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Preventing Hog Ears: A task-based noise analysis at a swine confinement
Chandran Achutan, PhD
Representative of AIHA

INTRODUCTION

There is a paucity of data on noise exposures and hearing loss from animal husbandry. A few studies have looked at occupational noise exposures among dairy farmers in New York. There is evidence to suggest that workers in swine confinements are exposed to high levels of noise (Siebens, 1997; Kristensen & Gimsing, 1988). Though most of the initial research on noise exposures in swine confinements was carried out in small-scale confinements, the shift over the years from small-scale confinements to industrial size confinements means that more workers are going to be exposed to noise for a longer time periods while performing a specific task for a full shift. Humann et al (2005) suggests that these workers are exposed to high noise levels. This study describes noise exposures experienced by students and staff at a community college that operated a small-scale swine confinement for academic training and profit. The paper employs a task-based approach in assessing noise levels during a variety of tasks, including castration, breeding activities, snout snaring, and power washing. The task-based exposure levels were extrapolated to show potential maximum daily exposure levels if the tasks were carried out for 8 hours a day, thus making the findings relevant to employees at large-scale swine confinements who may work on a specific task for approximately eight hours.

METHODS

Photo 1: Heat checking

Photo 2: Castration

Photo 3: Snout snaring and ear tagging

Facility and Process Description
The facility is a 150-head farrow-to-finish swine confinement center, located on the campus of a community college in Iowa. 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 the following processes: breeding and gestation, farrowing, weaning the piglets in nurseries, and finishing. The whole cycle can take up to 11 months. The facility is a small-scale swine confinement facility used to teach students at the community college. The day-to-day operations are handled by a farm technician with the assistance of students who work part-time. The facility is run by a veterinarian, who also examines the animals and assists with chores as needed.

In the breeding and gestation barn, it is determined if sows are ready for breeding. This is done by passing a boar in a cage in front of the sows’ pens. Sows that are ready for breeding are quiet, and those that are not, squeal in the presence of the boar. This process is called “heat checking.” Sows are inseminated 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 consists of different barns that house litters of similar age/weight groups. In the finishing area, the hogs have their snouts snared and ears tagged for identification. These activities are usually performed by two individuals, one to round up the animals, and the other who 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.

Study Population
All students and employees who were working on the two days of the study were invited to participate. The study population consisted of a veterinarian, a farm technician, and two students who worked from one to four hours during this study. The veterinarian who was also the director of the swine confinement had administrative and academic responsibilities in addition to assisting the with the confinement’s daily operations. The farm technician’s main responsibility was to handle day-to-day management of the swine confinement.

Instrumentation
Quest® Electronics Model Q-300 Noise Dosimeters were worn by a total of seven employees over a 2-day period while they performed their daily activities. Samples were collected throughout the work shifts that ranged from less than an hour to approximately 4 hours. The noise dosimeters were attached to the wearer’s belt and a small remote microphone was fastened to the wearer’s shirt at a point midway between the ear and the outside of the shoulder. A windscreen provided by the dosimeter manufacturer was placed over the microphone during recordings. At the end of the sampling period, the dosimeter was removed and paused to stop data collection. The information stored in the dosimeters was downloaded to a personal computer for interpretation with QuestSuite® Professional computer software. The dosimeters were calibrated before and after the measurement periods according to the manufacturer’s instructions.

Real time, instantaneous noise monitoring was done using a Quest Electronics Model 2400 Sound Level Meter (SLM). The instrument was set to measure noise levels between 70 and 140 dB, on an A-weighted slow-response scale. The SLM was calibrated before and after the measurement periods according to the manufacturer’s instructions. Real time spectral analysis was done with a Larson-Davis Laboratory Model 2800 Real-Time analyzer and a Larson-Davis Laboratory Model 2559 ½-inch random incidence response microphone. The analyzer allows for the analysis of noise into its spectral components in a real-time mode. The ½-inch diameter microphone has a frequency response range (± 2 decibels [dB]) from 4 Hertz (Hz) to 21 kilohertz (kHz) that allows for the analysis of sounds in the region of concern. One-third octave bands consisting of center frequencies from 25 Hz to 20 kHz were integrated for 10-60 seconds and stored in the analyzer.

