

INTRODUCTION

To treat and properly care for COVID-19 patients it is vital to have healthy healthcare workers to ensure the continued function of the healthcare system and to prevent transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to patients, co-workers, and the community. Personal protective equipment (PPE) can prevent healthcare workers from being infected with and transmitting SARS-CoV-2. Experience and training are pivotal to ensure optimal protection. This study aims to examine the use and failure of PPE and compliance with PPE guidelines during the first and the second wave of the COVID-19 pandemic among Danish healthcare workers.

METHODS

Healthcare workers from the Central Denmark Region and the Capital Region of Denmark were invited to participate April-June 2020 during the first wave and November 2020-April 2021 during the second wave. Day-by-day, participants reported work procedures, use and failure of PPE, and compliance with PPE guidelines. Register-based information on sex, age, department, and profession was available for all participants.

RESULTS

In total, 21 684 and 10 097 healthcare workers participated during the first and the second wave, respectively. During the first wave, 1.7% used filtering face piece-2 or -3 (FFP2 or FFP3) respirators and 8.2% used face masks [fluid resistant (type IIR) masks, masks with visor (typically type IIR), and other unspecified face masks] during physical contact with patients. During the second wave, the corresponding figures increased to 17.8% and 80.7%. During respiratory procedures, the use of FFP2 or FFP3 respirators increased from 5.6 to 24.3%, and the use of face masks from 14.7 to 77.8%. The no PPE use decreased from 21.3% during the first wave to 0.4% in the second wave, during respiratory procedures. Total PPE failures decreased from 0.7 to 0.4% from the first to second wave. The proportion not complying with PPE guidelines declined from 3.6 to 2.2% during physical contact with patients and from 6.5 to 4.6% during respiratory procedures. PPE failure and non-compliance varied by age, sex and type of department. Frequent reasons for non-compliance were forgetfulness and lack of time, and during the first but not during the second wave, limited availability of PPE.

CONCLUSION

We found a substantial increase in the use of PPE and a substantial decrease in PPE failures from the first to the second wave of COVID-19 in Denmark. However, there is still a need for continuous focus on compliance in use of PPE among healthcare workers.

A longitudinal study of morning, evening, and night light intensities and nocturnal sleep quality in a working population

We aimed to investigate whether higher light intensity in the morning is associated with better nocturnal sleep quality and whether higher light intensities in the evening or night have the opposite effect. Light intensity was recorded for 7 consecutive days across the year among 317 indoor and outdoor daytime workers in Denmark (55-56° N) equipped with a personal light recorder. Participants reported sleep quality after each nocturnal sleep. Sleep quality was measured using three parameters; disturbed sleep index, awakening index, and sleep onset latency. Associations between increasing light intensities and sleep quality were analyzed using mixed effects models with participant identity as a random effect. Overall, neither white nor blue light intensities during morning, evening, or night were associated with sleep quality, awakening, or sleep onset latency of the subsequent nocturnal sleep. However, secondary analyses suggested that artificial light during the morning and day contrary to solar light may increase vulnerability to evening light exposure. Altogether, we were not able to confirm that higher morning light intensity significantly improves self-reported sleep quality or that higher evening or night light intensities impair self-reported sleep quality at exposure levels encountered during daily life in a working population in Denmark. This suggests that light intensities alone are not important for sleep quality to a degree that it is distinguishable from other important parameters in daily life settings.

Severe Acute Respiratory Syndrome Coronavirus 2 Seroprevalence Survey Among 17 971 Healthcare and Administrative Personnel at Hospitals, Prehospital Services, and Specialist Practitioners in the Central Denmark Region

BACKGROUND

The objective of this study was to perform a seroprevalence survey on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among Danish healthcare workers to identify high-risk groups.

METHODS

All healthcare workers and administrative personnel at the 7 hospitals, prehospital services, and specialist practitioner clinics in the Central Denmark Region were invited to be tested by a commercial SARS-CoV-2 total antibody enzyme-linked immunosorbent assay (Wantai Biological Pharmacy Enterprise Co, Ltd, Beijing, China).

RESULTS

A total of 25 950 participants were invited. Of these, 17 971 had samples available for SARS-CoV-2 antibody testing. After adjustment for assay sensitivity and specificity, the overall seroprevalence was 3.4% (95% confidence interval [CI], 2.5%-3.8%). The seroprevalence was higher in the western part of the region than in the eastern part (11.9% vs 1.2%; difference: 10.7 percentage points [95% CI, 9.5-12.2]). In the high-prevalence area, the emergency departments had the highest seroprevalence (29.7%), whereas departments without patients or with limited patient contact had the lowest seroprevalence (2.2%). Among the total 668 seropositive participants, 433 (64.8%) had previously been tested for SARS-CoV-2 RNA, and 50.0% had a positive reverse-transcription polymerase chain reaction (PCR) result.

CONCLUSIONS

We found large differences in the prevalence of SARS-CoV-2 antibodies in staff working in the healthcare sector within a small geographical area of Denmark. Half of all seropositive staff had been tested positive by PCR prior to this survey. This study raises awareness of precautions that should be taken to avoid in-hospital transmission. Regular testing of healthcare workers for SARS-CoV-2 should be considered to identify areas with increased transmission.

