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Development of a Job Exposure Matrix for flour exposure in the Bakery Industry: Systematic review with field validation Open Access


Other title
exposure levels
flour dust exposure
geometric mean/arithmetic mean
job exposure matrix
Type of item
Degree grantor
University of Alberta
Author or creator
Aidoo, Henry K
Supervisor and department
Cherry, Nicola (Division of Preventive Medicine)
Beach, Jeremy (Division of Preventive Medicine)
Examining committee member and department
Straube, Sebastian (Division of Preventive Medicine)
Senthilselvan, Ambikaipakan (School of Public Health)
School of Public Health
Occupational Health
Date accepted
Graduation date
2017-06:Spring 2017
Master of Science
Degree level
Introduction: Flour has been a recognized allergen for many years. Although Alberta has an occupational exposure limit (OEL) for flour dust of 0.5 mg/m3, recent measurements in Alberta bakeries show that this level is frequently exceeded. Geometric mean (GM) exposure to inhalable particulates was highest among mixers (4.13 mg/m3) and bakers (1.57 mg/m3). This study was divided into two main parts. The first part was a systematic review which aimed to create quantitative exposure estimates to flour, based on a worker’s job/task description in the bakery industry using data from previously published exposure studies. The second part was a validation study using a questionnaire, with skin prick test and lung function measurements within a number of bakeries in Alberta. Method: Published and unpublished literature sources that included exposure measurement data within a bakery were extracted. Job/task titles were identified and reclassified into 9 main groups with products classified into 3 main groups. The results were grouped by sampling dates, task, product, number of samples, substance sampled. The grouped results were used to calculate the weighted geometric mean- inhalable dust, wheat allergen and fungal α-amylase by job/task group and product group. Job exposure matrices (JEM) were therefore created for inhalable dust, wheat allergen and fungal alpha-amylase. The JEM were validated through a cross-sectional study, conducted in 8 Alberta bakeries with 57 bakers. The weighted geometric mean was subsequently used to derive exposure indices among a group of current bakers (average exposure, maximum exposure and cumulative exposure) which were used along with duration of bakery exposure and other risk factors such as age, gender, smoking, atopy and family history of allergy to predict the risk of testing positive to skin prick tests for bakery allergens. Results: Dough formers were the predominant job/task group most exposed to inhalable dust (GM 4.69mg/m3), wheat allergen (GM 87.13 µg/m3) and fungal alpha-amylase (GM 43.1ng/m3) while packers/ shippers and front counter & sales workers had the least exposures. Exposure estimates were calculated for the other job/ tasks in the bakery industry. The bakers surveyed were mostly males with the majority being in the ages of 30 to 45 years. 44% of the bakery workers had a family history of allergy with 37% of bakers were atopic. Among the common allergens skin prick tests to grass and mites were most commonly positive. The prevalence rate of sensitivity to any bakery allergens was 18% but the skin prick tests in this group that was most commonly positive was oats (11%). Sensitivity to bakery allergens was influenced by bakery job duration, cumulative exposure and atopic status, particularly for inhalable flour dust. Conclusion: It was possible to produce job/task and product specific estimates of exposures. These estimates were associated with the risk of sensitization to bakery allergens. Thus, the job exposure matrices seem to be valid.
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