When respirable crystalline silica (RCS) is breathed in, it can cause a condition known as silicosis. This can be disabling or even fatal.
Silica dust enters the lungs and causes fibrosis (hardening or scarring) of lung tissue, as the body’s immune system tries to remove the RCS particles. This affects lung function and makes it difficult for the lungs to take in oxygen. People with silicosis will likely experience:
- severe shortness of breath
- difficulty in walking short distances, completing tasks or doing exercise
- fatigue and a loss of mobility
- weight loss
- becoming house- or bed-bound
- chest pain
- premature death, in some cases due to heart failure.
Silicosis usually occurs after 10 to 20 years of occupational exposure to RCS and is diagnosed via chest x-ray. There are three types of silicosis.
- Acute silicosis – occurs after a heavy exposure (over a short-term) to RCS. It can also increase the risk of lung infections such as tuberculosis.
- Accelerated silicosis – occurs after several years of high exposure levels to RCS.
- Chronic silicosis – occurs after more than 10 years of exposure where the scarring and inflammation of the lungs develops over a longer time. This can lead to heart failure and premature death.
Unfortunately, silicosis continues to develop after exposure has ceased and there is no cure for the condition. However, silicosis is preventable by controlling exposure to RCS.
Other diseases caused by silica
Exposure to RCS increases the risk of developing lung cancer and workers with silicosis are at an increased risk of developing the condition.
With lung cancer, abnormal cells grow into tumours that interfere with lung function. The cancer cells can also migrate to other parts of the body and cause further damage.
Chronic obstructive pulmonary disease (COPD)
This is a collection of long-term lung conditions that can be extremely disabling and even lead to death. Conditions include chronic bronchitis and emphysema.
The lungs and breathing tubes become damaged, making it difficult to breathe. COPD develops slowly and many do not realise they have the disease. It is not usually reversible.
Workers exposed to RCS are also at an increased risk of developing kidney disease. Kidney failure can occur in those who have had high silica exposures or have silicosis.
How many workers are affected by silica exposure?
An estimated 42,258 deaths worldwide between 2000-2016 have been attributed to occupational exposure to silica, according to a World Health Organization and International Labour Organization report (page 28). In addition, 1.3 million disability-adjusted life years (DALYs) have been attributed to occupational exposure to silica in the same period.
The deaths and DALYs are a result of trachea, bronchus and lung cancers caused by silica.
Which industries are affected by silica exposure?
Exposure to silica dust occurs in many industries, but particularly in construction, manufacturing, agriculture, and oil and gas. Industries include:
- abrasive blasting
- brick, concrete or tile manufacturing
- cement finishing
- ceramics manufacturing
- coke and other fuel manufacturing
- glass manufacturing
- metals and machinery manufacturing
- mineral product manufacturing
- mining and quarrying
- steel manufacturing
In fact, anywhere that silica-containing material is cut, ground or drilled.
What tasks are high risk for producing respirable silica dust?
Common tasks where people may be exposed to respirable silica dust include:
- breaking, crushing, grinding or milling silica-containing material such as concrete, aggregate or mortar
- drilling, cutting, chiselling or sanding silica-containing material
- dealing with cement
- moving earth, for example excavating, mining, quarrying or tunnelling
- abrasive blasting or sandblasting
- laying, maintaining or replacing ballast
- handling, mixing or shovelling dry materials that include silica
- using silica, sand or silica-containing products in the manufacturing process of glass and other non-metallic mineral products
- using sand as a moulding medium in foundries
- using silica flour, a finely ground form of crystalline silica
- dry sweeping of materials after a task where silica dust has been created.
It’s not just specific activities, such as drilling or cutting materials that contain RCS, which can expose people to silica dust. As well as disturbing fine silica dust, exposure can occur when someone cleans up after a task. The dust can also:
- stay in the air for a period after work has finished
- be released from clothes or surfaces
- become airborne again when disturbed by people, vehicles or equipment
- be released by equipment leaks or spillages.