Overexposure to Flour Dust in Small to Mid-size Bakeries
1SAIF Corporation, Salem, OR
Debra Corbin, CIH
The objective of this study was to evaluate flour dust exposure in Oregon bakeries after a case of recently-acquired de novo (new-onset) occupational allergies to wheat and rye flour in a baker with pre-existing childhood-onset allergic asthma was reported. The recommendation that the baker remove herself from continued workplace exposure to the flour allergens to which she was allergic on a permanent basis prompted the evaluation.
Situation / Problem:
Flour dust overexposures have been documented in multiple bakeries, from the smallest-scale operations up to larger ones. Bakers' work practices often contribute to flour dust exposures. The use of engineering controls and personal protective equipment, including respirators, is limited in bakery operations.
Preweighed 25 mm PVC filters in IOM samplers were used to collect task-based and full-shift samples for inhalable dust. The size-selective Institute of Occupational Medicine (IOM) sampler was used to sample inhalable dust because flour dust has an inhalable fraction TLV®. These dust particles are hazardous when deposited anywhere in the respiratory tract. Samples were analyzed using modified NIOSH 0500. Real-time sampling was conducted with several different direct-reading instruments. These measurements were made to determine relative dust concentration levels for specific tasks (weighing, mixing, scaling, etc.) for assessment of dust control measures, not for direct comparison to a recommended occupational exposure limit.
Results / Conclusions:
A total of 37 inhalable dust samples from employees working in small- to mid-size bakeries were collected and analyzed. Task-based sampling periods ranged from 15 to 452 minutes. Inhalable dust levels measured during these intervals were 0.25 to 150 mg/cu.m. The average inhalable dust level was 8.9 mg/cu.m. ± 24.8 mg/cu.m. The mean time-weighted average (TWA) inhalable flour dust level was 3.6 mg/cu.m.± 2.8 mg/cu.m.). The average was 7.2 times the ACGIH® TLV® of 0.5 mg/cu.m. for flour dust. The lowest inhalable dust levels were measured in personal samples collected from managerial employees. The highest inhalable dust levels were measured while employees hand-dumped bags of flour into mixers at a tortilla bakery: 43 mg/cu.m. (coarser corn flour) and 150 mg/cu.m. (wheat flour). Real-time sampling confirmed survey observations and personal sampling results. Bakery workers were overexposed to inhalable flour dust. Engineering controls were minimal. Employees do not wear respiratory protection. Given the potential for respiratory sensitization, flour dust exposures should be addressed through engineering and/or administrative controls and personal protective equipment. Medical surveillance to identify potential respiratory and skin issues should be part of a comprehensive program for bakery workers.
Acknowledgements and References
List any additional people who worked on the project or provided guidance and support along with details on the role they played in the research. (Please include first name, last name, organization, city, state and country).
Wm. David Johnson, CIH
David Johnson is the Industrial Hygiene Supervisor at SAIF Corporation. He initiated the analysis that led to the creation of an internal bulletin on flour dust. The IH bulletin was intended to educate SAIF safety consultants, claims adjusters, and underwriters. The bulletin has been shared with SAIF employers as a discussion point on the importance of recognizing and controlling flour dust exposures.
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