Evaluation of Eye and 

Respiratory Symptoms 

at a Poultry Processing 

Facility – Oklahoma

Lilia Chen, MS, CIH

Judith Eisenberg, MD, MS

Srinivas Durgam, MSPH, MSChE, CIH

Charles Mueller, MS

Health Hazard Evaluation Report

HETA 2007-0284 & 2007-0317-3155

March 2012 

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Centers for Disease Control and Prevention

Workplace

Safety and Health

 National Institute for Occupational 

Safety and Health
The employer shall post a copy of this report 

for a period of 30 calendar days at or near 

the workplace(s) of affected employees. The 

employer shall take steps to insure that the 

posted determinations are not altered, defaced, 

or covered by other material during such 

period. [37 FR 23640, November 7, 1972, as 

amended at 45 FR 2653, January 14, 1980].
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page i

Report Abbreviations................................................................................................i

Highlights of the NIOSH Health Hazard Evaluation........................iii

Summary .........................................................................................................v

Introduction ...................................................................................................1

Assessment.....................................................................................................5

Results..............................................................................................................8

Discussion.................................................................................................... 17

Conclusions................................................................................................. 25

Recommendations.................................................................................... 26

References.................................................................................................... 28

Contents

Acknowledgments Acknowledgments and Availability of Report................................ 4

Appendix A Methodology.............................................................................................. 32

Appendix B Occupational Exposure Limits and Health Effects................. 35

Appendix C Fluorescein Stain Scoring .................................................................. 39

Appendix Tables............................................................................................................ 4
Page ii Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Abbreviat

μg/m3 Micrograms per cubic meter

ACGIH® American Conference of Governmental Industrial Hygienists

AIHA American Industrial Hygiene Association

ASHRAE American Society of Heating, Refrigerating, and Air-Conditioning Engineers

cfm Cubic feet per minute

CFR Code of Federal Regulations

FEV1 Forced expiratory volume in 1 second

FVC Forced vital capacity

GM Geometric mean

HHE Health hazard evaluation

HVAC Heating, ventilating, and air-conditioning

IQF Individually quick frozen

IW Individually wrapped

LOD Limit of detection

LOQ Limit of quantitation

MDC Minimum detectable concentration

mL Milliliter

MQC Minimum quantifiable concentration

NAICS North American Industry Classification System

ND Not detected

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

PBZ Personal breathing zone

PEL Permissible exposure limit

ppm Parts per million

REL Recommended exposure limit

S&P Scalding and picking

STEL Short-term exposure limit

TLV® Threshold limit value

TWA Time-weighted average

USDA United States Department of Agriculture

WEELTM Workplace environmental exposure limit

WOG Without gizzards 
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page iii

The National Institute for 

Occupational Safety and 

Health (NIOSH) received 

employer requests from 

a poultry processing 

facility and a government 

agency for a health 

hazard evaluation at a 

poultry processing facility 

in Oklahoma. These 

requests were submitted 

because of reported eye 

and respiratory irritation 

symptoms among 

production employees 

and government food 

inspectors.

Highlights of 

NIOSH 

Hazard Eval

What NIOSH Did

● We visited the facility in October 2007, February 2008, and 

October 2008.

● We asked employees in two groups to fill out a survey about 

symptoms they had in the previous month. Employees who 

worked in areas with superchlorinated water made up the 

exposed group. Employees who worked in areas that did not 

use superchlorinated water made up the unexposed group.

● We performed breathing and eye tests on exposed employees 

before and after their shift. These employees also completed 

a symptom survey after their shift.

● We took air samples in the evisceration area. These 

samples were analyzed for trichloramine, soluble chlorine 

compounds, chlorine, and chlorine dioxide.

● We measured employees’ exposure to trichloramine and 

soluble chlorine in the evisceration area.

● We reviewed the company’s records of the chlorinated water 

concentrations.

● We looked at the heating, ventilating, and air conditioning 

systems. We used smoke tubes to determine the air flow 

patterns.

What NIOSH Found

● Employees in the exposed group were more likely to report 

certain work-related symptoms in the previous month 

than employees in the unexposed group. These symptoms 

included chest tightness, sneezing, dry eyes, blurry vision, 

and burning or itchy eyes.

● Increased levels of exposures to air trichloramine and soluble 

chlorine were not related to increased symptom reports 

during their shift.

● Of 39 exposed employees, 2 had significant declines in their 

breathing tests over a shift and 37 exposed employees did not.

● Most examinations for 38 participants had abnormal preshift 

tear film breakup times and even more were abnormal 

postshift. This can be a sign of eye irritation, but the cause 

cannot be definitively determined on the basis of our data.

● Most of the air samples we took for trichloramine had 

concentrations below the level that we could accurately 

measure.
Page iv Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

● We found higher levels of soluble chlorine compounds in the 

air in areas that used superchlorinated water.

● The chlorine concentrations in the wash water met the 

requirements of the U.S. Department of Agriculture.

● We measured very low concentrations of chlorine dioxide 

and chlorine in the air.

● The ventilation in the building follows the guidelines for 

air flowing from clean to dirty areas set by the American 

Society of Heating, Refrigerating, and Air-Conditioning 

Engineers. However, this air flow pattern was not done via 

positive pressure ventilation. Positive pressure ventilation 

helps minimize product contamination from contaminants 

in unfiltered air entering the process area.

What Managers Can Do

● Maintain chlorine and other water chemistry parameters 

within established guidelines. Staff should be properly 

trained on how to perform these tasks.

● Find a more accurate and timely way to monitor and adjust 

the water chemistry parameters for the superchlorinated water.

● Use positive pressure ventilation to achieve the air flow 

patterns that meet the American Society of Heating, 

Refrigerating, and Air-Conditioning Engineers’ guidelines.

● Consult with a ventilation engineer to evaluate the effectiveness 

of the air distribution systems in the processing areas.

● Minimize wastewater from different areas mixing in the drain 

channels. Also, reduce organic product contamination of the 

effluent as much as possible. Make sure that effluent can be 

quickly removed from the processing area.

● Periodically look for new cleaning and disinfecting agents 

that are safer to use than current products. Make sure that 

alternatives are safe to use and can maintain or improve 

current hygiene standards.

What Employees Can Do

● Report eye and respiratory irritation to your manager 

immediately. Seek prompt evaluation by a medical 

professional.

Highlights of 

NIOSH 

Hazard Eval

 (continued

 
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page v

NIOSH evaluated workrelated symptoms in 

poultry processing 

employees and 

government food 

inspectors in areas using 

superchlorinated water 

(exposed) and in areas not 

using superchlorinated 

water (unexposed). 

Exposed participants 

were more likely to report 

work-related symptoms in 

the previous month than 

unexposed participants. 

Of 39 exposed employees, 

2 had significant declines 

in their breathing tests 

over a shift and 37 

exposed employees did 

not. Most examinations 

for the exposed group had 

abnormal preshift tear 

film breakup times, and 

even more were abnormal 

postshift. The levels of 

chloramines found in 

the air were low, and the 

levels of soluble chlorines 

were higher in areas that 

used superchlorinated 

water. We recommend 

that managers monitor 

and maintain proper 

water chemistry 

parameters in the wash 

water and use positive 

pressure ventilation (to 

help minimize product 

contamination) to achieve 

air flow patterns following 

ASHRAE guidelines.

Summ

In July 2007, NIOSH received employer requests from a poultry 

processing facility and a government agency for an HHE in 

Oklahoma. These requests concerned eye and respiratory 

symptoms reported by poultry processing employees and 

government food inspectors. On October 16, 2007, we held 

an opening meeting with employer and union representatives, 

observed work process and practices, and interviewed employees 

privately. We found that eye and respiratory irritation were 

common among employees working in evisceration and paw 

harvest areas. On February 21–22, 2008, we returned to the 

facility to measure soluble chlorine and trichloramine levels in the 

evisceration area. The chloramine concentrations measured during 

this visit warranted further investigation of employees’ symptoms 

and exposure to these compounds.

On October 1–10, 2008, we returned to the facility. We asked 

government food inspectors and poultry processing employees who 

worked on lines using superchlorinated water (evisceration line, 

reprocessing, paw harvest, and gizzard harvest areas) and employees 

working in areas not using superchlorinated water (such as the 

IW, IQF, and WOG areas) to complete a survey about symptoms 

experienced at work in the previous month. These employees 

were designated as exposed and unexposed, respectively. Exposed 

participants also had eye exams and lung function (spirometry) 

testing before and after their work shift.

We collected area air samples for soluble chlorine and 

trichloramine in seven locations throughout evisceration, 

reprocessing, gizzard harvest, paw harvest, and two locations in the 

WOG and IQF areas. We collected PBZ air samples from exposed 

participants. Area air samples for chlorine and chlorine dioxide 

were taken, and we reviewed the company’s chlorine concentration 

records for the water used in reprocessing, evisceration, bird 

wash, and paw harvest areas. We visually inspected the ventilation 

system and used smoke to observe air movement throughout the 

evisceration area.

Exposed participants were more likely to report certain workrelated symptoms in the previous month than unexposed 

participants. These symptoms included chest tightness, sneezing, 

dry eyes, blurry vision, and burning or itchy eyes. Of the 39 

exposed participants, 2 had significant declines in their FEV1, a 

measure of a change in lung function, between the start and the 

end of their work shift. Some participants’ tear film breakup times 
Page vi Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Keywords: NAICS 311615 (Poultry Processing), chloramines, 

trichloramine, poultry processing, eye irritation, respiratory irritation, 

spirometry, eye examinations, fluorescein stain scoring

Summ

 (continued) worsened over the shift, but most participants started their shift

with an abnormal tear film breakup time. Overall, the results of 

the trichloramine and soluble chlorine air samples were low. We 

detected higher levels of soluble chlorine compounds in areas 

that used superchlorinated water compared to areas without 

superchlorinated water. Increased levels of exposures to air 

trichloramine and soluble chlorine were not related to increased 

symptom reports during their shift. All chlorine dioxide and all but 

one chlorine area air concentrations were very low and well below 

relevant OELs.

Poultry processing facilities have many potential sources of 

irritants in addition to the compounds we evaluated, which made 

identifying the exact causes of employee symptoms difficult. 

Sampling for these compounds is complicated by the irritant 

chemicals’ sporadic and unpredictable formation and release 

into the air. Irritant symptoms can be caused and exacerbated 

by a variety of factors, including exposure to a combination of 

chemical and biological compounds, poor water chemistry control, 

inadequate ventilation, and employee sensitivity to irritants. 

Establishing positive pressure ventilation, ensuring good air 

mixing, and maintaining proper water chemistry may help reduce 

employees’ symptoms.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 1

Introduct

NIOSH received employer requests from a poultry processing 

facility and a government agency for an HHE at a poultry 

processing facility in Oklahoma. These requests concerned eye and 

respiratory symptoms reported by poultry processing employees 

and government food inspectors. We conducted investigations in 

October 2007, February 2008, and October 2008. On October 16, 

2007, we toured the facility and interviewed 14 poultry processing 

employees and all 10 government food inspectors. All of the 

inspectors and most of the interviewed employees worked in the 

evisceration and paw harvest areas. Reports of eye irritation and 

respiratory irritation were common and occurred at unpredictable 

and irregular intervals among those interviewed, so we returned 

to determine if chloramine compounds might be responsible for 

the symptoms. We sampled the air in the evisceration area for 

chloramines in February 2008 and determined that chloramine 

concentrations were present at levels that warranted further 

investigation. This report details our investigation from October 

2008. Correspondence summarizing our activities was sent in 

November 2007, May 2008, and October 2008. Participants were 

notified of individual test results in July 2009.

