UBC Faculty Research and Publications

Exposure in grain elevators: are we measuring the relevant agent? (presentation) Kennedy, Susan M.; Bartlett, Karen H.; Dimich-Ward, Helen Jun 30, 1999

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Exposures in grain elevators: are we measuring the relevant agent? Relationship between grain dust, endotoxin, and 1,3 β - D glucan exposure levels  Susan Kennedy, Karen Bartlett, Helen Dimich-Ward Occupational and Environmental Hygiene Program University of British Columbia, Vancouver CANADA Presented at: American Industrial Hygiene Conference and Exhibition, Toronto Canada, 1999  Acknowledgements: • Human Resources Development Canada • Beryl Kirk; Lyn Peters, Jim Benyon  • BC Terminal Elevator Operators Association • Grain Workers Union • British Columbia Lung Association • Dept of Environmental Sciences, Wageningen Agricultural University  Composition of grain dust: • varies with geographic site, species, season, storage temperature, … • major components: • • • • • •  fractured kernels, seeds, husks animal feces storage mites, insects bacteria, moulds crustal particles (incl. silica) pesticides  Rationale: Grain components and respiratory health • Dust • assoc. with ↑ respiratory symptoms; ↓ lung function  • Endotoxins • potent pro-inflammatory agent (gram neg. bacteria) • assoc. with grain fever, acute & chronic resp. symptoms  • 1,3 β -D glucans • major fungal cell wall component (also found in some bacteria, most plants) • some evidence of link with irritant symptoms  Objectives: As part of mandated grain elevator monitoring program: • Measure dust, endotoxin and glucan levels • Record readily available “determinants of exposure” data • Compare exposure levels, determinants of exposure • Evaluate significance of results for future studies and for prevention  Sampling methods: method  detail  gravimetric sampling  37 mm open faced cassettes, flow rate: 1.7 l/min for 6-7 hours heat-depyrogenated glass fibre filtres  endotoxin analysis  kinetic, turbidimetric LAL assay; Pyrogent 5000 ® reagent  1,3 β-D glucan analysis  rabbit polyclonal anti-laminarin inhibition assay  Determinants of exposure evaluated: elevator  6 companies  job group  10 job title groups  time in tasks / locations  sweeping; maintaining machinery in elevator; outdoors; in office or control room; in maint.shop  weather / season season (2 sampling periods); temperature, humidity; % rain, sun  grain type / amt. tonnage of grain received / shipped per day; grain species: % wheat, barley, rye, canola, other  Personal Samples - Summary Results  n range < DL  dust 3 (mg/m )  endotoxin 3 (ng/m )  glucan 3 (μg/m )  376  371  187  < 0.13 - 63.7 <0.28 - 17,650  <2.9 - 96.8  21.0%  13.7%  19.8%  GM (GSD)  0.63 (3.8)  11.4 (17.6)  7.92 (2.8)  ‘reference’ level  4.0  % > ref. val  1  10.4%  5.0  2  50.1%  1: ACGIH ; 2: Dutch Health Council, proposed  Dust v. Endotoxin Concentration in Air Dust Concentration (mg/m3) 0.1  1  10  100 100000  10000  1000  100  10  R=0.83, p<.001  1  0.1  Endotoxin (ng/m 3)  0.01  Dust v. 1,3 β-D Glucan Concentration in Air Dust Concentration (mg/m3) 0.1  1  10  100 1000  R=0.77, p<.001 100  10  1  Glucan (ug/m3)  0.01  Endotoxin v. Glucan Content (per g. dust) Endotoxin Content (ng/g.dust) 1  10  100  1000  10000 100  10  R = -0.04 1  Glucan Content (ug/g.dust)  0.1  Factors associated with increased exposure Dust  Endotoxin  Glucan  Job groups  • sweeper • sweeper • sweeper • cleaner fl. op • cleaner fl. op • cleaner fl. op  Tasks (time)  • sweeping • sweeping • sweeping • maintenance • maintenance • maintenance • misc. tasks • company A • company A • company A  Elevator  Factors associated with decreased exposure Dust  Endotoxin  Glucan  (mg/m )  (ng/m )  (ug/m )  3  3  3  Job groups • trackshed op. • control op • supervisor  • trackshed op. • control op. • supervisor  none  • time outdoors  • time outdoors  none  Tasks  • winter  Season 2  model R  0.38  0.47  0.40  Determinants of exposure - summary of comparison • Endotoxin and glucan levels • highly correlated with dust level  • Determinants of dust v. endotoxin • jobs / tasks same rank order • endotoxin significantly decreased in winter  • Determinants of dust v. glucan • same high exposure jobs / tasks • signif. differences re low / med exposure rankings  Relevance: for future studies of possible health consquencies of grain elevator exposures  Question: With only job title and company information, how are jobs categorized into exposure risk groups, according to dust, endotoxin, glucan level?  ee tm  s  w  in  m  r/ b  l  ex  tp  e s w t al ee pe cl r ea ne rf l.  sh  st  .  ed  rv  nn  t r/  /a  ec  di  el  se  sh  lle  ck  pe  t ra  op  pe  ol  Dust Level (m g/m 3) 2  ba  nt  su  co 3  175  Dust Endotoxin 150  125  100  1 75  50  25  0 0  Endotoxin Level (ng/m 3)  Job groups - ordered by dust and endotoxin level 225  200  to lo p  er v. tr ac ks he d pe lle tp ba l se /a nn ex el ec tr /m w di st r/b in sh s ee tm et al sw ee pe r cl ea ne rf l.  su p  co n  Dust Level (mg/m3) 3  2  Dust Glucan  0 25  20  15  1 10  5  0  Glucan Level (ug/m3)  Job groups - ordered by dust and glucan level  35  30  Jobs ordered by mean endotoxin level (by season) sweeper cleaner fl.op basemt/gall./annex sheetmetal mech distributor/bintop pellet plant op  Aug-Oct Jan-Mar  electr./millwright supervisor pitman control operator 0.1  1  10  endotoxin (GM), ng/m3  100  1000  Endotoxin and Glucan Content in dust Endotoxin Glucan job groups  • • • • •  Sweeper Cleaner Fl. Op Sheet Metal tasks sweeping maintenance in elevator • time outside season/ weather • winter elevator 2  Model R  • company A • company B • company C  ↑ ↑ ↑ ↑ ↑  ↓ -  ↓  ↑ -  ↑ -  ↓ ↓ 0.16  0.43  Conclusions: is dust level a good surrogate for other biologically active grain components?  • Glucan: • dust a poor surrogate - esp. at low dust levels  • Endotoxin: • chronic effects studies: dust a reasonable surrogate, if … seasonal changes in endotoxin are cyclic (needs to be evaluated)  • acute effects studies: dust a poor surrogate  

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