An epidemiology study of lung function changes of toluene diisocyanate foam workers in the United Kingdom

Objective: To determine whether longitudinal declines in ventilatory capacity and the occurrence of respiratory symptoms in workers manufacturing polyurethane foam were related to toluene diisocyanate (TDI) exposure. Methods: A population of 780 workers in 12 United Kingdom factories was followed for 5 years. Modified United Kingdom Medical Research Council (MRC) respiratory questionnaires and three or more lung function measurements were completed for each subject. Mean TDI exposures for all jobs in which subjects were employed were assessed by personal monitoring (2294 measurements) and related to their occupational histories. Results: The United Kingdom 8-h and 15-min maximum exposure limits for TDI were exceeded in 4.7% and 19.0% of the samples taken, respectively. There was some increase in reported respiratory symptoms amongst exposed workers, but the annual declines of 1-s forced expiratory volume (FEV1) and forced vital capacity (FVC) were not related to TDI exposure and were typical of those observed in other longitudinal populations. FEV1 declines were smoking related. Evidence was found suggesting that a small excess decline in FEV1 and FVC occurred in the first few years of employment for workers not previously exposed to TDI. Conclusion: This study does not provide evidence that there is a TDI-related decline in FEV1 and FVC in workers exposed to less than the United Kingdom 8-h occupational exposure limit of 5.8 ppb.