| Summary: | Introduction: Workers in the grain industry have been reported to have adverse
respiratory symptoms, primarily due to occupational exposure to grain dust. Exhaled
breath condensate (EBC) may be a viable method in field studies to sample secretions of
the lower airways. It is suggested that these secretions can predict inflammatory
responses to inhaled irritants, such as grain dust. Studies have reported that the acid-base
equilibrium in EBC varies with the severity o f airway inflammation. The purpose of the
present study was to measure EBC pH and ammonium to assess the acid-base
equilibrium of the airways in grain elevator workers.
Methods: EBC collection was performed using commercially available equipment.
Methodological issues pertaining to the collection, storage, and analysis of EBC were
evaluated to produce a standard procedure suitable for our laboratory. The field
component consisted of sampling EBC from workers employed at terminal elevators in
the port of Vancouver. In addition, personal exposure monitoring to inhalable grain dust
and endotoxin, completion of a respiratory questionnaire, spirometry and allergy testing
were also performed, as part of a larger cross-sectional grain study.
Results: 76 workers participated. EBC pH values varied from 4.3 to 8.2 (median: 7.94);
ammonium values from 22 to 2384 μM (median: 420.4). Geometric mean dust and
endotoxin levels were: 0.9 mg/m3 (GSD: 4.0) and 435 EU/m3 (GSD: 4.9) respectively.
pH and ammonium were moderately correlated (1=0.53). Multivariable analysis showed
that pH was lower in association with current smoking intensity and obesity, yet higher in
current atopics. Lower pH was associated with duration of exposure on the study day
before EBC collection and with working in one work area (seed/pellet plant), but not with
measured grain dust or endotoxin exposure concentration. Lower ammonium was
associated with chronic smoking intensity, duration of exposure on the study day, years
of employment in the industry, and working in the seed/pellet plant; but significantly
higher in association with grain dust measured on the study day.
Conclusion: The collection of EBC is feasible in field studies. EBC pH and ammonium
may be useful to measure airway inflammation related to acute and chronic occupational
exposures. === Medicine, Faculty of === Medicine, Department of === Experimental Medicine, Division of === Graduate
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