A Strategy for Controlling Noise Exposures in Agriculture
BY CHANDRAN ACHUTAN
For those of us living in agricultural states, the arrival of autumn means that the harvest season is just around the corner. For farmers, it means long hours harvesting corn and soybeans on their combines. The time farmers spend in proximity to these machines adds to their already considerable exposure to noise. A 2005 paper published in the Journal of Agromedicine established that farmers experience higher rates of noise-induced hearing loss (NIHL) than non-farmers of similar age. Sources of hazardous noise on farms include machinery, equipment, and livestock. Although the newer tractors and combines have cabs that block engine noise, farmers are still overexposed when they step outside of their combines, work on equipment, and conduct other work-related tasks. (The sidebars throughout this article describe a few of the noisy tasks that farmers typically perform.) HEARING LOSS RISK NIOSH estimates that more than 22 million workers are exposed to hazardous noise on the job. An additional nine million are at risk for hearing loss from other sources, such as solvents and metals. While noise-induced hearing loss is 100 percent preventable, once acquired, it is permanent and irreversible. Workers in the agriculture, forestry, and fishing sector have a high prevalence of exposure to hazardous workplace noise (43.3 percent), according to a paper published in the Journal of Occupational and Environmental Medicine in 2008, and the second highest prevalence (22 percent) among all industries of hearing difficulty after construction. Farmers also experience higher rates of noise-induced hearing loss (NIHL) than non-farmers of similar age. Hearing loss among farmers may begin at an early age; farm children have been found to have greater hearing loss than urban children. Studies of noise from farm equipment have found average levels of 92 decibels. Unlike workers in general industry, farmers work in a non-regulated environment and are not commonly served by work-based health programs. Other challenges to using hearing protection in the farm work environment include intermittent noise exposure and diversity of noisy work activities. Although the best way to prevent NIHL is to eliminate noise whenever possible (for example, through “buy quiet” programs and the use of automation), elimination is often not technically or economically feasible in the farm work environment.
RESOURCES AAOHN Journal: “The Impact of Hearing Impairment, Perceptions and Attitudes about Hearing Loss, and Noise Exposure Risk Patterns on Hearing Handicap among Farm Family Members” (2007). American Journal of Preventive Medicine: “A Systematic Review of Farm Safety Interventions” (May 2000). Journal of Agricultural Safety and Health: “Noise Exposures during Potato Processing and Manufacture of Animal Feed” (November 2007). Journal of Agricultural Safety and Health: “Screening Events to Reduce Farmers’ Hazardous Exposures” (February 2007). Journal of Agromedicine: “A Task-Based Assessment of Noise Levels at a Swine Confinement” (2007). Journal of Agromedicine: “Hearing Loss in Migrant Agricultural Workers” (2005). Journal of Occupational and Environmental Medicine: “Hearing Difficulty Attributable to Employment by Industry and Occupation: An Analysis of the National Health Interview Survey–United States, 1997–2003” (January 2008). Public Health Nursing: “Populations at Risk across the Lifespan: Case Reports: A Pilot Study to Prevent Hearing Loss in Farmers” (November/December 2007). Scandinavian Journal of Work, Environment & Health: “Effectiveness of Interventions in Preventing Injuries in Agriculture—A Systematic Review and Meta-analysis”(October 2008).
