Evaluation of Health 

Effects of a Chlorine 

Gas Release in a Poultry 

Processing Plant –– 

Arkansas

Francisco Meza, MD, MPH

Charles Mueller, MS

Bradley King, MPH, CIH

Health Hazard Evaluation Report

HETA 2011-0128-3166

September 2012

Revised February 2013

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].

Revision Summary: The authors incorrectly identified that a Spanish-speaking employee poured sodium 

hypochlorite into a 55-gallon drum containing residual acidic antimicrobial solution, causing a chlorine gas 

release. The Spanish-speaking employee retrieved a 55-gallon drum containing residual acidic antrimicrobial 

solution. The drum was labeled in English. The English-speaking supervisor mixed the sodium hypochlorite 

into the 55-gallon drum containing residual acidic antimicrobial solution, but did not read the label.
Health Hazard Evaluation Report 2011-0128-3166 Page i

Report Abbreviations................................................................................................ii

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

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

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

Assessment.....................................................................................................2

Results..............................................................................................................4

Discussion.................................................................................................... 11

Conclusions................................................................................................. 13

Recommendations.................................................................................... 13

References.................................................................................................... 15

Contents

Acknowledgments Acknowledgments and Availability of Report................................ 26

Appendix A Diagnostic Criteria for RADS and PTSD............................................. 18

Appendix B Methacholine Challenge Testing......................................................... 20

Appendix C Occupational Exposure Limits and Health Effects......................... 21
Page ii Health Hazard Evaluation Report 2011-0128-3166

Abbreviations

ACGIH® American Conference of Governmental Industrial Hygienists

CFR Code of Federal Regulations

ECRHS European Community Respiratory Health Survey

FEV1 Forced expiratory volume in 1 second

mg/m3 Milligrams per cubic meter of air

mL Millilter

NAICS North American Industry Classification System

NIOSH National Institute for Occupational Safety and Health

OEL Occupational exposure limit

OSHA Occupational Safety and Health Administration

ppm Parts per million

PEL Permissible exposure limit

PTSD Posttraumatic stress disorder

RADS Reactive airway dysfunction syndrome

REL Recommended exposure limit

STEL Short-term exposure limit

TLV® Threshold limit value

TWA Time-weighted average

WEELTM Workplace environmental exposure level 
Health Hazard Evaluation Report 2011-0128-3166 Page iii

The National Institute 

for Occupational Safety 

and Health (NIOSH) 

received a request for a 

health hazard evaluation 

at a poultry processing 

plant in Arkansas. The 

Occupational Safety and 

Health Administration 

submitted the request 

to determine health 

outcomes of an 

unintentional chlorine 

gas release in June 2011. 

NIOSH investigators 

visited the plant in June 

2011, November 2011, and 

January 2012.

Highlights of the

NIOSH Health

Hazard Evaluation

What NIOSH Did

● We investigated the causes of the chlorine gas release.

● We interviewed 545 employees during part or all of our 

evaluation.

● We interviewed employees about exposure to the chlorine 

gas. Interviews were done in English, Spanish, and 

Marshallese.

● We asked about acute symptoms in the days following the 

chlorine gas release.

● We interviewed employees 4 months after the chlorine gas 

release. We wanted to see if they had symptoms of asthma or 

posttraumatic stress disorder.

● Employees who reported symptoms of asthma 4 months 

after the chlorine gas release had a breathing test done six 

months after the release. This test was used to see if they 

had reactive airway dysfunction syndrome. This condition is 

asthma caused by a single, high exposure to an irritant such 

as chlorine.

What NIOSH Found

● Several factors led to the chlorine gas release. Among 

them were labeling in English only, lack of literacy in 

English, storage of incompatible chemicals in similar 

containers, and failure to read labels.

● One hundred sixteen (21%) participants had asthma 

symptoms 4 months after the release. Of these, three 

participants had breathing tests consistent with reactive 

airway dysfunction syndrome 6 months after the release. 

● One hundred six (19%) participants had posttraumatic stress 

disorder symptoms 4 months after the release.

What Managers Can Do

● Find unique fittings that will prevent connections from the 

filling station to containers that should not be filled with 

sodium hypochlorite.

● Keep incompatible chemicals in different sized or different 

colored barrels to help keep from them being mixed up.

● Properly label containers in English, Spanish, and 

Marshallese. Labels should be written to meet at a reading 

level that all employees can understand.
Page iv Health Hazard Evaluation Report 2011-0128-3166

Highlights of the

NIOSH Health

Hazard Evaluation

 (continued)

 

● Teach employees about chemical hazards. This should be 

done in the employees’ native language.

● Train employees on the proper exit routes from the plant.

● Refer employees who are still experiencing symptoms to 

a trained healthcare provider. Employees who still have 

respiratory symptoms should be seen by a pulmonologist. 

Employees who have psychological symptoms should see a 

psychologist. Employees with other work-related symptoms 

should seek care from an occupational health physician.

What Employees Can Do

● Tell managers about any safety and health concerns that you 

may have about your workplace.