1510Development and validation of a Job Exposure Matrix for work related risk factors for COVID-19

Background

Studies have shown a higher mortality due to COVID-19 amongst certain professions. The risk of becoming infected with SARS-CoV-2 and the occupational conditions associated with this, have not been studied extensively. This study aimed to develop and validate a Job Exposure Matrix (JEM) to assess the risk of COVID-19 in the workplace.

Methods

Researchers from three European countries defined six dimensions (four transmission determinants, two mitigation measures) to classify occupational risk. A combination of national statistics and expert judgement was used to classify ISCO-08 codes in no, low, elevated, or high risk for each dimension. Two data driven aspects of precarious work were also included and classified in four categories. The JEM was translated to SOC2010-codes and validated by comparing it to UK infection survey data and ONS estimates of exposure based on ONET data.

Results

A slightly increasing proportion of COVID-19 cases was observed with increasing risk scores in each dimension of the JEM. There was a high correlation between the JEM and the ONS estimates for physical proximity (r = 0.71) and exposure to COVID-19 or SARS-CoV-2 infection (r = 0.80)

Conclusions

Successful development and initial validation of this JEM has resulted in a useful tool for risk assessment of COVID-19 in the workplace. Further validation exercises will continue.

Key messages

This publicly available JEM can play a key role in the essential assessment of occupational contribution to the total burden of the COVID-19 pandemic.

Serum levels of IgG antibodies against Aspergillus fumigatus and the risk of hypersensitivity pneumonitis and other interstitial lung diseases

Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) caused by the inhalation of antigens. Antigen-specific IgG antibodies (sIgG) are used as biomarkers of exposure when diagnosing HP, but little is known about the longitudinal relation between antibody levels and risk of HP or other ILD. In a follow-up design, we explored the relationship between sIgG antibodies against Aspergillus fumigatus and the diagnosis of HP in 647 subjects suspected of HP. We showed that IgG levels above the reference value resulted in a hazard ratio of 9.5 for subsequent HP. Our findings support a relationship between high levels of sIgG against A. fumigatus and risk of HP.

Symptoms reported by SARS-CoV-2 seropositive and seronegative healthcare and administrative employees in Denmark from May to August 2020

Background

The distribution and nature of symptoms among SARS-CoV-2 infected individuals need to be clarified.

Methods

Between May and August 2020, 11 138 healthcare and administrative personnel from Central Denmark Region were tested for SARS-CoV-2 antibodies and subsequently completed a questionnaire. Symptom prevalence and overall duration for symptoms persisting for more than 30 days were calculated. Logistic regression models were used to estimate adjusted odds ratios (ORs) with 95% CIs.

Results

In total, 447 (4%) of the participants were SARS-CoV-2-seropositive. Loss of sense of smell and taste was reported by 50% of seropositives compared with 3% of seronegatives. Additionally, seropositives more frequently reported fever, dyspnoea, muscle or joint ache, fatigue, cough, headache and sore throat, and they were more likely to report symptoms persisting for more than 30 days. In adjusted models, they had a higher risk of reporting symptoms, with the strongest association observed for loss of sense of taste and smell (OR = 35.6; 95% CI: 28.6–44.3).

Conclusion

In this large study, SARS-CoV-2-seropositive participants reported COVID-19-associated symptoms more frequently than those who were seronegative, especially loss of sense of taste and smell. Overall, their symptoms were also more likely to persist for more than 30 days.

Maternal life and work stressors during pregnancy and asthma in offspring

Background

Maternal stressors during pregnancy are potential risk factors for asthma in offspring. However, previous studies have been limited by the use of self-reported data focusing on stressors either in private life or at work. This study examined the association between maternal stressors both in private life and at work during pregnancy and asthma in offspring.

Methods

In the Danish National Birth Cohort, 75 156 live-born singletons born during 1996–2002 were identified. Maternal information on job title were available around weeks 12–16 of gestation. Data on maternal bereavement, life-threatening illness, suicide attempt and alcohol or drug abuse of a close relative and offspring childhood asthma (3–10 years of age) were obtained from Danish nationwide registers. Maternal psychosocial work stressors (job control, psychological job demands, emotional job demands, work-related violence and threats of work-related violence) were estimated by the use of job-exposure matrices. The association between maternal stress and childhood asthma was analysed in Cox models adjusted for maternal age, comorbidity and parity.

Results

Neither private-life nor work stressors were related to onset of asthma in offspring. Separate analyses by parental atopy or onset of asthma in offspring supported the main findings.

Conclusions

This study does not support an elevated risk of childhood asthma related to exposure to stress during pregnancy.

Day-by-day symptoms following positive and negative PCR tests for SARS-CoV-2 in non-hospitalized healthcare workers: A 90-day follow-up study

OBJECTIVE

Our study aimed to compare symptoms day by day for non-hospitalized individuals testing positive and negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

METHODS

In total, 210 positive-test and 630 negative-test healthcare workers in the Central Denmark Region were followed for up to 90 days after testing, between April and June, 2020. Their daily reported COVID-19-related symptoms were compared graphically and by logistic regression.

