بسم الله الرحمن الرحیم Silicosis S.N.Assadi

Introduction: Most common pneumoconiosis in world(occupational exposure to crystalline silica) *quartz,cristobalite,tridymite, … OSHA(PEL) :100 μg/m 3

Occupations: *mining *milling *quarrying & stone work *foundry work *sandblasting *pottery making *glass making *boiler work

Pathogenesis: 80% of silica dust cleared quickly *directly cytotoxic(cell membran e),*oxidant damage,*release of inflammatory mediators. *silicotic nodule=histo. Hallmark *polarized light microscopic *scanning electron microscopy

Silicosis: *simple silicosis *complicated or conglomerate s. (progressive massive fibrosis) *accelerated silicosis *acute silicosis

Simple silicosis: No chest symptoms;chronic prod- uctive cough. P/E: coarse sounds Rounded opacities(1-10mm) *p (up to 1.5 mm) *q (1.5-3 mm) *r (3-10 mm) Eggshell calcification***

Progressive massive fibrosis: Cough / exertional dyspnea to respiratory failure.P/E: decrease Sounds. *A (>10mm, <50mm) *B (>A but no > right upper zone) *C (> right upper zone) Pulmonary impairment

Accelerated silicosis: Time from exposure to X-Ray & PFT change is much shorter. *Rapid progression to progressive massive fibrosis.

Acute silicosis: Short duration and high concentr- ation. Respiratory failure to death. P/E: crackles (alveolar & airway fluid) *silicoproteinosis *restriction (Impairment)

Diagnosis: 1)History of silica exposure that sufficient to cause this illness. 2)Chest radiograph features con- sistent with silicosis. 3)Absence of other illness that mimic silicosis.

WHO recommendation: CXR : At baseline, after 2-3 years of ex- posure, then every 2-5 years. Spirometry+questionnaire : At baseline,then annually or at the same frequency as CXR.

Associated illnesses: *Mycobacterial infections PPD + / Isoniazid /at least 1 year *IARC: I lung cancer *Connective tissue disease (Caplan ’ s syndrome) *Glomerulonephritis *lesions(liver,spleen,BM,L.nodes)

Prevention & treatment : *Substitution *Engineering intervention *Respiratory protective devices *Corticosteroid with Isoniazid *Lung lavage *Tetrandrine * Lung transplant