● Read labels on all chemicals.

● Participate in all safety training that your employer offers.

● Tell your supervisor or the plant health clinic if you are still 

having any physical or psychological symptoms related to the 

chlorine gas release. They can help you get the proper care. 
Health Hazard Evaluation Report 2011-0128-3166 Page v

A large release of chlorine 

gas resulted from the 

unintentional mixing of 

sodium hypochlorite 

solution and an acidic 

antimicrobial used at this 

poultry processing plant. 

Several factors led to 

the chlorine gas release. 

Among them were labeling 

in English only, lack of 

literacy in English, storage 

of incompatible chemicals 

in similar containers, and 

failure to read labels. Three 

employees developed 

RADS, and more than 100 

had symptoms of PTSD.

Summary

NIOSH received a request for technical assistance from OSHA to 

evaluate employee health effects after a chlorine gas release in a 

poultry processing plant in Arkansas. On the morning of June 27, 

2011, human error resulted in the mixing of an acidic solution of 

Fresh FX, an antimicrobial used in poultry processing, with a sodium 

hypochlorite solution. This mixing of chemicals caused a release of 

chlorine gas into the plant. About 600 employees who were at work 

at the time of the release were evacuated.

We made three site visits to evaluate the employees who were 

at work on the morning of the release. Five hundred forty-five 

employees participated in part or all of our evaluation. Of those who 

participated in our evaluation, 195 reported seeking medical care, 

152 reported being hospitalized, and the company reported that 5 

were admitted to intensive care units immediately after the incident.

On our first site visit in June 2011, we spoke with an employee 

involved in the chlorine release and the managers about what led to 

the event. We administered questionnaires about medical history 

and symptoms in the days following the incident to employees 

in Spanish, English, and Marshallese. On the second site visit in 

November 2011, we evaluated participants for symptoms of asthma 

(because a single high level exposure to an irritant like chlorine can 

cause a type of asthma called RADS) and PTSD approximately 4 

months after the release. On our third site visit in January 2012, we 

did spirometry and methacholine challenge tests on participants 

who reported asthma symptoms at the second site visit, but had no 

history of asthma prior to the release.

Five hundred twenty-three participants were present at the first 

site visit and at work on the morning of the chlorine release. An 

additional 22 were later identified as present the morning of 

the chlorine release but not during the first site visit. Of the 545 

participants, 60% were female, 17% primarily spoke English, 68% 

primarily spoke Spanish, 12% primarily spoke Marshallese, and 3% 

spoke other languages. Eleven percent of participants were current 

smokers, and 6% reported a history of asthma. Strength of chlorine 

odor was used as a surrogate for intensity of exposure. Of the 542 

participants who responded to the question of whether or not they 

smelled chlorine, 29% reported not smelling chlorine, and 22% 

reported a light odor, 7% a moderate odor, and 42% a strong odor.

Of the 523 participants who were present at the first visit, 213 (41%) 

reported a strong chlorine odor. Their most commonly reported 
Page vi Health Hazard Evaluation Report 2011-0128-3166

Keywords: NAICS 311615 (Poultry Processing), asthma, reactive 

airways dysfunction syndrome, posttraumatic stress disorder, 

chlorine

symptoms within 24 hours of the chlorine release were burning 

throat, headache, burning eyes, and cough. Headache, burning 

throat, and cough were the most common symptoms reported 3–5 

days post-release by those reporting a strong chlorine odor.

Two hundred forty-five participants (47%) present at the first site 

visit reported lower respiratory tract symptoms (cough, shortness 

of breath, chest tightness, or wheeze). These 245 plus 22 additional 

participants who had not yet returned to work at the time of 

our first site visit were asked to complete the asthma symptoms 

questionnaire during the second site visit. Of the 240 who did so, 

116 (48%) had one or more asthma symptoms in the 2 weeks prior 

to that site visit.

Overall, 106 (22%) of 493 participants at the second site visit 

reported symptoms consistent with PTSD approximately 4 months 

after the release. The prevalence of PTSD symptoms increased with 

increasing strength of reported chlorine odor (from 4% among 

those who reported not smelling chlorine to 37% among those 

reporting a strong odor of chlorine, P<0.01).

At the third site visit we did spirometry on 101 subjects who 

reported asthma symptoms at the second site visit and had no 

history of asthma prior to the release. Methacholine challenge 

testing was done on 78 participants with a forced expiratory 

volume at 1 second at or above 70% (this means they did not 

have significant obstruction) and no medical contraindications for 

testing. Three had borderline bronchial hyperreactivity, two had 

mild bronchial hyperreactivity, and one had moderate to severe 

bronchial hyperreactivity. Mild, moderate, and severe bronchial 

hyperreactivity are consistent with RADS, or asthma.

The unintentional release of chlorine gas at this plant posed a 

serious health hazard to employees. Three employees developed 

RADS, and more than 100 developed symptoms of PTSD.

