Exposure and nasal inflammation in workers heating polyurethane

Abstract

Objective: To test the hypothesis that exposure to thermal-degradation products of polyurethane (PUR), particularly isocyanates, induced nasal inflammation.

Methods: Thirty-eight workers -14 with a history of work-related nasal symptoms (WRS/Nose), and 15 referents without such history - exposed to sprayed and heated PUR glue, were studied with regard to biomarkers of isocyanate exposure [4,4'-diphenylmethane diisocyanate (4,4'-methylenediphenyl diisocyanate; MDI) and 2,4- and 2,6-toluene diisocyanate (TDI), determined as 4,4'-diphenylmethane (U-MDX) and 2,4- and 2,6-toluene (U-2,4 and U-2,6-TDX) diamine in hydrolysed urine and nasal lavage fluid (NAL)], inflammation [albumin; eosinophilic cationic protein (ECP); myeloperoxidase (MPO) and cells in NAL], serum IgG specific for MDI (S-IgG-MDI) and TDI (S-IgG-TDI), and nose symptoms. Nine unexposed office workers were also examined.

Results: The exposure to sprayed and heated PUR glue, especially when heated by gun, was associated with the presence of biomarkers of isocyanate exposure in urine; after work the levels [median (range)] in all workers were: U-MDX 0.32 (<or=0.1-1.5); U-2,6-TDX 0.33 (<or=0.1-0.71) microg/g creatinine. Also, 5/38 workers had detectable levels in NAL. Furthermore, the biomarkers of inflammation in NAL - albumin ( P<or=0.05; Kendall), MPO ( P=0.01), and neutrophils ( P<or=0.01) - showed similar patterns of relationships with the exposure to glue heated by guns. After work, workers who had complained of WRS/Nose had higher levels of albumin (medians 3.5 vs. 1.9 mg/l; P=0.05, Mann-Whitney U-test) and MPO (14 vs. 11 microg/l; P<or=0.05) in NAL than those who had had no such complaints. U-2,6-TDX, as well as S-IgG-MDI and S-IgG-TDI, were associated with increased levels of the inflammation biomarkers, U-2,6-TDX also with the symptoms. As expected, acute symptoms after exposure were associated with the inflammation biomarkers.

Conclusions: The present data indicate that thermal degradation products of PUR induced a 'chronic' rhinitis. At exposure, there was an accentuation of symptoms; the signs of acute inflammation were less obvious.