RESULTS

Thirty per cent of the positive-test and close to 0% of the negative-test participants reported a reduced sense of taste and smell during all 90 days (adjusted odds ratio [aOR] 86.07, 95% CI 22.86-323). Dyspnea was reported by an initial 20% of positive-test participants, declining to 5% after 30 days, without ever reaching the level of the negative-test participants (aOR 6.88, 95% CI 2.41-19.63). Cough, headache, sore throat, muscle pain, and fever were temporarily more prevalent among the positive-test participants; after 30 days, no increases were seen. Women and older participants were more susceptible to long-lasting COVID-19 symptoms.

CONCLUSION

The prevalence of long-lasting reduced sense of taste and smell is highly increased in mild COVID-19 patients. This pattern is also seen for dyspnea at a low level, but not for cough, sore throat, headache, muscle pain, or fever.

Adverse childhood experiences and asthma: trajectories in a national cohort

Objective

Research has linked early adverse childhood experiences (ACEs) with asthma development; however, existing studies have generally relied on parent report of exposure and outcome. We aimed to examine the association of early life ACEs with empirically determined trajectories of childhood asthma risk, using independent register information on both exposures and outcome.

Methods

Based on nationwide registries, we established a study cohort of 466 556 children born in Denmark (1997–2004). We obtained information on ACEs during the first 2 years of life (bereavement, parental chronic somatic and/or mental illness) and childhood asthma diagnosis or medication use from birth through age 10 years from the Danish National Patient and Prescription Registries, respectively. We identified asthma phenotypes using group-based trajectory modelling. We then used multinomial logistic regression to examine the association between early ACEs and asthma phenotypes.

Results

We identified four asthma phenotypes: non-asthmatic, early-onset transient, early-onset persistent and late-onset asthma. Girls with early-onset transient asthma (OR 1.13, 95% CI 1.04 to 1.24), early-onset persistent asthma (1.27, 95% CI 1.08 to 1.48) or late-onset asthma (OR 1.28, 95% CI 1.11 to 1.48) vs no asthma were more likely to have early life ACE exposure compared with girls without ACE exposure. Results were similar for boys who also had experienced early life ACEs with ORs of 1.16 (95% CI 1.08 to 1.25), 1.34 (95% CI 1.20 to 1.51) and 1.11 (95% CI 0.98 to 1.25), respectively.

Conclusion

In a nationwide-population study, we identified three childhood onset asthma phenotypes and found that ACEs early in life were associated with increased odds for each of these asthma phenotypes among both girls and boys.

Are depressive disorders caused by psychosocial stressors at work? A systematic review with metaanalysis

In the last decade, many studies have examined associations between poor psychosocial work environment and depression. We aimed to assess the evidence for a causal association between psychosocial factors at work and depressive disorders. We conducted a systematic literature search from 1980 to March 2019. For all exposures other than night and shift work and long working hours, we limited our selection of studies to those with a longitudinal design. We extracted available risk estimates for each of 19 psychosocial exposures, from which we calculated summary risk estimates with 95% confidence intervals (PROSPERO, identifier CRD42019130266). 54 studies were included, addressing 19 exposures and 11 different measures of depression. Only data on depressive episodes were sufficient for evaluation. Heterogeneity of exposure definitions and ascertainment, outcome measures, risk parameterization and effect contrasts limited the validity of meta-analyses. Summary risk estimates were above unity for all but one exposure, and below 1.60 for all but another. Outcome measures were liable to high rates of false positives, control of relevant confounding was mostly inadequate, and common method bias was likely in a large proportion of studies. The combination of resulting biases is likely to have inflated observed effect estimates. When statistical uncertainties and the potential for bias and confounding are taken into account, it is not possible to conclude with confidence that any of the psychosocial exposures at work included in this review is either likely or unlikely to cause depressive episodes or recurrent depressive disorders.

Associations of Occupational Styrene Exposure With Risk of Encephalopathy and Unspecified Dementia: A Long-Term Follow-up Study of Workers in the Reinforced Plastics Industry

Exposure to industrial solvents has been associated with encephalopathy. Styrene is a neurotoxic industrial solvent, and we investigated the long-term risk of encephalopathy and unspecified dementia following styrene exposure. We followed 72,465 workers in the reinforced plastics industry in Denmark (1977–2011) and identified incident cases of encephalopathy (n = 228) and unspecified dementia (n = 565) in national registers. Individual styrene exposure levels were modeled from information on occupation, measurements of work place styrene levels, product, process, and years of employment. Adjusted analyses were performed using a discrete survival function. A positive trend for encephalopathy (P < 0.01) and a negative trend for unspecified dementia (P = 0.03) were seen with cumulative styrene exposure accrued during the recent period of up to 15 years. For unspecified dementia and the combination of unspecified dementia and encephalopathy, a positive trend was indicated when applying a 30-year exposure lag (P = 0.13 and P = 0.07). The risk patterns seen following recent exposure probably reflect diagnostic criteria for encephalopathy requiring recent industrial solvent exposure and referral bias rather than association with styrene exposure, while the increasing risk observed for unspecified dementia and the combination of encephalopathy and unspecified dementia following distant exposure indicates an increased risk of dementia following styrene exposure with a long latency period.

