Interstitial lung diseases
Interstitial lung diseases (ILDs) have been more closely associated with an occupational aetiology than any other category of respiratory disease. Classic examples of occupational diseases are the pneumoconioses caused by crystalline silica (silicosis), asbestos (asbestosis) and coal dust (coal worker’s pneumoconiosis). Figure 1 shows the mortality rate of pneumoconiosis in Europe. There are also less common pneumoconioses caused by nonfibrous silicates (such as talc, kaolin or mica) or other minerals.
Although individual susceptibility plays a role in mineral pneumoconioses, they are generally considered to be caused by the progressive accumulation of toxic dust in the lungs. In contrast, individual susceptibility and/or immunological sensitisation play a more dominant role in the pathogenesis of ILDs such as extrinsic allergic alveolitis (hypersensitivity pneumonitis) (EAA), chronic beryllium disease (berylliosis) or hard metal/cobalt-related lung disease.
The possibility of an occupational aetiology should always be considered in the differential diagnosis of ILDs, particularly for conditions such as sarcoidosis and idiopathic pulmonary fibrosis, because ‘occult’ exogenous causes are easily missed if a thorough occupational and environmental history is not taken. There are epidemiological reasons to believe that occupational and environmental factors may be involved in these conditions.