Associations of Chloramines and 

Symptoms in Poultry Processing

Eye and upper respiratory irritation symptoms have been 

reported at poultry processing facilities, and possible causes have 

been investigated by NIOSH, OSHA, USDA, and state health 

departments. These symptoms have usually been reported by 

employees working in evisceration, inspection, and reprocessing 

areas where superchlorinated water is used. Workers usually report 

that symptoms are intermittent, and the intensity of symptoms can 

vary from being a nuisance to such severity that the worker must 

leave the workplace. Individual tolerances also play a role. Some 

workers in the same area can be severely affected, whereas others 

may be only mildly affected.

In previous evaluations at poultry processing facilities, investigators 

have postulated that eye, mucosal, and respiratory symptoms were 

caused by chloramines, specifically trichloramine [NIOSH 1987, 

1993, 2000, 2003, 2006, 2007]. Studies have shown an association 

between trichloramine and eye and respiratory symptoms in indoor 

pool environments [Barbee 1983; Hery et al. 1995; Massin et al. 

1998] where chlorine (used as a disinfectant) mixed in the water 

with nitrogenous compounds produced by patrons and formed 
Page 2 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

trichloramine. The trichloramine volatilized from the water 

into the air. In poultry facilities, this irritant vapor is thought to 

form when the superchlorinated water mixes with nitrogenous 

waste from the poultry carcasses. Sampling for other suspected 

compounds (e.g., chlorine, chlorine dioxide, ammonia) that could 

cause reported symptoms resulted in levels that were lower than 

established OELs [NIOSH 1987, 1993, 2000, 2003; Sanderson et 

al. 1995].

Past NIOSH evaluations have investigated work-related symptoms 

in poultry facilities by use of questionnaires [NIOSH 1987, 1993, 

2000, 2003, 2006, 2007]. The symptoms most frequently reported 

were burning, stinging eyes; itchy, runny, or stuffy nose; cough; 

sneezing; sore throat; and asthma symptoms such as wheezing, 

chest tightness, or shortness of breath.

Evaluations also looked at preshift and postshift lung function 

[NIOSH 2003; King et al. 2006], evaluated water chemistry 

[NIOSH 1987, 1993, 2000], and observed ventilation systems 

and air movement in the facility [NIOSH 1993, 2000, 2003]. Air 

trichloramine and soluble chlorine levels were higher in areas that 

used superchlorinated water (i.e., evisceration) than in areas that 

did not use superchlorinated water. Employee symptoms were 

associated with working in areas that used superchlorinated water.

Respiratory and eye symptoms had been previously reported at 

this Oklahoma facility in 1992, and NIOSH was asked to conduct 

an evaluation [NIOSH 1992]. Symptoms were reported to be 

episodic and could not be linked to specific events or exposures. At 

that time, NIOSH found no detectable levels of chlorine, carbon 

monoxide, or chloramines in the air.

Process Description

This facility processes about 134,000 chickens per shift. 

Poultry processing occurs during the first and third shifts, and 

approximately 40 poultry processing employees and 8 government 

food inspectors work each shift. The government food inspectors 

work alongside the poultry processing employees on the processing 

lines and are represented by the American Federation of 

Government Employees. Poultry processing employees were not 

represented by a collective bargaining unit during the HHE.

Introduct

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 3

The processing started with live chickens that were unloaded 

and hung on two separate automated shackle lines. The chickens 

were stunned, killed, and then scalded in a hot water bath to 

loosen the feathers, which were removed by automated “picking” 

(defeathering) machines (Figure 1). The heads were pulled off, 

the paws (feet) removed, and the chickens rehung. The shackle 

lines moved the chickens into the evisceration room where 

automated machines removed the neck and oil glands, slit open 

the chicken, and extracted the edible and inedible viscera. All 

carcasses were sprayed with superchlorinated water to prevent 

potential fecal/bacterial cross contamination. The chickens and 

corresponding viscera were placed in a tray under the carcass 

that traveled down the line for inspection by poultry processing 

employees and government food inspectors. If a problem was 

identified, the chickens were redirected to the reprocessing area 

where they may be trimmed to salvage usable parts or hand washed 

with superchlorinated water. If the chicken did not pass the 

USDA/Food Safety Inspection Service inspection criteria, it was 

condemned and removed from the line. The inspected, eviscerated 

chickens were sent into the chiller room to lower the carcass 

temperature. The chickens were then separated, sent for cutting or 

marinating, then packaged and frozen.

Figure 1. Poultry processing flow diagram.

Introduct

 (continued
Page 4 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

The superchlorinated water was stored in a 150-gallon mix tank, 

where liquid sodium hypochlorite was mixed with water to a target 

concentration of 20–50 ppm of free available chlorine. Because 

the USDA requires chlorine levels to be within these parameters, 

poultry processing technicians tested chlorine concentrations 

every hour using a titration method. If chlorine concentrations 

needed adjustment, the technicians contacted building 

maintenance personnel who manually adjusted the amount of 

sodium hypochlorite injected into the water. Facility management 

personnel and government food inspectors also tested the chlorine 

concentration as needed to ensure that the standard was met.

Sanitation occurred on the second shift. All the machines were 

prerinsed using a high pressure tap water spray, sprayed with a 

quaternary ammonium solution, then rinsed with tap water after 

10 minutes. Another quaternary ammonium compound was 

then sprayed on all machines and left until the next shift started. 

Machines were also rinsed with tap water during the shift, when 

workers took 30-minute breaks. Foot baths containing a quaternary 

ammonium compound were placed throughout the processing 

area in front of doors. These baths were tested three to four times 

a shift to ensure the disinfectant concentration was maintained. 

The baths were changed out when needed. Automated devices also 

sprayed a foam containing quaternary ammonium compounds in 

front of the exits to disinfect employees’ boots.

Process Ventilation

Two roof top air-conditioning units supplied 100% outdoor, 

filtered, and conditioned air into the evisceration area. Air from 

the evisceration area was exhausted through the S&P room. The 

S&P room had five exhaust fans to exhaust air out of the building. 

Processing areas had interconnecting wall openings that allowed 

chickens on the automated shackle lines to pass from one area to 

another. These wall openings also allowed air movement between 

areas depending on the pressure differential between different 

areas. The legline had two air-conditioning units and the chiller 

area had one air-conditioning unit that recirculated air during the 

two production shifts to maintain the chiller room below 55°F. 

However, during the sanitation shift, all three air-conditioning 

units were switched from recirculation mode to the exhaust mode. 

In addition, wall mounted blowers provided chilled air into the 

south end of the legline area.

Introduct

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 5

The IW and IQF areas had eight exhaust fans. The packaging and 

storage areas had four units for conditioning and recirculating 

air. The facility’s administrative areas were served by separate 

air handling units. Inspection stations on evisceration lines 

had small personal cooling fans that employees could adjust for 

personal comfort.

Introduct

 (continued

Assessment

Medical Testing and Questionnaire

Employees and government food inspectors working in areas 

with superchlorinated water were asked to participate in medical 

testing that included preshift and postshift eye examinations and 

spirometry, also known as lung function testing (Appendix A). 

Medical testing occurred during five consecutive day and night 

shifts. Participation was voluntary. Employees were asked to 

participate in testing for as many shifts as they worked for up to 

five shifts. Informed consent was obtained prior to participation.

The eye examination consisted of several components. An initial 

examination in front of a slit lamp was used to evaluate the cornea 

and conjunctiva. Fluorescein dye was then placed in the eye to 

obtain the fluorescein staining score and measure the tear film 

breakup time. The fluorescein stain score is based on condition 

of the cornea. Use of the fluorescein dye allows for better 

visualization of defects in the cornea. Tear film breakup time is 

a measure of the stability of the tear film layer that keeps the eye 

lubricated. It is measured from the time the stain is distributed 

until disruptions in the tear film layer are seen. When the tear 

film layer dissolves prematurely, which can be caused by a chemical 

irritant exposure, the eye is no longer adequately moisturized, and 

irritation and dryness may develop. However, tear film breakup 

time is not a specific test to measure irritant exposure; a decreased 

tear film breakup time can occur as a result of existing eye 

conditions. We evaluated all eye surface structures to identify other 

potential causes of injury that would be detected by fluorescein 

staining. Most changes to the eyes from airborne chemical irritants 

can take many years to develop, and may include erosion of 

the corneal surface. Workplace environmental irritants such as 

chloramines are hypothesized to cause premature breakup of the 

tear film layer resulting in a decreased tear film breakup time at the 

end of the work shift.
Page 6 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Assessment

 (continued) Poultry processing employees and government food inspectors

working in areas with superchlorinated water (evisceration, paw 

harvest, gizzard harvest, and reprocessing) and those in areas 

without superchlorinated water (e.g., WOG, IW, IQF, marination, 

packing) were asked to complete a questionnaire, and these two 

groups were classified as exposed to superchlorinated water and 

unexposed to superchlorinated water. The questionnaire asked 

participants if they had any of the following symptoms during their 

work shift in the previous month: unusual shortness of breath, 

chest tightness, cough, wheezing, dry or gritty eyes, burning or 

itchy eyes, watery eyes, blurry vision, stuffy nose, runny nose, 

or sneezing. Symptoms were considered work-related if they 

improved on days away from work. The questionnaire included 

eye conditions that may affect tear formation and stability, such as 

dry eye. Participants in the exposed group who participated in the 

medical testing also completed a symptom survey after their work 

shift that inquired whether they experienced eye and respiratory 

symptoms during that particular shift. On the postshift symptom 

survey, symptoms were considered work-related if the symptom 

was not present before starting that shift and developed during 

that day’s shift. Participants were instructed to answer “no” to a 

symptom if they associated it with having a cold or respiratory 

infection.

Air Sampling for Disinfectants and 

Disinfectant Byproducts

Area and PBZ trichloramine and soluble chlorine 

(monochloramine, dichloramine, hypochlorous acid, and 

hypochlorite) air samples were taken on day and night shifts from 

October 6, 2008, through October 10, 2008. PBZ air samples 

were taken on all exposed participants who consented to the 

medical testing and on one participant who completed only the 

questionnaire. Trichloramine and soluble chlorine concentrations 

in air were measured over the participants’ full shift (~8 hours). We 

collected area air samples approximately 4 feet above the ground 

for trichloramine and soluble chlorine in nine locations. Seven 

locations were in the processing area and included reprocessing, 

paw harvest, the gizzard harvester, and the east and west ends of the 

evisceration lines. After the first sampling shift on the first day of 

our evaluation, we also took area air samples in the WOG and IQF 

areas, which were separate from the processing area.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 7

Assessment 

(continued) Air concentrations of chlorine and chlorine dioxide were measured

using direct reading Dräger tubes® (Luebeck, Germany) in the 

evisceration, reprocessing, and chilling areas once per shift. We 

also reviewed the poultry processing facility’s log sheets for chlorine 

concentration in wash water in the reprocessing, paw harvest, and 

gizzard harvest areas.

More details on health effects for substances we evaluated and on 

our sampling methods can be found in Appendices A and B.

Process Ventilation

We interviewed facility managers to obtain information on the 

HVAC systems serving the processing areas. We used ventilation 

smoke tubes to observe air flow patterns at doorways and to 

determine the pressure differential between the evisceration, 

reprocessing, chiller, and legline areas.

Statistical Analysis

SAS software Version 9.1.3 (SAS Institute, Cary, North Carolina) 

was used for statistical analysis. We used log-binomial regression 

models to evaluate associations between exposure groups and 

work-related symptoms while controlling for smoking status and/

or current asthma. Prevalence ratios were reported as a measure 

of association. We also calculated 95% confidence intervals. If the 

95% confidence interval excluded one, then the prevalence ratio 

was considered statistically significant.

