Studies of Ventilatory Capacity and Histamine Response during Exposure to Isocyanate Vapour in Polyurethane Foam Manufacture.

Complaints of respiratory symptoms amongst workers in a factory using isocyanate to produce polyurethane foam led to a study of changes in ventilatory capacity in the course of several working days. Mean decreases of the order of 018 1. were observed in the forced expiratory volume at one second in 15 employees during each of three normal working shifts. No significant change occurred on days when a process involving the liberation of isocyanate was stopped, or when the men were given an oral aminophylline compound prophylactically. An aerosol of isoprenaline failed to reverse the decrease in ventilatory capacity observed during one normal working day. Approximately half the subjects studied were found to show increased bronchial sensitivity to a histamine aerosol; all were smokers, whereas none of the non-smokers showed a significant (over 10%) reduction in ventilatory capacity after histamine. Smokers and/or positive histamine reactors tended to show a greater decrease in ventilatory capacity during a working day than non-smokers or non-reactors. The present findings, which confirm clinical reports of adverse respiratory effects of isocyanate in low concentrations, are compared with other studies of ventilatory capacity during occupational exposure to respiratory irritants.