Risk of hypersensitivity pneumonitis and other interstitial lung diseases following organic dust exposure.

BACKGROUND: Organic dust is associated with hypersensitivity pneumonitis, and associations with other types of interstitial lung disease (ILD) have been suggested. We examined the association between occupational organic dust exposure and hypersensitivity pneumonitis and other ILDs in a cohort study. METHODS: The study population included all residents of Denmark born in 1956 or later with at least 1 year of gainful employment since 1976. Incident cases of hypersensitivity pneumonitis and other ILDs were identified in the Danish National Patient Register 1994-2015. Job exposure matrices were used to assign individual annual levels of exposure to organic dust, endotoxin and wood dust from 1976 to 2015. We analysed exposure-response relations by different exposure metrics using a discrete-time hazard model. RESULTS: For organic dust, we observed increasing risk with increasing cumulative exposure with incidence rate ratios (IRR) per 10 unit-years of 1.19 (95% CI 1.12 to 1.27) for hypersensitivity pneumonitis and 1.04 (95% CI 1.02 to 1.06) for other ILDs. We found increasing risk with increasing cumulative endotoxin exposure for hypersensitivity pneumonitis and other ILDs with IRRs per 5000 endotoxin units/m3-years of 1.55 (95% CI 1.38 to 1.73) and 1.09 (95% CI 1.00 to 1.19), respectively. For both exposures, risk also increased with increasing duration of exposure and recent exposure. No increased risks were observed for wood dust exposure. CONCLUSION: Exposure-response relations were observed between organic dust and endotoxin exposure and hypersensitivity pneumonitis and other ILDs, with lower risk estimates for the latter. The findings indicate that organic dust should be considered a possible cause of any ILD. TRIAL REGISTRATION NUMBER: j.no.: 1-16-02-196-17.

Occupational exposure to respirable crystalline silica and incident idiopathic interstitial pneumonias and pulmonary sarcoidosis: a national prospective follow-up study.

BACKGROUND: Respirable crystalline silica is a well-known cause of silicosis but may also be associated with other types of interstitial lung disease. We examined the associations between occupational exposure to respirable crystalline silica and the risk of idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis. METHODS: The total Danish working population was followed 1977-2015. Annual individual exposure to respirable crystalline silica was estimated using a quantitative job exposure matrix. Cases were identified in the Danish National Patient Register. We conducted adjusted analyses of exposure-response relations between cumulative silica exposure and other exposure metrics and idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis. RESULTS: Mean cumulative exposure was 125 µg/m3-years among exposed workers. We observed increasing incidence rate ratios with increasing cumulative silica exposure for idiopathic interstitial pneumonias, pulmonary sarcoidosis and silicosis. For idiopathic interstitial pneumonias and pulmonary sarcoidosis, trends per 50 µg/m3-years were 1.03 (95% CI 1.02 to 1.03) and 1.06 (95% CI 1.04 to 1.07), respectively. For silicosis, we observed the well-known exposure-response relation with a trend per 50 µg/m3-years of 1.20 (95% CI 1.17 to 1.23). CONCLUSION: This study suggests that silica inhalation may be related to pulmonary sarcoidosis and idiopathic interstitial pneumonias, though these findings may to some extent be explained by diagnostic misclassification. The observed exposure-response relations for silicosis at lower cumulative exposure levels than previously reported need to be corroborated in analyses that address the limitations of this study.

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.

Occupational risk of SARS-CoV-2 infection: a nationwide register-based study of the Danish workforce during the COVID-19 pandemic, 2020-2021.