Values for the exposure measurements that were below the 

MDC were estimated by dividing the LOD by the square root 

of 2 [Hornung and Reed 1990]. We used generalized estimating 

equations to examine the relationship between symptom 

prevalence and levels of trichloramine or soluble chlorine in the 

air sampling. GMs were used to report exposure concentrations. 

P-values <0.05 were considered statistically significant.
Page 8 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Results

During the week of October 6, 2008, 81 of 85 employees and 16 

of 21 government food inspectors scheduled for work in the areas 

exposed to superchlorinated water participated in this evaluation. 

Of the 97 exposed participants, 41 (employees and government 

food inspectors) completed the questionnaire, wore the air 

sampling equipment, and participated in the medical testing. One 

employee completed the questionnaire, wore the air sampling 

equipment, and completed the postshift symptom survey but did 

not participate in the eye examinations or spirometry. Fifty-five 

workers completed the questionnaire only.

Of the approximately 325 day and night shift employees scheduled 

to work in the areas included in the unexposed group during the 

testing week, 271 completed the questionnaire. All unexposed 

employees present during the evaluation were asked to complete 

the questionnaire. Five unexposed employees declined or were 

unable to complete the questionnaire because of language barriers. 

Actual employees working at the time of the site visit varied from 

the initial roster we were given because of turnover, sick calls, etc.

Questionnaire

Table 1 compares the exposed and unexposed groups by work 

and personal characteristics. The exposed group was older, had 

been working longer at the plant, and had a higher percentage of 

women. Both groups were almost equivalent in prior diagnosis of 

dry eye and prevalence of asthma.

Table 1. Participant demographics

Exposed to 

superchlorinated water

Unexposed to 

superchlorinated water

Total number 97 271

Female 58/89 (65%) 152/271 (56%)

Mean age 43 (n=89) 38 (n=269)

Mean years of employment in current job 9.1 (n=89) 6.3 (n=270)

Current smoker 26/89 (29%) 85/270 (31%)

Former smoker 19/89 (21%) 76/270 (28%)

Never smoker 44/89 (49%) 109/270 (40%)

Current asthma 5/89 (6%) 13/269 (5%)

Prior diagnosis of dry eye 6/89 (7%) 15/270 (6%)
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 9

Results

 (continued) Although both groups reported work-related symptoms, exposed

participants were significantly more likely to have reported workrelated symptoms of chest tightness, sneezing, dry eyes, burning or 

itchy eyes, and blurry vision than unexposed participants (Table 2).

Table 2. Prevalence of work-related symptoms during work shift in the month before the evaluation

Work-related symptom Exposed group Unexposed group Prevalence ratio (95% 

confidence interval)

Chest tightness 18/89 (20%) 26/270 (10%) 1.83 (1.05, 3.15)*

Cough 37/89 (42%) 105/270 (39%) 1.01 (0.76, 1.30)*

Wheezing 12/89 (13%) 26/270 (10%) 1.33 (0.68, 2.45)*

Unusual shortness of 

breath 17/89 (19%) 36/270 (13%) 1.29 (0.76, 2.12)*

Dry eyes 36/89 (40%) 30/269 (11%) 3.50 (2.30, 5.40)†

Burning or itchy eyes 49/89 (55%) 57/269 (21%) 2.57 (1.92, 3.46)†

Blurry vision 13/89 (15%) 17/270 (6%) 2.30 (1.14, 4.55)†

Sneezing 46/89 (52%) 104/269 (39%) 1.34 (1.03, 1.71)†

Watery eyes 26/89 (29%) 55/270 (20%) 1.43 (0.94, 2.10)†

Runny nose 55/89 (62%) 140/269 (52%) 1.21 (0.98, 1.47)†

Stuffy nose 32/89 (36%) 88/270 (33%) 1.11 (0.79,1.52)†

 * Adjusted for current and former smoking status and for current asthma.

 † Adjusted for current and former smoking status.

Medical Testing

Over the 5 days of testing, 39 participants contributed 130 sets of 

preshift and postshift spirometry. Three sets from two participants 

demonstrated a >10% cross-shift decline in their individual FEV1. 

FEV1 results for the other 37 participants improved, stayed the 

same, or declined ≤10% over the shift.
Page 10 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Results

 (continued) More than 90% of 141 preshift and 137 postshift slit lamp

examinations of the conjunctiva and cornea of 43 participants 

were normal. In one corneal examination, the right eye worsened 

over the shift (see Appendix C for scoring); none of the 

examinations showed a worsening in the left eye over the shift. 

Approximately 95% of conjunctival examinations showed no 

change over the shift, but five examination results changed from 

normal to abnormal over the shift and nine examination results 

changed from abnormal to normal over the shift. More than 95% 

of the 133 preshift and 130 postshift fluorescein staining scores for 

the 39 participants were normal. For both the left and right eyes, 

one score changed from normal to abnormal over the shift and 

four scores changed from abnormal to normal over the shift.

Most examinations for 38 participants had abnormal preshift tear film 

breakup time and even more were abnormal postshift (Table 3). An 

abnormal tear film breakup time is defined as less than 10 seconds.

Table 3. Interpretation of tear film breakup time results

Eye

Abnormal

preshift tear film breakup 

time

Abnormal postshift tear 

film breakup time

Had a normal preshift 

exam and became 

abnormal on their 

postshift exam

Right 86/133 (65%) 109/129 (85%) 33/129 (26%)

Left 94/133 (71%) 116/129 (90%) 28/129 (22%)

Because so many participants started their shifts with an abnormal 

tear film breakup time, the abnormal scores were further divided 

into mild (tear film breakup time = 6 to < 10 seconds), moderate 

(tear film breakup time = 3 to < 6 seconds), and severe (tear 

film breakup time < 3 seconds) categories of abnormal tear film 

breakup times. This analysis was performed using 129 matched 

preshift and postshift pairs (Table 4). About 45% of participants’ 

tear film breakup time results decreased enough to move them to a 

worse category postshift compared to their tear film breakup time 

category preshift. About 55% either stayed the same or moved to a 

better category.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 11

Trichloramine and Soluble Chlorine Air 

Sampling Results

For the week of October 6, 2008, 284 PBZ trichloramine and 

soluble chlorine air samples were taken on exposed participants on 

either the day or night shifts. In addition, 174 area air samples were 

taken in seven areas in the processing area and two areas outside 

the processing area (WOG, IQF). Table 5 indicates the number 

and percentage of samples that fell below the MDC (analyte was 

not detected), between the MDC and MQC, and above the MQC 

(analyte was quantifiable). Most trichloramine air samples were not 

quantifiable. A higher number of soluble chorine air samples were 

quantifiable, but overall, concentrations were found to be low.

The LOD is the level at which a compound can be detected and 

distinguished from the blank response. The LOD is determined by 

the variability of the responses of blanks and low level standards. 

The MDC is calculated from the LOD by applying the average 

volume taken during sampling. The LOQ is the minimum level that 

can be reported with confidence. The LOQ is determined either as 

3.33 times the LOD or the level at which the minimum recovery for 

media spikes is 75%, whichever is higher. The MQC is calculated 

from the LOQ by applying the average volume taken during 

sampling. Values between the LOD and LOQ (or MDC and MQC) 

indicate samples where the compound was detected; however, levels 

were so low that they could not be quantified reliably.

Results

 (continued

Table 4. Tear film breakup time scores 

Eye

Remained in the same 

category for preshift and 

postshift exams

Moved to a worse 

category (tear film 

breakup time decreased) 

on their postshift exam

Moved to a better group 

(tear film breakup time 

increased) on their 

postshift exam

Right 48 (37%) 59 (46%) 22 (17%)

Left 56 (43%) 60 (47%) 13 (10%)
Page 12 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Results

 (continued

The overall GM for the PBZ soluble chlorine air samples was 30 

μg/m3. The geometric mean for soluble chlorine was highest on the 

first day of sampling (67 μg/m3) and tapered off to levels between 

the MDC and MQC as the week progressed (Figure 2).

Table 5. Trichloramine and soluble chlorine air sample characteristics

Soluble chlorine Trichloramine

 PBZ Area PBZ Area

Total number of samples collected 142* 87 142† 87

Samples below MDC 1 (1%) 17 (20%) 25 (18%) 24 (28%)

Samples between MDC, MQC 70 (49%) 5 (6%) 106 (75%) 59 (68%)

Samples above MQC 65 (46%) 65 (75%) 1 (1%) 4 (5%)

MDC‡ 8 μg/m3 15 μg/m3

MQC‡ 29 μg/m3 48 μg/m3

* Six samples were lost either due to damage to the sampler in the field or a greater than 10% difference in 

presampling and postsampling flow rates.

†Ten samples were lost either due to damage to the sampler in the field or a greater than 10% difference in 

presampling and postsampling flow rates.

‡Calculations based on an air volume of 480 liters.

Figure 2. Geometric means of soluble chlorine concentrations in PBZ air 

samples by day.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 13

Results

 (continued) The soluble chlorine concentration was highest on a participant

working in the reprocessing area (220 μg/m3). The GM of the 

soluble chlorine concentrations for those in the reprocessing area 

was greater than the GMs for those working in other areas (Figure 3).

Of the 142 PBZ trichloramine air samples, only 1 (1%) had 

a quantifiable concentration at 45 μg/m3 on the first day of 

sampling. Of these samples, 131 (92%) had concentrations between 

the MDC and MQC or were not detected, and 10 (7%) were lost. 

We used the laboratory’s best estimate for values between the 

MDC and MQC to calculate a GM of 17.2 μg/m3, which is a value 

between the MDC and MQC. For detailed PBZ trichloramine and 

soluble chlorine results, see Tables D1–D4 in Appendix D.

Of the 87 area air samples, 65 (75%) had quantifiable concentrations 

of soluble chlorine, and the overall GM was 37.8 μg/m3 (Table 6). 

Concentrations ranged from ND to 280 μg/m3. The highest GM 

area concentration was in the reprocessing area. Table 6 summarizes 

trichloramine and soluble chlorine concentrations in area air 

samples by location.

Concentrations of trichloramine in area air samples ranged from 

ND to 52 μg/m3. The highest GM area air concentration was 

found at the east evisceration line, station 1. Although only four 

(5%) samples were quantifiable, our best estimate for the GM for 

trichloramine was 22.4 μg/m3, which falls between the MDC and 

MQC. For detailed area chloramine results, refer to Tables D5 and 

D6 in Appendix D.

Figure 3. Geometric means of trichloramine and soluble chlorine 

concentrations in PBZ air samples by work area.
Page 14 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Results

 (continued

Postshift Symptom Surveys and Personal 

Breathing Zone Air Sampling Results

Exposed employees who participated in the medical testing and air 

sampling were asked to complete a postshift symptom survey at the 

end of each work shift. The analyses indicated that increased levels 

of exposures to air trichloramine and soluble chlorine were not 

related to increased symptom reports during their shift.

Process Ventilation

The evisceration area had two roof top air conditioning units that 

were each designed to provide an air supply flow rate of 16,000 

cfm. Air from the evisceration area was exhausted through the 

S&P room and out of the building by two large ceiling exhaust fans 

(each exhausting 45,000 cfm of air) and three small ceiling exhaust 

fans (each exhausting 15,000 cfm of air). On the basis of fan design 

specifications, this would result in a total of 135,000 cfm of air 

being exhausted from the S&P room. The employer reported that 

usually only one large exhaust fan ran constantly, while the second 

Table 6. Geometric mean* area air concentrations of soluble chlorine and trichloramine by location

Location Geometric mean (μg/m3)

n Soluble chlorine Trichloramine

Reprocessing 10 84 [22]

Paw harvest 10 56 [26]

East evisceration, Station 4 9 56 [26]

West evisceration, Station 4 10 53 [22]

East evisceration, Station 1 10 48 [27]

West evisceration, Station 1 10 46 [26]

Gizzard harvester 10 45 [23]

IQF† 9 [10] [18]

WOG 9 ND ND

Overall GM 87 37.8 [22.4]

* Samples taken over approximately 8 hours at a flow rate of 1 liter per minute.

