Evaluating Eye & Respiratory Irritation – Poultry Workers
Evaluating Eye and Respiratory Irritation in Poultry Slaughter and Processing Facilities
NIOSH’s Health Hazard Evaluation (HHE) Program has responded to a number of requests to evaluate reports of eye and respiratory irritation among workers in poultry slaughter and processing facilities. Symptoms commonly reported in these facilities include stinging or burning eyes, nose, and throat; sneezing or coughing; sore throat; shortness of breath or asthma-like symptoms; headaches; and nausea. During interviews conducted with workers, it has often been reported that such symptoms are intermittent in nature, increasing the difficulty in identifying a specific causative factor. In the past, chlorine use in the facilities’ chiller baths and evisceration lines for anti-microbial treatment of poultry carcasses and equipment sanitation has often been suspected as a culprit. While chlorine may be responsible for some of the symptoms, chlorine-related by-products called chloramines were often implicated as a more likely cause of the irritation symptoms. These by-products are the result of interaction between the chlorine source and nitrogenous material from the poultry.
Poultry slaughter and processing facility managers should be aware of the many contributing factors commonly found in facilities where symptoms are reported. Knowledge of the multi-factorial nature of the issues can allow prompt action to address such symptoms. Investigations conducted by industrial hygienists from both NIOSH and USDA have commonly found the following factors (either alone or in combination) that appeared to have contributed to the irritation symptoms. It is recommended that poultry processing facilities focus on addressing these symptom-contributing factors despite a lack of environmental sampling data for specific contaminants.
Chlorinated Wash and Chiller Bath Water
- excessive chlorine concentration in water
- increased numbers of chlorine sources on the equipment line
- increased water pressures on sprays resulting in aerosolization of a chlorinated water mist
- use of chlorine-containing cleaning chemicals during the cleaning shift without adequate ventilation prior to the start of the next work shift
- mixtures of chlorine, other chemicals, and organic materials in floor drains
- close proximity of chiller baths containing large quantities of chlorinated water to workers in the evisceration area
- chiller fill pipes located above the surface of water in chill tanks
- the addition of chlorine to chillers prior to the birds
- using carbon dioxide or other acid-based systems to lower water pH
- under-designed ventilation systems resulting in stagnant evisceration line locations receiving little to no fresh air
- lack of ventilation upgrades as new plant renovations are introduced
- presence of comfort fans on the evisceration line that may disrupt air flows patterns or blow directly on workers’ faces resulting in eye irritation or dryness
- airflow patterns and pressure imbalances that draw air from the areas of high chlorinated water use to areas of lower or no use of chlorinated water
- lack of enclosure cabinets around wash stations to provide adequate local exhaust ventilation
- presence of bird diseases such as air sacculitis
- presence of large amounts of ingesta and fecal contamination
Additionally, it is possible that individuals with pre-existing asthma, allergy, or sinus symptoms may experience an aggravation of these symptoms due to the exposure of even trace amounts of airborne chlorine compounds, particularly in high humidity environments. Furthermore, poultry proteins, viscera, fecal material or feathers/dander may also prompt or aggravate allergic reactions in susceptible workers.
In efforts to provide a safe and healthful work environment for their employees, company health and safety representatives can investigate a spectrum of factors that may play a role in complaints of worker health effects. As identified by industrial hygienists from both NIOSH and the U.S. Department of Agriculture, the following list of recommendations for improvements in engineering and process controls may help prevent reports of worker health effects. The identification of a process control manager responsible for consistently reviewing these areas of potential concern may prove beneficial. While many of these factors may play a role in reported health effects, efforts to prevent such effects will require the involvement and commitment by company management to improved occupational safety and health in an equal manner to their commitment to product safety.
Introduction of Chlorine or Other Antimicrobials
- Highly increased concentrations of chlorine in the wash water may play a role in reports of eye and respiratory irritation among poultry evisceration and processing workers. Determine that the chlorine injection points into the water are functioning properly and are injecting the chlorine (or other antimicrobial) at the appropriate concentration. It is recommended that facility and process control managers maintain the concentration of chlorine in water as close to 20 parts per million (ppm) as possible and do not exceed a chlorine concentration of 50 ppm. An automatic system that self-regulates the chlorine level may be ideal to prevent inadvertent introduction of excessive quantities of chlorine.
