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

Abstract

To the Editor: 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. A 54-year-old Kenyan male presented with a 2-year history of rhinitis, wheeze, dry cough and chest tightness, which were worse at night and while at work, and improved away from work on holiday. He had had rhinitis from grass pollen, perfumes and cleaning agents intermittently for 15 years, and acne due to metalworking fluid 5 years previously. There was no childhood or family history of asthma and he had never smoked cigarettes. He had been employed as a machine tool setter operator for 22 years manufacturing car axles. For the past 6 years he had worked on an enclosed computer numerical controlled milling, drilling and boring machine, with its own oil sump, using carbide-tipped tools. It was loaded by a robot but there was no delay between the end of machining and door opening, which produced a visible mist about 3 m from his work station. The machines used …