Mushroom worker’s lung: organic dust exposure in the spawning shed

Two people employed for several years in the spawning shed of a mushroom farm developed mushroom worker’s lung. The first patient presented in respiratory failure, with radiological features characteristic of hypersensitivity pneumonitis. The condition of the second patient was subacute on presentation, with a computed tomography (CT) scan showing ground-glass opacities. With absence from the workplace and no steroid therapy, the symptoms of both patients subsided and the results of lung function tests and CT scans improved markedly.

Two employees of the same mushroom farm presented to our hospital within a 5-month period. The farm is a large commercial producer of Agaricus bisporus mushrooms. Both workers were employed in the spawning shed, where mushroom compost is tipped onto a conveyor belt for mushroom spawn (sterilised grain inoculated with mushroom mycelia) distribution. The process is associated with increased levels of ambient organic dust.1 The principal means of minimising organic dust in the shed was local exhaust ventilation. Neither worker recalled receiving instructions about respiratory protection or the specific hazard of organic dust exposure during their employee-induction process.