Helle Laier Johnsen

Dust exposure assessed by a job exposure matrix is associated with increased annual decline in FEV1: a 5-year prospective study of employees in Norwegian smelters.

RATIONALE The relationship between dust exposure and annual decline in lung function among employees in the smelting industry is unknown. OBJECTIVES The aim of the study was to investigate the relationship between annual change in lung function and occupational dust exposure among workers in 15 Norwegian smelters. METHODS All employees (n = 2,620) were examined annually for 5 years (11,335 health examinations). At each examination spirometry was performed and a respiratory questionnaire was completed. The smelters were grouped as follows: (1) ferrosilicon alloys (FeSi) and silicon metal (Si-metal); and (2) silicon manganese (SiMn), ferromanganese (FeMn), and ferrochromium (FeCr). A job exposure matrix was available on the basis of 2,619 personal dust exposure measurements. The association between lung function expressed as FEV(1) and FVC per squared height (height(2)) and dust exposure was investigated using multivariate linear mixed model analyses. MEASUREMENTS AND MAIN RESULTS The annual change in FEV(1)/height(2) (deltaFEV(1)) related to dust exposure in the FeSi/Si-metal and SiMn/FeMn/FeCr smelters was -0.42 (95% confidence interval, -0.95 to 0.11) and -1.1 (-2.1 to -0.12) (ml/m(2)) x (mg/m(3))(-1) x year(-1), respectively. The annual decline in FEV(1)/height(2) was 1.6 ml/m(2) (0.15 to 3.1) steeper in smokers than in nonsmokers. The median geometric mean of the time-weighted dust exposure concentration levels of the employees was 2.3 mg/m(3) in the FeSi/Si-metal smelters and 1.6 mg/m(3) in the SiMn/FeMn/FeCr smelters. Among nonsmokers, deltaFEV(1) was -0.86 (-1.6 to -0.10) and -1.1 (-2.5 to 0.25) (ml/m(2)) x (mg/m(3))(-1) x year(-1) in the FeSi/Si-metal and SiMn/FeMn/FeCr smelters, respectively. Thus, for a 1.80 m tall employee the annual decline in FEV(1) associated with average dust exposure was 5.7 ml/year in the SiMn/FeMn/FeCr smelters, and 6.4 ml/year for a nonsmoker in the FeSi/Si-metal smelters. CONCLUSIONS In all smelters combined, the annual change in FEV(1) was negatively associated with increasing dust exposure. This association was also significant among workers in SiMn/FeMn/FeCr smelters and among nonsmokers in the FeSi/Si-metal smelters.

Prevalence of airflow limitation among employees in Norwegian smelters: a longitudinal study

Aims To investigate the association between airflow limitation and occupational exposure and to compare a fixed limit with an age adjusted limit for airflow limitation. Methods 3924 employees in 24 Norwegian smelters and related workplaces were investigated annually over 5 years (n=16 570) using spirometry and a respiratory questionnaire on smoking habits and job category. Employees working full time on the production line were classified as line operators; subjects who never worked on the production line were regarded as non-exposed. A job exposure matrix (JEM) was available in most smelters. Airflow limitation was expressed as (i) forced expiratory volume in 1 s/forced vital capacity (FEV1/FVC ratio) <0.7 and (ii) FEV1/FVC ratio less than the lower limit of normal (LLN). Longitudinal analyses on the prevalence of airflow limitation were performed using a generalised linear mixed model. Results The prevalence of airflow limitation was stable during follow-up. The OR of airflow limitation during follow-up was 1.24 (95% CI 1.03 to 1.50) in line operators compared with unexposed subjects for FEV1/FVC ratio <0.7 and 1.44 (1.14 to 1.81) for FEV1/FVC ratio <LLN. A dose–response relationship was also found between prevalence of airflow limitation and dust exposure. The annual decline in FEV1 was −77.5 (SD 99.9) ml/year in subjects with FEV1/FVC ratio <0.7 and −83.8 (114.2) ml/year in subjects with FEV1/FVC ratio <LLN. Conclusion Prevalence of airflow limitation was higher in exposed than non-exposed employees. Both the FEV1/FVC ratio <0.7 and FEV1/FVC ratio <LLN identify subjects with accelerated annual decline in FEV1.

Production of silicon metal and alloys is associated with accelerated decline in lung function : A 5-year prospective study among 3924 employees in norwegian smelters

Objectives: To investigate the association between decline in lung function and production of alloys in the Norwegian smelting industry. Methods: All employees (N = 3924) were examined annually for 5 years (16,570 examinations). The employees were classified into three categories: 1) line operators (employed full time in the production line), 2) nonexposed (no exposure last year), and 3) non-line operators (remaining subjects). The outcome variable was expressed as forced expiratory volume in 1 second per squared height (FEV1/height2). Results: In the subcohorts of the ferrosilicon/silicon metal and silicon carbide industries, the differences between line operators and nonexposed workers were −2.3 (−4.3 to −0.3) (CI = 95%) and −5.6 (−10.4 to −0.7) mL/(m2 × year), respectively. Conclusion: Line operators in the ferrosilicon/silicon metal and silicon carbide industries had a steeper annual decline in FEV1/height2 compared with nonexposed workers.

