OCCUPATIONAL ASTHMA CAUSED BY FD-AND-C BLUE-DYE NO 2

We report the case of a 55-year-old male who experienced cough, dyspne a, wheezing, and nasal congestion immediately upon exposure to FD&C Bl ue Dye No.2 (Indigotine) at work. The patient had worked for 10 years mixing and grinding powdered synthetic red, yellow, and blue dyes for use in foods; symptoms had occurred for 2 years and only with exposure to Indigotine (C16H8N2Na2O8S2), a free flowing blue powder. Prick tes ting to Indigotine (20 mg/mL) was negative. ELISA failed to detect spe cific IgE, IgA, IgM, or IgG to Indigotine-HSA conjugates. Bronchial ch allenge was done according to the method of Pepys et al. beginning wit h 4 x 10(-4) lactose dilution of Indigotine powder. After 5 minutes of exposure to 4 gm Indigotine/100 gm lactose, the patients developed dy spnea and audible wheezing. At 20 minutes postexposure, there was a 20 % decline in FEV(1) from prechallenge baseline; no late phase response was observed. A second bronchial challenge with sodium sulfate, the m ajor nondye product additive was negative. To our knowledge, this is t he first documented case of occupational asthma due to FD&C Blue Dye N o. 2. The pathogenesis is uncertain but does not appear to be IgR medi ated.