Summary

 (continued)
Health Hazard Evaluation Report 2011-0128-3166 Page vii

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Page 1 Health Hazard Evaluation Report 2011-0128-3166

Introduction

NIOSH received a request from OSHA to evaluate employee health 

effects after a chlorine gas release in a poultry processing plant 

in Arkansas. The plant prepared poultry for consumption from 

slaughtering through processing, seasoning, and packaging. A sodium 

hypochlorite solution was often used for disinfection. On the morning 

of June 27, 2011, an employee inadvertently mixed an acidic solution 

of Fresh FX, an antimicrobial, with a hypochlorite solution, releasing 

chlorine gas into the plant. About 600 employees were at work and were 

evacuated. Of those who participated in our evaluation, 195 reported 

seeking medical care, 152 reported being hospitalized, and the company 

reported that 5 were admitted to intensive care units immediately after 

the incident.

Background 

Chlorine, Reactive Airway Dysfunction 

Syndrome, and Posttraumatic Stress Disorder

Chlorine is a greenish-yellow gas. It has a strong, pungent smell, with an 

odor threshold of approximately 0.3–0.5 ppm. Chlorine is moderately 

water soluble, so it can enter the upper and lower respiratory tract, 

and often affects mucous membranes, eyes, and the lower respiratory 

tract. It forms hydrochloric and hypochlorous acid, two highly irritating 

compounds, upon contact with water in the eyes, mucous membranes, 

and lower respiratory tract [Das and Blanc 1993]. A possible long-term 

effect of a single, high-level chlorine gas exposure is RADS, which is a 

type of asthma [Shakeri et al. 2008]. Diagnostic criteria for RADS are 

listed in Appendix A.

Large, unintentional chemical releases can cause anxiety, which may 

manifest as a range of effects, spanning from an acute stress disorder 

in the short term to PTSD in the long term. For example, PTSD was 

documented after a chlorine release from a train derailment in South 

Carolina [Duncan et al. 2011]. PTSD occurs after a traumatic event 

that involves actual or threatened death or serious injury or a threat to 

the physical integrity of self or others [American Psychiatric Association 

2000]. The response to the traumatic experience may involve lasting fear 

and perseveration about the dangers of the event. Diagnostic criteria for 

PTSD are listed in Appendix A.
Health Hazard Evaluation Report 2011-0128-3166 Page 2

Assessment

First Site Visit (June 29–July 1, 2011) 

We met with management and employee representatives, the OSHA 

compliance officer investigating the incident, and representatives of 

the local health department to discuss the health hazard evaluation 

request. We also discussed safety procedures, medical support, and 

details of the chlorine gas release. We conducted a brief tour of the 

poultry plant, accompanied by the OSHA compliance officer, paying 

special attention to how and where the chlorine gas was released. We 

interviewed one employee directly involved in the release; the other 

employee involved in the release was not available for interview. We 

administered questionnaires about past medical history and acute 

symptoms related to the chlorine release to employees present during 

our visit. Questionnaires were given in the employees’ native language, 

including Spanish, English, and Marshallese.

Second Site Visit (November 2–4, 2011)

We surveyed two groups of participants, those present and 

participating during the first visit and an additional group of employees 

present during the incident but unavailable during the first visit. 

Questionnaires covered PTSD and asthma symptoms.

We evaluated all participants for symptoms of PTSD. We used the 

Trauma Screening Questionnaire, a validated questionnaire to screen 

for symptoms of PTSD [Brewin et al. 2002]. When used in rail crash 

survivors and crime victims, it had a sensitivity (i.e., correctly identified 

persons with PTSD) of 76%–86% and specificity (i.e., correctly 

identified persons without PTSD) of 93%–97% compared to a 

structured clinical interview [Brewin 2005].

From the first questionnaire, we identified participants who were 

present at the plant during the chlorine release who reported cough, 

shortness of breath, chest tightness, or wheeze at 3–5 days after the 

chlorine release. These participants, plus the employees not available 

during our first visit, were surveyed to determine if they had symptoms 

of RADS using modified questions from the ECRHS [Grassi et al. 

2003]. Answering yes to any one of these questions is 75% sensitive and 

80% specific for being assessed “asthma-like symptomatic,” compared 

with clinical examination, spirometry, and allergy testing.

In addition to the survey items described above, the employees absent 

during our first site visit but present during the chlorine release were 

also asked additional items. These included asthma history, strength of 

chlorine odor, and smoking status.
Page 3 Health Hazard Evaluation Report 2011-0128-3166

Assessment

 (continued) Third Site Visit (January 9–12, 2012)

We did spirometry on participants who reported asthma symptoms at 

our second site visit and had no history of asthma prior to the release. 

The spirometry test measures how well the lungs move air in and out. 