OBJECTIVE: Most earlier studies on occupational risk of COVID-19 covering the entire workforce are based on relatively rare outcomes such as hospital admission and mortality. This study examines the incidence of SARS-CoV-2 infection by occupational group based on real-time PCR (RT-PCR) tests. METHODS: The cohort includes 2.4 million Danish employees, 20-69 years of age. All data were retrieved from public registries. The incidence rate ratios (IRRs) of first-occurring positive RT-PCR test from week 8 of 2020 to week 50 of 2021 were computed by Poisson regression for each four-digit Danish Version of the International Standard Classification of Occupations job code with more than 100 male and 100 female employees (n=205). Occupational groups with low risk of workplace infection according to a job exposure matrix constituted the reference group. Risk estimates were adjusted by demographic, social and health characteristics including household size, completed COVID-19 vaccination, pandemic wave and occupation-specific frequency of testing. RESULTS: IRRs of SARS-CoV-2 infection were elevated in seven healthcare occupations and 42 occupations in other sectors, mainly social work activities, residential care, education, defence and security, accommodation and transportation. No IRRs exceeded 2.0. The relative risk in healthcare, residential care and defence/security declined across pandemic waves. Decreased IRRs were observed in 12 occupations. DISCUSSION: We observed a modestly increased risk of SARS-CoV-2 infection among employees in numerous occupations, indicating a large potential for preventive actions. Cautious interpretation of observed risk in specific occupations is needed because of methodological issues inherent in analyses of RT-PCR test results and because of multiple statistical tests.

Night work during pregnancy and small for gestational age: a Danish nationwide register-based cohort study.

OBJECTIVE: The aim was to investigate the association between night work during pregnancy and risk of having a small for gestational age (SGA) child. METHODS: This cohort study had payroll data with detailed information on working hours for employees in all Danish administrative regions (primarily hospital employees) between 2007 and 2015, retrieved from the Danish Working Hour Database. Pregnancies, covariates and outcome were identified from the national birth registry. We used logistic regression to investigate the association between intensity and duration of night work during the first 32 pregnancy weeks and SGA. The adjusted model included age, body mass index, socioeconomic status and smoking. Using quantitative bias analysis and G-estimation, we explored potential healthy worker survivor bias (HWSB). RESULTS: The final cohort comprised 24 548 singleton pregnancies in 19 107 women, primarily nurses and medical doctors. None of the dimensions of night work were associated with an increased risk of SGA. We found a tendency towards higher risk of SGA in pregnancies where the women stopped having night shifts during pregnancy. Using G-estimation we found an OR<1 for the association between night work and SGA if all workers continued having night work during pregnancy compared with daywork only. CONCLUSION: We found no increased risk of SGA in association with night work during pregnancy among healthcare workers. G-estimation was not precise enough to estimate the observed indication of HWSB. We need better data on pregnancy discomforts and complications to be able to safely rule out HWSB.

Recognition of COVID-19 with occupational origin: a comparison between European countries.

OBJECTIVES: This study aims to present an overview of the formal recognition of COVID-19 as occupational disease (OD) or injury (OI) across Europe. METHODS: A COVID-19 questionnaire was designed by a task group within COST-funded OMEGA-NET and sent to occupational health experts of 37 countries in WHO European region, with a last update in April 2022. RESULTS: The questionnaire was filled out by experts from 35 countries. There are large differences between national systems regarding the recognition of OD and OI: 40% of countries have a list system, 57% a mixed system and one country an open system. In most countries, COVID-19 can be recognised as an OD (57%). In four countries, COVID-19 can be recognised as OI (11%) and in seven countries as either OD or OI (20%). In two countries, there is no recognition possible to date. Thirty-two countries (91%) recognise COVID-19 as OD/OI among healthcare workers. Working in certain jobs is considered proof of occupational exposure in 25 countries, contact with a colleague with confirmed infection in 19 countries, and contact with clients with confirmed infection in 21 countries. In most countries (57%), a positive PCR test is considered proof of disease. The three most common compensation benefits for COVID-19 as OI/OD are disability pension, treatment and rehabilitation. Long COVID is included in 26 countries. CONCLUSIONS: COVID-19 can be recognised as OD or OI in 94% of the European countries completing this survey, across different social security and embedded occupational health systems.

Occupational noise exposure and tinnitus: the HUNT Study.

