After occupational exposure to napthylene-1,5 diisocyanate (NDI) for 2 years, a 33-year-old female worker developed work-related asthma attacks. Occupational-type exposure tests with NDI resulted in a late asthmatic response, whereas a corresponding challenge test with 4,4'-methylenediphenyl diisocyanate was negative. We conclude that NDI exposure in the range of its occupational exposure limit caused occupational asthma in this subject.

Key terms exposure test; isocyanates; late asthmatic reaction; lung function; occupational asthma; occupational exposure limit