Coffee dust exposure and respiratory health among workers in primary coffee processing factories in Ethiopia
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Date
2019-05
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Abeba University
Abstract
Background: Dust exposure is one of the major risk factors for health in many work places
including coffee processing factories. Dust generates at different stages of coffee handling
and processing. Excessive exposure to coffee dust can cause respiratory health problems.
Coffee workers in Ethiopia are exposed to coffee dust, but the level of exposure and the
magnitude of its health effect have not been widely investigated.
Objectives: The aims of this study were to assess the level of personal total dust exposure,
factors affecting dust exposure, the prevalence of respiratory symptoms and lung function
reduction among coffee workers. In addition, assessing microbial contamination of coffee at
different stages of both wet and dry method on farm coffee processing was a part of this
dissertation.
Methods: Comparative cross-sectional studies were conducted in primary coffee processing
factories involving 3 regions: Oromia Regional State; Addis Ababa City Administration; and
Southern Nations, Nationalities and Peoples’ Region. The study also included a comparative
population in 3 water bottling factories, one from each region mentioned above. A total of
360 dust samples were collected from 12 primary coffee processing factories for dust
exposure assessment. In addition, 60 total dust samples were collected from the 3 water
bottling factories. Dust samplings were collected from breathing zone of workers using 25mm
three
piece,
closed-faced
conductive
cassettes
with
a
cellulose
acetate
filter
attached
to
Side
Kick Casella pumps with a flow rate of 2 liter/ minute. Observational checklist was
used to identify possible determinants for dust exposure.
Lung function tests were performed for a total of 420 participants ( 120 male coffee workers,
120 male controls, 60 hand pickers with tables, 60 hand pickers without tables and 60 female
controls) using a portable spirometer (SPIRARE 3 sensor model SPS 320). Lung function
parameters such as Forced Vital Capacity (FVC), Forced Expiratory Volume in one second
(FEV
1
), the mean forced expiratory flow between 25% and 75% of the FVC (FEF
) and
ratio FEV
FVC were measured. Prevalence of chronic respiratory symptoms were assessed
with an interview, using a standardized questionnaire adopted from the American Thoracic
Society.
1/
Coffee cherries each weighing about 25 grams were sampled from each stage of the wet and
dry processes for microbial contamination assessment. Standard Plate Count agar was used
25-75%
to grow total bacteria and gram stain technique were used to identify gram negative and gram
positive bacteria.
Data were entered into an electronic database using EpiData version 3.1 and exported to
SPSS version 22 for analysis. Missing values and outliers were checked using frequency
tabulation, and then were managed accordingly. The results were described as arithmetic
mean, standard deviation, geometric mean (GM), and geometric standard deviation (GSD).
A one-way analysis of variance was performed to compare the GM of personal total dust
exposure level between different job groups and between tasks. Linear mixed effect
regression models were developed to identify significant determinants for personal total dust
exposure. Independent t-tests were used to compare the mean values for the continuous
variables. The Pearson Chi-square test or Fisher’s exact test, if the expected value was less
than 5, were used to test the difference between the groups regarding the categorical
variables. Poisson regression analysis with a robust variance was used to determine the
prevalence ratio of the different respiratory symptoms between the coffee workers and
controls. Analysis of covariance and linear regression were used to compare the mean lung
function parameters between the coffee workers and controls while adjusting for
confounders.
Results: The GM dust exposure among machine room workers ranged from 4.09 to 34.40
mg/m
3
, among transport workers from 3.51 to 24.19 mg/m
3
, and among hand pickers from
0.26 to 5.87 mg/m
3
. Overall the GM personal dust exposure was significantly higher (P =
0.001) for the machine room (12.54 mg/m
3
) and transport workers (12.30 mg/m
) than for the
hand pickers (1.08 mg/m
3
). In these three groups, 84.6%, 84.1%, and 2.6% of the samples
exceeded the occupational exposure limit of 5 mg/m
3
respectively. The result also indicated
that pouring coffee vigorously from a dropping height was the determinant with the highest
impact on personal total dust exposure with 3.2-fold increase compared to gradually pouring
coffee from a very short height.
Coffee workers had significantly higher prevalence of most of the chronic respiratory
symptoms compared with the controls. For most of the chronic respiratory symptoms, hand
pickers without tables displayed a significantly higher prevalence ratio than in hand pickers
with tables.
3
Male coffee workers in the age groups 28–39 years and ≥40 years, had a significantly lower
FVC and FEV
compared to the controls in the similar age groups. There were statistical
differences in FEF
1
25-75%
between hand pickers and controls. In addition, FVC and FEV
were
significantly lower among hand pickers without tables than among hand pickers with tables.
The results also indicated the presence of gram negative bacteria in dried and stored beans
from both the wet and dry process.
Conclusion: About 84% of the dust samples among machine room and transport workers in
primary coffee processing factories were above the occupational exposure limit value for
organic dust. Machine and transport workers in primary coffee processing factories had a
higher prevalence of chronic respiratory symptoms and lower FVC and FEV
than the
controls. Pouring coffee beans vigorously from a dropping height, mixing coffee and feeding
hopper were the main determinants for increased personal dust exposure level. The dust
exposure was related to reduced lung function and higher prevalence of chronic respiratory
symptoms among coffee workers. Gram negative bacteria found in dried and stored coffee
beans, might release endotoxin which may cause respiratory health problems among coffee
production workers.
Recommendations: Coffee workers should be provided with efficient respiratory protective
device and training on its importance prior to employment and regularly afterwards as
necessary. Changing process of pouring coffee beans from vigorously to gradual could
reduce personal dust exposure level in the coffee factories.
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1
Description
Keywords
Coffee dust exposure , respiratory health , coffee processing factories in Ethiopia