OBJECTIVE: We aimed to assess the association between occupational noise exposure and tinnitus. Further, to assess whether the association depends on hearing status. DESIGN: In this cross-sectional study, tinnitus (>1 h daily) was regressed on job exposure matrix (JEM)-based or self-reported occupational noise exposure, adjusted for confounders. STUDY SAMPLE: The 14,945 participants (42% men, 20-59 years) attended a population-based study in Norway (HUNT4, 2017-2019). RESULTS: JEM-based noise exposure, assessed as equivalent continuous sound level normalised to 8-h working days (LEX 8 h), over the working career or as minimum 5 years ≥85 dB) was not associated with tinnitus. Years of exposure ≥80 dB (minimum one) was not associated with tinnitus. Self-reported high noise exposure (>15 h weekly ≥5 years) was associated with tinnitus overall and among persons with elevated hearing thresholds (prevalence ratio (PR) 1.3, 1.0-1.7), however not statistically significantly among persons with normal thresholds (PR 1.1, 0.8-1.5). CONCLUSIONS: Our large study showed no association between JEM-based noise exposure and tinnitus. This may to some extent reflect successful use of hearing protection. High self-reported noise exposure was associated with tinnitus, but not among normal hearing persons. This supports that noise-induced tinnitus to a large extent depends on audiometric hearing loss.

Prevalence of skin sensitization and dermatitis among epoxy-exposed workers in the wind turbine industry.

BACKGROUND: A high prevalence of skin sensitization and dermatitis has been reported among workers exposed to epoxy components. OBJECTIVES: To estimate the risk of skin sensitization and dermatitis among workers exposed to epoxy components during production of wind turbine blades while using comprehensive safety measures. METHODS: A cross-sectional study of 180 highly epoxy-exposed production workers and 41 nonexposed office workers was conducted at two wind turbine blade factories in Denmark. Participants underwent a skin examination, were tested with a tailored patch test panel including epoxy-containing products used at the factories, and answered a questionnaire. RESULTS: Sixteen production workers (8·9%) were sensitized to an epoxy component compared with none of the office workers. Skin sensitization was more frequent within the first year of exposed employment. Strong selection bias by atopic status was indicated. Among nonatopic workers, the prevalence of dermatitis was higher among production workers (16·4%) than among office workers [6·5%, odds ratio (OR) 2·3, 95% confidence interval (CI) 0·6-9·1] and higher among the sensitized workers (43·8%) than the nonsensitized workers (14·6%, OR 4·5, 95% CI 1·6-12·7). Resins based on diglycidyl ether of bisphenol A and F were the most frequent sensitizers. One of the four workers sensitized to epoxy components used at the factories did not react to the epoxy resin of the TRUE test® panel. CONCLUSIONS: Despite comprehensive skin protection, sensitization and dermatitis are prevalent among highly epoxy-exposed workers in the wind turbine industry in Denmark. Our findings document the need for intensified preventive efforts and emphasize the importance of tailored patch testing. What is already known about this topic? Epoxy components are well-known sensitizers of the skin. A high prevalence of skin sensitization and dermatitis has been reported among workers exposed to epoxy components. Comprehensive protective equipment is recommended when working with epoxy components. What does this study add? Despite comprehensive skin protection, skin sensitization and dermatitis are prevalent among epoxy-exposed workers. We found that 40% of workers sensitized to epoxy products had dermatitis. Only 75% of the sensitized workers were detected by the epoxy resin of the TRUE test® , which emphasizes the importance of tailored testing.

Extent of smoking at a Danish hospital with a smoke-free policy.

AIM: One-fifth of the Danish population smoke and exposure to second-hand smoke has well-documented adverse health effects. The smoking policy at hospital level prohibits hospital staff from smoking on the hospital grounds while patients and visitors may smoke in outdoor smoking cabins. This study aimed to quantify smoking at a Danish hospital and document any policy breaches. METHODS: In April 2020, we collected cigarette butts and observed smokers at the outdoor grounds to document smoking behaviour. RESULTS: In total, 7152 cigarette butts were collected during one week and 368 people were observed smoking at the outdoor grounds during four observation days. Of all collected cigarette butts, 55% were collected outside the smoking cabins and 62% of all smokers were observed smoking outside the smoking cabins. In addition, 31 staff were observed smoking. CONCLUSIONS: This study documents that smoking is prevalent at a smoke-free hospital and that the smoking policy is frequently violated. The frequency of smoking outside the cabins may at least partly be influenced by the COVID-19 pandemic. Smoking at a hospital can expose patients, visitors and staff to second-hand smoke with subsequent adverse health effects. Hospitals could play an exemplary role towards a smoke-free society (and not the exception), but the opportunity is not always seized.

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

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

Quantitative levels of noise exposure and 20-year hearing decline: findings from a prospective cohort study (the HUNT Study).

