Causes of irritant contact dermatitis after occupational skin exposure: a systematic review.

PURPOSE: Irritant contact dermatitis (ICD) is a major cause of occupational disease. The aim was to review the relation between exposure to occupational irritants and ICD and the prognosis of ICD. METHODS: Through a systematic search, 1516 titles were identified, and 48 studies were included in the systematic review. RESULTS: We found that the evidence for an association between ICD and occupational irritants was strong for wet work, moderate for detergents and non-alcoholic disinfectants, and strong for a combination. The highest quality studies provided limited evidence for an association with use of occlusive gloves without other exposures and moderate evidence with simultaneous exposure to other wet work irritants. The evidence for an association between minor ICD and exposure to metalworking fluids was moderate. Regarding mechanical exposures, the literature was scarce and the evidence limited. We found that the prognosis for complete healing of ICD is poor, but improves after decrease of exposure through change of occupation or work tasks. There was no substantial evidence for an influence of gender, age, or household exposures. Inclusion of atopic dermatitis in the analysis did not alter the risk of ICD. Studies were at risk of bias, mainly due to selection and misclassification of exposure and outcome. This may have attenuated the results. CONCLUSION: This review reports strong evidence for an association between ICD and a combination of exposure to wet work and non-alcoholic disinfectants, moderate for metalworking fluids, limited for mechanical and glove exposure, and a strong evidence for a poor prognosis of ICD.

A nationwide follow-up study of occupational organic dust exposure and risk of chronic obstructive pulmonary disease (COPD).

OBJECTIVES: To study exposure-response relations between cumulative organic dust exposure and incident chronic obstructive pulmonary disease (COPD) among subjects employed in the Danish farming and wood industry. METHODS: We studied exposure-response relations between cumulative organic dust exposure and incident COPD (1997-2013) among individuals born during 1950-1977 in Denmark ever employed in the farming or wood industry (n=1 75 409). Industry-specific employment history (1964-2007), combined with time-dependent farming and wood industry-specific exposure matrices defined cumulative exposure. We used logistic regression analysis with discrete survival function adjusting for age, sex and calendar year. Adjustment for smoking status was explored in a subgroup of 4023 with smoking information available. RESULTS: Cumulative organic dust exposure was inversely associated with COPD (adjusted rate ratios (RRadj (95% CIs) of 0.90 (0.82 to 0.99), 0.76 (0.69 to 0.84) and 0.52 (0.47 to 0.58) for intermediate-low, intermediate-high and high exposure quartiles, respectively, compared with the lowest exposure quartile). Lagging exposure 10 years was not consistently suggestive of an association between cumulative exposure and COPD; RRadj (95% CI): 1.05 (0.94 to 1.16), 0.92 (0.83 to 1.02) and 0.63 (0.56 to 0.70). Additional stratification by duration of employment showed no clear association between organic dust exposure and COPD except for the longer exposed (15-40 years) where an inverse association was indicated. Subgroup analyses showed that smoking had no impact on exposure-response estimates. CONCLUSIONS: Our findings show no increased risk of COPD with increasing occupational exposure to organic dust in the farming or wood industry. Potential residual confounding by smoking can, however, not be ruled out.

Cross-shift and longitudinal changes in FEV1 among wood dust exposed workers.

OBJECTIVES: Acute lung function (LF) changes might predict an accelerated decline in LF. In this study, we investigated the association between cross-shift and longitudinal changes in forced expiratory volume in 1 s (FEV(1)) among woodworkers in a 6-year follow-up study. METHODS: 817 woodworkers and 136 controls participated with cross-shift changes of FEV(1) at baseline and FEV(1) and forced vital capacity at follow-up. Height and weight were measured and questionnaire information on respiratory symptoms, employment and smoking habits was collected. Wood dust exposure was assessed from 3572 personal dust measurements at baseline and follow-up. Cumulative wood dust exposure was assessed by a study-specific job exposure matrix and exposure time. RESULTS: The median (range) of inhalable dust at baseline and cumulative wood dust exposure was 1.0 (0.2-9.8) mg/m(3) and 3.8 (0-7.1) mg year/m(3), respectively. Mean (SD) for %ΔFEV(1)/workday and ΔFEV(1)/year was 0.2 (6.0)%, and -29.1 (41.8) ml. Linear regression models adjusting for smoking, age, height and weight change showed no association between cross-shift and annual change in FEV(1) among woodworkers or controls. Including different exposure estimates, atopy or cross-shift change dichotomised or as quartiles did not change the results. CONCLUSIONS: This study among workers exposed to low levels of wood dust does not support an association between acute LF changes and accelerated LF decline.

