Airflow obstruction in nonsmoking, asbestos- and mixed dust-exposed workers

Association between increased small airway obstruction and asbestos exposure in patients with asbestosis

BACKGROUND

Asbestos exposure may cause asbestos-related lung diseases including asbestosis, pleural abnormalities and malignancies. The role of asbestos exposure in the development of small airway obstruction remains controversial. Anatomic and physiologic small airway abnormalities may develop as part of the pathophysiologic process of asbestosis. We hypothesized that inhalation of asbestos may induce small airway defects in addition to asbestosis and pleural abnormalities.

METHODS

In total, 281 patients with newly diagnosed asbestosis were evaluated. Clinical data were collected from the patients' medical charts. The patients were classified into various stages according to their chest X-ray findings using the International Labour Organization classification. Pulmonary function was evaluated by plethysmography and the forced oscillation technique.

RESULTS

Expiratory flow, including the predicted values of the maximum expiratory flow between 25% and 50% of the forced vital capacity (MEF_25-50 ), was significantly lower in the different stages of asbestosis. Accordingly, the predicted percentage of R₅ -R₂₀ was significantly higher with increasing stages of asbestosis. Furthermore, the duration of exposure to asbestos was significantly associated with the forced expiratory volume in the first second (FEV₁ )/forced vital capacity (FVC) ratio and the predicted percentage of MEF₂₅ or MEF₅₀ according to the regression analysis in non-smoking patients with asbestosis. The predicted percentage of FEV₁ or the FEV₁ /FVC ratio was significantly lower and the predicted percentage of R₅ -R₂₀ was significantly higher in smokers than non-smokers.

CONCLUSIONS

The patients with asbestosis have small airway obstructive defects that are significantly associated with asbestos exposure.

Dust is in the air: effects of occupational exposure to mineral dust on lung function in a 9-year study

BACKGROUND

Occupational mineral dust exposure is a well-known risk factor for numerous respiratory and systemic diseases. The aim of the present longitudinal study was to assess the influence of work-associated dust exposure on spirometric results. Furthermore, the impact of implementation of stricter limit values for occupational contact with quartz dust on lung function was evaluated.

METHODS

Anthropometric data (age, gender, BMI), smoking behavior, and lung function parameters (FVC, FEV1, MEF50) from 7,204 medical examinations of 3,229 female and male workers during the years 2002-2010 were examined following Austrian standards for occupational medicine and the guidelines of the European Respiratory Society. Analysis of data was performed using models of multiple linear regression.

RESULTS

Lung function decrease over time was associated with smoking habits and duration of occupational dust exposure. Specifically, occupational quartz exposure negatively influenced the annual lung function parameters (FVC, -6.68 ml; FEV1, -6.71 ml; and MEF50, -16.15 ml/s, all p < 0.001). Thus, an overadditive effect of smoking and work-related contact with quartz was found regarding decline in MEF50 (p < 0.05). Implementation of stricter occupational limit values for dust exposure resulted in a highly significant deceleration of the annual decrease in respiratory function (p = 0.001).

CONCLUSIONS

Individual smoking habits and occupational dust exposure had a negative impact on lung function. To reduce the risk of loss of respiratory capacity, smoking cessation is especially recommended to workers exposed to quartz dust. Moreover, stricter limit values could prevent chronic occupational damage to the respiratory system.

Patterns of pulmonary dysfunction in asbestos workers: a cross-sectional study

BACKGROUND

Restrictive patterns of pulmonary function abnormalities associated with asbestos exposure are well described. Studies are less consistent, however, regarding the association of asbestos inhalation with airway dysfunction and obstructive impairment.

METHODS

We compared pulmonary function test results between 277 chrysotile exposed workers (22% non-smokers) and 177 unexposed controls (50.3% non-smokers). Information on exposure and smoking were collected using a standardized questionnaire. Standardized spirometric and DCLO Measurement methods were utilized. CXRs were read based on ILO pneumoconiosis guidelines.

RESULTS

Asbestos exposed subjects had significantly reduced FVC, FEV1, FEV1/FVC and DLCO. Restricting the analysis to non-smokers, asbestos workers still had about 3% lower FEV1/FVC ratio than controls, but this difference did not reach statistical significance. Among exposed workers, the presence of radiographic evidence of asbestosis further lowered FVC and DLCO but not FEV1/FVC compared to asbestos exposure without radiographic asbestosis. Additionally, smoking asbestos workers had significantly lower DLCO compared to non-smoking workers.

