Airway hyperresponsiveness among workers exposed to isocyanates at Yeocheon petrochemical plant

Jang, An Soo; Choi, Inseon S; Lee, Soong; Seo, Jeong Pyeong; Yang, Seung Won; Moon, Jai Dong; Lee, Kang Jin

Abstract

OBJECTIVE
To investigate the prevalence of airway hyperresponsiveness induced by isocyanate at one petrochemical industry complex in Yeochon, Korea. METHOD: Questionnaires, allergic skin prick test, toluene diisocyanate (TDI)-specific IgE, and non-specific airway hyperresponsiveness (AHR) were studied in 73 exposed workers and 27 control subjects. Methacholine challenge tests were done and bronc hial responsiveness (BR index) was defined as log (% fall of FEV1)/ log (last concentration of methacholine +10).
RESULTS
Twenty-three workers (31.5% ) had respiratory symptoms, 21 had nasal symptoms, and eight had skin symptoms. Exposed workers with respiratory symptoms (n=22) had significantly higher BR index than those without them (0.82+/-0.06 vs 0.60+/-0.02, p<0.05). Exposed workers tended to have higher BR index than controls (0.67+/-0.03 vs 0.62+/-0.02). Three exposed workers had PC20 methacholine <2.0 mg/ml. There were no significant differences in atopy score between exposed workers and controls (p>0.05). Specific IgE antibodies were found in 19.7% of exposed workers. FEV, showed a significant negative correlation with BR index (r =-0.25, p<0.05). Poor correlation was noted between BR index and atopy, smoking status, or exposure duration.
CONCLUSION
These findings suggest that workers exposed to isocyanates are at higher risk of airway hyperresponsiveness.