What are the health effects of exposure to Respirable Crystalline Silica (RCS)?

Respiratory Crystalline Silica (RCS) is hazardous to health, exposure can lead to respiratory diseases: Occupational Asthma, Chronic Obstructive Pulmonary Disease (COPD), and Silicosis.

The current WEL Workplace Exposure Limit for RCS is 0.1mg.m-3 as an 8 hour TWA (time weighted average). At exposures of as little as 0.3 mg.m-3 there is a 20% risk of developing silicosis.

A further reduction of the WEL to 0.05 mg.m-3 may be introduced.

Silicosis – A slow, progressive, irreversible disease that usually develops many years after initial exposure. The main symptom is breathlessness. In severe cases death can ensue. Silicosis is diagnosed by chest X‑ray where the presence of rounded nodules of scar tissue on the lungs is visible as white opacities. The highest risk of developing silicosis is from exposure to dry, freshly fractured fine particles of RCS that are generated during many common workplace tasks such as drilling, cutting, grinding, polishing etc.

Acute Silicosis – People who experience exceptionally high exposures over a few months or years can develop this rapidly progressive and often fatal condition (exposures in the order of 1.5 mg.m-3 on a daily basis for a year or two). This can result in death within months of exposure.

Lung cancer – Heavy and prolonged exposure to RCS under the conditions that produce silicosis can cause lung cancer.

Chronic Obstructive Pulmonary Disease (COPD) – an umbrella term that covers emphysema and chronic bronchitis. It is characterised by impaired airflow within the lungs and is not fully reversible. The symptoms are cough with phlegm, and/or wheezing and breathing difficulties and it too can result in death.

Workers with silicosis are at increased risk of tuberculosis and may develop kidney disease and arthritis (and related conditions).

Smoking may influence the development of symptoms in silica-exposed workers.