OBJECTIVE: We aimed to assess the association between occupational noise exposure and long-term hearing decline. DESIGN: This prospective cohort study used linear regression to investigate the association between occupational noise exposure and 20-year hearing decline, adjusted for important confounders. STUDY SAMPLE: The Norwegian cohort (N = 4,448) participated in two population-based health studies with pure-tone audiometry; HUNT2 1996-1998 and HUNT4 2017-2019. Exposure assessments included a quantitative job exposure matrix (JEM) and questionnaires. RESULTS: The participants (40.2% men, 20-39 years at baseline) had a mean 20-year decline (3-6 kHz) of 11.3 ± 9.8 decibels (dB). There was a positive association between 20-year logarithmic average noise level (JEM-based, LEX,20y) and 20-year hearing decline among men. Compared with no exposure ≥80 dB during follow-up, minimum 5 years of exposure ≥85 dB (JEM-based) predicted 2.6 dB (95% CI: 0.2-5.0) larger 20-year decline for workers aged 30-39 years at baseline, and -0.2 dB (95% CI: -2.2 to 1.7) for workers aged 20-29 years. Combining JEM information with self-reported noise exposure data resulted in stronger associations. CONCLUSION: This large longitudinal study shows an association between JEM-based noise exposure level and increased 20-year hearing decline among men. Contrary to expectations, the associations were weaker among younger workers, which might reflect a latency period.

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.

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.

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.

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.

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

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

A follow-up study of occupational styrene exposure and risk of autoimmune rheumatic diseases.

OBJECTIVES: Increased risk has been suggested for autoimmune rheumatic diseases following solvent exposure. The evidence for specific solvents is limited, and little is known about exposure-response relations. Styrene is an aromatic, organic solvent and the objective of this study was to analyse the association between occupational styrene exposure and autoimmune rheumatic diseases in men and women. METHODS: We followed 72 212 styrene-exposed workers of the Danish reinforced plastics industry from 1979 to 2012. We modelled full work history of styrene exposure from employment history, survey data and historical styrene exposure measurements. We identified cases in the national patient registry and investigated gender-specific exposure-response relations by cumulative styrene exposure for different exposure time windows adjusting for age, calendar year and educational level. RESULTS: During 1 515 126 person-years of follow-up, we identified 718 cases of an autoimmune rheumatic disease, of which 73% were rheumatoid arthritis. When adjusting for potential confounders and comparing the highest with the lowest styrene exposure tertile, we observed a statistically non-significantly increased risk of systemic sclerosis among women (incidence rate ratio (IRR)=2.50; 95% CI 0.50 to 12.50) and men (IRR=1.86; 95 % CI 0.50 to 7.00), based on 9 and 22 cases, respectively. Results were inconsistent for the other autoimmune rheumatic diseases examined. CONCLUSION: This study suggests an association between occupational styrene exposure and systemic sclerosis in men as well as in women but based on few cases. This is a new finding and has to be replicated before conclusions can be drawn.

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

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

Cancer mortality in an international cohort of reinforced plastics workers exposed to styrene: a reanalysis.

OBJECTIVE: To investigate the carcinogenicity of styrene by reanalysing data from a previous international cohort study of workers in the reinforced plastics industry. METHODS: Mortality from cancers of prior interest was analysed with more detailed consideration of exposure-response relations and an updated classification of leukaemias and lymphomas in data from a previous international cohort study of 37 021 reinforced plastics workers exposed to airborne styrene. RESULTS: Increased mortality from non-Hodgkin's lymphoma (NHL) was associated with the mean level of exposure to styrene in air (relative risk (RR) 2.31, 95% CI 1.29 to 4.12 per 100 ppm), but not with cumulative styrene exposure. Similar associations with mean exposure were observed for the oesophagus (RR 2.44, 95% CI 1.11 to 5.36 per 100 ppm) and pancreas (RR 1.89, 95% CI 1.17 to 3.09). Oesophageal cancer mortality was also associated with cumulative styrene exposure lagged 20 years (RR 1.16, 95% CI 1.03 to 1.31). No other cancer, including lung cancer, was associated with any indicator of styrene exposure. CONCLUSION: This reanalysis does not substantially change the conclusions of the original study with respect to NHL or lung cancer but new evidence concerning cancers of the oesophagus and pancreas merits further investigation.