† Approximately 75% of samples were below the MDC.

Concentrations between the MDC and MQC are shown with brackets to acknowledge that there is more 

uncertainty associated with these values than with concentrations above the MQC.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 15

Results

 (continued) fan was used only when needed. The smaller fans were manually

turned on and off by the facility manager to help control the 

temperature and humidity of the air in the evisceration area. Two 

wall-mounted exhaust fans, each with a 24,000 cfm capacity, pulled 

air from the evisceration area into the S&P room. The legline 

had two air-conditioning units, each with a 30,000 cfm capacity, 

and the chiller area had one air-conditioning unit of 25,000 cfm 

capacity; these units recirculated air during the two production 

shifts. The IW and IQF areas had eight exhaust fans, each with an 

operating capacity of 17,000 cfm.

Wall openings allowed air movement between areas depending 

on the pressure differential between areas. For example, a covered 

walkway linked IW to the evisceration area, reprocessing/chiller 

area, and locker room through doorways. The area above the 

covered walkway was a large, open space (13 feet by 11.5 feet) 

with no wall separation between the reprocessing/chiller and 

evisceration area. This space, which allowed the chickens on 

the automated shackle lines to pass from evisceration directly to 

reprocessing and chilling, could also let air move freely between 

these areas.

Figure 4 shows the air flow patterns in different areas of the facility 

during our evaluation. We observed that all exhaust fans in the 

S&P room were operating during our evaluation of the air flow 

patterns in the evisceration, legline, and reprocessing areas using 

ventilation smoke tubes. We observed that all openings to the S&P 

room were under negative pressure in relation to the evisceration 

area. The doors connecting the pump room and S&P room were 

closed and were not normally used; therefore, we did not evaluate 

air flow patterns between these two rooms.

We observed that air flowed into the evisceration area from the 

doorway connecting to the IW walkway. Air also flowed into 

the evisceration area from doorways connecting to the employee 

locker/break room and office areas. The reprocessing area was also 

under negative pressure; air flowed from the employee locker room 

and the IW walkway into the reprocessing area. Air flowed into the 

chiller area from the large cooler.

Employer representatives informed us that when all fans were 

operational in the S&P room, cold air drawn from the chiller areas 

can cause condensation and precipitation problems in the form of 

snow. However, we did not observe this during our evaluation.
Page 16 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Other Measurements and Observations

Of the ten chlorine air samples that were taken in the evisceration 

and reprocessing areas, one sample measured 0.2 ppm at the 

gizzard harvester, and the remaining nine measurements were 

below the LOD. Of the ten chlorine dioxide air samples that 

were taken, one sample had a concentration of 0.3 ppm; all other 

samples measured 0.1 ppm or lower. The results from the chlorine 

and chlorine dioxide samples suggest that neither chlorine nor 

chlorine dioxide in air were at levels of concern on the day air 

sampling was performed.

The concentration of chlorine in the wash water for reprocessing, 

gizzard harvest, paw harvest, and bird wash ranged from 20–50 

ppm as recorded in the company records. These concentrations 

are within the levels required by the USDA for spray water on 

reprocessing and salvage areas of poultry processing facilities [CFR 

1978].

There were no reports of respiratory symptoms in the poultry 

processing facility’s 2007 OSHA Form 300 Log of Work-related 

Injuries and Illnesses, and the facility nurse stated that no 

employees reported these types of symptoms to her office. However, 

during the same period, there were 17 reports of eye, throat, and 

respiratory irritation among the government food inspectors with 

whom these employees work side-by-side.

Results

 (continued

Figure 4. Direction of air flow in the facility observed using ventilation 

smoke tubes.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 17

Discussi

The United States is the world’s largest producer and second 

largest exporter of poultry meat, with 8.9 billion broiler birds 

produced in 2007 [USDA 2009]. Because of the high demand for 

poultry products, poultry slaughter and processing occur in largescale facilities that emphasize minimizing pathogen contamination 

and maximizing production efficiency. A complex combination 

of disinfectants and antimicrobials is used on the processing lines 

to maintain sanitary conditions and prevent pathogen transfer 

to humans. These chemical compounds have the potential 

of interacting with each other in addition to the biological 

components of the poultry carcasses, and when combined with 

inadequate ventilation, can cause employee health symptoms 

[NIOSH 2003, 2006; Dang et al. 2010].

In the past, it was suspected that chlorine, used as a disinfectant 

in superchlorinated water, could off-gas into the air, causing eye 

and respiratory irritation symptoms in employees. However, after 

repeated testing, very low to no chlorine was detected in the air. 

This led to the hypothesis that the mixing of superchlorinated 

water with nitrogenous materials, such as waste from the poultry 

lines, created chloramines. Exposure to chloramines, especially 

trichloramine, has been known to cause respiratory and eye 

irritation symptoms in indoor aquatic facilities [Hery et al. 1995; 

Massin et al. 1998]. Similar symptom reports have been noted at 

poultry facilities [NIOSH 2003, 2007; King et al. 2006] and at 

a green salad processing facility [Hery et al. 1998] where soluble 

chlorine concentrations were found to be related to symptoms. 

It was hypothesized that the soluble chlorine compounds are 

also irritants and are more likely to be aerosolized during food 

processing than at indoor pools [NIOSH 2003].

Eye Irritation

Employee interviews conducted during the initial site visit revealed 

that reports of eye irritation had been more prevalent than reports 

of respiratory irritation. Because eye irritation can be caused by 

workplace chemical irritants such as chloramines, comprehensive 

eye examinations were included in this investigation. No studies 

have examined eye irritation in poultry employees, but a few 

studies have compared symptom reports with detailed optometric 

or ophthalmological evaluations of the eye in employees in other 

industries. One study focused on eye irritation reported by flight 

attendants in airline cabins that allowed passenger smoking on 
Page 18 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Discussi

 (continued) flights between Scandinavia and Japan. Tear film breakup time

was measured on these crew members before and after smoking 

was banned on these flights. Crews with environmental tobacco 

smoke exposure had more eye irritation symptoms and decreased 

tear film breakup times [Wieslander et al. 2000]. Eye irritation and 

decreased tear film breakup time upon exposure to cigarette smoke 

was also found in a study that compared smokers to nonsmokers 

[Yoon et al. 2005].

Literature regarding quantitative assessment of the eye with 

exposure to irritants other than environmental tobacco smoke is 

scarce, but a great deal of literature addresses dry eye syndrome 

[Mathers et al. 1996; Lemp 1998; Oden et al. 1998; Nichols et al. 

2003; Nichols et al. 2004; DEWS Epidemiology Subcommittee 

2007]. Dry eye syndrome occurs when insufficient tears are 

produced to keep the eye surface lubricated, when there are 

problems with the tear film component proteins, or from 

environmental irritants that directly disperse the tear film. 

Whatever the cause, eyes that are not properly moisturized will 

exhibit signs and symptoms of irritation such as redness, a feeling 

of dryness, blurred vision, or even excessive tearing as the eye tries 

to compensate for the decreased lubrication across its surface.

We cannot fully explain why so many participants had abnormally 

short tear film breakup times on their preshift examinations. 

Possible reasons may be that participants have chronic work-related 

eye irritation that does not resolve before the next shift, or that 

these findings are a result of the aging process. One study showed 

that both men and women experience a slow, progressive decline 

in tear volume and production rates with a concomitant increase 

in tear osmolarity (a measure of salinity concentration) with age. 

Symptoms only became apparent after reaching a certain threshold 

[Mathers et al. 1996]. Dry eye is also more common in women than 

in men, and hormonal changes may play a role in this. The mean 

age of the exposed group was 43 and 65% were women; therefore, 

age and sex-related eye effects may be contributing factors to our 

findings. Use of decongestants and topical eye medicines, which 

we did not assess, may also contribute to dry eye symptoms. 

Although our questionnaires showed nearly equal percentages of 

participants in both groups reporting a prior diagnosis of dry eye 

(7% of exposed participants and 6% of unexposed participants), 

it is possible that additional participants had undiagnosed dry eye 

or other medical conditions that could have a dry eye component. 

Epidemiologic studies of dry eye across all age groups in the general 
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 19

Discussi

 (continued) population have reported prevalence rates ranging from 5%–35%

[DEWS Epidemiology Subcommittee 2007].

Another source of eye irritation to consider among our 

participants was tobacco smoke. About 50% of the exposed group 

were current or former smokers. Tobacco smoke is an eye irritant 

and can result in decreased tear film breakup time as an immediate 

effect of exposure. Some studies suggest that chronic exposure 

may also result in permanent changes to tear film production and 

tear film composition as well as to the cornea [Yoon et al. 2005]. 

Another investigator has suggested that exposure to environmental 

pollution or poor air quality may induce changes in the eye that 

may be subclinical (able to be measured on a test such as the 

tear film breakup time but without symptoms). Individuals with 

subclinical changes could develop symptoms after exposure to a 

second irritant, such as chloramines or soluble chlorine [Versura et 

al. 1999].

For employees and government food inspectors working on the 

evisceration lines, dry eye and eye irritation could also have been 

caused or exacerbated by the personal cooling fans located at the 

inspection stations. The fans blow air directly across these employees’ 

eyes. Employees of another poultry processing facility that NIOSH 

evaluated reported similar health concerns [NIOSH 2006].

Occupational Asthma

Of 39 participants, 37 had no evidence of occupational asthma. 

Of the 39 participants exposed to superchlorinated water, 2 

were found to have greater than a 10% decrease in their FEV1 

measurements when we compared their preshift and postshift 

pulmonary function tests. These changes are consistent with 

occupational asthma. Occupational asthma, or asthma symptoms 

that developed as a result of a workplace exposure to an irritant or 

sensitizer of the respiratory tract, has been estimated to account 

for approximately 20% of current diagnoses of adult onset asthma 

[Burge 2009]. NIOSH investigators previously found workers at 

a turkey processing facility with similar findings of self-reported 

symptoms consistent with occupational asthma when working 

around chloramines [King et al. 2006].

Occupational asthma has also been reported among personnel 

exposed to chloramines at indoor swimming pools [Thickett et al. 
Page 20 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Discussi

 (continued) 2002]. Improper mixing of cleaning products has been identified

as a separate risk factor for new onset asthma [Kogevinas et al. 

2007] due to inadvertent formation of chloramines when cleaning 

chemicals that contain bleach (sodium hypochlorite) and ammonia 

are mixed together.

Because no specific test to diagnose occupational asthma exists, 

a physician should evaluate employees with symptoms of chest 

tightness, persistent cough, and shortness of breath to determine 

appropriate tests (e.g., spirometry, lung function testing, or a 

methacholine challenge).

Exposure Monitoring

Because no OELs for trichloramine or soluble chlorine compounds 

exist, we compared our results with those observed in other studies. 

Trichloramine and soluble chlorine concentrations found at 

this facility were lower than those in other studies. For example, 

the GM concentration of evisceration participants’ PBZ soluble 

chlorine air samples at a turkey processing facility was 64 μg/m3 [King 

et al. 2006], which was higher than what we measured at this facility 

(29 μg/m3). In a poultry processing facility in Louisiana, the GM 

PBZ soluble chlorine air concentration in evisceration workers 

was 67 μg/m3, and the mean trichloramine air concentration was 

119 μg/m3 [NIOSH 2007]. At this facility, the highest trichloramine 

sample we measured was 45 μg/m3. However, the source water 

for the Louisiana facility was chloraminated for disinfection, 

which would mean that the water source by itself provided both 

the chlorine and ammonia (nitrogen) sources required to form 

chloramines. The source water in our evaluation was chlorinated, 

not chloraminated.

