[Occupational asthma caused by maleic anhydride].

Organic acid anhydrides (OAA) are widely used in the chemical industry. They are irritants and can cause sensitization and asthma. We describe the first documented case of occupational asthma caused by the OAA maleic anhydride (MA) in the production of insecticides. A 60-year-old man developed work-related respiratory symptoms after eight years of intermittent exposure to MA. Peak expiratory flow measurements showed greater variance on work days than on days off. Both a basophilic activation test and determination of the MA-specific IgE level in serum showed sensitization to MA.