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Dust and microbial exposures during silo unloading.

Morey PR; May JJ; Pratt DS; Stallones L; Olenchock SA; Sorenson WG
Principles of health and safety in agriculture. Dosman JA, Cockcroft DW, eds., Boca Raton, FL: CRC Press, Inc., 1989 Oct; :182-184
A study of dust and microbial exposures during silo unloading was conducted. Environmental and breathing zone samples were collected while moldy hay and corn from five tower silos on dairy farms in upstate New York were unloaded. These were analyzed for total and respirable dust, fungi, and bacteria. Bacterial endotoxin concentrations were determined. Total and respirable dust concentrations ranged from 0.6 to 129 and 0.2 to 22.1mg/m3, respectively. The highest dust concentrations occurred at a silo where dry moldy silage was being removed. The silage at the other silos was moist or wet. By sampling location, the highest dust concentrations occurred at the discharge chute or within the silo near the discharge chute doorway. Viable mesophilic fungi, thermotolerant fungi, thermophilic bacteria, and gram negative bacteria were detected in the airborne dusts. The highest concentrations, 1x10(8), 1x10(8), 4x10(9), and 4x10(6) per cubic meter (m3), respectively, were measured during removal of dry silage. Total microorganism counts during removal of wet or moist silage varied from 1.1x10(6) to 14x10(6)/m3. An average gram negative bacteria endotoxin concentration of 1 microgram/m3 was measured during dry, moldy silage removal. Endotoxin concentrations at another silo averaged 0.05 microgram/m3. Endotoxin concentrations could not be quantified in dust samples from the remaining silos because the amounts collected were too small. The authors conclude that bioaerosol exposures occurring when workers unload moldy silage from tower silos places them at risk for organic dust toxic syndrome.
Organic-dusts; Microorganisms; Plant-dusts; Agricultural-workers; Respirable-dust; Occupational-exposure; Endotoxins; Bacterial-dusts
Publication Date
Document Type
Book or book chapter
Dosman JA; Cockcroft DW
Fiscal Year
Source Name
Principles of health and safety in agriculture
Page last reviewed: February 25, 2022
Content source: National Institute for Occupational Safety and Health Education and Information Division