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At the time of our evaluation, employees on the hazardous materials team (mainly
refrigeration and select maintenance employees) were included in the respiratory protection
program. We did not review the respiratory requirements for the hazardous materials team
as part of this evaluation. While production employees were not required to wear respiratory
protection and were not included in the respiratory protection program, some employees used
NIOSH-approved N95 filtering facepiece respirators voluntarily. We saw some employees
wearing their filtering facepiece respirators incorrectly. Examples of incorrect filtering
facepiece respirator use included employees wearing their respirator over a beard guard,
incorrectly placing the respirator only over their mouth, and using only one strap.
The bread and batter lines were equipped with local exhaust ventilation. However, we saw
instances where the local exhaust ventilation was not connected to the duct work (Figures 1,
2, 3, and 4). Local exhaust ventilation was absent from the dispensing hoppers at the point
where dry ingredients were transferred from paper bags to the dispensing hoppers (Figure
5). We observed that many of the local exhaust ventilation collection points between the
breading line machines did not collect all the flour dust, evidenced by dust accumulation
in the immediate work area (Figure 4). We observed product conveyers that were neither
enclosed nor equipped with local exhaust ventilation (Figures 3, 4, and 6). On batter and
bread hoppers and breading machines that were enclosed, access doors were not closed
(Figure 5 and 7), resulting in dust escaping because of machine vibration.
Table 10. Prevalence of sensitization to breading dust
components, by atopy
Atopy
P value
Yes (n=81)
No (n=155)
Sensitized to flour dust
Number (%)
47 (58)
19 (12)
< 0.01
Sensitized to wheat
Number (%)
51 (63)
21 (14)
< 0.01
Sensitized to soy
Number (%)
27 (33)
2 (1)
< 0.01
Sensitized to corn
Number (%)
42 (52)
4 (3)
< 0.01
Sensitized to garlic
Number (%)
32 (40)
3 (2)
< 0.01
Sensitized to
paprika
Number (%)
17 (21)
1 (1)
< 0.01
Sensitized to onion
Number (%)
26 (32)
1 (1)
< 0.01
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Figure 1. Disconnected and uncapped local exhaust ventilation duct on line one.
Figure 2. Disconnected and uncapped local exhaust ventilation duct on line one.
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Figure 3. Local exhaust ventilation attachment not in use on breader.
Figure 4. Local exhaust ventilation attachment not in use on breader and non-
enclosed product conveyer belt.
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Figure 5. Dispensing hopper lid on breading machine.
Figure 6. Unenclosed conveyor belt without local exhaust ventilation and transfer
point between machines.
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We observed employees using poor techniques to transfer dry powdered ingredients, resulting
in unnecessary exposures to breading dust (Figure 8). For example, some employees
transferred dry ingredients to overhead hoppers or hoppers in difficult to reach locations.
This often required them to place their head into the dust cloud generated by the transfer. We
also observed employees transferring dry powdered ingredients into the hoppers using quick
movements that generated visible dust clouds. These practices increased exposure to the
airborne breading dust.
Figure 7. Open enclosure on breading machine.
Figure 8. Employee transferring dry powdered ingredients into a breading machine hopper at breathing
zone height.
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Discussion
A health hazard existed at this plant from exposure to breading dust. Personal breathing
zone air sampling showed that employees in almost all areas of the plant had the potential
for exposure to flour dust levels above the American Conference of Governmental Industrial
Hygienists (ACGIH®) threshold limit value (TLV®) for flour dust. We compared our
sampling results to the ACGIH TLV because it is specific to flour dust and was established
to minimize the potential for wheat flour sensitization. At the time of this evaluation the
company evaluated employee exposures by comparing them to the less protective OSHA
PEL for particulates not otherwise regulated. We believe this practice led to the high
prevalences of sensitization to flour dust, wheat, spices, and other ingredients; and to work-
related asthma symptoms, cough, and rhinoconjunctivitis. Exposures to flour dust in the
plant must be reduced to prevent adverse health effects and minimize worsening of existing
symptoms and disease.
The prevalence of sensitization to wheat among the higher-exposure group in this evaluation
(36%) is higher than that found in studies of bakers (5%–28%) [Houba et al. 1996; Baatjies et
al. 2010]. The prevalence of sensitization to wheat among participants in the lower-exposure
group (15%) was within the range found in bakers and higher than in the general population
(1.2% to 4.1%) [Houba et al. 1996; Gautrin et al. 1997; Biagini et al. 2004]. This is consistent
with our data showing exposure to flour dust and wheat throughout the plant.
We placed participants into exposure groups on the basis of our observations of their work,
a review of historical exposure data collected by the plant, and our professional judgment,
but we may have misclassified some employees. Additionally, after reviewing our personal
breathing zone results, we concluded that few, if any, plant employees are unexposed to flour
dust and other breading ingredients.
As a result of our classification strategy, although the higher-exposure group had a median
inhalable flour dust concentration several times higher than the lower-exposure group the
exposures were overlapping. Moreover, airborne concentrations of inhalable flour dust and
wheat for the higher-exposure group in our evaluation were much higher and those of our
lower-exposure group were similar or higher than those found in Belgian bakeries [Bulat et
al. 2004]. Median inhalable flour dust concentrations in a study of 55 bakeries in the United
Kingdom were midway between those of our two exposure groups; however, peak exposures
were much higher in our higher-exposure group [Elms et al. 2005]. Inhalable flour dust and
wheat concentrations were also much higher than personal breathing zone samples from
supermarket bread bakers in South Africa, even for the lower-exposure group [Baatjies
et al. 2010]. Exposures to flour dust occurred throughout the plant, including areas where
batter or breading mixes were not used. While the inhalable flour dust sampling method is a
weight gain analysis not specific to flour dust, the presence of wheat allergens on the samples
confirmed that flour dust was present in those areas.
While 23 participants reported changing jobs because of respiratory tract or mucous