Gitte Jacobsen

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/m3 (2.05) in study 1 to 0.60 mg/m3 (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.

Longitudinal lung function decline and wood dust exposure in the furniture industry

The aim of the present study was to investigate the relationship between change in lung function and cumulative exposure to wood dust. In total, 1,112 woodworkers (927 males, 185 females) and 235 reference workers (104 males, 185 females) participated in a 6-yr longitudinal study. Forced expiratory volume in one second (FEV1), forced vital capacity (FVC), height and weight were measured, and questionnaire data on respiratory symptoms, wood dust exposure and smoking habits were collected. Cumulative inhalable wood dust exposure was assessed using a study-specific job exposure matrix and exposure time. The median (range) for cumulative wood dust exposure was 3.75 (0–7.55) mg·year·m−3. A dose–response relationship between cumulative wood dust exposure and percent annual decrease in FEV1 was suggested for female workers. This was confirmed in a linear regression model adjusted for confounders, including smoking, height and age. An additional difference of -14.50 mL·yr−1 and −27.97 mL·yr−1 was revealed for females exposed to 3.75–4.71 mg·yr·m−3 or to >4.71 mg·yr·m−3, respectively, compared with non-/low-exposed females. For females, a positive trend between wood dust exposure and the cumulative incidence proportion of FEV1/FVC <70% was suggested. In conclusion, in the present low-exposed cohort, female woodworkers had an accelerated decline in lung function, which may be clinically relevant.

Increased incidence of respiratory symptoms among female woodworkers exposed to dry wood

The aim of the present study was to investigate the occurrence of new respiratory symptoms in relation to wood dust exposure in a 6-yr follow-up study. A total of 1,377 woodworkers (1,137 males; 240 females) and 297 reference workers (137 males; 160 females) participated. Data on respiratory symptoms, employment and smoking habits were collected. Wood dust exposure was assessed from baseline dust measurements, and cumulative wood dust exposure was assessed by study-specific job exposure matrices and exposure time. The geometric mean (geometric sd) dust level decreased during the study period from 0.94 (2.1) to 0.60 (1.6) mg·m−3. Adjusted analysis revealed positive associations for cumulative incidence proportion of chronic bronchitis and daily coughing for female woodworkers versus female reference workers. The cumulative incidence proportion of daily coughing and chronic bronchitis were found to be associated with baseline wood dust exposure in a dose-dependent manner. The odds ratio (95% confidence interval) for daily coughing (with reference to the lowest exposure quartile) was 1.6 (0.6–4.3), 3.2 (0.9–6.8) and 3.8 (1.5–9.7), respectively, in the second and third lowest and the highest quartile. The figures for chronic bronchitis were, accordingly, 2.3 (0.4–14.5), 3.0 (0.5–18.7) and 6.0 (1.2–28.8). In conclusion, female woodworkers in this low exposure cohort showed an increased incidence of coughing and bronchitis, whereas no relations to wood dust exposure were seen for male woodworkers.

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 (FEV1) among woodworkers in a 6-year follow-up study. Methods 817 woodworkers and 136 controls participated with cross-shift changes of FEV1 at baseline and FEV1 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/m3 and 3.8 (0–7.1) mg year/m3, respectively. Mean (SD) for %ΔFEV1/workday and ΔFEV1/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 FEV1 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, β-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, β-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.

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 (β [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.

0434 A meta-analysis of occupational silica exposure and risk of autoimmune rheumatic diseases: does study quality matter?

Objectives Increased risks of rheumatoid arthritis, small vessel vasculitis, systemic lupus erythematosus, and systemic sclerosis have been observed following crystalline silica exposure. Our aims are to estimate pooled risk estimates and assess the impact of study quality. Methods We followed the PRISMA criteria, identified 1162 articles, and included 21 studies that we classified according to eight quality parameters (high vs. low). We estimated pooled overall and disease specific odds ratios (ORs) with random effects meta-regressions. Results We observed an increased overall OR of 2.3 (1.7–3.1, 21 studies) and for rheumatoid arthritis (OR 1.7, 95% CI 0.8–3.41, 6 studies), small vessel vasculitis (OR 2.4, 95% CI 1.2–4.7, 6 studies), systemic lupus erythematosus (OR 2.8, 95% CI 0.5–14.7, 3 studies), and systemic sclerosis (OR) 2.9, 1.7–4.9, 6 studies). The following high-quality characteristics were associated with decreased ORs: appropriate control group, high response rate, appropriate confounder control, independent exposure information, and many participants; and with increased ORs: quantitative or semi-quantitative exposure measure, hospital based diagnosis, and well-defined diagnostic criteria. Only the latter was statistically significant (p<0.05). When we consecutively excluded low quality studies, the overall OR value decreased to 1.3 (0.4–4.2, 3 studies) but this exercise was sensitive to the order. Egger’s test of no small study effect was highly statistically significant (p<0.01). Conclusion This review provides some evidence that crystalline silica is associated with systemic sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and small vessel vasculitis. However, more high-quality studies are needed to confirm or refute if this represents causal associations.

O26-4 Inverse associations between occupational organic dust exposure and incidence of chronic obstructive pulmonary disease (copd) – healthy worker survivor bias?

Background Organic dust exposure common in the farming and wood industry is a suggested risk factor for COPD. Aims To investigate exposure-response relations between different exposure metrics for organic dust and the incidence of COPD in the farming and wood industry. Methods We identified 35,957 blue-collar workers and followed them since their first employment in farming or wood industry 1997–2007. Information on exposure was obtained from two industry-based exposure matrices with time-dependent quantitative exposure estimates for organic dust in farming and wood industry. Incident COPD cases as defined by ICD-codes 1997–2013 were identified in the Danish national patient register. We analysed data with discrete-time hazard logistic regression with person-years as the unit of analysis and adjusted for age, sex, calendar year, and labour market attachment. Results We observed an inverse association between levels of organic dust and COPD (P trend < 0.0001). The adjusted RRs (95% CIs) for cumulative exposure for the 2nd, 3rd, and 4th exposure quartiles compared with the 1st were; 1.01 (0.82; 1.26), 0.66 (0.51; 0.84), and 0.70 (0.53; 0.91). Comparable results were seen for average exposure and exposure duration. Analyses on a subset of the population with individual smoking information showed a slightly declining prevalence of smokers with increasing organic dust exposure, but adjusting for smoking did not affect the observed associations. Conclusions We found an inverse association between organic dust exposure and COPD. In this inception cohort our results should be less affected by a healthy hire effect or left truncation bias, although this can still not be ruled out completely. We find it unlikely that the declining risk of COPD reflects a gainful effect of organic dust exposure, but rather healthy worker survivor bias related to exposure level, smoking, or other underlying individual factors associated with exposure level even if our sub-analyses were unable to detect a confounding effect of smoking.