Pneumoconiosis of workers in the coal industry

Pneumoconiosis of workers in the coal industry (anthracosis, black lung disease, pneumoconiosis of miners)) are caused by inhalation of coal dust. The deposition of dust leads to the accumulation of dusts overloaded by macrophages around bronchioles (coal maculae), sometimes causing central bronchiolar emphysema.

Pneumoconiosis usually does not cause any symptoms, but can develop to progressive massive fibrosis with decreased lung function. The diagnosis is based on an anamnesis and a roentgenography of a thorax. Treatment of pneumoconiosis is generally effective.

[1], [2], [3], [4], [5], [6], [7], [8]

What causes pneumoconiosis?

Pneumoconiosis is caused by chronic inhalation of dust of high-carbon coal (anthracite and bituminous coal), typically for more than 20 years. Inhalation of quartz contained in coal can also contribute to the clinical manifestations of the disease. Alveolar macrophages absorb dust, secrete cytokines that stimulate inflammation, and accumulate in the interstitial lungs around the bronchioles and alveoli (coal macula). Coal nodules develop due to the accumulation of collagen, and central emphysema develops due to the weakening and dilatation of the walls of the bronchioles. Fibrosis may occur, but is usually limited to areas adjacent to coal maculae. Changes in lung architectonics, bronchial obstruction and functional impairment are usually moderate, but can be severe in some patients.

Two forms of the disease are described: simple, with single coal makuls, and complicated, with confluent maculae and progressive massive fibrosis (PMF). In patients with simple pneumoconiosis, PMP develops at a frequency of approximately 1-2%. In this condition, the nodules merge, forming black, elastic parenchymal masses usually in the upper posterior pulmonary areas. Masses can invade and disrupt blood supply and respiratory pouches or turn into caverns. PMP can develop and progress even after exposure to coal dust has ceased. Despite the similarity of coal-induced PMP and silicic conglomerate, the development of pneumoconiosis in coal workers is not related to the content of quartz in coal.

The relationship between pneumoconiosis and the characteristic symptoms of rheumatoid arthritis is well described. It is unclear whether the pneumoconiosis of miners predisposes to the development of rheumatoid arthritis, or in patients with pneumoconioses develops a special form of rheumatoid arthritis, or rheumatoid arthritis increases the sensitivity of miners to coal dust. Multiple rounded nodules in the lung that appear in a relatively short time (Kaplan syndrome) are an immunopathological reaction associated with rheumatoid diathesis. Histologically, they resemble rheumatoid nodules, but have a peripheral zone of more acute inflammation. Patients with pneumoconiosis are in the group of moderately increased risk of active tuberculosis and non-tuberculous mycobacterial infection. With pneumoconiosis the same principles of observation and treatment of tuberculosis as with silicosis are applied. There was a weak association between pneumoconiosis and progressive systemic sclerosis and stomach cancer.

Symptoms of pneumoconiosis

Pneumoconiosis is usually asymptomatic. Most of the chronic pulmonary symptoms in miners are caused by other conditions, for example industrial bronchitis caused by coal dust, or concomitant emphysema due to smoking. Coughing can be chronic and bother the sick even after they change jobs, even those who do not smoke.

PMP causes progressive dyspnea. Black sputum (melanophthisis) is rare and is caused by the breakthrough of sections of PMF in the respiratory tract. PMP often progresses to the development of pulmonary hypertension with right ventricular failure.

Diagnosis of pneumoconiosis

The diagnosis depends on the history of the influence of the aggressive factor and on the chest or chest CT scan of scattered, small round infiltrates or nodules (PUR) or at least one infiltrate larger than 10 mm in the background of pneumoconiosis (PMF). The specificity of chest X-ray for PMP is low, since up to a third of the lesions identified as PMF are malignant neoplasms, scars or other lesions. CT of the chest is more sensitive than chest radiography to identify confluent nodules, early PMF and cavitation. Lung function tests are not diagnostic, but are useful for assessing lung function in patients who may develop obstructive, restrictive or mixed external respiratory disorders. Since gas exchange disorders occur in a number of patients with extensive simple pneumoconiosis and complicated pneumoconiosis, it is recommended that the diffusion capacity of carbon monoxide (DLC0) and arterial blood gases be evaluated at the onset of pulmonary disease and periodically at rest and during exercise.

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Treatment of pneumoconiosis

Treatment of pneumoconiosis is rarely necessary with simple pneumoconiosis, although smoking cessation and tuberculosis surveillance are recommended. Patients with pulmonary hypertension and / or hypoxemia are prescribed additional oxygen therapy. Pulmonary rehabilitation can help more severely affected workers to withstand daily physical activities.

How to prevent pneumoconiosis?

Preventive measures include the removal of dust, smoking cessation and vaccination against pneumococcus and influenza. Workers with pneumoconiosis, especially those with PMP, should be protected from further exposure to dust, especially at high concentrations. Tuberculosis is treated according to current recommendations.

Pneumoconiosis can be prevented by suppressing the formation of coal dust in coal seams. Despite multiple instructions, dust contact continues to occur in the extractive industry. Breathing masks provide only limited protection.