About Silica
What is Silica?
Silica, sometimes referred to as quartz, is a very common material, in fact about half of the earth’s crust is made from it. It’s found in stone, rock, sand, gravel and clay, as well as bricks, tiles, concrete, manufactured stone and some plastic and other common materials.
When these materials are cut, sanded, drilled or worked in other ways, significant levels of airborne dust is likely to be created and workers may be exposed to this dust.
Silica dust is harmful when inhaled into the lungs. It is 100 times smaller than a grain of sand, so it can be breathed in without realising it.
It is estimated that around 600,000 Australian workers each year are exposed to silica dust at work, including miners, construction workers, farmers, engineers, bricklayers and road construction workers, as well as those working in demolition. Of these, up to 6,000 are likely to develop lung diseases during their working life.
Health Effects
Exposure to silica dust can cause respirable diseases such as silicosis and lung cancer. The likelihood of developing these diseases depends on how much Respirable crystalline silica (RCS) dust a worker breathes in and for how long.
Silicosis is a fibrosis (scarring) of the lung resulting in loss of lung function. This fibrosis is incurable and continues to develop after exposure has stopped. Persons with advanced silicosis suffer severe shortness of breath and may suffer complications such as heart failure.
Silicosis can be further classed into:
- Chronic (or classic) silicosis, typically observed in workers after 15 years or more since they were first exposed
- Accelerated silicosis, appearing in workers after high exposure over a shorter period of time (five to 10 years)
- Acute silicosis, observed in workers within a few months to two years after exposed to silica at very high concentrations. Acute silicosis can cause very serious health effects and is life threatening
Significant long term exposure to crystalline silica has also been associated with an increased risk of developing lung cancer. Approximately 230 cases of lung cancer a year are attributed to exposure to silica dust
Silicosis History
While lung diseases cause by exposure to silica dust has be recognised for over 400 years, with names like miners asthma, potters rot, phthisis, it has been responsible for millions of cases of disease and death since civilization, stone masonry and mining began.
Agricola described a pulmonary disease that affected stonecutters and minors as far back as 1556. As technology advanced with high pressure and air equipment for mining and airblasting for other industries, worker were exposed to much higher levels of silica dust.
Some experts believe that silicosis is currently more than a global health concern, but that it is an epidemic in the making.
It is critical then that precautions be taken to reduce the exposure, by worker, to this potentially dangerous dust.