1. Background Occupational lung diseases – many are on the rise Occupational respiratory diseases are conditions of the respiratory system that have occupational exposure as a risk factor for developing the disease,5 and can be caused by exposure to dust, fumes, vapours, gasses and microorganisms. These include occupational asthma, work‑related chronic obstructive pulmonary disease (including chronic bronchitis) and a group of pneumoconiosis diseases such as coal worker’s pneumoconiosis or black lung disease, asbestosis and silicosis. Pneumoconioses are a group of non-malignant interstitial, fibrotic lung diseases caused by inhaling certain kinds of dust particles such as fine silica dust. Occupational silica dust exposure is one of the oldest known causes of lung disease,6 in particular silicosis. Silica, also known as silicon-dioxide, is a naturally occurring and widely abundant mineral. It accounts for 59 per cent of the earth’s crust, and is a major constituent of rocks, sand, glass, quartz, natural stones and particularly engineered stone products. Engineered stone products can contain up to 97 per cent silica. The high amount of silica means that there is a very high risk of workers developing breathing problems and silicosis if they breathe in dust made from these products.7 Silicates such as asbestos, talc and kaolinite are formed when silicon-dioxide combines with other elements, and are also risk factors for lung diseases. Exposure to silica is also linked to an increased risk for a number of other diseases such as lung cancer, kidney disease, renal failure and some autoimmune diseases. There are crystalline and non-crystalline forms of silicon-dioxide. While inhalation of the amorphous form does not often cause clinically significant complications, inhalation of the crystalline form can cause lung disease. For silica particles to be biologically active, they must be small enough to reach minute structures within the lungs. These particles are defined as “respirable” and are usually less than 5µm in diameter.8 Occupational exposure to hazardous airborne contaminants contributes substantially to the burden of lung disease in Australia. There are many occupations that expose workers to contaminants that put them at risk. While some occupational lung diseases such as work-related asthma and asbestosis are showing a downward trend, fibrotic lung diseases including silicosis are increasing in Australia. Evidence
5
Alif SM, Glass DC, Abramson M, Hoy R, Sim MR (2020) Occupational Lung Diseases in Australia 2006–2019, Safe Work Australia
6
Hoy, R and Chambers, D.C (2020) Allergy, 2020 Vol75 Issue 11 Silica-related diseases in the modern world, doi. org/10.1111/all.14202, accessed 10 January 2021
7
Safe Work Australia Crystalline silica and silicosis
8
Hoy et al (2020) (reproduced from Rees DM et al, Parkes’ Occupational Lung Disorders, 4th edn. FL:CRC Press, 2017), accessed 10 January 2021
The National Dust Disease Taskforce’s Final Report JUNE 2021
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