Predictors of monoterpene exposure in the Danish furniture industry.

OBJECTIVES: Individuals who work with pine in the furniture industry may be exposed to monoterpenes, the most abundant of which are α-pinene, ß-pinene, and Δ(3)-carene. Monoterpenes are suspected to cause dermatitis and to harm the respiratory system. An understanding of the predictors of monoterpene exposure is therefore important in preventing these adverse effects. These predictors may include general characteristics of the work environment and specific work operations. We sought to assess the extent to which workers are exposed to monoterpenes and to identify possible predictors of monoterpene exposure in the pine furniture industry in Denmark. METHODS: Passive measurements of the levels of selected monoterpenes (α-pinene, ß-pinene, and Δ(3)-carene) were performed on 161 subjects from 17 pine furniture factories in Viborg County, Denmark; one sample was acquired from each worker. Additionally, wood dust samples were collected from 145 workers. Data on potential predictors of exposure were acquired over the course of the day on which the exposure measurements were recorded and could be assigned to one of four hierarchic ordered levels: worker, machine, department, and factory. In addition to univariate analyses, a mixed model was used to account for imbalances within the data and random variation with each of the hierarchically ordered levels. RESULTS: The geometric mean (GM) monoterpene content observed over the 161 measurements was 7.8 mg m(-3) [geometric standard deviation (GSD): 2.4]; the GM wood dust level over 145 measurements was 0.58 mg m(-3) (GSD: 1.49). None of the measured samples exceeded the occupational exposure limit for terpenes in Denmark (25 ppm, 150 mg m(-3)). In the univariate analyses, half of the predictors tested were found to be significant; the multivariate model indicated that only three of the potential predictors were significant. These were the recirculation of air in rooms used for the processing of wood (a factory level predictor), the presence of a supplementary cold air intake (departmental level), and the operation of a glue press (machine level). However, only one factory of the 17 examined used a supplementary cold air intake, and while very high monoterpene levels were observed there, this may be due to factors other than the supplementary intake. In contrast to the situation with wood dust, we found that the bulk of the variation in the data (65%) was attributable to variability on the factory level, with comparatively little being due to the departmental (16%) and machine (0.5%) levels. The fixed terms in the model accounted for 31.8% of the total variance. CONCLUSIONS: The predictors of monoterpenes are not the same as those for wood dust exposure; this has implications for the implementation of preventative measures in factories. In order to decrease monoterpene exposure, efforts should be focused on minimizing the recirculation of air in rooms used for woodworking and on increasing awareness of the importance of effective ventilation and enclosure when operating a glue press.

Wood Dust Exposure Levels and Respiratory Symptoms 6 Years Apart: An Observational Intervention Study Within the Danish Furniture Industry.

OBJECTIVES: Occupational exposure to wood dust can cause respiratory diseases, but few studies have evaluated the impact of declining exposure on health outcome. This study aimed to investigate whether a decline in wood dust exposure between two cross sectional studies performed in 1997-1998 and 2003-2004 was related to the prevalences of respiratory symptoms among woodworkers in a well-defined geographical area. METHODS: Two thousand and thirty-two woodworkers from 54 plants in study 1 and 1889 woodworkers from 52 plants in study 2 returned a questionnaire on respiratory diseases and symptoms, employment and smoking habits. Current individual wood dust exposure level was assessed from 2 study specific job exposure matrix's based on task, factory size and personal passive dust measurements (2217 in study 1 and 1355 in study 2). RESULTS: The median (range) of inhalable dust was 1.0 mg/m3 (0.2-9.8), 0.6 mg/m3 (0.1-4.6) in study 1 and study 2, respectively. In study 2, the prevalence's of self-reported asthma was higher and the prevalence's of respiratory symptoms were lower compared to study 1. In adjusted logistic regression analyses using GEE methodology to account for clustering, dust exposure level could explain the differences in prevalence of coughing, chronic bronchitis and nasal symptoms between study 1 and study 2, while no effect was found for asthma. CONCLUSIONS: A 40% decline in wood dust exposure in a 6 year period may serve as an explanation for the decline in most respiratory symptoms, but do not seems to impact the prevalence of self-reported asthma.

Dust exposure and the impact on hospital readmission of farming and wood industry workers for asthma and chronic obstructive pulmonary disease (COPD).

