Hypersensitivity Pneumonitis Due to Metalworking Fluid Aerosols

This review summarises the clinical knowledge of hypersensitivity pneumonitis in workers exposed to aerosols of metalworking fluid, reviewing published outbreaks and clinical cases.

Metalworking fluid exposure has become the commonest recognised cause of occupational hypersensitivity pneumonitis, having been rare before 2000. There are many possible agents in the metalworking fluid which may be the cause of disease including bacteria, mycobacteria, fungae, biocides, emulsifiers, reodorants and dissolved chrome and cobalt. Causes are likely to be different in different outbreaks. Mycobacteria growing in the metalworking fluid have generated immune responses in some workers, but their role in disease causation is not yet established. Many outbreaks have been identified in large workplaces using common sumps. It is not possible to prevent microbial contamination of metalworking fluids in use. Disease prevention should focus on stopping inhalation of aerosols, particularly by re-engineering to remove recirculation.