Research, mainly at indoor pools, has been done to determine 

trichloramine levels at which people begin exhibiting symptoms. 

Hery et al. documented 500 μg/m3 for trichloramine as a level 

at which people experienced eye and respiratory irritation 

symptoms [Hery et al. 1995]. Another study showed that teenage 

swimmers exhibited health symptoms at or above trichloramine 

concentrations of 370 μg/m3 [Levesque et al. 2006]. The World 

Health Organization recommends using an air trichloramine 

concentration of 500 μg/m3 as a provisional value to prevent 

symptom occurrence [WHO 2006]. However, this guideline 

was specified for indoor aquatic environments and may not 
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 21

Discussi

 (continued) be applicable to poultry facilities. The highest quantifiable

trichloramine concentration we measured was 52 μg/m3

, well 

below the World Health Organization’s provisional guideline. At 

this poultry facility, we measured soluble chlorine levels that may 

have been a cause or contributed to employee symptom reports. 

However, increased levels of exposures to air trichloramine and 

soluble chlorine were not related to increased symptom reports 

during their shift. The lack of an observable association may be 

due to trichloramine and soluble chlorine concentrations that were 

too low for our method to quantify. Other possible explanations 

may be that the symptoms are a result of exposures to chemical 

compounds we did not evaluate, such as quaternary ammonium 

compounds or byproducts of chemical and biological mixtures, or 

that symptoms are not related to occupational exposures.

Process Ventilation

HVAC systems in poultry processing facilities should serve dual 

roles: to control air contaminants to ensure product safety and to 

ensure employees’ health and comfort. Areas where slaughtering 

and S&P processes occur are potentially the most contaminated, 

with high concentrations of bioaerosols and microorganisms 

that could be harmful to humans and the final product [Heber 

et al. 1995; Lutgring et al. 1997]. Therefore, the ventilation 

strategy in poultry processing facilities is to move air from the 

cleanest part of the facility (i.e., storage and packaging areas) 

to the highest potentially contaminated area (i.e., slaughtering 

and S&P areas) [Heber et al. 1995; ASHRAE 2010] where it is 

exhausted outdoors. This concept is depicted in Figure 5. In 

addition, ASHRAE recommends achieving this air flow pattern 

in poultry processing facilities using positive pressure ventilation 

with the storage and packing areas having the higher static 

pressure and the S&P room being neutral [ASHRAE 2010]. This 

can be achieved by supplying filtered outdoor air to the packing 

room and exhausting air through the S&P room. Using positive 

pressure ventilation will help minimize product contamination 

from contamination that could result from unfiltered air entering 

the process area through infiltration from cracks in the building 

envelope and door openings.

We evaluated the air flow patterns in the processing areas of the 

facility to identify if the air flow pattern met ASHRAE guidelines 

and if it possibly contributed to employees’ symptoms. Our 
Page 22 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Figure 5. Recommended air flow pattern in a poultry processing facility [Keener 2000].

Discussi

 (continued

observations showed that large interconnecting wall openings 

between the processing areas affected the air distribution. For 

example, the difference between the air supplied to the evisceration 

area (32,000 cfm) and the air exhausted out of the S&P room 

(135,000 cfm), requires additional makeup air. This air will be 

drawn from around doorways and other openings. At this facility, 

some of this air was drawn into the chiller/reprocessing area 

through the doors connecting to the break and locker rooms and 

the covered walkway. The air was then drawn through the opening 

above the covered walkway from the chiller/reprocessing area to 

the evisceration area, as well as through the doors connecting 

evisceration to the covered walkway and the locker and break 

rooms. In addition, air flow through the interconnecting wall 

openings can cause condensation and/or precipitation when cold 

air from the chiller or product storage areas mixes with warm, 

moist air.

We observed that the negative pressure in the S&P room created 

by the exhaust fans caused air to move from the cooler and 

packing areas, past the chillers/reprocessing area, through the 

interconnecting opening, and into the evisceration area. The air 

was exhausted out of the building through the S&P room. This air 

flow pattern agrees with ASHRAE’s recommended flow pattern for 

poultry processing facilities. However, this air flow pattern was not 

achieved via positive pressure ventilation as ASHRAE recommends 

but by keeping the S&P room at much higher negative pressure 

compared to the rest of the facility.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 23

Discussi

 (continued) Although we did not evaluate the slaughtering area, the negative

pressure in the S&P room will result in air being drawn from 

the slaughtering area, which was open to the outdoor poultry 

unloading area. This air flow pattern could expose employees 

working in the slaughtering area to harmful bioaerosols, such as 

endotoxin.

We also observed that outdoor air was supplied to many of the 

processing areas by roof top units with supply diffusers near the 

ceiling (approximately 35 feet from ground). Air was exhausted out 

of the processing areas either by ceiling fans or roof top units that 

were also placed at approximately the same height from the floor. 

Because of the high positioning of the supply and exhaust systems, 

it is possible that outdoor air is not being adequately mixed at the 

employees’ breathing zone in the processing areas. This can reduce 

ventilation effectiveness and lead to pockets of high contaminant 

concentrations [ASHRAE 2009]. Air supplied to the occupied 

space should facilitate good mixing with contaminated air at 

employee locations and without significant interruption [ANSI/

AIHA 2007].

Water Chemistry

The USDA allows a range of 20–50 ppm of free chlorine in the 

wash water. Technicians measured the chlorine concentration three 

times a shift. At this facility, a technician took a sample of water 

off the line, took it to the lab and used a titration test to measure 

the chlorine concentration. If the concentration needed adjusting, 

the technician contacted facility personnel who then manually 

adjusted the hypochlorite injection system. The time it took for the 

detection and adjustment of an abnormal chlorine reading may 

have allowed periodic spikes in chlorine concentrations in the wash 

water and greater opportunity for chloramines to form. Because 

water chemistry control is essential in minimizing the formation 

of airborne irritant compounds, strict control should be practiced. 

Observers in other poultry facilities have noted that staff may set 

the concentration of the chemical agent too high, especially where 

manual dosing is used [IPPC 2003]. In addition, high pressure 

sprays could aerosolize the spikes in chlorine concentration when 

the wash water approached 50 ppm, which could contribute to 

employees’ reports of sporadic and episodic irritation symptoms.
Page 24 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

We observed covered drain channels built into the processing 

area floors that collected wastewater produced during poultry 

processing. From our review of the drain schematic provided by 

the employer, all drains appeared to flow from cleaner (toward 

the end of processing) to dirtier (toward the start of processing) 

areas. It was reported that the chiller area drip channels had a gate 

that separated them from the evisceration drip channels during 

processing. This prevented mixing of the effluent from each area. 

The gate could be opened when cleaning so the channels could 

be flushed. To reduce the possibility of a chemical reaction taking 

place and releasing irritating compounds into the air, substances 

should not be allowed to pool in the channels or drains.

Limitations

The intermittent formation and release of irritant compounds 

into the air that can occur in a poultry facility environment may 

not have occurred during our sampling period, thus we may have 

underestimated exposures and missed the peak time for reporting 

of symptoms. A variety of compounds used in the poultry facility 

that we did not evaluate could have caused similar irritant 

symptoms in employees. For example, some participants worked 

near the pepper marinades, which can be irritating. Also, the draft 

NIOSH chloramine sampling and analytical method we used does 

not allow for quantification of chloramines at low concentrations. 

Additionally, we could not take ventilation air flow measurements 

because of the complexity and large size of the facility. Instead, we 

observed air flow movement using smoke tubes, which limited our 

ability to observe airflow throughout the entire evisceration area 

and surrounding areas.

Discussi

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 25

Conclusion

Exposed participants reported significantly more work-related 

chest tightness, sneezing, dry eyes, burning or itchy eyes, and 

blurry vision in the previous month than unexposed participants. 

Of 39 exposed participants, 2 had cross-shift declines in FEV1 

and needed further evaluation for work-related asthma. The rest 

of the exposed participants (37) did not have spirometry findings 

consistent with occupational asthma. Most exposed participants 

had abnormally short preshift tear film breakup times, which 

for many shortened even further by the end of their shift. The 

unexpected finding of so many employees with abnormal preshift 

tear film breakup times should be further investigated in future 

studies of eye irritation symptoms at poultry plants. Although 

abnormal tear film breakup times could be a result of eye irritation 

from repeated exposure to irritants in the workplace, other causes 

should be investigated such as undiagnosed medical conditions 

that cause dry eye. Employees with chronic eye irritation should 

follow up with their own eye doctor for an individual evaluation.

Areas with superchlorinated water had higher levels of soluble 

chlorine in the air than areas without superchlorinated water, but we 

were unable to determine whether soluble chlorine compounds were 

associated with the irritation symptoms or the reduced tear film 

breakup times. Increased levels of exposures to air trichloramine 

and soluble chlorine were not related to increased symptom reports 

in the postshift symptom survey. Although we did not find high 

levels of chloramine compounds at the time of our evaluation, the 

sporadic formation and release of these compounds may be higher 

at other times, potentially causing irritant symptoms. A variety of 

factors can affect the formation and release of irritant compounds 

into the air, including the combination of chemical compounds and 

organic byproducts, aerosolization potential, and water chemistry 

control. Maintaining water chemistry (i.e., chlorine concentration, 

pH) within recommended parameters and ensuring good air mixing 

in the processing areas may help reduce employee symptoms. 

Ventilation in this processing facility followed the ASHRAE 

guideline for air flowing from clean to dirty areas; however, this 

was not done via positive pressure ventilation which would help 

minimize product contamination.
Page 26 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Recommendatio

On the basis of our findings, we recommend the actions listed below 

to create a more healthful workplace. We encourage this poultry 

processing facility to use a labor-management health and safety 

committee or working group to discuss the recommendations in this 

report and develop an action plan. Those involved in the work can 

best set priorities and assess the feasibility of our recommendations 

for the specific situation at this poultry processing facility. Our 

recommendations are based on the hierarchy of controls approach 

(Appendix B: Occupational Exposure Limits and Health Effects). 

This approach groups actions by their likely effectiveness in reducing 

or removing hazards. In most cases, the preferred approach is to 

eliminate hazardous materials or processes and install engineering 

controls to reduce exposure or shield employees. Until such controls 

are in place, or if they are not effective or feasible, administrative 

measures and/or personal protective equipment may be needed.

Engineering Controls

Engineering controls reduce exposures to employees by removing 

the hazard from the process or placing a barrier between the 

hazard and the employee. Engineering controls are very effective 

at protecting employees without placing primary responsibility of 

implementation on the employee. Design of ventilation systems 

in poultry processing facilities is challenging because of the large 

interconnecting wall openings. To improve the health and safety of 

employees and prevent contaminant transfer from the outdoors to 

the product areas, we recommend the following:

1. Use positive pressure ventilation to achieve the air flow 

patterns following ASHRAE guidelines [ASHRAE 2010], 

which will help minimize product contamination. The 

air should be well mixed at employees’ breathing zone 

levels. Consult a ventilation engineer to determine the best 

approach to achieve the recommended air flow pattern 

using positive pressurization. The office or break room 

areas connected to the process area should be at relatively 

higher static pressures to prevent movement of possible 

contaminants from process areas.

