Occupational Hygiene Around the World: Exposure to Dust and α-Amylase in Bakeries

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Abstract
α-Amylase enzyme is added to baking flour to compensate the natural amylase content and to increase the quality of bread. α-Amylase is, however, a strong sensitizer and has been reported to cause respiratory symptoms in workers. The purpose of this study was to evaluate the exposure of the workers to airborne total dust and α-amylase (an Aspergillus enzyme) in Finnish bakeries. Methods to reduce the exposure are also discussed. The concentration of total dust and α-amylase were measured in six bakeries during the processes of weighing of flours or flour additives, making of dough, and making of bread. The method to analyze the α-amylase activity in the flour dust was a spectrophotometric, enzymatic method, which was based on the determination of the active enzyme in the dust samples. The mean concentration of total dust was highest during the making of dough (4.6 ± 3.6 mg/m3, mean ± SD) and the mean concentration of α-amylase was highest during the weighing of flour additives (7.3 ± 6.7 μg/m3), and both concentrations were the lowest during the making of bread (2.3 ± 0.9 mg/m3 for dust, 0.2 ± 0.1 μg/m3 for α-amylase). The concentrations were usually higher in the breathing zone of the workers than at the stationary sampling sites. The amount of α-amylase in the studied additives was 1.5 to 3 times higher than that in the wheat flours. The amount of α-amylase added to the dough in the bakeries was about 2 to 3 percent. In the reduction of the α-amylase exposure in the bakeries, the dust control is very important. We recommend the use of hoods for weighing tables of flours and flour additives containing α-amylase, and the dough pots should be equipped with enclosures and local ventilation system. The workers should also be informed about the careful, relevant handling of the enzymes and about the proper personal protection and hygiene, so that the exposure levels could be reduced.