Light Exposure during Days with Night, Outdoor, and Indoor Work

OBJECTIVE

To assess light exposure during days with indoor, outdoor, and night work and days off work.

METHODS

Light intensity was continuously recorded for 7 days across the year among indoor (n = 170), outdoor (n = 151), and night workers (n = 188) in Denmark (55-56°N) equipped with a personal light recorder. White light intensity, duration above 80, 1000, and 2500 lux, and proportion of red, green, and blue light was depicted by time of the day and season for work days and days off work.

RESULTS

Indoor workers' average light exposure only intermittently exceeded 1000 lux during daytime working hours in summer and never in winter. During daytime working hours, most outdoor workers exceeded 2500 lux in summer and 1000 lux in winter. Night workers spent on average 10-50 min >80 lux when working night shifts. During days off work, indoor and night workers were exposed to higher light intensities than during work days and few differences were seen between indoor, outdoor, and night workers. The spectral composition of light was similar for indoor, outdoor, and night workers during days at and off work.

CONCLUSION

The night workers of this study were during night hours on average exposed for a limited time to light intensities expected to suppress melatonin. The indoor workers were exposed to light levels during daylight hours that may reduce general well-being and mood, especially in winter. Outdoor workers were during summer daylight hours exposed to light levels comparable to those used for the treatment of depression.

A Quantitative General Population Job Exposure Matrix for Occupational Noise Exposure

Occupational noise exposure is a known risk factor for hearing loss and also adverse cardiovascular effects have been suggested. A job exposure matrix (JEM) would enable studies of noise and health on a large scale. The objective of this study was to create a quantitative JEM for occupational noise exposure assessment of the general working population. Between 2001–2003 and 2009–2010, we recruited workers from companies within the 10 industries with the highest reporting of noise-induced hearing loss according to the Danish Working Environment Authority and in addition workers of financial services and children day care to optimize the range in exposure levels. We obtained 1343 personal occupational noise dosimeter measurements among 1140 workers representing 100 different jobs according to the Danish version of the International Standard Classification of Occupations 1988 (DISCO 88). Four experts used 35 of these jobs as benchmarks and rated noise levels for the remaining 337 jobs within DISCO 88. To estimate noise levels for all 372 jobs, we included expert ratings together with sex, age, occupational class, and calendar year as fixed effects, while job and worker were included as random effects in a linear mixed regression model. The fixed effects explained 40% of the total variance: 72% of the between-jobs variance, −6% of the between-workers variance and 4% of the within-worker variance. Modelled noise levels showed a monotonic increase with increasing expert score and a 20 dB difference between the highest and lowest exposed jobs. Based on the JEM estimates, metal wheel-grinders were among the highest and finance and sales professionals among the lowest exposed. This JEM of occupational noise exposure can be used to prioritize preventive efforts of occupational noise exposure and to provide quantitative estimates of contemporary exposure levels in epidemiological studies of health effects potentially associated with noise exposure.

Exposure to neuroactive non-organochlorine insecticides, and diabetes mellitus and related metabolic disturbances: Protocol for a systematic review and meta-analysis

OBJECTIVES

To assess whether exposure to specific classes of neuroactive non-organochlorine insecticides is associated with diabetes mellitus or related metabolic traits.

METHODS

Eligibility criteria: Any type of epidemiological and human exposure studies providing an exposure contrast to neuroactive non-organochlorine insecticides and a measure of association to diabetes mellitus or related metabolic traits. We will include published peer-reviewed studies in both English and non-English language.

INFORMATION SOURCES

Articles will be located in the NCBI PubMed, Embase, Scopus, Web of Science and LILACS databases, supplemented with manual searching of reference lists and articles citing the included studies. Risk of bias assessment: Risk of bias in individual studies will be assessed using tools from the Navigation Guide systematic review methodology, while the risk of bias at the outcome level will be assessed according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) guidelines. Data synthesis and analysis: When studies are sufficiently similar in population, exposure, comparator and effect estimate to meaningfully allow quantitative synthesis, we will perform meta-analysis. Otherwise, results will be summarized qualitatively.

FUNDING

The authors are paid employees of their respective institutions. MRHH is a Ph.D. student working under grants from Aarhus University and the National Research Centre for the Working Environment.

REGISTRATION

PROSPERO CRD42017068861.