2. Ensure that exhaust fans are cleaned and maintained 

regularly. Bird feathers and dust deposited on the fan can 

severely affect fan performance. Air flow should be directed 

away from the workers’ faces to reduce inhalation or eye 

contact with potential allergens and irritants.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 27

Recommendatio

 (continued) 3. Investigate alternatives for a more accurate and timely way

to monitor and adjust chlorine concentration and other 

water chemistry parameters of the superchlorinated water. 

For example, an injection pump could be self-regulating 

if equipped with automatic flow control and fail-safe shut 

down options. This can prevent the spikes in chlorine levels 

that may contribute to irritant gas formation.

4. Minimize the mixing of wastewater containing various 

chemicals and/or organic byproducts with wastewater from 

other areas, and remove effluent in the drain channels as 

quickly as possible [IPPC 2003].

5. Reduce the aerosolization of chemicals in the wash water 

by using spray nozzles that produce larger droplets. Another 

option is to place a barrier around machines that aerosolize 

superchlorinated water.

Administrative Controls

Administrative controls are management-dictated work practices 

and policies to reduce or prevent exposures to workplace hazards. 

The effectiveness of administrative changes in work practices 

for controlling workplace hazards is dependent on management 

commitment and employee acceptance. Regular monitoring and 

reinforcement are necessary to ensure that control policies and 

procedures are not circumvented in the name of convenience or 

production.

1. Continue to ensure that staff are adequately trained to test 

and control water chemistry parameters.

2. Periodically review alternative cleaning agent options that 

are safer to use than current products. Newer or alternative 

formulations may reduce the amount of chemical required 

while also improving hygiene standards [IPPC 2003].

3. Encourage poultry processing employees to report workrelated symptoms to the facility health office so that the 

employer can investigate these events and ensure prompt 

medical care. Government food inspectors working 

alongside poultry processing employees should report 

symptoms to their supervisors for similar investigation.
Page 28 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Referenc

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– Fundamentals. Atlanta, GA: American Society of Heating, 

Refrigerating, and Air-Conditioning Engineers, Inc., pp. 20.1–

20.22.

ASHRAE [2010]. American Society of Heating, Refrigerating, 

and Air-Conditioning Engineers Handbook – Refrigeration. 

Atlanta, GA: American Society of Heating, Refrigerating, and AirConditioning Engineers, Inc., pp. 31.1–31.11.

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Swiss Med Weekly 140(9–10):128–132.

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Government Printing Office, Office of the Federal Register.

Dang B, Chen L, Mueller C, Dunn KH, Almaguer D, Roberts 

JL, Otto CS [2010]. Ocular and respiratory symptoms among 

lifeguards at a hotel indoor waterpark resort. J Occup Environ Med 

52(2):207–213.

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poultry slaughtering and processing plants. Building ventilation 

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Lafayette, IN.

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J [1995]. Exposure to chloramines in the atmosphere of indoor 

swimming pools. Ann Occup Hyg 39(4):427–439.

Hery M, Gerber JM, Hecht G, Subra I, Possoz C, Aubert S, 

Dieudonne M, Andre JC [1998]. Exposure to chloramines in a 

green salad processing plant. Ann Occup Hyg 42(7):437–451.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 29

Referenc

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AM [2006]. Eye and respiratory symptoms in poultry processing 

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[1997]. Distribution and quantification of bioaerosols in poultryslaughtering plants. J Food Prod 60(7):804–810.

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G [1998]. Respiratory symptoms and bronchial responsiveness in 

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Mathers WD, Lane JA, Zimmerman MB [1996]. Tear film changes 

associated with normal aging. Cornea 15(3): 229–334.

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clinical measurements of dry eye. Cornea 23(3):272–284.

NIOSH [1987]. Hazard evaluation and technical assistance report: 

Columbia Farms poultry plant, Columbia, SC. By Ferguson R. 

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for Occupational Safety and Health, NIOSH HETA Report No. 

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Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, NIOSH HETA 92-098.

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report: Tyson Foods, Monett, MO. By Parker M, Weber AM, and 

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Human Services, Centers for Disease Control and Prevention, 

National Institute for Occupational Safety and Health, NIOSH 

HETA Report No. 93-0230-2405.

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Prevention, National Institute for Occupational Safety and Health, 

NIOSH HETA Report No. 2000-0105-2794.

NIOSH [2003]. Hazard evaluation and technical assistance report: 

Bil-Mar Foods, Inc., Storm Lake, IA. By King B and Page E. 

Cincinnati, OH: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, NIOSH HETA Report No. 2002-

0257-2916.

Referenc

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 31

NIOSH [2006]. Hazard evaluation and technical assistance 

report: Sara Lee Foods, Storm Lake, IA. By King B and Page E. 

Cincinnati, OH: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, NIOSH HETA Report No. 2006-

0153-3022.

NIOSH [2007]. Hazard evaluation and technical assistance report: 

U.S. Department of Agriculture, Food Safety and Inspection 

Service, Natchitoches, LA. By King B, Warren A, Mueller C. 

Cincinnati, OH: U.S. Department of Health and Human Services, 

Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, NIOSH HETA Report No. 2004-

0337-3051.

Oden NL, Lilienfeld DE, Lemp MA, Nelson D, Ederer F [1998]. 

Sensitivity and specificity of a screening questionnaire for dry eye. 

Adv Exp Med Biol 438:807–820.

Sanderson W, Weber A, Echt A [1995]. Case reports: epidemic eye 

and upper respiratory irritation in poultry processing plants. Appl 

Occup Environ Hyg 10(1):43–49.

Thickett KM, McCoach JS, Gerber JM, Sadhra S, Burge PS [2002]. 

Occupational asthma caused by chloramines in indoor swimming 

pool air. Eur Respir J 19:827–832.

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Department of Agriculture. [http://www.ers.usda.gov/Briefing/

Poultry/]. Date accessed: November 2011.

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Eye discomfort and air pollution. Ophthalmologica 213:103–109.

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Wieslander G, Lindgren T, Norback D, Venge P [2000]. Changes 

in the ocular and nasal signs and symptoms of aircrews in relation 

to the ban on smoking on intercontinental flights. Scand J Work 

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and ocular surface. Korean J Ophthalmol 19(1):18–22.

Referenc

 (continued
Page 32 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Spirometry

Preshift and postshift spirometry was performed on each participant. Spirometry refers to the 

measurements of exhaled air volume and flow rates from individuals who are coached by trained 

technicians using either volume-based or flow-based measuring equipment. The standard measurements 

taken in spirometry are the FVC and FEV1. The FVC is the volume of air exhaled from a maximal 

inspiration to a complete exhalation. The FEV1 is the volume of air exhaled in the first second of a FVC 

maneuver. We focused on the FEV1 as previous studies have defined work-related asthma as a decrease of 

>10% in the FEV1 in the postshift testing as compared to the preshift testing [Moscato 2003]. Irritation 

of the respiratory tract by environmental compounds can manifest as asthma and is reflected by previously 

described changes in the spirometry parameters.

Spirometry was performed by NIOSH spirometry technicians using EasyOneTM “worldspirometer” 

spirometers (ndd Medical Technologies Inc., Zurich, Switzerland). All spirometry data collection 

procedures conformed to the American Thoracic Society’s standardization of spirometry [American 

Thoracic Society 1995]. At least three maximal expiratory maneuvers or FVC maneuvers were performed 

at each session. The selection and interpretation of results also conformed to standard guidelines 

[American Thoracic Society 1991]. Predicted values were determined from published reference equations 

[Hankinson et al. 1999].

Eye Examinations

Eye examinations (Figure A1) were performed by a licensed optometrist and consisted of a slit lamp 

examination of the cornea (the clear membrane that covers the iris and pupil) and conjunctiva (the 

clear membrane that covers the whites of the eyes and lines the insides of the eyelids). This allows the 

optometrist to see a magnified view of the eye 

and determine if the cornea and conjunctiva 

are quiet (i.e., normal) or abnormal. This initial 

assessment is followed by applying a fluorescein 

dye to measure the tear film breakup time and to 

highlight abnormalities of the cornea. Premature 

breakup of the tear film may be due to exposure 

to environmental irritants, inadequate tear 

production, defects in the protein components 

of the tear film, or other factors. Once the dye 

is placed in the eye, the subject is instructed to 

blink several times to distribute the dye, and 

then the optometrist measures how long it takes 

for darkened areas in the tear film to appear, 

signaling the breakup of the tear film layer 

containing the dye. The tear film breakup time 

Appendix A: Methodolo

Figure A1. Optometrist conducting slit lamp examination of 

a poultry processing employee.
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 33

in a normal eye is greater than or equal to 10 seconds. The optometrist also uses the dye to give each eye 

a fluorescein staining score; a fluorescein staining score greater than 4 is considered abnormal. Appendix 

C provides a full description of the fluorescein staining score scoring system and illustrative photographs. 

Each component of the eye examination was analyzed separately and for each component, the right and 

left eyes were tested and scored separately.

Chloramines

Chloramine samplers consist of a sampling train that includes a pump that pulls air through a sorbent 

tube that traps soluble chlorine compounds (which include monochloramine, dichloramine, hypochlorite, 

and hypochlorous acid) onto silica gel coated with sulfamic acid. The air then passes through a 37-

millimeter polystyrene cassette loaded with two quartz fiber filters coated in sodium carbonate and 

diarsenic trioxide to capture trichloramine.

The air samples were collected using calibrated AircheckTM 2000 sampling pumps (SKC, Eighty 

Four, Pennsylvania) at a flow rate of 1 liter per minute. The sampling pumps were precalibrated and 

postcalibrated with a DryCal® DC Lite primary air flow meter (Bios International Corp., Butler, New 

Jersey). Samplers were attached to the employees’ clothing (in the employees’ breathing zones) and checked 

throughout the day for correct positioning and to ensure that the sampling pumps functioned correctly. 

Samples were refrigerated in the dark and analyzed within 3 days of collection by the NIOSH contract 

lab Bureau Veritas (Novi, Michigan) using ion chromatography and by NIOSH using inductively coupled 

plasma atomic emission spectroscopy.

During analysis, each filter was removed from the cassette and placed in a 20 mL sample vial. After 10 

mL of deionized water was added, the samples were periodically agitated for 30 minutes. Samples were 

refrigerated and filtered prior to analysis by ion chromatography. The LOD and LOQ were determined for 

each sample set.

For analysis of the sorbent tubes, the samples were desorbed by placing the impregnated silica gel from the 

tube into a 20 mL vial. Ten mL of a 1 gram per liter sulfamic acid solution was added to each vial, and the 

samples were periodically agitated for 30 minutes. The sample extracts were decanted into another vial and 

refrigerated until analysis. Samples were analyzed for chloride by ion chromatography. The LOD and LOQ 

were determined for each sample set.

Chlorine Dioxide and Chlorine

Chlorine dioxide and chlorine in air were measured using a colorimetric detector tube and bellows pump. 

Detector tubes have a standard deviation of +/- 10% to 15% and measuring range of 0.2 ppm to 3 ppm 

for chlorine and 0.025 ppm to 1 ppm for chlorine dioxide.

Appendix A: Methodolo

 (continued
Page 34 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

References

American Thoracic Society [1991]. Lung function testing: selection of reference values and interpretative 

strategies. Am Rev Respir Dis 144(5):1202–1218.

American Thoracic Society [1995]. Standardization of spirometry – 1994 Update. Am J Respir Crit Care 

Med 152(3):1107–1136.

Hankinson JL, Odencrantz JR, Fedan KB [1999]. Spirometric reference values from a sample of the U.S. 

general population. Am J Respir Crit Care Med 159(1):179–187.

Moscato G, Malo JL, Bernstein D [2003]. Diagnosing occupational asthma: how much, how far? Eur 

Respir J 21(5):879–885.

