Cambridge Encyclopedia :: Cambridge Encyclopedia Vol. 68

silicosis - Silica, Pathology, Prevalence, Symptoms, Types of Silicosis, Diagnosis, Treatment, Prevention

An industrial disease of occupations such as coal mining, stone dressing, and sand blasting, and of the ceramics industry. It is caused by inhalation of fine particles of silica which induce scarring of the lungs.

Silicosis
Classifications and external resources
ICD-10 J62
ICD-9 502

Silicosis (also known as Grinder's disease) is a form of pneumoconiosis caused by inhalation of crystalline silica dust, and is marked by inflammation and scarring in forms of nodular lesions in the upper lobes of the lungs. (The name has been described as a "trophy word" -- its only job is to serve as the longest word .)

Silicosis (especially the acute form) is characterized by shortness of breath, fever, and cyanosis (bluish skin).

This respiratory disease was first recognized in 1705 by Ramazzini who noticed sand-like substances in the lungs of stonecutters.

Silica

Silica is the second most common mineral on earth.

The induction period between initial silica exposure and development of radiographically detectable nodular silicosis is usually 10 years.

Pathology

When the small silica dust particles are breathed into the lungs, they can embed themselves deeply into the tiny alveolar sacs and ducts where oxygen and carbon dioxide gases are exchanged.

When fine particles of silica dust are deposited in the lungs, macrophages that ingest the dust particles will set off an inflammation response by releasing tumor necrosis factor, interleukin-1, leukotriene B4 and other cytokines.

Furthermore, the surface of silicon dust can generate silicon-based radicals that lead to the production of hydroxyl and oxygen radicals, as well as hydrogen peroxide, which can inflict damage to the surrounding cells.

Characteristic lung tissue pathology in nodular silicosis consists of fibrotic nodules with concentric "onion-skinned" arrangement of collagen fibers, central hyalinization, and a cellular peripheral zone, with lightly birefringent particles seen under polarized light.

Prevalence

Although silicosis has been known for centuries, the industrialization of mining has led to an increase in silicosis cases.

Also, the mining establishment of Delamar Ghost Town, Nevada was ruined by a dry-mining process that produced a silicosis-causing dust.

Indeed, silicosis is an occupational hazard to mining, sandblasting, quarry and foundry workers, as well as grinders, stonecutters and those continually exposed to silica dust.

Protective measures such as respirators have brought a steady decline in death rates due to silicosis in Western countries.

Symptoms

The symptoms of silicosis include:

Tachypnea or shortness of breath after physical exertion Dry or severe cough, often persistent and accompanied by hoarseness of the throat Fatigue or tiredness Changes in breathing pattern (rapid breathing or shallow breathing) Loss of appetite Chest pain Fever

In advanced cases, the following may also occur:

Cyanosis Cor pulmonale Respiratory insufficiency

Patients with silicosis are particularly susceptible to tuberculosis (TB) infection.

Types of Silicosis

Classification of silicosis is made according to the disease's severity, onset, and rapidity of progression. These include:

Chronic silicosis

A form of the disease that develop after 20 years or longer of exposure to low levels of silica dust.

Asymptomatic silicosis

Early cases of the disease do not present any symptoms

Acute silicosis

Silicosis that develops after 1 to 3 years of exposure to very high concentration of silica dust.

Accelerated silicosis

Silicosis that develops after an average of 10 years of exposure to high concentration of silica dust.

Diagnosis

Patient history should reveal exposure to silica dust due to occupation.

Chest x-ray will confirm the presence of nodules in the lungs, especially in the upper lobes.

Treatment

Silicosis is an irreversible condition, with no cure.

Prevention

The best way to prevent silicosis is to identify work-place activities that produce crystalline silica dust and then to eliminate or control the dust.

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