A Quantitative General Population Job Exposure Matrix for Occupational Daytime Light Exposure

High daytime light levels may reduce the risk of affective disorders. Outdoor workers are during daytime exposed to much higher light intensities than indoor workers. A way to study daytime light exposure and disease on a large scale is by use of a general population job exposure matrix (JEM) combined with national employment and health data. The objective of this study was to develop a JEM applicable for epidemiological studies of exposure response between daytime light exposure, affective disorders, and other health effects by combining expert scores and light measurements. We measured light intensity during daytime work hours 06:00–17:59 for 1–7 days with Philips Actiwatch Spectrum® light recorders (Actiwatch) among 695 workers representing 71 different jobs. Jobs were coded into DISCO-88, the Danish version of the International Standard Classification of Occupations 1988. Daytime light measurements were collected all year round in Denmark (55–56°N). Arithmetic mean white light intensity (lux) was calculated for each hour of observation (n = 15,272), natural log-transformed, and used as the dependent variable in mixed effects linear regression models. Three experts rated probability and duration of outdoor work for all 372 jobs within DISCO-88. Their ratings were used to construct an expert score that was included together with month of the year and hour of the day as fixed effects in the model. Job, industry nested within job, and worker were included as random effects. The model estimated daytime light intensity levels specific for hour of the day and month of the year for all jobs with a DISCO-88 code in Denmark. The fixed effects explained 37% of the total variance: 83% of the between-jobs variance, 57% of the between industries nested in jobs variance, 43% of the between-workers variance, and 15% of the within-worker variance. Modeled daytime light intensity showed a monotonic increase with increasing expert score and a 30-fold ratio between the highest and lowest exposed jobs. Building construction laborers were based on the JEM estimates among the highest and medical equipment operators among the lowest exposed. This is the first quantitative JEM of daytime light exposure and will be used in epidemiological studies of affective disorders and other health effects potentially associated with light exposure.

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.

Risk of childhood asthma following prenatal exposure to negative life events and job stressors: A nationwide register-based study in Denmark

Objectives This study aimed to examine the association between negative life events, job stressors (low job control or high psychosocial job demands) and offspring asthma phenotypes (early-onset transient, early-onset persistent and late-onset asthma). Methods In a population-based cohort study comprising 547 533 liveborn singletons, we determined negative life events and offspring asthma at age six years using data from Danish nationwide registers. We assessed job demands and job control from gender-specific job exposure matrices. Prevalence ratios (PR) of each asthma phenotype were estimated using log-binomial regression. Results Maternal exposure to negative life events prenatally was not significantly associated with offspring asthma. Among mothers with low job demands, low job control was associated with increased risk for early-onset transient asthma [PR=1.14, 95% confidence interval (CI) 1.09-1.19], early-onset persistent asthma (PR=1.17, 95% CI 1.11-1.23), and late-onset asthma (PR=1.06, 95% CI 1.00-1.14). Among mothers with high job demands, low job control was not associated with offspring asthma apart from a reduced risk of early-onset persistent asthma (PR=0.94, 95% CI 0.90-0.97). These associations were independent of child sex and parental atopic history. Conclusions Maternal stressors in private life do not seem to influence offspring asthma significantly. Low job control is associated with offspring asthma, which is modified by maternal psychosocial job demands. Our findings warrant further exploration.

Sinonasal adenocarcinoma following styrene exposure in the reinforced plastics industry

Background

Sinonasal adenocarcinoma is a rare disease expected to have rare causes and potential for strong risk factors as reflected by the strong association with occupational wood dust exposure. High level styrene exposure is a rare and suspected carcinogen, and this study examines the exposure–response relation between occupational styrene exposure, sinonasal adenocarcinoma and other subtypes.

Methods

We followed 73 092 styrene-exposed workers from 1968 to 2011 and identified sinonasal cancers in the Danish Cancer Registry. We modelled cumulative styrene exposure and estimated incidence rates and age, sex and wood-industry adjusted ORs.

Results

During 1 585 772 person-years, we observed nine cases of adenocarcinoma, corresponding to a fivefold non-significantly increased OR for estimates of high versus low cumulative styrene exposure (OR 5.11, 95% CI 0.58 to 45.12). The increased risk was confined to exposure received during the recent 15 years. The other histological subtypes showed no increased risk.

Conclusion

This study suggests increased risk of sinonasal adenocarcinoma following styrene exposure. The observations are, however, few, confounding from wood dust exposure cannot be ruled out, and additional studies are needed before firm conclusions can be drawn.

Prolonged perceived stress and saliva cortisol in a large cohort of Danish public service employees: cross-sectional and longitudinal associations

Purpose

It is well known that acute stress can lead to a transient increase in cortisol secretion, but the effects of prolonged stress on cortisol secretion are uncertain. This study examines the cross-sectional and longitudinal associations between prolonged perceived stress and salivary cortisol.

Methods

In 2007, 4467 Danish public service employees participated in a study of stress and mental health, and 3217 participated in a follow-up in 2009. Perceived stress during the past 4 weeks was assessed by Cohen’s four item perceived stress scale. Participants were asked to collect saliva 30 min after awakening and at approximately 20:00 in the evening. The cortisol dependence on perceived stress was examined in regression analyses adjusted for effects of potential confounders. We adjusted for a large variation in saliva sampling times by modelling the time trajectory of cortisol concentrations in the morning and in the evening and examined if they were influenced by perceived stress.

Results

Perceived stress had no statistically significant effects on the level or time trajectory of morning or evening cortisol, neither cross-sectionally nor longitudinally. The 1 month prevalence of frequently perceived stress was low, approximately 2.5%.

Conclusion

Our results did not support the hypothesis that prolonged perceived stress is associated with the level or time trajectory of morning or evening salivary cortisol.