- Ensure that quality control processes for the introduction of chlorine or other antimicrobials into water are in place and effective. Past investigations of poultry evisceration and processing facilities have found that the level of total chlorine within the wash water can vary on a day-to-day basis depending on the introduction of chlorine sources into the water. Implementing a program to evaluate and ensure that the level of chlorine remains at a constant and appropriate concentration in the wash water throughout every day is essential. This includes ensuring that the staff is adequately trained to test and adjust chlorine levels if necessary.
- Evaluate the number of sources of chlorine introduction into water needed for the facility’s operation. Greater number of chlorine sources increases the opportunity for unintentional over-introduction of chlorine. Reduce the number of chlorine sources to the minimum necessary for the facility.
- Ensure that staff is adequately trained in how to test for chlorine and how to adjust the levels if necessary. Reliance on manual adjustment is discouraged. Self-regulating adjustment of chlorine levels is preferred.
- The availability of chlorine for disinfection in wash or chiller water can be impacted by the presence of other organic material such as waste, blood, or fat from the poultry. Ensure that such organic material which could consume the available chlorine is not present in excessive amounts in chlorinated chiller baths. This will promote the availability of chlorine for antimicrobial activity and prevent the need for excessive chlorine concentrations in the water.
- General ventilation in the facility plays an important part in ensuring adequate indoor air quality for evisceration and processing facilities. Maintain the heating, ventilating, and air conditioning (HVAC) system on a regular basis to ensure proper functioning of all components of the system. This includes ensuring that all fans associated within the system are functioning and turned on as intended.
- Evaluate the ventilation system for possible short-circuiting of the introduced air. Short-circuiting occurs when air introduced by the ventilation system is removed prior to its mixing with the room air. Often in these cases, the supply air is removed in this fashion because an exhaust fan is located in close proximity to the supply vent. The result is stagnant air in the work zone, deprived of the dilution effect that the proper supply of fresh outdoor or conditioned air would have provided.
- Ensure that the ventilation system is providing adequate numbers of air exchanges for the areas the system serves. If insufficient fresh air is introduced into these areas, the impact of general dilution of airborne contaminants may be minimal. Consult a qualified ventilation engineer to determine appropriate air exchanges for the areas in question.
- Ensure that the flow of air provided by the positive-pressure ventilation system is directed through the facility from the cleanest areas of a facility to the dirtiest areas. In general, this would ensure air flows from areas of little chlorine use (such as the packaging and storage area) towards areas of higher chlorine use (such as the slaughter, evisceration, and chiller baths areas).
- Consider the impact that new upgrades or renovations to the facility may have on the existing ventilation system. When such facility upgrades or renovations are introduced, the existing HVAC system may be insufficient to meet the needs of the renovations and may require upgrading as well.
- Ensure that the use of comfort fans do not disrupt the intended air flow and direction through the facility.
- After cleaning shifts when chlorine-containing chemicals are used, allow sufficient time prior to the start of the next work shift for ventilation to introduce adequate air for maximum dilution of airborne chlorine compounds.
- Evaluate work processes in evisceration and processing facilities to determine if operations that currently involve open spraying of chlorinated water can be enclosed within spray cabinets.
- Consider installing local exhaust ventilation to the spray cabinets to remove air contaminants and prevent their movement from the cabinet to the outer work environment.
- Ensure that the water pressure of chlorinated water sprays used in cabinets is adequate for their intended purpose. When sprayed at too high of a pressure, a fine mist of chlorinated water may be created, which is difficult to control and maintain within the interior of the cabinet, potentially impacting nearby workers.
- Replace spray nozzles that have small sized holes with nozzles that have larger sized holes. This will result in a spray with larger water droplets that are easier to control than a smaller sized droplet mist.
- Determine that all spray nozzles are in their proper alignment, facing into the interior of the cabinet. Outward-facing or misdirected nozzles may present an opportunity for chlorinated water spray to be released outside of the cabinet.
- Check to identify if spray nozzles are plugged with debris. Plugged nozzles may impact the spray pressure of other nozzles on the same system, preventing proper application of the chlorinated water at the proper pressure in the cabinet.
