Coal Workers Pneumoconiosis - Types, Symptoms, Diagnosis, and Treatment

Introduction:

Coal workers' pneumoconiosis is an occupational hazard commonly called black lung disease. It occurs in people who work with coal. The inhaled coal dust progressively builds in the lungs and results in inflammation, fibrosis, and necrosis. The risk of developing this disease depends on how long the person has been exposed to coal dust. Older people who are more than 50 years of age are commonly affected.

What Are the Types of Pneumoconiosis?

Pneumoconiosis is a group of lung diseases caused by inhaling dust particles. The types of pneumoconiosis include:

• Asbestosis - It is caused by inhaling dust particles from asbestos.

• Silicosis - It is caused by inhaling silica dust.

• Coal workers' pneumoconiosis - It is caused by inhaling coal dust.

Other forms of pneumoconiosis can be caused by inhaling aluminum, antimony, barium, graphite, iron, kaolin, mica, and talc dust particles. Prolonged exposure to organic dust like molds from hay, malt, sugarcane, mushrooms, and barley can produce lung disease. Brown lung disease is a type of pneumoconiosis caused by cotton, flax, or hemp fibers. It stimulates histamine release and constricts the air passage.

How Does Coal Workers' Pneumoconiosis Develop?

The coal dust that enters the lungs cannot be removed or destroyed by the body. The resident alveolar or interstitial macrophages engulf the dust particles and remain in the lungs' connective tissue or lymph nodes. These particles stimulate the macrophages to release enzymes, cytokines, oxygen radicals, and fibroblast growth factors and cause inflammation, fibrosis, and the formation of nodular lung lesions. Macrophages loaded with dust particles appear as granular, black areas under the microscope. Necrosis is seen in areas of dense lesions. This leads to the formation of large cavities within the lungs. Pneumoconiosis develops after a milder form of the disease known as anthracosis. Prolonged exposure results in severe forms of the disease, simple coal workers' pneumoconiosis and complicated coal workers' pneumoconiosis or progressive massive fibrosis.

How Does Coal Workers' Pneumoconiosis Appear?

Simple pneumoconiosis presents 1 mm to 2 mm nodular aggregations of anthracosis macrophages supported by a collagen network. 1 mm to 2 mm diameter nodules are called coal macules, and larger ones are called coal nodules. This is present in the initial site of dust accumulation - the respiratory bronchioles. The coal macule is surrounded by airspace, known as focal emphysema, which extends into progressive centrilobular emphysema. Simple pneumoconiosis progresses to complicated pneumoconiosis following continuous exposure to coal dust. Large masses of dense fibrosis greater than 1 cm develop in the upper lung zones with decreased lung function. The coal macules coalesce to form coal nodules.

What Are the Symptoms of Coal Workers' Pneumoconiosis?

The symptoms include:

• Cough.

• Shortness of breath.

• Chest tightness.

• Coughing up black sputum.

What Are the Complications?

Complications of coal workers' pneumoconiosis include:

• Airway obstruction.

• Chronic bronchitis.

• Respiratory tract infection.

• Respiratory failure.

• Hypoxemia.

• Cor pulmonale.

• Arrhythmias.

• Pneumothorax.

Significant silica exposure causes Mycobacterial infection. Diffuse interstitial fibrosis accelerates peripheral squamous cell carcinoma. If it occurs with rheumatoid arthritis, it is called Caplan syndrome.

How Is It Diagnosed?

• Radiography:

A chest radiograph is an important diagnostic tool in coal workers' pneumoconiosis. The presence of nodular opacity larger than 1 cm is complicated pneumoconiosis.

• Computed Tomography (CT) Scan:

CT scans are more sensitive to evaluating coal workers' pneumoconiosis than chest X-rays. Both chest X-rays and CT are necessary diagnostic tests. Magnetic resonance imaging (MRI) scan improves the specificity and accuracy of diagnosis. CT scan helps monitor the progression of pneumoconiosis.

• Pulmonary Function Test:

In simple coal workers' pneumoconiosis, significant lung impairment is not seen. A slight decrease in the alveolar-arterial pressure, reduction in diffusion capacity, and minimal hypoxemia are observed. In complicated pneumoconiosis, a reduction in the ventilatory capacity in proportion to the mass's size decreased diffusion capacity, and hypoxemia is observed. Simple pneumoconiosis is seen in elevated bronchoalveolar lavage fluid concentrations of antioxidants, proinflammatory cytokines, and mediators that increase fibroblast proliferation. The simple 6-minute walk test is performed in addition to chest imaging and pulmonary function test to quantify the impairment caused by pneumoconiosis.

• Biopsy:

A biopsy is not usually needed for coal workers' pneumoconiosis. A biopsy is done only if malignancy is suspected.

How Is Coal Workers' Pneumoconiosis Treated?

There is no cure for this disease. Treatment is symptomatic. Supportive care improves respiratory management.

Medical Care:

Bronchodilators are given for airflow limitation, antibiotics for respiratory infections, and supplemental oxygen for managing hypoxemia. Caplan syndrome is treated similarly to progressive massive fibrosis. The possibility of mycobacterial infection should be considered in patients with unexplained loss of weight, chronic cough, fever, or night sweats. Patients affected with fibrosis require oxygen therapy for adequate ventilation.

Surgical Care:

Lung transplantation is done in end-stage coal workers' pneumoconiosis. Their posttransplant survival is up to 4 years.

How to Prevent Coal Workers' Pneumoconiosis?

It is preventable by minimizing exposure to dust particles. Coal miners are encouraged to take chest radiographs at 5-year intervals. Patients should receive influenza and pneumococcal vaccinations.

What to Expect From Coal Workers' Pneumoconiosis?

The prognosis is poor in patients with progressive massive fibrosis. Treatment is palliative. Survival entirely depends on the length of the exposure. Rapidly progressive forms are associated with significant respiratory compromise and death. The following variables predicted the outcome suggests disease.

• The partial pressure of carbon dioxide greater than 45mmHg at intubation suggests less severe illness.

• Acute physiology and chronic health evaluation II score greater than 25 at intubation suggests worse mortality.

• A ratio of partial pressure of oxygen to the fraction of inspired oxygen, less than 200 mmHg at the time of intubation, suggest increased mortality.

Conclusion:

Coal workers' pneumoconiosis, also called black lung disease, is a chronic lung disease. It requires long-term management of the symptoms to prevent lung damage. The best way to prevent pneumoconiosis is to wear a respirator mask while working with coal. Regular physical examinations and chest X-rays should be taken for coal workers to monitor their lung health. Prevention is important because this disease cannot be cured or reversed.