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Information

Editors

IrmeliLindstöm
HeikkiFrilander

Silicosis (Grinders' Disease) and and other Diseases Caused by Exposure to Quartz Dust

Essentials

  • Silicosis (grinders' disease) presents as nodular fibrosis of the lung tissue particularly in the upper lung fields, caused by crystalline silica.
  • Susceptibility to lung cancer and pulmonary tuberculosis are increased in people with silicosis.
  • Workers at risk of developing occupational silicosis should go through an initial health examination and then regular follow-up examinations every three years.

Exposure

  • Within European Union, the employer and employee associations have agreed on reducing exposure to crystalline silica dust. The Good practice guide linked to the agreement provides guidance for different industrial sectors in achieving this goal http://guide.nepsi.eu/.
  • The primary goal is to prevent exposure to crystalline silica (silicon dioxide) dust, i.e. quartz, cristobalite or tridymite. This is achieved by preventing the spread of dust from the source - by
    • adopting less dusty materials and methods
    • partitioning the dust source
    • capturing the generated dust by ventilation solutions (e.g. local exhaust) or
    • binding the dust with a water spray.
    • Often there is a reason to use a respirator mask which is suitable for the task and which has an adequate protection factor for the exposure conditions.
  • Exposure may occur in the following occupations:
    • mining, quarrying, stone work, construction, and foundry work
    • manufacture of glass, porcelain, enamel, clay and stone products
    • manufacture of lime, cement, mortar, bricks, concrete and concrete products
    • sand blasting and grinding
    • manufacture of agglomerated stone slabs (countertops)
    • stone washing of denim fabric
    • production and dismantling of refractory material
    • construction industry: demolishing old structures for renovation work, dry grinding and clearance.

Diseases

  • Crystalline forms of silica usually cause chronic pulmonary fibrosis, silicosis (grinders' disease).
  • The patients with silicosis usually have a history of silica dust exposure over a time period exceeding 10 years, and the latency period has usually been over 20 years.
  • The more rare acute silicosis may already develop within a few weeks or months after an exceptionally heavy exposure and may rapidly lead to respiratory failure. Cases associated with sand blasting and the manufacture of agglomerated stone slabs have been described.
  • Rarely, silicoproteinosis, which resembles alveolar proteinosis, may develop.
  • Silicosis predisposes the individual to pulmonary tuberculosis (silicotuberculosis) which is considered as an occupational disease if the original silicosis was classified as such.
  • IARC (International Agency for Research on Cancer/WHO) classifies crystalline silica dust as carcinogenic to humans (Group 1). Lung cancer in patients with silicosis is compensated as an occupational disease.
  • Quartz dust and other industrial dusts, gases and fumes have been shown to be associated with chronic bronchitis and COPD. An occupational disease should be suspected in a COPD patient with exposure to quartz or other dusts if the smoking history is less than 10 pack years.
  • An association between quartz dust exposure and autoimmune diseases (scleroderma, rheumatism) and chronic kidney diseases has been described.

Clinical picture

  • Chest x-ray typically shows nodular fibrosis in the upper lung fields and calcification of hilar lymph nodes. HRCT shows much more clearly the different changes in silicosis. In the acute form, ground-glass opacities may be seen in the lung parenchyma.
  • In a slowly progressing disease the patient remains symptomless for a long time. At a later stage and in the acute form the symptoms may include an irritative cough and dyspnoea.
  • Fine mid- and end-inspiratory rales can be heard on auscultation.
  • Lung function tests may initially show a decrease in vital capacity. As the disease progresses, obstruction and diffusion impairment may be observed.

Diagnosis

  • Significant exposure to silica dust
  • Even when abnormalities on radiological findings are visible the patient may remain asymptomatic.
  • E.g. sarcoidosis should be excluded in the differential diagnostics.
  • Sometimes lung biopsy
  • Pulmonary function tests help to determine the degree of disability.

Surveillance

  • There are specific national instructions concerning regular surveillance of workers at risk of developing occupational silicosis.
  • The worker should go through an initial health examination and then regular follow-up examinations every three years.
  • The initial examination should include medical history, clinical examination, chest x-ray (PA and lateral views) and spirometry.
  • The follow-up examinations contain the same investigations, except that the need for a chest x-ray is evaluated on a case-by-case basis, as the person's age and cumulative exposure increase.For those heavily exposed to stone dust, lung X-rays are recommended every three years after ten years of exposure.
  • Consult local guidance for more information on regular surveillance.
  • If the findings in an exposed person suggest pneumoconiosis, the clinical diagnostic examinations should be performed in a specialized hospital department or other specialized unit.
  • The doctor who diagnoses the occupational disease must report it to the occupational safety and health authority in accordance with local policies.
  • People with silicosis need to be followed up by a specialist according to their clinical situation and at least every three years. Consult local guidance about sending copies of medical records to an insurance company.
  • Because the diseases due to the exposure may emerge only after many years, health examinations should be continued also after the exposure has ceased, if the exposure has been sufficient to cause silicosis. Occupational health service should guide persons who end their employment, retire or become unemployed to seek health checks at an appropriate place.

    References

    • The European network for silica (NEPSI). Good practice guide http://guide.nepsi.eu/
    • Rees D, Murrey J. Silica. In: Newman Taylor A, Cullinan P, Blanc P, Pickering A (eds). Parkes' Occupational Lung Disorders. 4th edition. Taylor & Francis Group, Boca Raton, 2017. Pages 187-202.