Electronic supplementary material

The online version of this article (doi:10.1007/s00420-017-1241-z) contains supplementary material, which is available to authorized users.

Risk of hypersensitivity pneumonitis and interstitial lung diseases among pigeon breeders

We studied the risk of hypersensitivity pneumonitis and other interstitial lung diseases (ILDs) among pigeon breeders.This is a retrospective follow-up study from 1980 to 2013 of 6920 pigeon breeders identified in the records of the Danish Racing Pigeon Association. They were compared with 276 800 individually matched referents randomly drawn from the Danish population. Hospital based diagnoses of hypersensitivity pneumonitis and other ILDs were identified in the National Patient Registry 1977-2013. Stratified Cox regression analyses estimated the hazard ratios (HR) of hypersensitivity pneumonitis and other ILDs adjusted for occupation, residence and redeemed prescription of medication with ILDs as a possible side-effect. Subjects were censored at death, emigration or a diagnosis of connective tissue disease.The overall incidence rate of ILD was 77.4 per 100 000 person-years among the pigeon breeders and 50.0 among the referents. This difference corresponded to an adjusted HR of 1.56 (95% CI 1.26-1.94). The adjusted HRs of hypersensitivity pneumonitis and other ILDs for pigeon breeders were 14.36 (95% CI 8.10-25.44) and 1.33 (95% CI 1.05-1.69), respectively.This study shows an increased risk of ILD among pigeon breeders compared with the referent population. Protective measures are recommended even though ILD leading to hospital contact remains rare among pigeon breeders.

Are changes in workplace bullying status related to changes in salivary cortisol? A longitudinal study among Danish employees

OBJECTIVES

This study aims to investigate whether incident workplace bullying and its dicontinuance is related to subsequent change in morning and evening saliva cortisol concentrations.

METHODS

Participants came from two Danish cohort studies, the PRISME cohort (n=4489) and the Workplace Bullying and Harassment Cohort (n=3707). At baseline and follow-up exposure to bullying was measured by a single question on bullying (preceded by a definition). Two saliva samples to measure cortisol were collected during a work-day (30 min after awakening and at 8 p.m.). All participants responding to the item on workplace bullying, giving saliva samples and participated at both baseline and follow-up were included. The reference group consisted of non-bullied respondents at both baseline and follow-up. Multilevel mixed-effects linear regressions were used to test for changes in salivary cortisol after newly onset of and discontinuance of workplace bullying. All analyses were adjusted for the potentially confounding effect of differences from baseline to follow-up in education, smoking, alcohol consumption, body mass index, cohort, sampling waves, time of awakening, and time of sampling.

RESULTS

We found no indication of statistically significant difference in saliva cortisol, neither when participants changed their self-labelling from not bullied at baseline to being bullied at follow-up, nor when they at follow-up two years later reported discontinuance of bullying.

CONCLUSION

This longitudinal study on the impact of changes in bullying status on change in cortisol levels showed consistent lack of associations with onset and discontinuance of workplace bullying.

Atherogenic risk factors and hearing thresholds

The objective of this study was to evaluate the influence of atherogenic risk factors on hearing thresholds. In a cross-sectional study we analyzed data from a Danish survey in 2009-2010 on physical and psychological working conditions. The study included 576 white- and blue-collar workers from children's day care units, financial services and 10 manufacturing trades. Associations between atherogenic risk factors (blood lipids, glycosylated hemoglobin, smoking habits, body mass index (BMI), and ambulatory blood pressure) and hearing thresholds were analyzed using multiple linear regression models. Adjusted results suggested associations between smoking, high BMI and triglyceride level and low high-density lipoprotein level and increased low-frequency hearing thresholds (average of pure-tone hearing thresholds at 0.25, 0.5 and 1 kHz). Furthermore, an increasing load of atherogenic risk factors seemed associated with increased low-frequency hearing thresholds, but only at a borderline level of statistical significance. Associations were generally strongest with hearing levels of the worst hearing ear. We found no statistically significant associations between atherogenic risk factors and high-frequency hearing thresholds (average of pure-tone hearing thresholds at 4, 6 and 8 kHz).

[Occupational asthma caused by maleic anhydride]

Organic acid anhydrides (OAA) are widely used in the chemical industry. They are irritants and can cause sensitization and asthma. We describe the first documented case of occupational asthma caused by the OAA maleic anhydride (MA) in the production of insecticides. A 60-year-old man developed work-related respiratory symptoms after eight years of intermittent exposure to MA. Peak expiratory flow measurements showed greater variance on work days than on days off. Both a basophilic activation test and determination of the MA-specific IgE level in serum showed sensitization to MA.

Salivary cortisol and depression in public sector employees: cross-sectional and short term follow-up findings

INTRODUCTION

Increased cortisol levels have been suggested to play a role in the development of depression. An association has been shown in some studies but not consistently. The timing of an association is uncertain, and long-term follow-up studies may miss associations in narrower time windows. In the present study, we examined the association of several cortisol measures and depression in a repeated cross-sectional and short-term follow-up design. Depression was assessed by both self-reported symptoms of depression and clinical interviews.