Objectives It is still not well established how occupational air pollutants affect the prognosis of asthma or chronic obstructive pulmonary disease (COPD). This study uses nationwide Danish registers and quantitative dust industry exposure matrices (IEM) for the farming and wood industries to estimate whether previous year dust exposure level impacts hospital readmissions for workers diagnosed with asthma or COPD. Methods We identified all individuals with a first diagnosis of either asthma (769 individuals) or COPD (342 individuals) between 1997 and 2007 and followed them until the next hospital admission for asthma or COPD, emigration, death or 31 December 2007. We included only individuals who worked in either the wood or farming industries at least one year during follow-up. We used logistic regression analysis to investigate associations between dust exposure level in the previous year and hospital readmission, adjusting for sex, age, time since first diagnosis, socioeconomic status, and labor force participation. Results Asthma readmissions for individuals with low and high dust exposure were increased [adjusted rate ratio (RR adj) 2.52, 95% confidence interval (CI) 1.45-4.40] and RR adj2.64 (95% CI 1.52-4.60), respectively. For COPD readmission, the risk estimates were RR adj1.36 (95% CI 0.57-3.23) for low and RR adj1.20 (95% CI 0.49-2.95) for high exposure level in the previous year. For asthma readmission, stratified analyses by type of dust exposure during follow-up showed increased risks for both wood dust [RR adj2.67 (95% CI 1.35-5.26) high exposure level] and farming dust [RR adj3.59 (95% CI 1.11-11.59) high exposure level]. No clear associations were seen for COPD readmissions. Conclusions This study indicates that exposure to wood or farm dust in the previous year increases the risk of hospital readmission for individuals with asthma but not for those with COPD.

Determinants of wood dust exposure in the Danish furniture industry--results from two cross-sectional studies 6 years apart.

OBJECTIVES: This paper investigates determinants of wood dust exposure and trends in dust level in the furniture industry of Viborg County, Denmark, using data from two cross-sectional studies 6 years apart. METHODS: During the winter 1997/1998, 54 factories were visited (hereafter study 1). In the winter 2003/2004, 27 factories were revisited, and personal dust measurements were repeated. In addition, 14 new factories were included (hereafter study 2). A total of 2303 woodworkers participated in study 1, and 2358 measurements from 1702 workers were available. From study 2, 1581 woodworkers participated and 1355 measurements from 1044 workers were available. Information on occupational variables describing potential determinants of exposures like work task, exhaust ventilation, enclosure and cleaning procedures were collected. A total of 2627 measurements and 1907 persons were included in the final mixed model in order to explore determinants of exposure and trends in dust level. RESULTS: The overall inhalable wood dust concentration (geometric means (geometric standard deviation)) has decreased from 0.95 mg/m(3) (2.05) in study 1 to 0.60 mg/m(3) (1.63) in study 2, representing a 7% annual decrease in dust concentration, which was confirmed in the mixed model. From study 1 to study 2 there has been a change towards less manual work and more efficient cleaning methods, but on the contrary also more inadequate exhaust ventilation systems. The following determinants were found to 'increase' dust concentration: sanding; use of compressed air; use of full-automatic machines; manual work; cleaning of work pieces with compressed air; kitchen producing factories and small factories (<20 employees). The following determinants of exposure were found to 'decrease' dust concentration: manual assembling/packing; sanding with adequate exhaust ventilation; adequate exhaust ventilation; vacuum cleaning of machines and special cleaning staff. CONCLUSIONS: Despite a substantial drop in the dust concentration during the last 6 years in the furniture industry in Viborg County, further improvements are possible. There should be more focus on improved exhaust ventilation, professional cleaning methods and avoiding use of compressed air.

New-onset COPD and Decline in Lung Function Among Wood Dust-Exposed Workers: Re-analysis of a 6-year Follow-up Study.

Objectives: There is a lack of longitudinal studies exploring the association between organic wood dust exposure and new-onset chronic obstructive pulmonary disease (COPD) and change in lung function. We have re-investigated these associations in a 6-year follow-up cohort of furniture workers exposed to wood dust using improved outcome measures and methods. Methods: A large follow-up study of 1112 woodworkers (63%) from the Danish furniture industry and 235 controls (57%) was conducted between 1998 and 2004. Forced expiratory volume in the first second (FEV1), forced vital capacity (FVC), and the ratio (FEV1/FVC) standardized for age, height, and sex using the Global Lung Function Initiative 2012 equations were assessed at baseline and follow-up. Questionnaires on respiratory symptoms, wood dust exposure, and smoking habits were collected. Exposure was assessed as exposure level at baseline and as cumulative exposure in the follow-up period from quantitative task specific job exposure matrix available at both baseline and follow-up based on personal dust sampling using passive dust monitors. The association between exposure to wood dust and new-onset COPD was assessed with logistic regression, whereas the association between wood dust and the longitudinal change in z-score for lung function was assessed with linear regression. Results: Similar associations were seen for different exposure metrics. An exposure-response relation was seen for new-onset COPD for female smokers with an odds ratio (OR) (95% confidence interval [CI]) of 8.47 (0.9-82.4) in the highest exposed group compared to controls, and a significant test for trend P = 0.049. No such association was seen among males for whom only smoking was strongly associated to new-onset COPD. For change in lung function, a significant exposure-response was seen for females, confirming previous findings, with increasing levels of wood dust exposure showing larger decline in lung function (ß [95% CI]: -0.32 ΔzFEV1 (-0.56 to -0.08, P = 0.009) for third quartile exposure compared to controls, test for trend, P = 0.005, equivalent to an excess loss of 125 ml in the 6 years of follow-up). An opposite association was seen for men. Conclusion: In conclusion, we found that female woodworkers have a dose-dependent increased OR of new-onset COPD and an excess decline in lung function suggesting that female woodworkers may be more susceptible to wood dust exposure than male woodworkers. Among male woodworkers, only smoking and asthma were significant predictors for new-onset COPD and excess decline in lung function. These results emphasize that reduction in both smoking and wood dust exposure should continuously be an effort to prevent adverse pulmonary health effects.