RESULTS

The results presented describe potential exposures to employees at the swine confinement during the 2 days of the survey. The workday at the confinement may vary depending on the number of hogs, number of student helpers, and the veterinarian’s schedule. On the assumption that the 2 days evaluated were typical workdays at the confinement, the data were analyzed to project an 8-hour dose for each individual. In addition, 8-hour doses for specific tasks were calculated to predict exposures in large-scale confinements. Spectral data collected during the heat checking and the snout snaring and ear tagging processes show that pig squeals can exceed a sound pressure level of 85 dB from 1000–6000 Hz.

During the 2 days that NIOSH collected personal dosimetry data, noise exposures exceeded the NIOSH REL for three people for the actual time that they worked in the confinement facility. When the results were extrapolated to simulate an 8-hour work shift, five of the seven personal dosimetry samples exceeded the NIOSH REL, and two exceeded the OSHA AL (more than 50%). The extrapolation assumes that the percent dose collected during the actual work shift is representative of an 8-hour shift, and the dose has been increased accordingly. The actual and extrapolated results ate shown in Tables 1 and 2 respectively.

An analysis of noise exposures by tasks show that the highest exposures occurred during the power washing job, and during the snout snaring and ear tagging operation. The power washing operation was observed for 29 minutes and snout snaring for 17 minutes. During both operations, the percent dose exceeded the NIOSH criterion for the short time period for at least one of the employees performing the task. When all tasks were extrapolated to an 8-hour work day, the NIOSH criterion was exceeded on eight occasions (128% to 3111%), and the OSHA AL was exceeded four times (178% to 265%) during the snout snaring and the power washing operations, and once during activities at the breedingand gestation barn. The exposure time, actual noise dose, and the 8-hour extrapolated noise dose of each task are given in table 3.

Table 3. Noise exposures expressed as percent dose, as a function of tasks

DISCUSSION

Though none of the workers’ noise levels in this survey exceeded any regulatory standards, noise levels of two employees exceeded the daily percent dose over the course of the survey, as calculated by the NIOSH criterion. The noise level exceeded one worker’s dose on both days that personal samples were collected. An analysis of associated tasks revealed that the power-washing job presents the highest noise hazard at this facility, contributing as much as 104% of the daily dose for approximately 30 minutes of exposure. All employees were wearing ear muffs during the work day, but a close inspection of the ear muffs showed that the cushions were cracked and needed repair.

Over the past several years, there has been a shift from small-scale swine confinements to large-scale production facilities (Mallin & Cahoon, 2003). At some of these large production facilities, employees perform dedicated chores throughout the work day. For example, employees may be required to power wash pens for a full work shift. The 8-hour task-based results from this survey are useful to characterize potential noise exposures for these employees. Data from this evaluation suggest that some tasks related to swine production may result in excessive noise exposure, and employees should be enrolled in a hearing conservation program.

CONCLUSIONS

There is potential excessive noise exposure to employees at the swine confinement, though none of the values measured in this limited survey exceeded any recommended or regulatory standards. However, if employees were to carry out their tasks over an 8-hour work day, the NIOSH REL would have been exceeded on five occasions, and the OSHA AL would have been exceeded twice. The OSHA PEL would not have been exceeded.

An analysis of specific tasks revealed that the power washing and snaring and ear tagging operations were the most hazardous. These jobs exceeded the 100% 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 AL for noise exposure during breeding, power washing, and snaring exceeded 50% of the employees’ daily dose.

REFERENCES

Siebens D. Noise and hearing loss in agriculture, forestry, and fisheries. In: Langley RL, McLymore RL, Meggs WJ, Robertson GT, editors. Safety and Health in Agriculture, Forestry, and Fisheries. Rockville, MD, Government Institutes. 1997; 59-66.

Kristensen S, Gimsing S. Occupational hearing impairment in pig breeders. Scand Audiol. 1988; 17(3):191-192.

Mallin, MlA.; Cahoon, LB. Industrialized Animal Production-A Major Source of Nutrient and Microbial Pollution to Aquatic Ecosystems. Population & Environment. 2003; 24(5):369-385

Humann MJ, Donham KJ, Jones ML, Achutan C, Smith BJ. Occupational Noise Exposure Assessment in Intensive Swine Farrowing Systems : Dosimetry, Octave Band, and Specific Task Analysis. Journal of Agromedicine. 2005; 10(1):23-37