Appendix A: Methodolo

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 35

Appendix B: Occupational Exposure Limits and H

In evaluating the hazards posed by workplace exposures, NIOSH investigators use both mandatory (legally 

enforceable) and recommended OELs for chemical, physical, and biological agents as a guide for making 

recommendations. OELs have been developed by federal agencies and safety and health organizations to 

prevent the occurrence of adverse health effects from workplace exposures. Generally, OELs suggest levels 

of exposure that most employees may be exposed to for up to 10 hours per day, 40 hours per week, for a 

working lifetime, without experiencing adverse health effects. However, not all employees will be protected 

from adverse health effects even if their exposures are maintained below these levels. A small percentage 

may experience adverse health effects because of individual susceptibility, a preexisting medical condition, 

and/or a hypersensitivity (allergy). In addition, some hazardous substances may act in combination with 

other workplace exposures, the general environment, or with medications or personal habits of the 

employee to produce adverse health effects even if the occupational exposures are controlled at the level set 

by the exposure limit. Also, some substances can be absorbed by direct contact with the skin and mucous 

membranes in addition to being inhaled, which contributes to the individual’s overall exposure.

Most OELs are expressed as a TWA exposure. A TWA refers to the average exposure during a normal 8- 

to 10-hour workday. Some chemical substances and physical agents have recommended STEL or ceiling 

values where adverse health effects are caused by exposures over a short period. Unless otherwise noted, 

the STEL is a 15-minute TWA exposure that should not be exceeded at any time during a workday, and 

the ceiling limit is an exposure that should not be exceeded at any time.

In the United States, OELs have been established by federal agencies, professional organizations, state 

and local governments, and other entities. Some OELs are legally enforceable limits, while others are 

recommendations. The U.S. Department of Labor OSHA PELs (29 CFR 1910 [general industry]; 29 

CFR 1926 [construction industry]; and 29 CFR 1917 [maritime industry]) are legal limits enforceable 

in workplaces covered under the Occupational Safety and Health Act of 1970. NIOSH RELs are 

recommendations based on a critical review of the scientific and technical information available on a 

given hazard and the adequacy of methods to identify and control the hazard. NIOSH RELs can be found 

in the NIOSH Pocket Guide to Chemical Hazards [NIOSH 2010]. NIOSH also recommends different 

types of risk management practices (e.g., engineering controls, safe work practices, employee education/

training, personal protective equipment, and exposure and medical monitoring) to minimize the risk of 

exposure and adverse health effects from these hazards. Other OELs that are commonly used and cited 

in the United States include the TLVs recommended by ACGIH, a professional organization, and the 

WEELs recommended by the American Industrial Hygiene Association, another professional organization. 

The TLVs and WEELs are developed by committee members of these associations from a review of the 

published, peer-reviewed literature. They are not consensus standards. ACGIH TLVs are considered 

voluntary exposure guidelines for use by industrial hygienists and others trained in this discipline “to assist 

in the control of health hazards” [ACGIH 2011]. WEELs have been established for some chemicals “when 

no other legal or authoritative limits exist” [AIHA 2011].

Outside the United States, OELs have been established by various agencies and organizations and 

include both legal and recommended limits. The Institut für Arbeitsschutz der Deutschen Gesetzlichen 

Unfallversicherung (IFA, Institute for Occupational Safety and Health of the German Social Accident 
Page 36 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Insurance) maintains a database of international OELs from European Union member states, Canada 

(Québec), Japan, Switzerland, and the United States. The database, available at http://www.dguv.de/ifa/

en/gestis/limit_values/index.jsp, contains international limits for over 1,500 hazardous substances and is 

updated periodically.

Employers should understand that not all hazardous chemicals have specific OSHA PELs, and for some 

agents the legally enforceable and recommended limits may not reflect current health-based information. 

However, an employer is still required by OSHA to protect its employees from hazards even in the absence 

of a specific OSHA PEL. OSHA requires an employer to furnish employees a place of employment free 

from recognized hazards that cause or are likely to cause death or serious physical harm [Occupational 

Safety and Health Act of 1970 (Public Law 91–596, sec. 5(a)(1))]. Thus, NIOSH investigators encourage 

employers to make use of other OELs when making risk assessments and risk management decisions to 

best protect the health of their employees. NIOSH investigators also encourage the use of the traditional 

hierarchy of controls approach to eliminate or minimize identified workplace hazards. This includes, in 

order of preference, the use of (1) substitution or elimination of the hazardous agent, (2) engineering 

controls (e.g., local exhaust ventilation, process enclosure, dilution ventilation), (3) administrative controls 

(e.g., limiting time of exposure, employee training, work practice changes, medical surveillance), and (4) 

personal protective equipment (e.g., respiratory protection, gloves, eye protection, hearing protection). 

Control banding, a qualitative risk assessment and risk management tool, is a complementary approach 

to protecting employee health that focuses resources on exposure controls by describing how a risk 

needs to be managed. Information on control banding is available at http://www.cdc.gov/niosh/topics/

ctrlbanding/. This approach can be applied in situations where OELs have not been established or can be 

used to supplement the OELs, when available.

Chloramines

Chloramines, specifically trichloramine and soluble chlorine compounds, are inorganic compounds 

formed by the reaction between chlorine disinfectants and nitrogenous compounds such as ammonia, 

amines, or organic nitrogen-containing material. The species and concentrations of chloramine are 

influenced by the concentration of residual chlorine, ammonia (or other nitrogen sources), pH, and 

temperature. In general, the lower the pH and the greater the chlorine to ammonia ratio, the higher the 

likelihood of producing trichloramine.

Soluble Chlorine Compounds

The term soluble chlorine refers to the chlorine compounds collected using the silica gel tube portion 

of the sampler used. These chlorine compounds include monochloramine, dichloramine, hypochlorous 

acid, and hypochlorite. No OELs have been developed for soluble chlorine or for its specific possible 

constituents.

Monochloramine and dichloramine are less volatile than trichloramine; monochloramine is released 

into the air about 300 times slower and dichloramine about three times slower than trichloramine 

Appendix B: Occupational Exposure Limits and H

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 37

[Holzwarth 1984]. They tend to be more abundant in water than in air. However, high air concentrations 

of monochloramine and dichloramine have been found in environments where water is aerosolized. In 

studies of chloramine exposures at poultry facilities and a green salad processing facility, eye and upper 

respiratory irritation symptoms were associated with soluble chlorine concentrations. In these scenarios, 

soluble chlorine compounds are generated from the mixing of chlorinated water with nitrogenous proteins 

produced by animals and plants [Hery et al. 1998; NIOSH 2003, 2006].

Trichloramine

Trichloramine, or nitrogen trichloride, is a brownish-yellow gas, has a pungent chlorine odor, is a strong 

irritant, and causes excessive tearing of the eyes [Barbee 1983]. Trichloramine, the most volatile and 

prevalent chloramine compound in the air around swimming pools [Thickett et al. 2002], has low 

solubility and decomposes rapidly in sunlight. Eye and respiratory tract irritation appear to be the primary 

effects of exposure. Currently, no NIOSH or OSHA OELs exist for air trichloramine concentration.

Chlorine

Chlorine is a greenish-yellow gas with a characteristic irritating odor. Exposure to chlorine gas can cause 

severe irritation of the eyes and respiratory tract, resulting in tearing, runny nose, sneezing, coughing, 

choking, and chest pain [NIOSH 1978; Proctor et al. 2004]. Breathing difficulty, with a delayed onset, can 

also occur. Severe exposure can result in edema and can be fatal. Mucous membrane and eye irritation 

has been reported to occur at concentrations as low as 0.2 ppm [Proctor et al. 2004]. The NIOSH REL 

for chlorine is 0.5 ppm as a ceiling limit [NIOSH 2010]. The OSHA PEL for chlorine is 1 ppm as a ceiling 

limit [NIOSH 2010]. The ACGIH TLV for chlorine is 0.5 ppm; ACGIH has established a STEL for 

chlorine of 1 ppm [ACGIH 2011].

Chlorine Dioxide

Chlorine dioxide has an unpleasant chlorine-like odor and has an air odor threshold of 0.1 ppm. Exposure 

to chlorine dioxide can cause eye, nose, throat irritation; coughing, wheezing, bronchitis; pulmonary 

edema; chronic bronchitis. The NIOSH REL and OSHA PEL TWA for chlorine dioxide is 0.1 ppm 

[NIOSH 2010]. The ACGIH TLV for chlorine dioxide is 0.1 ppm; ACGIH has established a STEL for 

chlorine dioxide of 0.3 ppm [ACGIH 2011].

References

ACGIH [2011]. 2011 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

agents and biological exposure indices. Cincinnati, OH: American Conference of Governmental 

Industrial Hygienists.

Appendix B: Occupational Exposure Limits and H

 (continued
Page 38 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

AIHA [2011]. AIHA 2011 Emergency response planning guidelines (ERPG) & workplace environmental 

exposure levels (WEEL) handbook. Fairfax, VA: American Industrial Hygiene Association.

Barbee SJ, Thackara JW, Rinehart WE [1983]. Acute inhalation toxicology of nitrogen trichloride. Am Ind 

Hyg Assoc J 44(2):145–146.

CFR. Code of Federal Regulations. Washington, DC: U.S. Government Printing Office, Office of the 

Federal Register.

Hery M, Gerber JM, Hecht G, Subra I, Possoz C, Aubert S, Dieudonne M, Andre JC [1998]. Exposure to 

chloramines in a green salad processing plant. Ann Occup Hyg 42(7):437–451.

Holzwarth G, Balmer RG, Soni L [1984]. The fate of chlorine and chloramines in cooling towers. Water 

Res 18(11):1421–1427.

NIOSH [1978]. NIOSH/OSHA occupational health guidelines for chemical hazards–occupational health 

guideline for chlorine. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for 

Disease Control and Prevention, National Institute for Occupational Safety and Health. DHHS (NIOSH) 

Publication No. 81-123.

NIOSH [2003]. Hazard evaluation and technical assistance report: Bil-Mar Foods, Inc., Storm Lake, IA. By 

King B and Page E. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational Safety and Health, NIOSH HETA Report 

No. 2002-0257-2916.

NIOSH [2006]. Hazard evaluation and technical assistance report: Sara Lee Foods, Storm Lake, IA. By 

King B and Page E. Cincinnati, OH: U.S. Department of Health and Human Services, Centers for Disease 

Control and Prevention, National Institute for Occupational Safety and Health, NIOSH HETA Report 

No. 2006-0153-3022.

NIOSH [2010]. NIOSH pocket guide to chemical hazards. Cincinnati, OH: U.S. Department of Health 

and Human Services, Centers for Disease Control and Prevention, National Institute for Occupational 

Safety and Health, DHHS (NIOSH) Publication No. 2010-168c. [http://www.cdc.gov/niosh/npg/]. Date 

accessed: November 2011.

Proctor NH, Hathaway GH [2004]. Chemical hazards of the workplace, 5th ed. Hoboken, NJ: John Wiley 

& Sons, Inc.

Thickett KM, McCoach JS, Gerber JM, Sadhra S, Burge PS [2002]. Occupational asthma caused by 

chloramines in indoor swimming pool air. Eur Respir J 19(5):827–832.

Appendix B: Occupational Exposure Limits and H

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 39

Fluorescein Stain Grading Score

0 - Normal: negative slit-lamp findings

1 - Mild: superficial stippling

2 - Moderate: punctuate staining including superficial abrasion of the cornea

3 - Severe: abrasion or corneal erosion, deep corneal abrasion, or recurrent erosion

Each eye was divided into five segments as seen on the scoring sheet below.

