Tapioca starch powder as a new cause of occupational asthma in bakers

Background: Gluten-free products are increasingly popular, made with several non-wheat starch powders including maize, potato, and tapioca. Occupational asthma (OA) to tapioca starch powder has not been described. Aim: To present a case of tapioca starch OA. Methods: A 41 year old gluten-free bakery worker was referred with symptoms of work-related rhinitis, chest tightness and wheeze. Skin prick tests (SPTs) to common and specific flour allergens were performed, with a wheal size >3mm positive. Specific IgE (SIgE) was measured using Immunocap (Phadia, Sweden). Serial peak flow analysis, fractional exhaled nitric oxide (FENO), histamine non-specific bronchial hyperresponsiveness (NSBHR), and spirometry were measured to ATS/ERS standards. Specific inhalation challenge (SIC) was performed to maize, potato, and tapioca starch, with a lactose control. A drop in FEV1 of >15% from baseline was considered positive. Results: The patient was most symptomatic on working with tapioca. SPTs were positive to oats, maize, barley, rye, and corn flour. SIgE was positive to potato and rice. An early and sustained late response was seen during SIC with tapioca starch. FEV1 fell 30% within six minutes of exposure, with a further sustained fall of 25% at 360 minutes (figure 1). Control SIC was negative. Conclusion: We present the first case of tapioca starch OA. The potential for non-wheat flours to cause OA is important in light of their increasing use.