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Determinants of flour dust exposure in bakeries

University of British Columbia

This thesis presents the results of an investigation into factors that are associated with flour dust exposures in B.C. bakeries. We describe observed exposure levels and advise on control measures which may reduce an individual's exposure to flour dust. In this investigation, flour dust exposure was assesed using three measures: inhalable dust, wheat antigen and fungal a-amylase. Inhalable dust was measured gravimetrically. The wheat antigen and a-amylase content of the water soluble fraction of inhalable dust was assayed via ELISA. Ninety-six bakery workers, employed in seven different bakeries, participated in the investigation. Two side-by-side full-shift inhalable dust samples were obtained from each study participant on a single occasion. We were able to obtain useable exposure measurements for all three exposure measures from each study participant. During sampling, information on potential determinants of exposure was collected. It was used in analysis of variance and multiple regression to identify significant predictors of exposure (determinants). The exposure levels observed in this study indicated that the bakery workers were subject to a mean inhalable dust exposure of 8.2 mg/m3 (ranging from 0.1 to 110 mg/m3), a mean a-amylase exposure of 22.0 ng/m3 (ranging from below limit of detection of 0.1 to 307.1 ng/m3) and a mean wheat antigen exposure of 109 ug/m3 (ranging from below limit of detection of 1 to 1018 ug/m3). Seventeen percent of the measured inhalable dust exposures exceeded the regulatory exposure limit of 10 mg/m3. Some wheat antigen and a-amylase exposures showed levels capable of causing respiratory symptoms. Regression, models which explained 74 to 79% of variability in inhalable dust, a-amylase and wheat antigen exposures were constructed. According to the models, tasks such as weighing, pouring and operating dough forming machinery increased flour dust exposure, while fully automated forming, packing, catching and decorating decreased exposure. Bread, bun and puff pastry production lines were associated with increased exposure, while cake production was associated with decreased exposures. We describe a novel method of controlling the exposures in bakeries via the substitution of dusting with the use of the divider oil, and discuss which pieces of equipment appear to be associated with elevated exposures.

Thesis/Dissertation

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2009-02-17

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http://hdl.handle.net/2429/4722

Occupational and Environmental Hygiene

University of British Columbia

UBCV

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