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silicosis

Classification: 1) acute silicosis 2) chronic simple silicosis 3) complicated silicosis 4) silicotuberculosis Epidemiology: - any occupation that disturbs the earth's crust or uses silica-containing rock or sand - silica is the most obundant mineral on earth - the most common form is quartz [2] - silica exposure in mines, quarries, sand-blasting areas, road construction, hydraulic fracturing, stone finishing, masonry, pottery, ceramics, foundry work - occupational silica exposure to dust from engineered stone* (Quartz) used in countertop fabrication - affected workers primarily young Latino immigrant men - many patients present with severe disease, some cases are fatal [6] - older males * also referred to as artificial stone [7] Special laboratory: - pulmonary function testing - may show obstructive lung disease Radiology: - chest X-ray may show multiple small nodules throughout the lung with upper lobe predominance - rule out pulmonary tuberculosis - CT of chest - deterioration of status - suspicion of lung cancer [2] Complications: - silica exposure may result in immune dysfunction - increased risk of - tuberculosis - autoimmune disease - systemic sclerosis - rheumatoid arthritis - lupus erythematosus - lung cancer [2,4] - RR = 1.26, 1.54, 1.68, & 1.70 by quartiles of cumulative silica exposure (25 year lag) [4] - absolute lifetime risk small, 0.51% (45 years exposure at 0.1 mg/m3) [4] - once fibrosis develops, no therapy alters course of disease [2] Management: 1) symptomatic treatment with inhaled bronchodilators [2] a) beta2 adrenergic agonist b) tiotropium 2) antibiotics for pulmonary infections - treatment of tuberculosis 3) supplemental oxygen for hypoxemia [2] 4) annual PPD 5) patients with old fibrotic lesion on chest X-ray & positive PPD a) 4 month therapy with isoniazid plus rifampin, or b) 12 months of isoniazid alone 6) glucocorticoids have been used to mitigate immune reaction to silica (investigational) [2]

Specific

acute silicosis (silicoproteinosis) chronic simple silicosis complicated silicosis; progressive massive (silico) fibrosis silicotuberculosis

General

occupational lung disease

References

  1. Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed) Lippincott-Raven, Philadelphia, 1998, pg 758-59
  2. Medical Knowledge Self Assessment Program (MKSAP) 16, 17, 18. American College of Physicians, Philadelphia 2012, 2015, 2018. - Medical Knowledge Self Assessment Program (MKSAP) 19 Board Basics. An Enhancement to MKSAP19. American College of Physicians, Philadelphia 2022
  3. Nasrullah M, Mazurek JM, Wood JM, Bang KM, Kreiss K. Silicosis mortality with respiratory tuberculosis in the United States, 1968-2006. Am J Epidemiol. 2011 Oct 1;174(7):839-48. PMID: 21828370
  4. Liu Y, Steenland K, Rong Y et al Exposure-response analysis and risk assessment for lung cancer in relationship to silica exposure: a 44-year cohort study of 34,018 workers. Am J Epidemiol. 2013 Nov 1;178(9):1424-33 PMID: 24043436
  5. Esswein EJ, Breitenstein M, Snawder J, Kiefer M, Sieber WK. Occupational exposures to respirable crystalline silica during hydraulic fracturing. J Occup Environ Hyg. 2013;10(7):347-56. PMID: 23679563
  6. Fazio JC, Gandhi SA, Flattery J et al Silicosis Among Immigrant Engineered Stone (Quartz) Countertop Fabrication Workers in California. JAMA Intern Med. Published online July 24, 2023 PMID: 37486642 https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2807615 - Hua JT, Rose CS, Redlich CA. Engineered Stone-Associated Silicosis - A Lethal Variant of an Ancient Disease. JAMA Intern Med. Published online July 24, 2023. PMID: 37486690 https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2807621
  7. Leso V, Fontana L, Romano R et al Artificial Stone Associated Silicosis: A Systematic Review. Int J Environ Res Public Health. 2019 Feb 16;16(4):568. PMID: 30781462 Free PMC article.