Because asthma demonstrates intermittent obstruction, spirometry can 

be normal between attacks. Therefore, we conducted methacholine 

challenge testing on participants whose forced expiratory volume in 1 

second was 70% or greater, which means they did not have significant 

obstruction. Methacholine causes obstruction in people with bronchial 

hyperreactivity, indicating they may have asthma. We also administered 

the modified ECRHS for asthma symptoms that we used at our second 

site visit, but asked about asthma symptoms in the 2 weeks prior to the 

testing. An interpreter assisted when needed, and informed consent 

was obtained. The flow diagram below outlines activities from all three 

site visits. A detailed description of methacholine challenge testing is in 

Appendix B.

Figure 1. Flow diagram of activities from all three site visits.
Health Hazard Evaluation Report 2011-0128-3166 Page 4

Assessment

 (continued) Statistical Analysis

All data were analyzed using SAS 9.2 (SAS Institute Inc., Cary, 

North Carolina). We reported descriptive statistics for demographic 

characteristics and symptoms of participants. We also did CochranArmitage tests for trends to assess the presence of an association 

between exposure (based on chlorine odor strength) and asthma 

symptoms and exposure and PTSD symptoms. A P value equal to or 

less than 0.05 was considered statistically significant.

First Site Visit

Interview 

We spoke, in Spanish, with an employee who was directly 

involved in the chlorine release. He reported that the employee 

who normally filled the barrel was busy and instructed him to 

get the barrel so it could be refilled with sodium hypochlorite. 

He found a nearly empty barrel that was labeled in English only. 

He was not aware that the barrel contained Fresh FX. The other 

employee actually dispensed the sodium hypochlorite into the 

barrel. This employee reported he did not read the label on the 

drum. Chlorine gas was released immediately. That employee 

was forced to leave the room immediately and could not shut 

off the valve, but immediately reported what had happened and 

the hypochlorite valve was shut off remotely. By then the gas had 

spread throughout the plant.

Questionnaire 

Five hundred twenty-three employees participated in the survey 

at the first site visit. An additional 22 employees were at work the 

morning of the chlorine release, but not during the first site visit. 

Demographic and other characteristics of all 545 participants are 

shown in Table 1. Sixty percent of survey participants were female, 

17% spoke primarily English, 68% spoke primarily Spanish, 12% 

spoke primarily Marshallese, and 3% spoke other languages. 

Eleven percent of participants were current smokers, and 6% 

reported a history of asthma.

Results
Page 5 Health Hazard Evaluation Report 2011-0128-3166

Results

 (continued) Table 1. Characteristics of participants (n=543–545)* 

Age (years) Mean 42 (range:18–72)

No. (%)

Sex

Male

Female

219 (40)

326 (60)

Primary Language

English

Spanish

Marshallese

Other

91 (17)

371 (68)

68 (12)

15 (3)

Smoking Status

Never

Former

Current

411 (76)

73 (13)

59 (11)

History of asthma 34 (6)

*The number of responses varies because of missing data.

Strength of chlorine odor was used as a surrogate for intensity 

of exposure (Figure 2). Of the 213 participants who reported 

a strong odor at the first site visit, burning throat, headache, 

burning eyes, and cough were the most commonly reported 

symptoms within 24 hours of the chlorine release (Table 2). For 

all symptoms, prevalence increased with increasing odor strength.

Figure 2. Reported strength of chlorine odor (n=542).
Health Hazard Evaluation Report 2011-0128-3166 Page 6

Results

 (continued) Table 2. Prevalence of reported symptoms among participants within 

24 hours of chlorine gas release by self-reported strength of chlorine 

odor (n=520)*

Symptoms Strength of Chlorine Odor

% None 

n=154

% Light 

n=117

% Moderate 

n=36

% Strong 

n=213

Mucous membrane

 Burning throat

 Burning eyes

 Burning nose

Constitutional

 Headache 

 Dizziness/ 

lightheadedness

Chest

 Coughing 

 Shortness of breath

 Chest pain 

 Chest tightness 

 Chest congestion or 

phlegm

 Wheezing in chest

 Coughing up blood 

Gastrointestinal

 Nausea 

 Vomiting

Skin

 Irritation/pain/burning 

of skin

11

10

5

15

6

8

4

5

6

6

2

0

5

2

3

33

31

21

43

23

32

12

20

9

9

6

1

13

6

5

56

50

33

61

44

58

39

33

36

31

11

0

36

14

8

82

74

58

81

63

72

67

66

56

49

40

10

52

25

26

*Only participants who were present at our first site visit were included.