Immunoglobulin E-mediated sensitization to pine and beech dust in relation to wood dust exposure levels and respiratory symptoms in the furniture industry.

OBJECTIVES: Wood dust exposure may cause Immunoglobulin E (IgE)-mediated allergic diseases. Our objectives were to estimate pine and beech dust sensitization rates among woodworkers and a reference group, explore the association between exposure and sensitization and between sensitization and respiratory symptoms, and finally investigate the impact of proteinogenic specific IgE (sIgE) epitopes on respiratory symptoms. METHODS: In a Danish study among 52 furniture factories and 2 reference factories, we evaluated the workers' asthma and rhinitis status using questionnaires and blood samples collected from 1506 woodworkers and 195 references. Workers with asthma symptoms (N=298), a random study sample (N=399) and a random rhinitis sample (N=100) were evaluated for IgE-mediated sensitization to pine and beech dust. RESULTS: The prevalence of pine and beech sensitization among current woodworkers was 1.7 and 3.1%, respectively. No differences in sensitization rates were found between woodworkers and references, but the prevalence of wood dust sensitization was dose-dependently associated with the current level of wood dust exposure. No relation was observed between wood dust sensitization per se and respiratory symptoms. Only symptomatic subjects had proteinogenic IgE epitopes to pine. Increased odds ratios for sIgE based on proteinogenic epitopes to beech and respiratory symptoms were found, although they were not statistically significant. CONCLUSIONS: Sensitization rates to pine and beech were the same for woodworkers and references but dependent on the current wood dust exposure level. The importance of beech and pine wood sensitization is limited, but may be of clinical significance for a few workers if the IgE epitopes are proteinogenic.

Non-malignant respiratory diseases and occupational exposure to wood dust. Part I. Fresh wood and mixed wood industry.

This paper reviews associations in literature between exposure to wood dust from fresh wood and non-malignant respiratory diseases. Criteria for inclusion are epidemiological studies in English language journals with an internal or external control group describing relationships between wood dust exposure and respiratory diseases or symptoms. The papers took into account smoking, and when dealing with lung function took age into consideration. A total of 25 papers concerning exposure to fresh wood and mixed wood formed the basis of this review. The results support an association between fresh wood dust exposure and asthma, asthma symptoms, coughing, bronchitis, and acute and chronic impairment of lung function. In addition, an association between fresh wood dust exposure and rhino-conjunctivitis was seen across studies. Apart from plicatic acid in western red cedar wood, no causal agent was consistently disclosed. Type 1 allergy is not suspected of being a major cause of wood dust induced asthma. Concurrent exposure to microorganisms and terpenes probably add to the inherent risk of wood dust exposure in the fresh wood industry.

Non-malignant respiratory diseases and occupational exposure to wood dust. Part II. Dry wood industry.

This paper reviews the literature on associations between dry wood dust exposure and non-malignant respiratory diseases. Criteria for inclusion are epidemiological studies in English language journals with an internal or external control group describing relationships between dry wood dust exposure and respiratory diseases or symptoms. Papers took into consideration smoking and when dealing with lung function age. A total of 37 papers forms the basis of this review. The results support an association between dry wood dust exposure and asthma, asthma symptoms, coughing, bronchitis, and acute and chronic impairment of lung function. In addition, an association between wood dust exposure and rhino-conjunctivitis is seen across the studies. Apart from plicatic acid in western red cedar wood, no causal agent has consistently been disclosed. Type 1 allergy is not suspected to be a major cause of wood dust induced asthma.