Researchers at the University of Nebraska Medical Center, where I am an associate professor in the College of Public Health, measured noise exposures during three common processes on farms in the Midwest and South West United States. During evaluation of swine confinement processes, we collected seven full-shift dosimeter samples. The daily noise levels were all well below OSHA’s Permissible Exposure Limit (90 decibels on an A-weighted scale, or dBA) but exceeded the NIOSH Recommended Exposure Limit (85 dBA) on three occasions. The potential for high noise exposures is evidenced in the noise dose measured for specific activities such as power washing, ear clipping, and snout snaring. Area samples taken during the various activities are consistent with dosimetry for specific activities. An analysis of specific tasks revealed that the power washing, ear snaring, and ear tagging operations were the most hazardous. These jobs exceeded the 100 percent daily dose for the time period worked, per the NIOSH criteria. When the results from this survey were projected to reflect an 8-hour exposure, the OSHA action level for noise exposure during breeding, power washing, and snaring exceeded 50 percent of the employees’ daily dose. At the potato and alfalfa processing areas—see the sidebars on pages 24 and 25 for information on these tasks—twenty-seven percent of the employees who were monitored for noise attained or exceeded the NIOSH REL. In addition, the packaging of potatoes presented an ergonomic hazard, and the manufacture of alfalfa pellets included potential for respiratory hazards. HPD USE Working in close proximity to machinery and equipment is a well-recognized source of noise exposure among agricultural workers, yet one in four agricultural workers report not using hearing protection devices (HPDs). Although the most effective and ideal method for controlling loud noise is to engineer it out, proper use of HPDs is also effective and more cost efficient. But HPD use among farmers is low. While OSHA-regulated hearing conservation programs may be in place on industrial and construction work sites, use of HPDs may be less than adequate on the farm, where mandatory requirements do not apply and where the work involves frequent changes in job tasks, dirty hands (which are problematic for inserting ear plugs), and other reasons that make PPE use inconvenient. A 2007 paper published in the Journal of the American Association of Occupational Health Nurses estimated that farmers use their HPDs only 7 percent of the time when exposed to loud noise. Other studies in Public Health Nursing and the Journal of Agricultural Safety and Health have documented rare usage of HPDs among farmers. Factors influencing use of HPDs among farmers have been identified as functional barriers, such as difficulty communicating and fear of not hearing warnings, access to and availability of HPDs, and interpersonal influences, such as family support for HPD use. From anecdotes and past observations, we know that agricultural workers often do not wear HPDs because they leave the devices at home or in another work area. Instead of spending time getting the HPDs, farmers are likely to forgo them. To effectively use engineering controls and HPDs, farmers must know the hazards, and the injury and disease risks caused by these hazards; know how to effectively control the hazards; have access and means to control the hazards; have the intention to control the hazards; and act upon their intention and implement and maintain the controls.
Reviews published in the American Journal of Preventive Medicine and the Scandinavian Journal of Work, Environment & Health argue that educational interventions to increase the use of protective devices among farmers have had mixed results. There have been many limitations to the studies conducted in the past. Some studies have not randomized study subjects or had an appropriate control group. Many studies have not conducted pre- and post-intervention hazard assessments to evaluate the effectiveness of the interventions to control hazards. Most studies have not used behavior models to provide information on the characteristics of participants and allow for evaluation of their attitudes, beliefs, and intentions. Rarely has follow-up been conducted to learn from study participants how the intervention efforts might have been modified to improve their effectiveness. Overall, evaluation of the effect of interventions on disease and injury incidence is largely lacking in the literature. THE POINT-SOURCE STRATEGY Studies support the notion that limited availability of HPDs in noisy work areas is a barrier for HPD use. Our research team at the University of Nebraska Medical Center aims to remove this barrier with a new concept. Rather than focusing only on personal HPD use, as is the current practice, we performed a study where we placed HPDs in a box near identified noise sources, readily available for all workers exposed to the point sources of noise. The novelty of this approach is that it associates the PPE with a noise source and not a person. The box was made of hinged weatherproof aluminum and contained one pair of earmuffs and several ear plugs. We found that the farmers all used the earmuffs at least once, with a median usage of 7.5 times. A preliminary analysis suggests a significant increase in HPD use. Our ongoing study involves a point-source strategy of placing HPDs on or next to sources of loud noise, and preliminary findings include:
- farmers are more likely to use HPDs when educated in the context of their personal noise and hearing test results
- farmers will utilize hearing protectors if they are conveniently placed in areas where there is loud noise
- the point-source strategy reminded farmers to wear HPDs
- farmers were able to get their friends interested in the point-source strategy
OVERCOMING BARRIERS One of the barriers to workers not wearing HPDs is that they are not available when they are needed. Rather than taking the time to obtain the PPE from where it is stored (home, office, locker, vehicle), workers may ignore the noise exposure, even if they are aware that they should use PPE. Our findings suggest that a point-source strategy of placing HPDs near the source of noise is a promising way to overcome this barrier. CHANDRAN ACHUTAN, PhD, is an associate professor in the Department of Environmental, Agricultural and Occupational Health at the University of Nebraska Medical Center College of Public Health. He is also the vice chair of the Council for the Accreditation of Occupational Hearing Conservationists and secretary-elect of the AIHA Noise Committee. He can be reached at (402) 559-8599 or email@example.com. Part of the research mentioned in this article was funded through the Central States Center for Agricultural Safety and Health (CS-CASH) and NIOSH (U54 OH010162).
Photo by Sean Navarrette.