Headache, burning throat, and cough were the most common 

symptoms reported 3–5 days post-release (Table 3). For all 

symptoms, prevalence increased with increasing odor strength. Of 

those who reported a strong chlorine odor, 69% reported seeking 

medical care, 58% reported they were hospitalized, and 51% were 

prescribed medication immediately after the release. In those who 

experienced no odor, only 4% reported seeking medical care, 3% 

reported receiving hospital care, and 3% reported being prescribed 

medication (Figure 3). In addition, many employee questions and 

comments raised during our evaluation indicated the need for 

timely and clear risk communication to the employees and staff 

about what occurred on June 27, 2011.
Page 7 Health Hazard Evaluation Report 2011-0128-3166

Results

 (continued) Table 3. Prevalence of reported symptoms among participants 3 to 5 

days after chlorine gas release by self-reported strength of chlorine 

odor (n=520)*

Symptoms Strength of Chlorine Odor

% None 

n=154

 % Light

n=117

% Moderate 

n=36

% Strong

n=213

Mucus membrane

 Burning throat

 Burning eyes

 Burning nose

Constitutional

 Headache

 Dizziness/

lightheadedness

Chest

 Coughing

 Shortness of breath

 Chest pain

 Chest tightness

 Chest congestion or 

phlegm 

 Wheezing in chest

 Coughing up blood

Gastrointestinal

 Nausea 

Skin

 Irritation/pain/burning 

of skin

9

5

4

15

5

8

5

5

5

8

3

1

3

4

29

21

17

32

14

23

16

19

10

14

4

0

9

7

39

31

19

42

22

44

25

19

31

25

11

0

17

6

66

48

33

69

47

64

55

53

46

43

28

8

34

20

*Only participants who were present at our first site visit were 

included.
Health Hazard Evaluation Report 2011-0128-3166 Page 8

Results

 (continued)

Figure 3. Level of medical care among participants by strength of reported chlorine odor (n=533–541). 

[The number of responses varies because of missing data.]

Second Site Visit

Post-traumatic Stress Disorder

Twenty-two percent (106/493) of participants reported 

symptoms consistent with PTSD. The prevalence of PTSD 

symptoms increased with increasing strength of reported 

chlorine odor (P<0.01) (Figure 4).
Page 9 Health Hazard Evaluation Report 2011-0128-3166

Results

 (continued)

Figure 4. Prevalence of PTSD symptoms by reported chlorine odor strength (n=490).

Reactive Airway Dysfunction Syndrome 

Forty-seven percent (245/523) of participants from the first site 

visit reported one or more respiratory tract symptoms (cough, 

shortness of breath, chest tightness, wheeze) at 3–5 days postrelease. An additional 22 participants who were at work on the 

day of release but were not present during our first site visit were 

surveyed in the second site visit. Ninety percent (240/267) of 

these participants completed the asthma symptoms questionnaire, 

and of these, 116 (48%) reported one or more asthma symptoms 

in the 2 weeks prior to the second site visit. The prevalence of 

asthma symptoms increased with increasing strength of chlorine 

odor (P=0.048) (Figure 5).
Health Hazard Evaluation Report 2011-0128-3166 Page 10

Results

 (continued)

Figure 5. Prevalence of asthma symptoms by reported chlorine odor strength (n=238).

Third Site Visit

Of the 116 participants with asthma symptoms at the second site 

visit (4 months after the chlorine release), 11 participants had a 

history of asthma prior to the chlorine release and were excluded 

from spirometry. One hundred one subjects participated in 

spirometry. Ninety-four (93%) had normal spirometry, four had a 

restrictive pattern (RADS normally shows an obstructive pattern), 

one had low forced expiratory volume in 1 second, and two had 

uninterpretable results.

Methacholine challenge testing was done on the 78 participants 

who had no medical contraindications for testing and whose 

forced expiratory volume in 1 second was 70% or greater. Seventytwo (92%) had a normal test. Three participants had borderline 

bronchial hyperreactivity, two had mild bronchial hyperreactivity, 

and one had moderate to severe bronchial hyperreactivity. Mild, 

moderate, or severe bronchial hyperreactivity is consistent with the 

diagnosis of RADS.
Page 11 Health Hazard Evaluation Report 2011-0128-3166

Discussion

Of 545 employees, 3 developed RADS from this release of chlorine 

gas, a preventable event. While almost 200 participants sought 

medical care for their symptoms immediately after the release, 

and more than 150 reported being hospitalized, including 5 

who received intensive care, the vast majority had no evidence 

of long-lasting respiratory complications. The employees with 

RADS and borderline RADS need continued medical follow-up 

by a physician. In one previous study of persons diagnosed with 

RADS, more than half continued to report symptoms and one 

third required medication years after their diagnosis [Malo et al. 

2009]. RADS has been associated with decreased quality of life and 

increased depression and anxiety [Malo et al. 2009].

Many employee questions and comments raised during 

our evaluation indicated the need for timely and clear risk 

communication to the employees and staff about what occurred 

on June 27, 2011. In our experience, lack of clear information 

or a management response that is perceived as unsatisfactory 

can lead to distortions of information, development of rumors, 

and unneeded stress and worry among employees. This could 

contribute to PTSD symptoms. PTSD symptoms affected more 

than 20% of participants. Because these findings were based on a 

screening test, and diagnosis of PTSD is done with a psychological 

or psychiatric clinical evaluation, we believe employees with 

continuing symptoms should receive medical follow-up to 

determine if they have clinical PTSD and, if so, get treatment. 

