Eurosil - The European Association of Industrial Silica Producers

1.7. What are the health effects/risks from RCS?

Respirable dust can penetrate deep into the lungs. The body’s natural defence mechanisms may eliminate much of the respirable dust inhaled. However, in case of prolonged exposure to excessive levels of this dust, it becomes difficult to clear the dust from the lungs and an accumulation can, in the long term, lead to irreversible health effects. Exposure to any type of respirable dust may cause health effects.

For many years, it has been known that prolonged inhalation of fine dust containing a proportion of crystalline silica can cause a specific type of lung damage called silicosis. In fact, silicosis is the world’s oldest known occupational disease. However, the health risks associated with exposure to crystalline silica dust can be controlled and, by using appropriate measures, reduced or eliminated completely. It is just a matter of assessing the risk and taking appropriate action.

A recent hazard assessment of Respirable Crystalline Silica health effects has been commissioned to a team of scientific experts who produced two reports:

  • Review and Hazard Assessment of the Health Effects of Respirable Crystalline Silica (RCS) Exposure to inform Classification and Labelling under the Global Harmonised System: Overview Report (Borm P, Brown T, Donaldson K, Rushton L, 2009); and
  • Review of the Literature of the Health Effects of Occupational Exposure to Crystalline Silica: Silicosis, Cancer and Autoimmune Diseases (Brown T, Rushton L, 2009).

A summary of these reports by Dr Peter Morfeld (Institute for Occupational Medicine of Cologne University, Institute for Occupational Epidemiology and Risk Assessment of Evonik Industries, Essen, Germany) is available at the following link.

  • Silicosis is the main health effect of RCS exposure.
  • Any potential cancer risk due to RCS exposure is limited to lung cancer.
  • Any lung cancer excess risk is demonstrated only under high occupational exposures to RCS and is heterogeneous across industries.
  • Any cancer effect is indirect/secondary to silicosis

More recently links have been made between exposure to respirable crystalline silica dust and other respiratory diseases in addition to silicosis, including lung cancer (see question 1.11.) and Chronic Obstructive Pulmonary Disease (COPD).

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Lung Cancer

The weight of evidence suggests that exposures to respirable crystalline silica which are insufficient to cause silicosis would be unlikely to lead to any increased risk of lung cancer. Different regulatory authorities have recognised that the relative lung cancer risk is increased in persons with silicosis, therefore, according to health authorities such as the SCOEL (Scientific Committee for the setting-up of Occupational Exposure Limits), preventing the onset of silicosis will also reduce any cancer risk.

Furthermore, the risks can be eliminated completely by following good practice principles to reduce exposure to RCS to the lowest levels possible.

Chronic Obstructive Pulmonary Disease (COPD)

COPD is a very common disease affecting many thousands of individuals (normally above retirement age) for whom the main symptoms are shortness of breath and frequent episodes of bronchitis. Approximately 80-85% of COPD cases are caused by smoking but recent evidence suggests that long term occupational exposure to dusts (and respirable crystalline silica dust in particular), fumes and gas may also give an increased risk of COPD. There is also evidence of synergistic effects in smokers who are also exposed to dust.

COPD causes a progressive decline in lung function which ultimately results in disability and premature death. While most COPD is caused by lifestyle factors (smoking), the synergistic effects potentially caused by occupational exposure to dusts, fumes and gas mean that COPD is increasingly being recognised as an occupational disease and as a major health issue for European workers. COPD, as silicosis, is a dose-dependent lung disease.