|DANA O. PORTER, P.E.
WVU Extension Service
Agricultural Engineering Specialist
Storage and handling of grain, feed, and other bulk materials can present hazards to agricultural workers. This article provides a brief overview of these hazards, some safety recommendations, and a list of references that provide more in-depth information about specific safety concerns.
Hazards Associated with Grain Storage and Handling
Flowing grain can quickly submerge a worker and cause suffocation. According to the National Institute for Occupational Safety and Health (NIOSH, 1995), suffocation under silage or grain was the leading cause of grain-handling fatalities between 1985 and 1989. Loading and unloading of trucks and bins, collapsing surface crusts, and collapsing steep or vertical grain piles can bring about sudden, unexpected movement of grain. A worker can be caught in the flow and can be buried in just a few seconds.
Grain handling machinery is the second largest cause of farm machinery-related deaths and causes many severe disfiguring injuries and amputations (NIOSH, 1995). Many of these injuries result from bodily entanglement in machinery. Augers, power take-offs (PTOs), and other moving or rotating machinery should be used with caution. Be aware that loose-fitting clothing, gloves, hair, and jewelry (including wedding bands) can get caught in moving machinery. Automatic unloading machinery may activate unexpectedly. Practice good lock-out/tag-out procedures and maintain machine guards and other safety devices.
Confined spaces, as defined by the National Institute for Occupational Safety and Health, have atmospheres that are likely to contain toxic substances and insufficient oxygen (NIOSH, 1987). Many deaths have occurred in grain bins, silos, manure pits, and other confined spaces. The typical scenario involves a worker entering an oxygen-deficient or toxic atmosphere and collapsing. Co-workers notice the collapsed worker and enter the same atmosphere and attempt a rescue; however, if they do not use proper precautions (respirators, ventilator fans, etc.), they also collapse.
Dusts, molds, and toxins (aflatoxin, mycotoxin, endotoxin, etc.) can cause illness or
acute respiratory reactions. Fermenting silage produces "silo gases," which
include nitric oxide (NO), nitrogen dioxide (NO2), and nitrogen tetroxide (N2O4).
Carbon dioxide (CO2) accumulates in stored grain. Other harmful gaseous
products of microbial decomposition in stored organic products include methane (CH4),
ammonia (NH3), and hydrogen sulfide (H2S). Fumigants used for pest
control purposes may be present. Carbon monoxide (CO) and other combustion by-products may
accumulate when machinery is used in or near confined spaces; accidental ignition of
building materials, hydraulic fluid, etc., can release other toxic gases and fumes into
the atmosphere. Oxygen in confined spaces can be displaced by accumulated gases or
depleted by microbial activity in stored products, workers in the spaces, and/or
combustion (internal combustion engines and fires). When flammable or explosive gases
(such as methane) or dusts (such grain dust or cotton lint) have accumulated in the
environment, special precautions should be taken.
Electrical and Automatic Equipment
Electrocution and fire hazards associated with grain handling equipment can be minimized through preparation and precautions. Maintain electrical equipment in good condition, and ensure that wiring and grounding of equipment follow recommendations of the National Electric Code (NEC). Use only the properly rated fuses, wiring, insulation, etc. Practice good lock-out/tag-out procedures to prevent accidental activation of unloading equipment when you are in the bin or silo. Avoid personal or equipment contact with overhead power lines.
Grain Dust Explosions and Fires
All that is needed for a fire or explosion are a sufficient fuel source, oxygen, and heat or spark. Grain dusts, cotton lint, and many other organic materials are flammable. Under certain conditions, they present explosion hazards. Methane, gasoline, or diesel fuels may be present in agricultural facilities.
Dust concentrations can be controlled or reduced in some conditions, and ventilation can help dissipate flammable gases and fumes. Maintenance of grain-handling equipment can reduce overheated bearings (a possible ignition source). If you are working in a possibly flammable environment, refrain from smoking or using open flames for light or heat.
Falls and Equipment Overturns
Falls from machinery and structures were the second largest single cause of grain and silage handling fatalities between 1985 and 1989, (NIOSH, 1995). Be especially careful when using ladders. Use handrails, guardrails, safety ropes, and fall-arrest devices as appropriate.
Equipment overturns are possible when tractors or other vehicles are used to pack silage in bunker silos. Use only equipment with rollover protective structures (ROPS) and seat belts.
There are times when workers must enter such confined spaces as grain bins or silos. Properly trained and prepared workers and adequate maintenance of safety equipment are essential to worker safety. A few safety recommendations compiled from resources in the reference list include:
Sources of Information
For more information about safety in storage and handling of silage and grain, you may contact the Cooperative Extension Service and the following references.
Arble, William C. and Dennis J. Murphy. 1989. Extinguishing Silo Fires. NRAES-18. Northeast Regional Agricultural Engineering Service, Cooperative Extension, Riley-Robb Hall, Ithaca, NY. (List price $4)
Baker, Dale L., William E. Field, Rollin Schneider, Clair W. Young, Robert A. Parsons, and Dennis J. Murphy. 1991. Farm Accident Rescue. NRAES-10. Northeast Regional Agricultural Engineering Service, Cooperative Extension, Riley-Robb Hall, Ithaca, NY. (List price $5)
Bean, Thomas L. "Flowing Grain." WVU Cooperative Extension Service Fact Sheet SA-30.0.
Iowa State University Cooperative Extension Service. 1987. "Suffocation Hazards Associated with Stored Grain." Iowa State University Cooperative Extension Service Fact Sheet Pm-1293i.
Iowa State University Cooperative Extension Service. 1987. "Hazards of Confined Space." Iowa State University Cooperative Extension Service Fact Sheet Pm-1293h.
Midwest Plan Service. 1987. Structures and Environment Handbook, 11th ed. MWPS-1. Midwest Plan Service, Ames, Iowa. (List price $25)
Murphy, Dennis J., John Pollok, Gary Smith, Thomas Bean, and Marty Sailus. 1989. First on the Scene. NRAES-12. Northeast Regional Agricultural Engineering Service, Cooperative Extension, Riley-Robb Hall, Ithaca, NY. (List price $7)
NIOSH. 1986. "Preventing Occupational Fatalities in Confined Spaces." NIOSH Publication No. 86-110. National Institute for Occupational Safety and Health Division of Safety Research.
NIOSH. 1984. "Preventing Scalping and Other Severe Injuries from Farm Machinery." NIOSH Publication No. 94-105. National Institute for Occupational Safety and Health Division of Safety Research.
Pettit, Ted, and Herb Linn. 1987. A Guide to Safety in Confined Spaces. National Institute for Occupational Safety and Health. U.S. Department of Health and Human Services.
Snyder, Karl A. and Thomas G. Bobick. Safe Grain and Silage Handling. NIOSH
Publication No. 95-109. National Institute for Occupational Safety and Health Division of
Safety Research. Morgantown, WV.
Midwest Plan Service materials may be ordered from:
122 Davidson Hall
Northeast Regional Agricultural Engineering Service materials may be ordered from:
152 Riley-Robb Hall
National Institute for Occupational Safety and Health information is available from:
Division of Safety Research, NIOSH
Special thanks to Terry Wilkinson, WVU Extension Service, safety and health specialist, for his assistance in compiling this information.