Bisson found that symptoms can continue for up to 6 years in 

one-third of people diagnosed with PTSD, decreasing the quality 

of life for affected individuals [Bisson 2007]. In another chlorine 

gas release following a train derailment in Graniteville, South 

Carolina, approximately 48% of respondents reported symptoms 

of PTSD [Duncan et al. 2011]. The occurrence of fatalities at 

Graniteville may explain the higher rate of PTSD symptoms than 

in our evaluation.

Several factors may have contributed to the improper mixing of 

chemicals that caused the chlorine release in this plant. Among 

them were the fact that containers were labeled only in English, 

yet English was not the primary language of most employees, 

the similarity of containers containing different chemicals, and 

the failure to read the label. This incident demonstrates the 

importance of using appropriate languages when communicating 

in the workplace. This can be challenging given the number 

and diversity on non-English speaking employees present in 
Health Hazard Evaluation Report 2011-0128-3166 Page 12

Discussion

 (continued) the workforce. The Bureau of Labor Statistics reported that 

the U.S. workforce in animal slaughtering and processing was 

38.1% Hispanic or Latino and 8.6% Asian in 2011 [Bureau of 

Labor Statistics 2011]. The potential for injury due to inadequate 

attention to foreign language health and safety training extends 

beyond this industry, with approximately 39.9 million foreign-born 

residents in the United States; 47.1% are Latino and 51.6% report 

inability to speak English very well [American Community Survey 

2010]. We did not extensively evaluate the training programs at 

this plant but this information is relevant to all workplaces with 

employees who are not fluent and/or literate in English.

In addition to language differences, low-level literacy is an 

impediment to understanding. While we did not formally assess 

literacy in native language or in English if it was the secondary 

language, literacy was reported to be low among employees in 

this plant. The National Assessment of Adult Literacy found that 

11 million adults are not literate in English, with 7 million who 

could not answer simple questions and 4 million who could not 

take the test because of language barriers [Institute of Education 

Sciences 2003]. An additional 30 million adults had below basic 

literacy skills, e.g., skills needed for understanding a television 

guide or comparing ticket prices. Thus, people with no more than 

basic literacy skills represent a substantial part of the workforce 

and often are working in dangerous jobs [U.S. Government 

Accountability Office 2005; Johnson and Ostendorf 2010]. This 

situation presents a challenge for employers and for occupational 

safety and health professionals. Most material safety data sheets 

used in industry are written at a college reading level, making it 

difficult to communicate with average employees who are often at a 

9th to 12th grade reading level; the problem is compounded when 

employees do not speak English well or at all [Arcury et al. 2010].

Workplace safety and health training and labeling should be 

conducted in the specific languages of the workforce. Overcoming 

the issues of limited English literacy in workers goes beyond 

providing written training in the appropriate language; it also 

requires active engagement of employees in hands-on training 

[Wallerstein 1992]. To decrease communication gaps, training 

should be interactive, and employees and employers should 

work together on a health and safety team to analyze and 

improve workplace policies and programs. You could use your 

joint labor management safety committee to do this. From a 

regulatory perspective, OSHA has made changes to the hazard 
Page 13 Health Hazard Evaluation Report 2011-0128-3166

Discussion

 (continued) communication standard that will be phased in over the next 

4 years in accordance with recommendations from the United 

Nations [OSHA 2012]. These changes establish a standardized 

international labeling system (the Global Harmonized System 

of Classification and Labeling of Chemicals) to be used by 

manufacturers of chemicals. Using symbols and simplified text, 

its intent is to improve understanding of chemical hazards for 

all employers and employees regardless of primary language or 

literacy level.

The findings of this evaluation may have certain limitations. 

No questionnaires were validated in all three languages, so 

differences may have occurred as a result of translations. One 

hundred one subjects had spirometry, but only 78 subjects had 

methacholine challenge testing. Therefore, the incidence of 

RADS may be underestimated.

Conclusions The unintentional release of chlorine gas at this plant posed a 

serious health hazard to employees, and at follow-up we found 

that three employees had developed RADS after the release, and 

more than 100 employees reported symptoms of PTSD. Affected 

employees should be encouraged to report ongoing symptoms 

to their supervisor or to the plant health clinic for referral to 

appropriate care. Steps should be taken by the employer to ensure 

that health and safety messages are communicated effectively to 

everyone at risk, whatever their primary language or level of literacy.

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

below to create a more healthful workplace. We encourage the 

plant to use their labor-management health and safety committee 

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 the plant. Our recommendations are based 

on the hierarchy of controls approach (refer to Appendix C: 

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. 
Health Hazard Evaluation Report 2011-0128-3166 Page 14

Recommendations

 (continued)

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.

1. Investigate technology that may prevent future human 

error. We suggest finding unique fittings that will prevent 

connections from the filling station to the container.

2. Keep incompatible chemicals in different sized or different 

colored barrels to help keep from them being mixed up.

Elimination and Substitution

Elimination or substitution of a toxic/hazardous process material 

is a highly effective means for reducing hazards. Incorporating 

this strategy into the design or development phase of a project, 

commonly referred to as “prevention through design,” is most 

effective because it reduces the need for additional controls in 

the future.

