Understanding Occupational Lung Diseases: Causes, Diagnosis, and Management**

1. Occupational lung disease A. H. Mehrparvar, MD Occupational Medicine department Yazd University of Medical Sciences

2. Introduction • Respiratory tract a common site of occupational injury • Two sites: • Airways • Parenchyma • Site of injury depends on: • Gas solubility • Particle size

4. Evaluation • History • Physical exam • Pulmonary function tests: • Spirometry • Body plethysmography • DLCO • Imaging: • Chest X ray • HRCT

5. Acute inhalational injury • Short-term exposure to high concentration of gases, fumes, or mists • Generally as an accident • Irritation of membranes • Chemical pneumonitis • ARDS • Chmicals: • Formaldehyde • Cadmium salts • chlorine

7. Signs and symptoms • Upper respiratory tract irritation • Cough • Stridor • Hoarseness • Wheezing • PFT: normal, obstructive, mixed • Chest X ray: normal to pulmonary edema

8. Occupational asthma • Reversible airway obstruction, with airway inflammation and bronchial hyperresponsiveness as a consequence of occupational exposures

9. Types of asthma • Sensitizer-induced • Type 1 immune reaction (IgE) • Latent period for sensitization • In a percent of workers • Irritant-induced • RADS • Without latency • Exposure to a high concentration • In most workers

11. Diagnosis • History: • Hx of dyspnea (exertional), cough, in an episodic mode, night symptoms • Physical exam • wheezing • PFT • Spirometry: normal or obstructive • BD test: mostly responsive • Chest X ray • Not helpful

12. Treatment • Reduction or elimination of exposure • Beta agonists • corticosteriods

13. Hypersensitivity pneumonitis • Immunologically mediated inflammatory disease of lung parenchyma caused by some organic dusts

15. Diagnosis • History • Acute: cough, fever, chills, malaise, dyspnea after an acute exposure • Chronic • Physical exam” • Basilar inspiratory crackles • PFT: • Restrictive or mixed pattern, low DLCO • CXray: • normal, reticulonodular pattern, infiltration

16. Management • Avoidance of exposure • Corticosteroids

17. Pneumoconiosis • A type of O-ILDs. • Due to inhalation and deposition of mineral dust within lung parenchyma. • Induce tissue reaction • May cause disruption of alveolar architecture or collagen fibrosis.

18. Common features of all pneumoconioses • Deposition of mineral dusts in lung tissue. • Presence of parenchymal tissue reaction • Positive chest x-ray findings • PFT may be abnormal depending on the stage and severity and complications.

19. Types of pneumoconioses • Benign: • Asymptomatic • Normal spirometric findings • Collageneous: • Symptomatic • Abnormal spirometric findings

20. Main clues for diagnosis( usually sufficient for legal compensation) • Sufficient and reasonable exposure. (intensity and duration) • Positive chest x-ray findings (good quality is required) • No other concomitant diseases that mimic pneumoconiosis.

21. Collagenous pneumoconiosis • Silicosis • Asbestosis • Coal-workers’ pneumoconiosis

22. Silicosis • A collagenous pneumoconiosis caused by inhalation of respirable (0.2 – 10 µm ) free crystalline silicon dioxide ( SiO2 ). • Chronic diffuse interstitial fibronodular lung disease. • High-dose and long-time inhalation is required. • A strict dose-response relationship is present • Cumulative exposure • Intensity × duration

23. Sources of exposure • Removal of stone • Hard rock mining • Tunnel drilling • Stone quarrying • Processing stone or sand • Stone crushing • Granite carving

25. Sources of exposure • Abrasive use of silica or sand • Abrasive blasting • Foundry casting • Knife sharpening • Production of fine silica powder

27. Sources of exposure • Utilization of sand or silica powder • Glass manufacture • Plastic manufacture • Paint manufacture • Pottery • Ceramic manufacture • Construction work

28. Silica-induced diseases • Chronic bronchitis • Emphysema • Silicosis • Tuberculosis • Lung cancer • Collagen vascular diseases

29. Clinical presentation • Chronic simple ( classic ) silicosis • Chronic complicated ( PMF ) silicosis • Accelerated silicosis • Acute silicosis

30. Chronic simple silicosis • Moderate long-time exposure (at least 10 yr) to less than 30% quartz • Symptoms and signs: • Mostly asymptomatic • Chronic productive cough or DOE due to chronic bronchitis • Progressive DOE and dry cough (late finding) • Ph. exam normal or crackles • PFT: normal or restrictive (mainly) obstructive or mixed pattern • CXRay: small (<1 cm), round nodules predominantly in upper lobes, hilar lymphadenopathy and calcification

31. Complications • Progressive massive fibrosis • Tuberculosis(3-fold to 20-fold) • Pulmonary and extrapulmonary • Typical and atypical mycobacteria • Immune-mediated • Scleroderma (m/c) • SLE, RA , … • Renal (GN, nephrotic syndrome)(usually in heavy exposure) • Lung cancer • Fungal diseases • Cryptococcus • Blastomycosis • coccidiopmycosis