Sodium metabisulphite induced airways disease in the fishing and fish-processing industry

Background Sodium metabisulphite (SMBS) is recognized as a potential cause of airway irritation and possibly occupational asthma, but awareness of its use in the fishing and fish-processing industry is low. Aims and methods To describe three cases of occupational airways disease due to SMBS exposure and to review the literature. Results Three patients, one trawlerman and two prawn processors, developed work-related airways disease due to exposure to SMBS, one with irritant-induced asthma with a positive-specific bronchial challenge associated with very high sulphur dioxide exposures, one with occupational asthma and one with vocal cord dysfunction and underlying asthma. Of the nine cases recorded in the literature, most were non-atopic and responses to specific bronchial challenge when undertaken showed an immediate response. Exposures to sulphur dioxide in these settings are very high, in excess of 30 ppm. Conclusion SMBS should be regarded as a cause of occupational airways disease and its use in the fish and prawn-processing industry investigated further to better identify risks from exposure and handling of the agent in the workplace.