Appendix C: Fluorescein Stain

Each segment was scored separately. The total fluorescein staining score for that eye was the sum of the 

five scores (maximum score/eye = 15). Examples of each score are illustrated by the photographs taken 

from the slide show portion of the website http://www.staininggrid.com/.

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Permission to copy, view, and print Staining Grid documents available from the Web is authorized 

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Notwithstanding the above, nothing contained herein shall be construed as conferring any right or license 

under any copyright of Gary Andrasko, OD, LLC.
Page 40 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Appendix D: Ta

Table D1. Personal breathing zone soluble chlorine and trichloramine air concentration results in the 

evisceration area 

Day Soluble chlorine Trichloramine 

(μg/m3) (μg/m3)

1 130 45

5 120 [39]

4 110 [28]

1 100 [30]

2 93 [33]

1 86 [29]

1 68 [20]

1 65 [20]

1 64 NA*

1 63 [13]

1 63 [20]

1 62 [14]

1 61 [22]

1 60 [17]

1 58 [22]

1 57 [21]

2 54 NA

1 54 [21]

5 54 [33]

1 52 [13]

2 51 [26]

1 51 [23]

1 49 [21]

1 49 [23]

5 48 [31]

2 46 [21]

2 45 [20]

4 44 [14]

1 44 [15]

3 42 [18]

2 42 [26]

4 37 [14]
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 41

Table D1. Personal breathing zone soluble chlorine and trichloramine air concentration results in the 

evisceration area (continued)

Day Soluble chlorine Trichloramine 

(μg/m3) (μg/m3)

5 36 [25]

2 36 [23]

2 35 [20]

5 33 [20]

2 33 [18]

2 33 [26]

4 32 [16]

4 32 [21]

5 30 [17]

5 29 [27]

4 29 ND†

4 28 [22]

5 [28] [30]

4 [26] ND

2 26 ND

4 26 ND

4 26 ND

5 26 [31]

4 [26] ND

5 [26] [28]

5 [26] [37]

5 [24] [30]

4 24 [19]

4 [24] [18]

5 [24] [25]

5 [23] [25]

5 [23] [25]

2 [23] ND

2 23 [20]

5 [23] [25]

4 [22] [24]

5 [22] [28]

Appendix D: Ta

 (continued
Page 42 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Table D1. Personal breathing zone soluble chlorine and trichloramine air concentration results in the 

evisceration area (continued)

Day Soluble chlorine Trichloramine 

(μg/m3) (μg/m3)

5 [22] [28]

3 [22] [15]

5 [22] [22]

4 [21] [20]

4 [21] [15]

5 [21] [26]

4 [21] [18]

5 [21] [14]

5 [21] [16]

4 [21] ND

3 [20] [22]

4 [20] [20]

2 [20] ND

2 [20] ND

4 [19] [14]

2 [19] [15]

3 [19] [14]

4 [19] [23]

4 [19] ND

3 [18] [18]

3 [18] [17]

3 [18] ND

4 [17] ND

3 [17] [17]

5 [16] [23]

3 [16] [17]

3 [16] ND

3 [16] ND

2 [16] [25]

3 [16] [19]

3 [15] [19]

3 [15] [15]

Appendix D: Ta

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 43

Table D1. Personal breathing zone soluble chlorine and trichloramine air concentration results in the 

evisceration area (continued)

Day Soluble chlorine Trichloramine

(μg/m3) (μg/m3)

3 [15] ND

3 [15] ND

3 [15] [17]

3 [14] ND

3 [14] [19]

3 [10] ND

2 [9.1] ND

3 [8.8] ND

3 ND ND

1 NA NA

1 NA NA

1 NA NA

4 NA NA

4 NA NA

Overall geometric mean: 28.6 [16.7]

Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty 

associated with these values than with concentrations above the MQC.

*NA – Sample was lost either because of damage to the sampler in the field or a greater than 10% difference 

between presampling and postsampling flow rates.

†ND – Not detected

Appendix D: Ta

 (continued

Table D2. Personal breathing zone soluble chlorine and trichloramine air concentration results in the gizzard 

harvest area

Day Soluble chlorine (μg/m3) Trichloramine (μg/m3)

1 60 NA*

5 [30] [28]

4 [18] [14]

3 [16] [22]

Overall geometric mean: [26.9] [20.5]

Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty 

associated with these values than with concentrations above the MQC.

*NA – Sample was lost either because of damage to the sampler in the field or a greater than 10% difference 

between presampling and postsampling flow rates.
Page 44 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155

Table D3. Personal breathing zone soluble chlorine and trichloramine air concentration results in the paw harvest 

area

Day Soluble chlorine (μg/m3) Trichloramine (μg/m3)

1 65 [26]

4 [28] [18]

5 [24] [24]

5 [23] [14]

4 [22] [14]

2 [21] [16]

4 [18] [16]

3 [13] ND

Overall geometric mean: 24.0 [15.9]

Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty 

associated with these values than with concentrations above the MQC.

Appendix D: Ta

 (continued

Table D4. Personal breathing zone soluble chlorine and trichloramine air concentration results in the reprocessing 

area

Day Soluble chlorine (μg/m3) Trichloramine (μg/m3)

1 220 [39]

2 210 [34]

3 130 NA*

4 120 [33]

4 83 [25]

5 83 [25]

1 79 ND†

1 64 [21]

2 49 [22]

2 44 [29]

5 29 [21]

3 [23] [21]

3 [23] [20]

4 [22] [15]

4 [18] [13]

5 [18] [29]

Overall geometric mean: 54.0 [21.9]

Concentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty 

associated with these values than with concentrations above the MQC.

*NA – Sample was lost either because of damage to the sampler in the field or a greater than 10% difference 

between presampling and postsampling flow rates.

†ND – Not detected
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 45 Appendix D: Ta

 (continue)

Table D5. Area trichloramine air concentration results by location

Day 1 Day 2 Day 3 Day 4 Day 5 Geometric

PM AM PM AM PM AM PM AM PM AM mean

Area location Trichloramine concentration (μg/m3)East evisceration, Station 1 [26] 47 [29] [23] [17] [21] [24] [35] [21] [34] [26.6]East evisceration, Station 4 [29] [33] [30] [29] ND* NA† [23] [29] [35] [21] [25.7]Paw harvest [19] [34] [39] [28] ND [19] [24] [28] [27] [31] [26.2]Reprocessing 48 [30] ND‡ [19] ND [21] [38] [21] 49 ND [22.0]Gizzard harvest ND [31] [32] [24] [14] [25] [21] [22] [19] [38] [22.5]West evisceration, Station 1 [23] [39] [39] [30] ND [24] [22] [22] [28] [37] [26.2]West evisceration, Station 4 ND [29] [24] [30] [16] [14] [21] [23] [25] [37] [21.7]IQF NA 32 ND ND 52 ND ND ND ND ND [18.0]§WOG NA ND ND** ND ND ND ND ND ND ND NDConcentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty associated with these values than with concentrations above the MQC.*ND – Not detected†NA – No sample taken for this location‡Cassette detached from sampling train and was found assembled backwards during postcalibration.§Approximately 75% of samples were below the MDC.**Shorter sampling time; WOG finished early
Page 46 Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Table D6. Area soluble chlorine air concentration results by location Day 1 Day 2 Day 3 Day 4 Day 5 Geometric PM AM PM AM PM AM PM AM PM AM mean Area location Soluble chlorine concentration (μg/m3

)

East evisceration, Station 1 68 75 56 49 41 46 46 35 28 59 48.4East evisceration, Station 4 110 74 63 54 56 NA* 55 34 41 46 55.8Paw harvest 86 73 89 44 [39] 48 60 48 30 80 56.3Reprocessing 280 140 ND†,‡ 84 170 99 200 [33] 210 42 83.5Gizzard harvest 77 48 45 36 52 51 40 [32]§ 33 50 45.0West evisceration, Station 1 60 70 [23.8]§ 53 41 62 47 35 36 61 46.4West evisceration, Station 4 73 87 48 59 50 51 48 36 35 63 52.9IQF NA 36 ND ND§ [51.7] ND ND ND ND ND [10.3]**WOG NA ND ND†† ND ND ND ND ND ND ND NDConcentrations between the MDC and MQC are shown in brackets to acknowledge that there is more uncertainty associated with these values than with concentrations above the MQC.*NA – No sample taken for this location†ND – Not detected‡Cassette detached from sampling train and was found assembled backwards during post calibration.

§ Silica gel tube broke during sampling.**Approximately 75% of samples were below the MDC. ††Shorter sampling time; WOG finished early

Appendix D: Ta

 (continued
Health Hazard Evaluation Report 2007-0284 & 2007-0317-3155 Page 47

Acknowledgments a

Availability of Re

The Hazard Evaluations and Technical Assistance Branch (HETAB) 

of the National Institute for Occupational Safety and Health (NIOSH) 

conducts field investigations of possible health hazards in the 

workplace. These investigations are conducted under the authority of 

Section 20(a)(6) of the Occupational Safety and Health Act of 1970, 29 

U.S.C. 669(a)(6) which authorizes the Secretary of Health and Human 

Services, following a written request from any employer or authorized 

representative of employees, to determine whether any substance 

normally found in the place of employment has potentially toxic effects 

in such concentrations as used or found. HETAB also provides, upon 

request, technical and consultative assistance to federal, state, and local 

agencies; labor; industry; and other groups or individuals to control 

occupational health hazards and to prevent related trauma and disease.

Mention of any company or product does not constitute endorsement 

by NIOSH. In addition, citations to websites external to NIOSH do 

not constitute NIOSH endorsement of the sponsoring organizations 

or their programs or products. Furthermore, NIOSH is not responsible 

for the content of these websites. All Web addresses referenced in this 

document were accessible as of the publication date.

This report was prepared by Lilia Chen, Judith Eisenberg, Srinivas 

Durgam, and Charles Mueller of HETAB, Division of Surveillance, 

Hazard Evaluations and Field Studies. Industrial hygiene field 

assistance was provided by Donald Booher, Srinivas Durgam, Stefanie 

Evans, Karl Feldmann, Todd Niemeier, and Jessica Ramsey. Industrial 

hygiene equipment and logistical support was provided by Donald 

Booher and Karl Feldmann. Medical field assistance was provided by 

Diana Freeland, Matthew Groenwald, Soo-Jeong Lee, and Jim Taylor. 

Optometric consultation and field assistance was provided by Daniel 

Powell, Ohio State University College of Optometry. Optometric 

consultation was provided by Kelly Nichols, University of Houston, 

College of Optometry. Analytical support was provided by Jennifer 

Roberts of the Division of Applied Research and Technology, and 

Bureau Veritas. Health communication assistance was provided by 

Stefanie Evans. Editorial assistance was provided by Ellen Galloway. 

Desktop publishing was performed by Greg Hartle.

Copies of this report have been sent to employee and management 

representatives at this poultry processing facility, the government 

agency which submitted the technical assistance request, the Oklahoma 

state health department, and the Occupational Safety and Health 

Administration Regional Office. This report is not copyrighted and 

may be freely reproduced. The report may be viewed and printed at 

http://www.cdc.gov/niosh/hhe/. Copies may be purchased from the 

National Technical Information Service (NTIS) at 5825 Port Royal 

Road, Springfield, Virginia 22161.
Below is a recommended citation for this report:

NIOSH [2012]. Health hazard evaluation report: evaluation of eye and respiratory 

symptoms at a poultry processing plant – Oklahoma. By Chen L, Eisenberg J, 

Durgam S, Mueller C. Cincinnati, OH: U.S. Department of Health and Human 

Services, Centers for Disease Control and Prevention, National Institute for 

Occupational Safety and Health, NIOSH HETA No. 2007-0284 & 2007-0317-3155.

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