Silicosis: everything you need to know about this lung disease

Silicosis: the “miner’s disease”

Also known as “miner's disease”, silicosis was described as early as the 16th century. The word silicosis appeared in 1871, defined by an Italian doctor, Achile Visconti, while this occupational environmental disease, caused by the inhalation of particles (it is classified among pneumoconioses, which are diseases of “pulmonary overload”) already existed. since a long time.

Silicosis, which is characterized by inflammation and progressive fibrosis of the lungs, is one of the deadliest occupational diseases in history: it has claimed numerous victims all over the world, including tens of thousands of workers in Europe since 1945.

Silicosis: what is this lung disease?

It is a chronic disease, which comes from the inhalation of crystalline silica dust (quartz) or more rarely, silicates (talc). Silica is a common naturally occurring crystal and the main component of sand. “When this dust is inhaled over a long period, the silica particles infiltrate into the respiratory tree, lodge and accumulate deep in the lungs (at the level of the lower airways, the pulmonary alveoli, where the gas exchanges), creating nodules and gradually leading to the destruction of the alveoli.explains Dr Frédéric Le Guillou, pulmonologist, allergist and president of the Santé respiratory Europe association.

The silica particles thus destroy the white blood cells, which form scar spots on the surface of the alveoli and cause them to lose their elasticity. Gradually, this damage reduces gas exchange, generating shortness of breath in the affected person. In the terminal stage, the patient can no longer breathe properly and needs an oxygen bottle constantly, even if only to walk a few steps.

An occupational disease

This occupational disease, observed in mines, quarries, construction sites or during prolonged contact with substances such as concrete or glass, is unfortunately irreversible (even after stopping exposure to silica dust ): not only does it cause disability, but its complications are often fatal.

The onset of silicosis and its severity vary depending on the concentration of silica dust present in the air and the duration of this exposure. Generally speaking, studies show that it is dangerous when you are exposed to a high concentration over a few weeks or over several years, but also when you are exposed to a low concentration over a prolonged period.

Category 1 carcinogen crystalline silica

According to the International Agency for Research on Cancer (IARC), crystalline silica is carcinogenic in humans when inhaled in the workplace in the form of quartz or cristobalite: the IARC has therefore classified it among the Category 1 carcinogens. The American Conference of Governmental Industrial Hygienists (ACGIH) has also classified quartz as a Category 2 human carcinogen.

Asbestos: do not confuse silicosis and asbestosis

“Moreover, it has nothing to do with asbestosis which refers to a very diffuse scar lesion of the lung tissue, due to the inhalation of asbestos dust”specifies our specialist.

What is the process of lung tissue destruction?

Silicosis is a form of pneumoconiosis (lung inflammation due to inhalation of dust), which manifests itself by shortness of breath and lung impairment.

When an exposed person breathes silica dust, it enters the lungs and reaches the air sacs, where gas exchange of oxygen and carbon dioxide takes place. The silica particles are taken up by immune cells called macrophages, which are designed to destroy foreign organisms in the body using special enzymes. “Unfortunately, the lungs do not have the means to completely eliminate silica dust: instead of being destroyed by macrophages, silica attacks immune cells, which release enzymes as they die. Once these enzymes are released, they irritate the lungs and initiate an inflammatory process: the release of cytokines then leads to inflammation, as well as fibrosis. This is because special cells – called fibroblasts (which produce collagen) – move and then begin to lay down fibrous tissue around the particles, forming nodules of scar tissue in the lungs (so-called “eggshell” microcalcifications). “details Dr Frédéric Le Guillou.

The accumulation of scars gradually reduces the exchange of oxygen in the lungs and leads to worsening shortness of breath, gradually hampering breathing. Neither the secretion of mucus nor the often associated dry cough can stop this shortness of breath. Silicosis can also cause chest pain and sputum containing traces of blood. Hardened scars appear as fibrosis on a chest x-ray.

Are there different categories of silicosis?

There are three forms of silicosis which have their own manifestations:

Acute silicosis

Also called silicoproteinosis, it can appear after just a few months to two years of exposure to a high concentration of silica particles. It is characterized by shortness of breath, feeling weak, fever, cough and weight loss. “On the x-ray, the inflammation is localized in the tops of the lungs, and not in the bases,” specifies the pulmonologist.

Chronic silicosis

This is the most common form, often developing after more than ten years of low to moderate exposure to silica dust; at first asymptomatically then the condition deteriorates over many years. “Chest x-rays help determine damage to the lungs when chronic silicosis is suspected: microcalcifications are easily visible.”, continues Dr Frédéric Le Guillou. The symptoms that should be taken into account are: shortness of breath during physical activity, as well as clinical signs of poor oxygen and carbon dioxide exchange. At an advanced stage of the disease, fatigue, extreme shortness of breath, chest pain, and respiratory failure are also present.

Accelerated silicosis

It develops more quickly than chronic silicosis, after only one to ten years of exposure to silica dust. Severe shortness of breath, weakness and weight loss are the signs that should alert you.

Please note: The disease continues to progress, even when the affected person has stopped being exposed to silica. This damage is irreversible. Pulmonary fibrosis can also develop into lung cancer.

There are also simple silicoses and complicated silicoses, called progressive massive fibrosis (PMF). Simple silicosis may never get worse.

To summarize, several factors are likely to cause silicosis, to varying degrees:

• The amount and type of dust inhaled;
• The amount of free crystalline silica in the dust;
• The form of silica (crystalline or amorphous);
• The size of inhaled particles;
• The duration of the exhibition;
• Individual capacity for resistance: some people are more sensitive to it than others;
• The presence of associated smoking or not;
• The age of the worker.

Illness of miners: are other professions exposed?

Silicosis is caused by the inhalation of silica dust particles (crystalline silica). The main mineral component of the earth's crust, its dust is therefore produced by most industrial activities.

The professionals most affected are people working in mines: “But there are very few of them today.“, raises the pulmonologist. “For miners, silicosis is a bit of a disease of the past.”. There are also other professions which are still affected by this illness today.

Where is silica dust found?

However, silicosis does not only affect miners. It may also concern people who work in quarries, tunnel boring, building sites (construction, demolition and rehabilitation of buildings or infrastructure) and public works (sanding, sweeping, shot blasting, breaking, drilling, grinding or sawing). concrete, mortars, milling, use of hammer drills, polishing, cutting or cutting of siliceous stones, bricks, glass, roof coverings, etc.), jeans manufacturing factories, and even certain flour mills.

In the construction sector, exposure levels to crystalline silica still exceed…