FARM TASKS: MANUFACTURE OF ALFALFA PELLETS The first step in the manufacture of alfalfa pellets is the grinding of raw alfalfa. The alfalfa used to manufacture pellets is sometimes moldy, and could also be mixed with moldy hay. The grinder is about 20 feet high and 10 feet wide; part of it is on the main floor, but most of it is in a basement. To prevent the grinder from clogging, raw alfalfa is loaded a little at a time onto the grinder by a front loader. The ground alfalfa is transported via a vacuum system to the pellet-mill, where, under heat and pressure, it is compressed into pellets. The pellets are cylindrical in shape, and are cut into lengths of six to eight inches. Then they are cooled, sieved, and transferred to storage bins via a vacuum system. The pellet-mill operation is carried out by two employees: a front-loader driver who loads the alfalfa onto the grinder and an operator who runs the pellet-mill machine. (For more information refer to “Noise Exposures during Potato Processing and Manufacture of Animal Feed” in volume 13, issue 4 of the Journal of Agricultural Safety and Health.)
FARM TASKS: POTATO PROCESSING Potatoes are brought into the unloading area in trucks and transferred into a storage bin via a conveyor. Employees are positioned between the end of the truck and the beginning of the conveyor and along the conveyor to separate good potatoes from rotten potatoes, mud clods, and other debris. (Between four and eight truckloads of potatoes were unloaded each day this process was observed.) The potatoes are stored in a bin, from which they are sent to the washer. The washer is automated. When not unloading, employees assist with other tasks in the plant. Three sorting lines at this facility separate the potatoes by size and quality. The washed potatoes come off a conveyor to Sorting Line I. This sorting line is split into two lanes. Five metal bins are located between both lanes. Rotten potatoes are discarded in one of the bins, which are then transported outside the facility via a conveyor. In the remaining four bins, oversized or fused potatoes are placed for further processing. The rest of the potatoes are passed over a set of rollers that separates them by size. From there, the potatoes are sent to Sorting Line II. Potatoes are further sorted for size and quality, and sent for packaging. Potatoes discarded at Sorting Line II and the oversized and fused potatoes from Sorting Line I are further processed at Sorting Line III. At Sorting Line III, potatoes are discarded or sent for packaging. Two employees work in Sorting Line I, one on each lane. About four employees work in each of Sorting Lines II and III. The packaging operation includes one or two employees who assemble cardboard boxes, one who weighs boxes, two to three employees who feed boxes to the boxing line, three who stack the 50-pound filled boxes on pallets, four who fill and weigh 100-pound bags, two to three who stack the 100-pound bags on pallets, and a forklift driver who removes the stacked pallets for storage and shipment. (For more information refer to “Potato Processing and Manufacture of Animal Feed” in volume 13, issue 4 of the Journal of Agricultural Safety and Health.)
FARM TASKS: SWINE CONFINEMENT A majority of the swine confinements in the Midwest are farrow-to-finish operations. Farrow-to-finish refers to the breeding and farrowing of sows and raising the piglets until they weigh 200 pounds, at which stage they are sold. The farrow-to-finish operation involves breeding and gestation, farrowing, weaning the piglets in nurseries, and finishing. The whole cycle can take up to 11 months. In the breeding and gestation barn, farm workers determine whether sows are ready for breeding by passing a boar in a cage in front of the sows’ pens. Sows that remain quiet are ready for breeding; those that squeal in the presence of the boar are not ready. This process is called “heat checking.” Sows are seminated artificially, and the pregnant sows remain in the barn during their gestation period. Upon giving birth, the sows and their litters are moved to the farrowing rooms, where the piglets are nursed. After a few months, the piglets are moved to the nursery where the males are castrated. In the farrowing and nursery barns, piglets and the mothers are routinely checked for health problems. The animals are also given appropriate vaccinations in these rooms. As the piglets get bigger, they are moved to the finishing area. The finishing area comprises different barns that house litters of similar age and weight. In the finishing area, the hogs have their snouts snared and ears tagged for identification. These activities are usually performed by two individuals: one rounds up the animals, and the other manually performs the snout snaring and ear clipping. Hogs are periodically weighed in the finishing area, and when they have attained the optimal weight (usually 200 pounds), they are sold. (For more information, refer to “A Task-Based Assessment of Noise Levels at a Swine Confinement” in volume 12, issue 2 of the Journal of Agromedicine.)