- Ensure that unnecessary openings to the cabinet are identified and closed to reduce excess spray from being released outside the cabinet. Likewise, ensure that openings through which the poultry enter into and exit from the cabinet are sized properly. If these openings are too large, panels or curtains may be installed to reduce their size to reflect the size of the poultry passing through the cabinet.
- Consider installing a dedicated drain line from the cabinet rather than allowing the chlorinated water to fall on the floor. This may prevent unwanted or unnecessary mixing of the chlorinated water with organic material on the floor or in open floor drains.
- Provide grates on floor drains and drainage troughs to capture fallen poultry material. If poultry products fall into open floor drains and drainage troughs, ensure they are adequately cleaned throughout each shift to prevent stagnant pools of organic poultry material and chlorinated water.
- If possible, prevent waste water from the chiller baths from mixing with the waste water from the evisceration areas through separate drainage systems.
- Design the facility in such a way as to prevent close proximity between the chiller bath area and the evisceration area.
- Introduce new chiller bath water into the bottom of the chiller baths rather than from pipes at the surface of the water. This allows for decreased opportunities for aerosolization of chlorinated water.
- Conduct symptom surveillance to assess the impact of newly implemented controls. This would also entail removing potential barriers that workers may feel are present that prevent their reporting of symptoms experienced.
- Consider the availability of other jobs within the facility for transferring symptomatic employees who may show a particular sensitivity to this type of exposure.
As technology moves forward in the industry, the reliance on the use of chlorine compounds for disinfection during slaughtering and processing is decreasing. New disinfection systems using a variety of other antimicrobials besides chlorine (e.g., ozone, bromine compounds, lactic acid, citric acid, chlorine dioxide, and peroxyacetic acid) continue to be approved by the U.S. Department of Agriculture (USDA). As these systems are introduced to the market and implemented by industry facilities, it should be noted that USDA approval of such systems falls under their food safety directive for purposes of killing bacteria. USDA approval does not speak to potential occupational exposure concerns for workers in facilities where such systems are installed and operated. Therefore, safety and health professionals in the industry should be aware of the potential for such occupational exposures and act to prevent such exposures accordingly. While facilities may vary in their use of chlorine or other disinfectants, similarities exist in how facilities can respond to prevent occupational exposures to these chemicals. While past experience has focused on chlorine and chloramines, the steps developed to address the multi-factorial nature of symptoms reported by workers in relation to chlorine or chloramines exposure can be applied in facilities where other disinfectants are used as well.
Integrated air sampling methods for chlorine have been published by both NIOSH and OSHA. However, the use of these available air sampling methods for chlorine in poultry processing facilities has often led to results showing non-detectable concentrations or concentrations well below applicable occupational exposure limits (OELs), despite reports of health symptoms or chlorine-like odors by workers in poultry-processing facilities.
Developing the ability to sample for chloramines has been an area of study for NIOSH scientists for the past several years. As part of this effort, NIOSH investigators adapted a sampling and analytical method for chloramines as reported in the scientific literature by French researchers and used it to attempt chloramine exposure assessments at poultry processing facilities. While the method showed some initial success in assessing correlations between levels of exposure and a variety of reported irritation symptoms, several deficiencies in the method have been encountered. These include a lack of consistency in the limits of detection (LOD) and limits of quantitation (LOQ) between investigations and the inability to produce a laboratory chloramine standard against which lab results can be compared. These limitations have necessitated further research towards a more robust and reliable method for inclusion in the NIOSH Manual of Analytical Methods (NMAM). NIOSH investigators continue to pursue such research as resources permit. Until that time, no valid NIOSH air sampling method for chloramines is available.
As with chloramines, no suitable air sampling methodologies often exist for a number of the other antimicrobial chemicals being introduced on the market for this industry. Additionally, the use of direct reading instruments such as colorimetric detector tubes has been attempted with minimal success in correlating readings with symptoms reported.
Because of the limitations associated with air sampling, it is recommended that facilities in which health effects are reported by workers address the symptom-contributing factors detailed above rather than relying on inconclusive or non-existent industrial hygiene sampling results.