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 1999-06-30

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Exposures in grain elevators: are we measuring the relevant agent?Relationship between grain dust, endotoxin, and 1,3 ?-D glucan exposure levelsSusan Kennedy, Karen Bartlett, Helen Dimich-WardOccupational and Environmental Hygiene ProgramUniversity of British Columbia, Vancouver CANADAPresented at:  American Industrial Hygiene Conference and Exhibition, Toronto Canada, 1999Acknowledgements: ?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 UniversityComposition 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 ?-D glucans?major fungal cell wall component  (also found in some bacteria, most plants) ?some evidence of link with irritant symptomsObjectives: As part of mandated grain elevator monitoring program:?Measuredust, endotoxin and glucan levels   ?Recordreadily available ?determinants of exposure?data   ?Compareexposure levels, determinants of exposure ?Evaluatesignificance of results for future studies and for preventionSampling methods:methoddetail gravimetric sampling37 mm open faced cassettes,flow rate: 1.7 l/min for 6-7 hoursheat-depyrogenated glass fibre filtres endotoxin analysiskinetic, turbidimetric LAL assay;Pyrogent 5000 ? reagent1,3 ?-D glucananalysisrabbit polyclonal anti-laminarininhibition assayDeterminants of exposure evaluated:elevator6 companiesjob group10 job title groupstime in  tasks /locationssweeping; maintaining machinery in elevator;outdoors; in office or control room; in maint.shopweather / seasonseason (2 sampling periods); temperature,humidity; % rain, sungrain type / amt.tonnage of grain received / shipped per day;grain species: % wheat, barley, rye, canola, otherPersonal Samples -Summary Resultsdust(mg/m3)endotoxin(ng/m3)glucan(?g/m3)n376371187 range< 0.13 - 63.7<0.28 - 17,650<2.9 - 96.8< DL21.0%13.7%19.8%GM (GSD)0.63 (3.8)11.4 (17.6)7.92 (2.8) ?reference?level4.0 15.0 2% > ref. val10.4%50.1%1: ACGIH ;  2: Dutch Health Council, proposedDust v. Endotoxin Concentration in Air0.11101001000100001000000.010.1110100Dust Concentration (mg/m3)EndotR=0.83, p<.001Dust v. 1,3 ?-D Glucan Concentration in Air11010010000.010.1110100Dust Concentration (mg/m3)GlucaR=0.77, p<.001Endotoxin v. Glucan Content  (per g. dust)1101000.1110100100010000Endotoxin Content (ng/g.dust)GR = -0.04Factors associated with increasedexposureDustEndotoxinGlucanJob groups? sweeper?cleaner fl. op? sweeper ?cleaner fl. op? sweeper ?cleaner fl. opTasks (time)? sweeping?maintenance? sweeping ?maintenance? sweeping ?maintenance? misc. tasksElevator? company A? company A? company AFactors associated with decreasedexposureDust(mg/m3)Endotoxin(ng/m3)Glucan(ug/m3)Job groups? trackshed op.? control op? supervisor? trackshed op.? control op.? supervisornoneTasks? time outdoors? time outdoorsnoneSeason? wintermodel R20.380.470.40Determinants 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 consquenciesof grain elevator exposuresQuestion:With only job title and company information, how are jobs categorized into exposure risk groups, according to dust, endotoxin, glucan level? Job groups -ordered by dust and endotoxin level0123cpsutrpbeldshswclD0255075100125150175200225EDust EndotoxinJob groups -ordered by dust and glucan level0123cstpebaeldissclDu05101520253035GDust GlucanJobs ordered by mean endotoxin level (by season)0.11101001000control operatorpitmansupervisorelectr./millwrightpellet plant opdistributor/bintopsheetmetal mechbasemt/gall./annexcleaner fl.opsweeperendotoxin (GM), ng/m3Aug-Oct Jan-MarEndotoxin and Glucan Contentin dustEndotoxinGlucanjob groups? Sweeper? Cleaner Fl. Op? Sheet Metal???--? tasks? sweeping? maintenance inelevator? time outside?? ---?season/ weather? winter?-elevator? company A? company B? company C?--??Model R20.430.16Conclusions: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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