Dust exposure is associated with increased lung function loss among workers in the Norwegian silicon carbide industry

Objectives To investigate the relationship between dust exposure and annual change in lung function among employees in Norwegian silicon carbide (SiC) plants using a quantitative job exposure matrix (JEM) regarding total dust. Methods All employees, 20–55 years of age by inclusion (n=456), were examined annually for up to 5 years (1499 examinations). Spirometry was performed at each examination, and a questionnaire encompassing questions of respiratory symptoms, smoking status, job and smoking history, and present job held was completed. A JEM was constructed based on 1970 personal total dust exposure measurements collected during the study period. The association between lung function and total dust exposure was investigated using linear mixed models. Results The annual change in forced expiratory volume (FEV) in one second per squared height, FEV1/height2, per mg/m3 increase in dust exposure was −2.3 (95% CI −3.8 to −0.79) (mL/m2)×year−1. In an employee of average height (1.79 m) and exposure (1.4 mg/m3) the estimated contribution to the annual change in FEV1 associated with dust was 10.4 mL/year. The annual change in FEV1/height2 in current, compared with non-smokers was −1.9 (−7.2 to 3.4) (mL/m2)×year−1. The estimated overall annual decline in FEV1 among current and non-smokers in the highest exposed group was −91.2 (−124.3 to −58.1) (mL/m2)×year−1 and −49.0 (−80.2 to −17.8) (mL/m2)×year−1, respectively. Conclusions Dust exposure, expressed by a quantitative JEM, was found to be associated with an increased yearly decline in FEV1 in employees of Norwegian SiC plants.

The Incidence of Work-related Asthma-like Symptoms and Dust Exposure in Norwegian Smelters

RATIONALE The prevalence of respiratory symptoms among employees in smelters is positively associated with dust exposure. OBJECTIVES To investigate the association between the incidence of work-related asthma-like symptoms (WASTH) and dust exposure. METHODS All the employees were invited to participate in a 5-year longitudinal study. The outcome of WASTH was defined as the combination of dyspnea and wheezing improving on rest days or vacation in an individual who had no asthma previously. Information about smoking and occupational status was obtained from a questionnaire. A job exposure matrix of total dust was developed. Multivariate data analyses were performed using Cox regression. MEASUREMENTS AND MAIN RESULTS The total follow-up time of the employees (n = 2,476) was 8,469 years, and the median follow-up time for participants was 4.0 years. During the follow-up, 91 employees developed WASTH, and the corresponding incidence rate for WASTH per 1,000 person-years was 8.9 (7.3-10.9) (95% confidence interval in parentheses). The risk ratio of WASTH increased significantly (P = 0.0001) with dust exposure in the middle and high categories (1.0-2.9 and ≥ 3.0 mg/m(3)). Stratified analyses showed that the effect of current dust exposure varied with both previous exposure (PE) to dust and fumes (P = 0.006) and airflow limitation (AFL) (P = 0.033). The final analyses showed that the risk ratios for WASTH per 1 mg/m(3) increase in current dust exposure were 1.1 (0.93-1.2), 1.4 (1.1-1.8), 1.6 (1.1-2.3), and 1.9 (1.2-3.0) for the categories (PE+/AFL-), (PE-/AFL-), (PE+/AFL+, and (PE-/AFL+). CONCLUSIONS In conclusion, dust exposure was associated with an increased incidence of WASTH.

Incidence of airflow limitation among employees in Norwegian smelters

We have investigated the association between the incidence of airflow limitation and occupational exposure. The employees (n = 3,924) were investigated annually during five years (n = 16,570) using spirometry. Exposure was classified using job category and a job exposure matrix. Airflow limitation was expressed using two indices: (i) as forced expiratory volume in one second/force vital capacity (FEV(1) /FVC) <0.7 and (ii) lower limit of normal (LLN). The incidence of airflow limitation was 21.2/1000 years(-1) and 15.1/1000 years(-1) using the fixed limit (0.7) and the LLN criterion, respectively. We found a dose-response relationship between the incidence of airflow limitation and tobacco consumption and with job-category in non-smokers. The associations between airflow limitation and covariates were independent of how airflow limitation was defined. The incidence of airflow limitation defined as FEV(l) /FVC <0.7 yielded higher incidence rates of airflow limitation than LLN. We found a significant association between the incidence of airflow limitation and occupational exposure in non-smokers.

