The type of
lung disease caused by
metal compounds depends on the nature of the offending agent, its physicochemical form, the dose, exposure conditions and host factors. The fumes or gaseous forms of several metals, e.g.
cadmium (Cd),
manganese (Mn),
mercury (Hg),
nickel carbonyl (Nl(CO)4,
zinc chloride (ZnCl2),
vanadium pentoxide (
V2O5), may lead to acute chemical
pneumonitis and pulmonary oedema or to acute tracheobronchitis.
Metal fume
fever, which may follow the inhalation of
metal fumes e.g.
zinc (Zn),
copper (Cu) and many others, is a poorly understood
influenza-like reaction, accompanied by an acute self-limiting neutrophil alveolitis.
Chronic obstructive lung disease may result from occupational exposure to
mineral dusts, including probably some metallic dusts, or from jobs involving the working of
metal compounds, such as welding. Exposure to
cadmium may lead to
emphysema.
Bronchial asthma may be caused by complex
platinum salts,
nickel,
chromium or
cobalt, presumably on the basis of allergic sensitization. The cause of
asthma in
aluminium workers is unknown. It is remarkable that
asthma induced by
nickel (Ni) or
chromium (Cr) is apparently infrequent, considering their potency and frequent involvement as dermal sensitizers. Metallic dusts deposited in the lung may give rise to
pulmonary fibrosis and functional impairment, depending on the fibrogenic potential of the agent and on poorly understood host factors. Inhalation of
iron compounds causes
siderosis, a
pneumoconiosis with little or no
fibrosis.
Hard metal lung disease is a
fibrosis characterized by desquamative and giant cell
interstitial pneumonitis and is probably caused by
cobalt, since a similar disease has been observed in workers exposed to
cobalt in the absence of
tungsten carbide. Chronic
beryllium disease is a
fibrosis with sarcoid-like epitheloid
granulomas and is presumably due to a cell-mediated immune response to
beryllium. Such a mechanism may be responsible for the
pulmonary fibrosis occasionally found in subjects exposed to other metals e.g.
aluminium (Al),
titanium (Ti), rare earths. The proportion of
lung cancer attributable to occupation is around 15%, with exposure to metals being frequently incriminated. Underground mining of e.g.
uranium or
iron is associated with a high incidence of
lung cancer, as a result of exposure to
radon. At least some forms of
arsenic,
chromium and
nickel are well established lung
carcinogens in humans. There is also evidence for increased
lung cancer mortality in
cadmium workers and in
iron or steel workers.