Wheat antigen content of inhalable dust in bakeries: modeling and an inter-study comparison

The purposes of this study were (a) to compare wheat antigen content of inhalable bakery dust in Canada and the Netherlands and, (b) to evaluate the validity of dust exposure measurement as a surrogate of specific antigen exposure. Wheat antigen exposure data from the studies of Canadian and Dutch bakeries were used to explore the correlation between dust and antigen levels, and identify factors explaining variability of the antigen content of bakery dust. Direct comparison and pooling of the data were possible because the same antigen assay was used in both studies. Wheat antigen exposure samples totaling 544 were available, all originating from personal full-shift monitoring of bakery workers. The wheat antigen content of bakery dust varied greatly between the two studies and with different products within each study. Bakery dust from the Canadian study had a much higher wheat antigen content. Therefore, the interstudy difference in the wheat antigen content of bakery dust was by far the most significant in undermining the validity of the use of dust levels as a surrogate measures of wheat antigen exposure. The production of croissants, wheat bread and buns, puff pastry, bagels, and cinnamon buns was associated with increased wheat antigen content of bakery dust, while in rye bread production, bakery dust with less wheat antigen content was emitted. Although we can, in part, account for the pattern of variability in the wheat antigen content of bakery dust (explaining 49% of it), we concluded that the effort involved in modeling it accurately would probably exceed that expended in direct measurement of the antigen level. Therefore, for the exposure assessments carried out for the purpose of managing occupational risks of aeroallergen exposure in bakeries, we recommend the use of analytical techniques that can directly measure antigen exposure.