Introduction We describe a unique outbreak of occupational asthma in toolmakers due to chrome. We investigated four employees of a medium-sized manufacturer of precision jet-engine parts for work-related asthma at our city hospital Occupational Lung Disease Unit.

Case Series The four patients were aged between 35 and 56 and three of them had never smoked. They presented with new onset asthma and rhinitis symptoms that were subsequently diagnosed as occupational based on 2-h peak expiratory flow measurements (OASYS-2 scores range: 3.25–4.00). Two of the patients had impaired lung function at diagnosis. One case showed a dual asthmatic response and two cases showed early asthmatic reactions to potassium dichromate 2 mg/ml on specific inhalation challenges. The fourth case had a small late reaction only to cobalt chloride 10 mg/ml. (Abstract P8 Figure 1).

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Abstract P8 Figure 1

Specific inhaled challenge test from case 1, showing dual asthmatic responses to inhaled potassium dichromate (2 mg/ml). There was no response to either used MWF or cobalt chloride (not shown on the plot).

Discussion All workers were sensitised within the preceding 5 years, before which the metalworking fluid brand and composition was changed. The latency onset of symptoms ranged from 6 to 24 months. This suggests leaching of the chrome and cobalt into this particular oil. Skin prick responsiveness and exhaled nitric oxide were not good predictors of airways response. Occupational asthma caused by chrome sensitisation is rare but has been described in electroplaters (1), steel welders (2) and construction workers (3); this is the first outbreak in toolmakers.