Occupational asthma from sensitisation to 4,4-methylene-bismorpholine in clean metalworking fluid.

European Respiratory Society guidelines on the management of work-related asthma recommend that occupational asthma with an allergic mechanism should be diagnosed by both identifying the workplace as the cause, and confirming sensitisation to the asthmagen by specific inhalational challenge (SIC), in the absence of any available specific IgE tests [1, 2]. Used (contaminated) metalworking fluid is the usual cause of occupational asthma in exposed workers. We present the first case of occupational asthma due to the biocide additive 4,4-methylene-bismorpholine present in clean metalworking fluid.