Silica diseases are caused by the inhalation of silica dust. Sandstone has a very high silica content and is prevalent on the east coast of NSW, particularly in the Sydney basis where the excavation of Hawkesbury sandstone is necessary during the course of road construction, tunnel construction or other developments. Such excavation work creates high levels of silica dust. Consequently, labourers and construction workers who work on these projects are at risk of developing silica diseases. Foundry workers can also be exposed to high levels of silica dust during the course of their work, placing them at risk of developing silica diseases. Pottery or ceramic workers are also at risk of developing silica diseases. The diseases caused by the inhalation of silica dust are set out below:
Simple and Accelerated Silicosis
Simple silicosis is caused by the inhalation of silica dust which causes inflammation and scarring in the lungs resulting in nodular lesions forming in the upper lobes of the lungs. In its early stages, it may not cause any symptoms. As time goes on, the worker may develop a cough and shortness of breath on exertion. Simple silicosis tends to result from low level exposures to silica dust over a number of years and does not always progress.
Accelerated silicosis tends to result from very heavy and prolonged exposure to silica dust. It tends to develop earlier and progresses. Symptoms include a chronic cough and severe shortness of breath on exertion.
Progressive massive fibrosis is the end stage of silicosis. It occurs when the nodular lesions that appear in silicosis become confluent and in effect, form the one mass. Progressive massive fibrosis is associated with a severe cough and very severe shortness of breath on exertion. It is associated with reduced life expectancy.
Silicosis can predispose a worker to tuberculosis. In cases where that occurs, the disease is referred to as silico-tuberculosis.
Like asbestos, substantial and prolonged exposure to silica dust can cause lung cancer. As with the disease asbestosis, the development of silicosis and progressive massive fibrosis substantially increases the risk of developing lung cancer, especially among people who are already at risk due to other factors such as smoking.
Scleroderma is a disease of the skin and in extreme cases, the internal organs, which causes the skin to become taut and firm. Symptoms can include extreme pain.
Scleroderma is the result of a dysfunctional immune system. It is believed that substantial exposure to silica dust can cause or materially contribute to the impairment of the immune system, giving rise to the development of scleroderma.
Occupational asthma results from the inhalation of dust or fumes in the work place. The potential causes are numerous. Exposure to welding fumes (which often contain dust particulars) is a leading cause. Drilling or grinding into certain metals is another cause. Exposure to the fumes generated during the aluminium smelting process is another. The delay between exposure and the onset of symptoms varies. If the exposure is brief but very high, symptoms may commence within days. In other cases, it may take weeks to months for symptoms to develop.
The symptoms of occupational asthma are similar to asthma. The worker can experience shortness of breath, a chronic cough, tightness of the chest, wheezing and irritation of the nasal passages. Some forms of occupational asthma can cause hypersensitivity to dust generally.
Bagassosis is caused by exposure to spores from fungi that develop on the fibrous matter left over from the processing of sugar cane stalks. It can cause an immune response in the lungs, resulting in respiratory impairment.
Farmer’s lung is caused by the inhalation of the spores of fungi which grow on wheat or hay.
Talcosis is caused by the inhalation of talc. The small particles inhaled cause lung damage resulting in respiratory impairment.
Aluminosis is caused by the inhalation of alumina particles. It causes a fibrosis (scarring) of the lung which results in respiratory impairment.
Byssinosis is caused by the inhalation of cotton dust resulting in asthma like symptoms, including a cough, chest tightness, sensitivity to other dusts and breathlessness.
Berylliosis is caused by the inhalation of beryllium. This is usually found in various metals that are used in manufacturing and metals used in electronics.
Short or prolonged exposures can cause the worker to become sensitised to beryllium. Small inflammatory nodules then develop in the lung. Symptoms include a cough, shortness of breath, chest pain, joint aches, weight loss and fever.