Metal-Induced Pulmonary Fibrosis

The incidence of pulmonary fibrosis is increasing worldwide and may, in part, be due to occupational and environmental exposures. Secondary fibrotic interstitial lung diseases may be mistaken for idiopathic pulmonary fibrosis with important implications for both disease management and prognosis. The purposes of this review are to shed light on possible underlying causes of interstitial pulmonary fibrosis and to encourage dialogue on the importance of acquiring a thorough patient history of occupational and environmental exposures. A recent appreciation for various occupational and environmental metals inducing both antigen-specific immune reactions in the lung and nonspecific "innate" immune system responses has emerged and with it a growing awareness of the potential hazards to the lung caused by low-level metal exposures. Advancements in the contrast and quality of high-resolution CT scans and identification of histopathological patterns of interstitial pulmonary fibrosis have improved clinical diagnostics. Moreover, recent findings indicate specific hotspots of pulmonary fibrosis within the USA. Increased prevalence of lung disease in these areas appears to be linked to occupational/environmental metal exposure and ethnic susceptibility/vulnerability. A systematic overview of possible occupational and environmental metals causing interstitial pulmonary fibrosis and a detailed evaluation of vulnerable/susceptible populations may facilitate a broader understanding of potential underlying causes and highlight risks of disease predisposition.