1. Consider using a less hazardous disinfectant. The United 

States Department of Agriculture, Food Safety and 

Inspection Service publishes and periodically updates 

Directive 7120.1, Safe and Suitable Ingredients Used in the 

Production of Meat, Poultry, and Egg Products [USDA 2012]. 

We recommend choosing the least hazardous, most 

effective disinfectants for each application from the lists in 

this directive.

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. Ensure employee training programs regarding the hazardous 

chemicals used on-site and needed protective measures 
Page 15 Health Hazard Evaluation Report 2011-0128-3166

Recommendations

 (continued) comply with the upcoming changes in the OSHA hazard 

communication standard.

2. Establish evacuation plans for chemical releases which 

include rapidly conveying information on routes to take 

to evacuate and avoid the area where the chemical release 

occurred. This likely will include announcements over your 

public address system in appropriate languages. Practice 

these evacuation plans because employees need to know the 

proper evacuation routes from their workstation and feel 

that they are safe and effective.

3. Improve employee-management communication. This will 

be complicated because of the language barriers that are 

present in the plant. We recommend the following actions 

to address these important issues:

● Provide details about the unintentional chlorine 

gas release (why it happened and what is being 

done to prevent future events) and the health risks 

of chlorine gas exposure. The Centers for Disease 

Control and Prevention has a fact sheet on chlorine 

that can be used (http://www.bt.cdc.gov/agent/

chlorine/basics/facts.asp), as does the New Jersey 

Department of Health (http://web.doh.state.nj.us/

rtkhsfs/factsheets.aspx?lan=spanish&alph=A&carci

nogen=False&new=False#top).

● Provide recommendations to employees about 

medical care post-exposure. We suggest seeking 

care from physicians trained in occupational 

and environmental medicine or toxicology. The 

employees we interviewed had received mixed 

messages about health risks from local physicians.

4. Continue the existing joint employee-management 

committee to address workplace safety and health issues. 

Bilingual employee representatives who can communicate 

in the employees’ primary languages are important to the 

committee’s success.

References American Community Survey [2010]. Population of United States 

by People, Origin, Foreign and Native Born S0501 in 1 year. 

[http://www.census.gov/population/foreign/data/afftables_sub.

html]. U.S. Census Bureau. Date accessed: September 2012.
Health Hazard Evaluation Report 2011-0128-3166 Page 16

References

 (continued) American Psychiatric Association [2000]. Diagnostic and Statistical 

Manual of Mental Disorders. Rev. 4th ed. Washington, DC.

Arcury TA, Estrada JM, Quandt SA [2010]. Overcoming language 

and literacy barriers in safety and health training of agricultural 

workers. J Agromedicine 15(3):236–248.

Bisson JI [2007]. Post-traumatic stress disorder. BMJ 

334(7597):789–793.

Brewin CR, Rose S, Andrews B, Green J, Tata P, McEvedy C, 

Turner S, Foa E [2002]. Brief screening instrument for posttraumatic stress disorder. Br J Psychiatry 181(Aug):158–162.

Brewin CR [2005]. Systematic review of screening instruments for 

adults at risk of PTSD. J Traum Stress 18(1):53–62.

Bureau of Labor Statistics [2011]. Current population survey. 

Employment and Earnings. Household data annual averages. 18. 

Employed persons by detailed industry, sex, race, and Hispanic 

or Latino ethnicity. Washington, DC: U.S. Department of Labor, 

Bureau of Labor Statistics. [http://www.bls.gov/cps/cpsa2010.

pdf]. Date accessed: September 2012.

Das R, Blanc R [1993]. Chlorine gas exposure and the lung: a 

review. Toxic Industr Hlth 9(3):439–455.

Duncan MA, Drociuk D, Belflower-Thomas A, Van Sickle D, 

Gibson J, Younglood C, Daley WR [2011]. Follow-up assessment 

of health consequences after a chlorine release from a train 

derailment-Graniteville, SC, 2005. J Med Tox 7(1):85–91.

Grassi M, Rezzani C, Biino G, Marinoni A [2003]. Asthma-like 

symptoms assessment through ECRHS screening questionnaire 

scoring. J Clin Epidem 56(3):238–247.

Institute of Education Sciences, National Center for Educational 

Statistics, U.S. Department of Education [2003]. National 

assessment of adult literacy. [http://nces.ed.gov/naal/].

Date accessed: September 2012.

Johnson S, Ostendorf J [2010]. Hispanic employees in the 

workplace: higher rate of fatalities. AAOH 58(1):11–16.
Page 17 Health Hazard Evaluation Report 2011-0128-3166

References

 (continued) Malo JL, L'archevêque J, Castellanos L, Lavoie K, Ghezzo H, 

Maghni K [2009]. Long-term outcomes of acute irritant-induced 

asthma. Am J Respir Crit Care Med 179(10):923–928.

OSHA [2012]. Safety and Health Topics. Hazard Communication, 

April 4, 2012. [http://www.osha.gov/dsg/hazcom/index.html]. 