CONCLUSION

Asbestos exposure, especially when radiographic evidence of interstitial fibrosis from asbestosis is present, leads to significant decreases in FVC, FEV1 and the DLCO. However, asbestos exposure alone is not significantly associated with a reduction of the FEV1/FVC. Smoking-asbestos workers had significantly lower DLCO than their non-smoking counterparts. Whether asbestos interacts with smoking additively or synergistically on DLCO needs further investigation. Similarly, further studies are needed to assess the progression and clinical significance of asbestos induced airway dysfunction.

Grand rounds: asbestos-related pericarditis in a boiler operator

CONTEXT

Occupational and environmental exposures to asbestos remain a public health problem even in developed countries. Because of the long latency in asbestos-related pathology, past asbestos exposure continues to contribute to incident disease. Asbestos most commonly produces pulmonary pathology, with asbestos-related pleural disease as the most common manifestation. Although the pleurae and pericardium share certain histologic characteristics, asbestos-related pericarditis is rarely reported.

CASE PRESENTATION

We present a 59-year-old man who worked around boilers for almost 30 years and was eventually determined to have calcific, constrictive pericarditis. He initially presented with an infectious exacerbation of chronic bronchitis. Chest radiographs demonstrated pleural and pericardial calcifications. Further evaluation with cardiac catheterization showed a hemodynamic picture consistent with constrictive pericarditis. A high-resolution computerized tomography scan of the chest demonstrated dense calcification in the pericardium, right pleural thickening and nodularity, right pleural plaque without calcification, and density in the right middle lobe. Pulmonary function testing showed mild obstruction and borderline low diffusing capacity.

DISCUSSION

Based on the patient's occupational history, the presence of pleural pathology consistent with asbestos, previous evidence that asbestos can affect the pericardium, and absence of other likely explanations, we concluded that his pericarditis was asbestos-related.

RELEVANCE TO CLINICAL PRACTICE

Similar to pleural thickening and plaque formation, asbestos may cause progressive fibrosis of the pericardium.

Clinical Correlation of Asbestos Bodies in BAL Fluid

BACKGROUND

Asbestos bodies (AB) in BAL cells are specific markers of asbestos exposure.

METHODS

We retrospectively reviewed BAL cytocentrifuge slides of 30 utility workers with a history of asbestos exposure and 30 normal volunteers. BAL cytocentrifuge slides were blinded and scanned under 40 x light microscope.

RESULTS

AB were found more frequently in subjects with a history of asbestos exposure compared to normal volunteers (10 of 30 subjects, 33%, vs 0 of 30 subjects). The mean number of AB seen in the AB-positive group was 2.7 per slide. Demographic data were comparable including age, gender, and smoking. Exposure histories were also similar: duration > 20 years, onset > 30 years ago, and time since last exposure > 7 years. More AB-positive patients reported respiratory symptoms (70% vs 26%, p < 0.05). High-resolution CT scans of AB-positive patients revealed a higher prevalence of parenchymal disease (70% vs 26%, p < 0.05). AB-positive subjects had reduced pulmonary function compared to AB-negative subjects: FVC (86% vs 97% predicted), FEV(1) (77% vs 92% predicted, p < 0.05), and diffusion capacity of the lung for carbon monoxide (76% vs 104% predicted, p < 0.01).

CONCLUSION

In individuals with a history of asbestos exposure, the presence of AB in BAL cells is associated with higher prevalence of parenchymal abnormalities, respiratory symptoms, and reduced pulmonary function.

Bronchiolitis obliterans in an animal feed worker

A nonsmoking animal feed worker developed severe irreversible airflow obstruction during a 2-year occupational exposure to organic matter, microorganisms, proteolytic enzymes, and both amorphous and synthetic silicates. Her pulmonary dysfunction failed to improve despite removal from the workplace and treatment with bronchodilators and corticosteroids. Open lung biopsy demonstrated peribronchiolar inflammation, scarring within the small airways, and neolumen formation, findings consistent with bronchiolitis obliterans. Energy dispersive analysis of both the bronchoalveolar lavage fluid as well as the biopsy specimens revealed the presence of silicate particles, suggesting a potential link between the silica exposure and the pathologic findings. This case suggests bronchiolitis obliterans can occur as a consequence of occupational exposure in the animal feed industry. In addition, this entity should henceforth be considered when evaluating symptomatic patients with exposure to amorphous and synthetic silicates.