Sputum neutrophils are elevated in smelter workers, and systemic neutrophils are associated with rapid decline in FEV1

Objectives In a previous study on smelter workers we, found significant relationship between exposure to dust and accelerated annual decline in forced expiratory volume in 1 s (FEV1). In this cross-sectional study at the end of a follow-up, we aimed to investigate the possible association between annual decline in FEV1 and markers of airways, and systemic inflammation in smelter workers. Methods Employees (n=76 (27 current smokers)) who had been part of a longitudinal study (9–13 years) that included spirometry (>6 measurements) and respiratory questionnaires, performed induced sputum, exhaled NO and had blood drawn. Participants with annual decline in FEV1≥45 mL were compared with participants with annual decline <45 mL; also 26 non-exposed controls were included. Results Compared with non-exposed controls, smelter workers demonstrated a significantly increased percentage of neutrophils (mean (SD)) (57% (17) vs 31% (15)) and matrix metalloproteinases 8 (MMP-8) levels in sputum, and MMP-9, surfactant protein D (SpD) and transforming growth factor β (TGFb) levels in blood. A significant association in FEV1≥45 mL was found for blood neutrophils when controlling for smoking habits (OR=1.7 (95% CI 1.0 to 2.8), p=0.045). Airway and blood protein markers were not associated with annual decline in FEV1. Conclusions All workers displayed airway and systemic inflammation characterised by increased levels of neutrophils and MMP-8 in sputum, and MMP-9, SpD and TGFβ in blood compared with non-exposed controls. Blood neutrophils in particular were significantly elevated in those workers with the most rapid decline in lung function. A similar observation was not seen with airway neutrophils. In the present study, we were able to identify systemic but not airway inflammatory markers that can predict increased decline in FEV1 in smelter workers.

Increased Decline in Pulmonary Function Among Employees in Norwegian Smelters Reporting Work-Related Asthma-Like Symptoms.

Objective: To investigate associations between work-related asthma-like symptoms (WASTH) and annual pulmonary function decline among employees of 18 Norwegian smelters. Methods: A 5-year longitudinal study in which WASTH was defined as a combination of dyspnea and wheezing that improved on rest days and vacation. Results: A total of 12,966 spirometry examinations were performed in 3084 employees. Crude annual decline in forced expiratory volume in 1 second (FEV1) (dFEV1) was 32.9 mL/yr (95% confidence interval, 30.5 to 35.3), and crude annual decline in forced vital capacity (FVC) (dFVC) was 40.9 mL/yr (37.8 to 43.9). After adjustment for relevant covariates, employees reporting WASTH showed higher dFEV1 by 16.0 m:/yr (3.4 to 28.6) and higher dFVC by 20.5 mL/yr (6.0 to 35.0) compared with employees not reporting WASTH. Conclusion: Work-related asthma-like symptom was associated with greater annual declines in FEV1 and FVC, indicating a restrictive pattern.

Respiratory hazards of metal smelting.

Purpose of review The metal smelting industry is an important industry in the majority of countries in the world and employs millions of workers. In most of the production types, a variety of pollutants are emitted into the workplace atmosphere. Some of these pollutants have sensitizing properties, whereas other act as irritants in the respiratory tract. This review will explore the recent studies (2010–2012) which address the impact of exposure to pollutants in the smelting industry on nonmalignant respiratory disorders. Recent findings The association between different respiratory symptoms as well as pulmonary function and the level of exposure to different agents has been investigated. Likewise, the effect of primary prevention (exposure reduction) and secondary prevention (relocation) has been studied. Finally, the association between the incidence of community-acquired pneumonia and exposure to pollutants encountered at work in the smelting industry and the results from mortality studies are reported. Summary It appears that exposure to emissions of pollutants in the smelting industry is associated with respiratory symptoms, including asthma, lung function decline and chronic obstructive pulmonary disease, depending on the type of production. Moreover, it is possible that these exposures may enhance the risk of infectious pneumonia.

Fungal Fragments and Fungal Aerosol Composition in Sawmills

Abstract Assessment of exposure to fungi has commonly been limited to fungal spore measurements that have shown associations between fungi and development or exacerbation of different airway diseases. Because large numbers of submicronic fragments can be aerosolized from fungal cultures under laboratory conditions, it has been suggested that fungal exposure is more complex and higher than that commonly revealed by spore measurements. However, the assessment of fungal fragments in complex environmental matrix remain limited due to methodological challenges. With a recently developed immunolabeling method for field emission scanning electron microscope (FESEM), we could assess the complex composition of fungal aerosols present in personal thoracic samples collected from two Norwegian sawmills. We found that large fungal fragments (length >1 µm) dominated the fungal aerosols indicating that the traditional monitoring approach of spores severely underestimate fungal exposure. The composition of fungal aerosols comprised in average 9% submicronic fragments, 62% large fragments, and 29% spores. The average concentrations of large and submicronic fragments (0.2–1 µm) were 3 × 105 and 0.6 × 105 particles m−3, respectively, and correlated weakly with spores (1.4 × 105 particles m−3). The levels of fragments were 2.6 times higher than the average spore concentration that was close to the proposed hazardous level of 105 spores per m3. The season influenced significantly the fungal aerosol concentrations but not the composition. Furthermore, the ratio of spores in the heterogeneous fungal aerosol composition was significantly higher in saw departments as compared to sorting of green timber departments where the fungal fragments were most prevalent. Being the dominating particles of fungal aerosols in sawmills, fungal fragments should be included in exposure-response studies to elucidate their importance for health impairments. Likewise, the use of fungal aerosol composition in such studies should be considered.