METHOD

In 2007, 10,036 public sector employees received a questionnaire along with salivary cortisol test tubes for home administration. Morning (30min after awakening) and evening (2000h) salivary samples were collected. Questionnaires and valid saliva samples were returned from 3536 employees. Approximately 3.6 months later a subsample of the participants collected three morning saliva samples (at awakening, 20min and 40min after awakening) plus an evening sample (2000h); participants with high baseline scores of self-reported depressive symptoms, burnout and perceived stress were invited to a standardized interview (SCAN) to detect clinical depression; and the symptom questionnaire was repeated for subsample participants. The study was repeated in 2009 with questionnaires and salivary test tubes (n=2408). In four cross-sectional and two short-term follow-up analyses odds ratios of depressive symptoms and of clinical depression were estimated by logistic regression for morning, evening, mean and the difference between morning and evening cortisol (slope). For the subsample, awakening response (CAR) and area under the curve (AUC) cortisol measures were calculated. We adjusted for sex, age, income, education, family history of depression, physical activity and alcohol consumption.

RESULTS

None except one of the measures of salivary cortisol were associated with self-reported depressive symptoms or clinical depression, neither in the four cross-sectional analyses nor in the two short term follow-up analyses. E.g. in 2007, the adjusted odds ratios (OR) of depressive symptoms by a one unit increase in morning and evening cortisol (ln(nmol/litre saliva)) were 1.01 (95% CI: 0.88-1.17) and 1.05 (0.93-1.18), respectively. The one exception was significant at p=0.04 and was considered as due to chance.

CONCLUSION

In this large study, salivary cortisol was not associated with self-reported symptoms of depression or with clinical depression.

Recent and long-term occupational noise exposure and salivary cortisol level

Environmental and occupational noise exposure have been related to increased risk of cardiovascular disease, hypothetically mediated by stress-activation of the hypothalamic-pituitary-adrenal (HPA) axis. The objective of this study was to investigate the relation between recent and long-term occupational noise exposure and cortisol level measured off work to assess a possible sustained HPA-axis effect. We included 501 industrial, finance, and service workers who were followed for 24h during work, leisure, and sleep. Ambient occupational noise exposure levels were recorded every 5s by personal dosimeters and we calculated the full-shift LAEq value and estimated duration and cumulative exposure based on their work histories since 1980. For 332 workers who kept a log-book on the use of hearing protection devices (HPD), we subtracted 10 dB from every noise recording obtained during HPD use and estimated the noise level at the ear. Salivary cortisol concentration was measured at 20.00 h, the following day at awakening, and 30 min after awakening on average 5, 14 and 14.5h after finishing work. The mean ambient noise exposure level was 79.9 dB(A) [range: 55.0-98.9] and the mean estimated level at the ear 77.7 dB(A) [range: 55.0-94.2]. In linear and mixed regression models that adjusted for age, sex, current smoking, heavy alcohol consumption, personal income, BMI, leisure-time noise exposure level, time since occupational noise exposure ceased, awakening time, and time of saliva sampling, we observed no statistically significant exposure response relation between recent, or long-term ambient occupational noise exposure level and any cortisol parameter off work. This was neither the case for recent noise level at the ear. To conclude, neither recent nor long-term occupational noise exposure levels were associated with increased cortisol level off work. Thus, our results do not indicate that a sustained activation of the HPA axis, as measured by cortisol, is involved in the causal pathway between occupational noise exposure and cardiovascular disease.

A two-year follow-up study of salivary cortisol concentration and the risk of depression

Stress is a suspected cause of depression. High cortisol concentration, a biomarker of an activated stress response, has been found in depressed patients. The aim of this study was to determine if a high level of salivary cortisol is a risk factor of depression. In 2007, we enrolled 4467 public employees. Morning and evening salivary cortisol concentration were measured for each participant. Participants reporting high levels of depressive, burnout, or stress symptoms, assessed by questionnaires were assigned to a psychiatric interview. In this interview 98 participants were diagnosed with depression and subsequently excluded. Two years later in 2009, 2920 participants who had provided at least one valid saliva cortisol measurement at baseline participated at follow up. The psychiatric interviews were repeated and 62 cases of newly onset depression were diagnosed. Odds ratios of depression were estimated for every 1.0nmol/l increase in morning, evening, and daily mean cortisol concentration, as well as for the difference between morning and evening cortisol concentration. The risk of depression decreased by increasing daily mean cortisol concentration and by increasing difference between morning and evening concentrations, while morning and evening cortisol concentrations were not significantly associated with depression. The adjusted odds ratios for 1.0nmol/l increase in morning, evening, and daily mean cortisol concentration were 0.69 (95% CI: 0.45, 1.05), 0.87 (95% CI: 0.59, 1.28), and 0.53 (95% CI: 0.32, 0.90), respectively. The adjusted odds ratio for 1.0nmol/l increase in difference between morning and evening concentration were 0.64 (95% CI: 0.45, 0.90). This study did not support the hypothesis that high salivary cortisol concentration is a risk factor of depression, but indicate that low mean salivary cortisol concentration and a small difference between morning and evening cortisol concentration may be risk factors of depression.

