Respiratory symptoms and wheat flour exposure: a study of flour millers

The objective of this study was to determine the prevalence of respiratory symptoms and their relationship to sensitization to wheat flour allergens a nd fungal amylase, in a group of workers from the UK flour milling industry . A cross-sectional study was used to evaluate symptoms, using a structured interview technique, and sensitization, using skin prick test findings, fr om 679 employees in flour milling and packing operations at 18 flour mills. A total of 147 workers (147/679, 22%) described upper respiratory tract sy mptoms of some kind. In the majority (139/147, 95%) these symptoms were of an occasional or transitory nature and were related to short-term exposures to high levels of dust. Three individuals (3/679, 0.4%) were identified wh ose symptoms were thought to be the result of allergy to wheat flour. The p revalence of positive skin prick tests to wheat flour allergens and to fung al amylase was 1.2% (8/678) and 0.9% (6/678), respectively. Measurements of total inhalable dust exposure for personnel exposed to flour dust were tak en at 10 of the sites (116 samples). For production personnel the levels we re typically between 1 and 10 mg/m(3) (8-h time weighted average), with a m edian of 6.2 mg/m(3). Hygiene operatives had appreciably higher exposure th an production personnel, with a median of 18.7 mg/m(3). Overall, 43% (50/11 6) of all samples exceeded 10 mg/m(3) (8-h time weighted average). The find ings suggest that the risk of sensitization to wheat flour allergens from c urrent dust exposures in flour mills is very low. Wheat allergy was respons ible in only a small proportion of the total who had respiratory symptoms. The principal causation of symptoms experienced by the workforce was consid ered to be a non-specific irritant effect related to short-term exposures t o high levels of total inhalable dust.