Background
Chronic exposure to high concentrations of respirable crystalline silica (RCS) can cause silicosis, which is a progressive fibrotic disease of the lungs that leads to chronic shortness of breath and scarring of the lung tissue. In 1997, the International Agency for Research on Cancer (IARC) determined that crystalline silica inhaled in the form of quartz or cristobalite from work-related sources is carcinogenic to humans (Group 1).
The main forms of crystalline silica are quartz, cristobolite and tridymite. Quartz is most common and occurs in higher concentrations in granite, shale and sandstones and is present in most metal, nonmetal and coal mines.
Summary of hazard
Crystalline silica occurs in fine respirable dusts created by crushing and handling ores. Also commonly referred to as silica, RCS is comprised of crystalline forms of silicon dioxide that are abundant in most soils and rocks. Amorphous and fumed forms of silica are less harmful than RCS.
Very fine respirable dusts characteristically have low density and diameter which facilitates easy transport to the alveolar regions of the lungs when inhaled.
Contributory factors
- Mining, crushing and handling ores with high quartz content.
- Ineffective use of dust control measures to minimise worker exposure directly or from fugitive dust emissions from exploration and mining activities, including haulage roads.
- Over-reliance on personal protective equipment.
- Absence of sufficient information and training of the risks associated with inhalation of dusts, including how and when to use appropriate respiratory protective equipment.