Silica and silicosis: history

Silica hazards = Silicosis = Mining ?

When discussing silica hazards, the word ‘silicosis’ instantly springs to mind. And silicosis itself tends to be associated with the mining industry. The debilitating lung disease, triggered by inhalation of crystalline silica dust, has loomed large in medical, political and social policy responses, and captured the public imagination as expressed in popular culture, from mining ballads to representative art. There are good reasons for this – not least the mass suffering caused by the disease around the world, its status as an occupational disease and the importance of mining in the global economy.

But the mining industry is not the full story when it comes to silicosis, and silicosis is not the full story when it comes to silica hazards. Silica, the main component of the Earth’s crust, is present in an extraordinarily wide range of industrial and non-industrial settings and everyday products (including many cosmetics and cat litter).

Since the 1990s, medical science has been re-evaluating the possible role of silica in triggering a number of systemic inflammatory diseases including systemic lupus erythematosus, scleroderma, rheumatoid arthritis, and sarcoidosis. Although previously thought to be harmful only when inhaled in dust form, there is now a question as to whether exposure to silica in other forms may be also risky.

Silicosis vs. silica hazards

So why, then, has the focus historically been on silicosis rather than the full range of potential silica hazards? A number of factors may have played a role in silicosis – particularly silicosis in the mining industry – taking centre stage.

• Silicosis wrought particular devastation in the mining industry and other sectors which were crucial to industrialization. As such, it became an important economic issue that governments, industry and medical science could no longer ignore. The limitations of the 1930 definition of silicosis – driven very much by the financial interests of the mining industry – kept the focus on mining-related silicosis and may have indirectly shut down further investigation of other silica risks.
• Silica is universal and therefore difficult to prove as a unique pathogenic agent. For example, workers who have been exposed to silica have generally been exposed to a range of toxic chemicals and inorganic dust particles as well.
• Limitations in medical technology undoubtedly played a role.  New medical instruments (electronic microscopes, scanners) and new procedures (bronchoalveolar lavage) are facilitating a fresh perspective on silica risks, while new forms of exposure to silica dust (notably the health crisis among rescue workers after the September 11, 2001 terrorist attacks) have forced the issue.