AIRWAY SYMPTOMS AND LUNG-FUNCTION IN PIPELAYERS EXPOSED TO THERMAL-DEGRADATION PRODUCTS FROM MDI-BASED POLYURETHANE

Objectives-To study the prevalence of symptoms from the eyes and the u pper and lower respiratory tract, lung function, and immunological sen sitisation towards isocyanates in pipelayers exposed to thermal degrad ation products from methylene diphenyl diisocyanate (MDI)-based polyur ethane (PUR). Material and methods-50 presently active and 113 formerl y active pipelayers were examined. Also, 65 unexposed workers were inv estigated for comparison. The one year prevalence of symptoms and smok ing history (questionnaire data), lung function (vital capacity (VC) a nd forced expiratory volume in one second (FEV1), and atopy (positive skin prick tests towards standard allergens) were assessed among pipel ayers and controls. For the pipelayers, the presence of work related s ymptoms and estimates of isocyanate and welding exposure were obtained from an interview. Skin prick tests towards specific isocyanate antig ens and determinations of IgE-MDI and IgG-MDI in serum were also perfo rmed. Results-The prevalence of episodes (more than once a month) of i rritative eye symptoms, congestion of the nose, and soreness or drynes s in the throat was much higher among the PUR pipelayers than among th e controls. Most of the pipelayers with symptoms reported that these h ad started and occurred in relation to the PUR welding tasks. Presentl y active pipelayers with recent high PUR exposure showed a significant reduction of FEV1 compared with the controls. The estimated reduction , adjusted for smoking, was -0.3 1 (P=0.04). There was no confounding effect of ordinary welding. None of the pipelayers showed positive ski n prick reactions against the specific isocyanate antigens used, or po sitive IgE-MDI, and only two had increased IgG-MDI. Conclusions-The fi ndings indicate that exposure to thermal degradation products from MDI -based polyurethane has adverse effects on the mucous membranes and ai rways.