Makindo Medical Notes

Related Subjects: |Idiopathic Pulmonary Fibrosis |Diffuse Parenchymal Lung disease |Asbestos Related Lung disease |Sarcoidosis |Coal Worker's Pneumoconiosis |Silicosis |Farmer's Lung |Cryptogenic Organising Pneumonia (COP-BOOP) |Extrinsic Allergic alveolitis (Hypersensitivity) |Pneumoconiosis |Cor Pulmonale

Silicosis

Respirable crystalline silica (RCS) is found in stone, rocks, sands, and clays. Exposure to RCS over a long period can cause fibrosis (hardening or scarring) of the lung tissue with a consequent loss of lung function. In Britain, RCS exposure has a workplace exposure limit (WEL), which controls exposure below a set limit, preventing excessive exposure.

About

• Exposure to silica (SiO₂) occurs in various industries and occupations, including stone cutting, glass and cement manufacturing, and quarrying.
• The disease can progress even when exposure stops.

Epidemiology

• Disease is dose-related to exposure levels and duration.
• Usually requires 10-20 years of exposure, but some cases present with less.
• Typically progresses slowly over years or decades, but short-term high-level exposure can result in acute silicosis.
• In the UK, there were 14 deaths from silicosis in 2006 and 7 in 2007.

Occupations with Exposure to RCS

• Quarrying, slate works, foundries, potteries, and stonemasonry.
• Construction (cutting/breaking stone, concrete, or brick).
• Industries using silica flour to manufacture goods.
• Different types of stone contain varying amounts of silica.

Different Types of Stone Contain Different Amounts of Silica

Clinical

• Progressive breathlessness, especially with exertion.
• Chest pain or tightness may be present.
• A persistent, nonproductive cough is common.
• Progressive massive fibrosis (PMF) may develop, leading to severe impairment.
• Fatigue and weakness, especially in advanced cases.
• Weight loss is common in advanced disease.

Complications

• Progressive Massive Fibrosis (PMF): Development of large areas of dense fibrosis that severely impair respiratory function.
• Tuberculosis (TB): Increased risk due to impaired macrophage function in the lungs.
• Chronic Obstructive Pulmonary Disease (COPD): Silicosis can contribute to the development of COPD, particularly among smokers.
• Lung Cancer: Prolonged exposure to silica dust is a known risk factor for lung cancer.
• Right-Sided Heart Failure (Cor Pulmonale): Chronic lung disease can lead to pulmonary hypertension and subsequent right-sided heart failure.

Investigations

• Chest X-ray: Shows multiple well-circumscribed nodular opacities, especially in the mid and upper lobes. "Eggshell" calcification of the hilar lymph nodes is characteristic.
• High-Resolution CT (HRCT) Scan: Provides detailed imaging, revealing nodules, fibrosis, and sometimes emphysematous changes.
• Pulmonary Function Tests (PFTs): Typically show a restrictive pattern with reduced lung volumes and impaired gas exchange.
• Bronchoalveolar Lavage (BAL): May reveal silica particles within macrophages, supporting the diagnosis.
• Biopsy: Can confirm the diagnosis by showing silica nodules and interstitial fibrosis.

Management

• Early Detection and Exposure Cessation: There is no cure for silicosis, so prevention through minimizing exposure and early detection is critical.
• Occupational Controls: Using water sprays, ventilation systems, and other controls to reduce airborne silica dust in the workplace.
• Personal Protective Equipment (PPE): Use of N95 respirators when working in environments with silica dust.
• Smoking Cessation: Important to reduce the risk of lung cancer and COPD.
• Regular Monitoring: Periodic lung function tests and chest X-rays for workers exposed to silica.
• Supportive Care: Management of symptoms like cough and breathlessness, including bronchodilators or oxygen therapy if necessary.
• Supervision and Legal Reporting: Reporting cases of occupational silicosis for compensation and implementing safety standards in the workplace.

References

• Silicosis at HSE