Work-unit measures of organisational justice and risk of depression--a 2-year cohort study

OBJECTIVES

The aim of this study is to analyse if low justice at work, analysed as aggregated workplace means, increases the risk of depression.

METHODS

A total of 4237 non-depressed Danish public employees within 378 different work units were enrolled in 2007. Mean levels of procedural and relational justice were computed for each work unit to obtain exposure measures that were robust to reporting bias related to depression. Two years later in 2009, 3047 (72%) participated at follow-up. Those reporting high levels of depressive, burn-out or stress symptoms were assigned to a psychiatric diagnostic interview. In the interview 58 cases of new onset depression were identified. Depression ORs by work unit level of procedural and relational justice were estimated by multivariable logistic regression accounting for established risk factors for depression.

RESULTS

Working in a work unit with low procedural justice (adjusted ORs of 2.50, 95% CI 1.06 to 5.88) and low relational justice (3.14, 95% CI 1.37 to 7.19) predicted onset of depression.

CONCLUSIONS

Our results indicate that a work environment characterised by low levels of justice is a risk factor for depression.

[Silica exposure and the risk of systemic sclerosis]

The aetiology of systemic sclerosis (Ssc) is unknown, but there is evidence of environmental factors playing a part in disease development in a number of cases. By examining a group of male patients with Ssc we found significant exposure to silica in 26% (6/23) of the patients compared to 2,1% in the general working population in Denmark. In the article we review the association between silica and Ssc and suggest how to question and refer patients with SSc who are suspected to have been exposed to silica.

A two-year follow-up study of risk of depression according to work-unit measures of psychological demands and decision latitude

OBJECTIVES

The aim of this study was to examine if high psychological demands and low decision latitude at work increase the risk of depression.

METHODS

In 2007, 4237 non-depressed Danish public employees within 378 different work units were enrolled in the study. Mean levels of psychological demands and decision latitude were computed for each work unit to obtain exposure measures that were robust to reporting bias. In 2009, 3046 (72%) participated at follow-up, and those reporting high levels of depressive, burnout or stress symptoms went through a psychiatric interview by which 58 cases of new onset depression were diagnosed. Odds ratios (OR) of depression for different levels of work unit mean psychological demands and decision latitude were estimated by logistic regression taking established risk factors into account.

RESULTS

The OR for depression according to psychological demands was 1.07 [95% confidence interval (95% CI) 0.42-2.49] for every unit of change on a 5-point scale. The corresponding OR for decision latitude was 1.85 (95% CI 0.55-6.26). No interactive effects of psychological demands and decision latitude were observed.

CONCLUSION

These findings suggest that low decision latitude may predict depression, but confidence intervals are wide and findings are also compatible with no increased risk.

Salivary cortisol and sleep problems among civil servants

OBJECTIVE

The present study used information from a field study conducted among 4489 civil servants (70% women) in Denmark in 2007. The purpose was to examine the association between sleep problems and salivary cortisol by using a cross-sectional design with repeated measures in a subsample three-month later.

METHODS

Sleep problems during the past night and the past 4 weeks were assessed by a self-administered questionnaire on overall sleep quality, disturbed sleep, sleep length and awakening problems. Saliva samples were collected in a single day, using cotton tubes, 30 min after awakening and again at 2000 h. A subsample of 387 participants collected saliva samples three-month later at awakening, +20 min and +40 min after awakening and at 2000 h. We adjusted for confounders related to sampling time, life style and personal characteristics, socioeconomic status and work aspects.

RESULTS

Sleep problems during the past four weeks were associated with low morning and evening saliva cortisol concentrations: [-3.1% per score of disturbed sleep (p=.009); and -4.7% per score of awakening problems (p<.001)]. Whereas sleep problems were not related with slope (the morning to evening change in cortisol levels). Awakening problems predicted lower cortisol (-7.51% per score; p=.003) three-month later. Cortisol awakening response (CAR) and slope three-month later were significantly associated with disturbed sleep (-7.84% and -8.24%) and awakening problems (-6.93). Area under the curve (AUC(morning)) increased with disturbed sleep (3.77%).

CONCLUSION

Surprisingly, low morning cortisol was associated with increased sleep problems during a four-week period prior to sampling among 4066 Danish civil servants. At follow-up three-month later, those with sleep problems had a flattened cortisol profile. Those with awakening problems also had low salivary cortisol in general.

[Health effects following occupational styrene exposure in the reinforced plastics industry]

This is a summary of the health risks of occupational styrene exposure based on recent reviews. We conclude about the exposure levels that there is strong evidence that styrene causes acute irritation of eyes and respiratory tract above 25 ppm, genotoxic effects above 10 ppm, and persistent nervous system effects with for instance reduced psychological performance, colour discrimination and hearing level following long-term styrene exposure above 10 ppm. There is moderate evidence of a causal association with cancer, but data are not sufficient to allow us to pinpoint specific cancers at risk or relevant exposure levels. We recommend reconsideration of the current Danish threshold limit value of 25 ppm, biological monitoring of styrene exposed workers, and epidemiological analyses of styrene exposure levels and long-term health effects among employees of the Danish reinforced plastics industry.