Date accessed: September 2012.

Shakeri MS, Dick FD, Ayres JG [2008]. Which agents cause 

reactive airway dysfunction syndrome (RADS)? A systematic 

review. Occup Med 58(3):205–211.

USDA [2012]. Directive 7120.1: safe and suitable ingredients used 

in the production of meat, poultry, and egg products. [http://

www.fsis.usda.gov/oppde/rdad/fsisdirectives/7120.1.pdf]. Date 

accessed: February 2013.

U.S. Government Accountability Office [2005]. Safety in the 

meat and poultry industry, while improving, could be further 

strengthened. Washington, DC: USGAO-05-96.

Wallerstein N [1992]. Health and safety education for workers with 

low-literacy or limited-English skills. Am J Ind Med 22(5):751–765. 
Health Hazard Evaluation Report 2011-0128-3166 Page 18

Appendix A: Diagnostic Criteria for RADS and PTSD

The diagnostic criteria for RADS [Brooks et al. 1985] are listed below.

1. A documented absence of preceding respiratory complaints.

2. The onset of symptoms occurred after a single specific exposure incident or accident.

3. The exposure was to a gas, smoke, fume or vapor which was present in very high concentrations 

and had irritant qualities to its nature.

4. The onset of symptoms occurred within 24 hours after the exposure and persisted for at least 3 months.

5. Symptoms simulated asthma with cough, wheeze, and dyspnea predominating.

6. Pulmonary function tests may show airflow obstruction.

7. Methacholine challenge testing was positive.

8. Other types of pulmonary diseases were ruled out.

The diagnostic criteria for PTSD [American Psychiatric Association 2000] are listed below.

1. The person has been exposed to a traumatic event in which both of the following were present:

a. The person has experienced, witnessed, or was confronted with an event or events that involved 

actual or threatened death or serious injury, or a threat to the physical integrity of oneself or 

others.

b. The person’s response involved intense fear, helplessness, or horror.

Note: in children, this may be expressed instead by disorganized or agitated behavior

2. The traumatic event is persistently re-experienced in at least one of the following ways:

a. Recurrent and intrusive distressing recollections of the event, including images, thoughts, or 

perceptions

b. Recurrent distressing dreams of the event

c. Acting or feeling as if the traumatic event were recurring (includes a sense of reliving the 

experience, illusions, hallucinations, and dissociative flashback episodes, including those that 

occur upon awakening or when intoxicated)

d. Intense psychological distress at exposure to internal or external cues that symbolize or resemble 

an aspect of the traumatic event

e. Physiologic reactivity on exposure to internal or external cues that symbolize or resemble an 

aspect of the traumatic event

3. Persistent avoidance of stimuli associated with the trauma and numbing of general responsiveness 

(not present before the trauma), as indicated by three (or more) of the following:

a. Efforts to avoid thoughts, feelings, or conversations associated with the trauma

b. Efforts to avoid activities, places, or people that arouse recollections of the trauma

c. Inability to recall an important aspect of the trauma

d. Markedly diminished interest or participation in significant activities

e. Feeling of detachment or estrangement from others
Page 19 Health Hazard Evaluation Report 2011-0128-3166

Appendix A: Diagnostic Criteria for RADS and PTSD

 (continued)

f. Restricted range of affect (e.g., unable to have loving feelings)

g. Sense of a foreshortened future (e.g., does not expect to have a career, marriage, children, or a 

normal life span)

4. Persistent symptoms of increased arousal (not present before the trauma) as indicated by two (or 

more) of the following:

a. Difficulty falling or staying asleep

b. Irritability or outbursts of anger

c. Difficulty concentrating

d. Hypervigilance

e. Exaggerated startle response

5. Duration of the disturbance (symptoms in criteria 2, 3, and 4) is more than 1 month.

6. The disturbance causes clinically significant distress or impairment in social, occupational, or other 

important areas of functioning.

Specify if: Acute: if duration of symptoms is less than 3 months.

 Chronic: if duration of symptoms is 3 months or more.

Specify if: With delayed onset: onset of symptoms at least 6 months after the stressor

References

American Psychiatric Association [2000]. Diagnostic and statistical manual of mental disorders. 4th rev. 

ed. Washington, DC.

Brooks SM, Weiss MA, Bernstein IL [1985]. Reactive airways dysfunction syndrome (RADS). Persistent 

asthma syndrome after high level irritant exposures. Chest 88(3):376–384.
Health Hazard Evaluation Report 2011-0128-3166 Page 20

Appendix B: Methacholine Challenge Testing

Participants were evaluated by questionnaire, medical history, pulse, and blood pressure to determine 

suitability for spirometry. Participants who had a medical condition that restricted them from spirometry 

or methacholine challenge testing were not tested. We followed the algorithm shown below to test 

participants for bronchial hyperresponsiveness.

Methacholine Challenge Test Algorithm

1. Do baseline spirometry

2. a. If baseline FEV1 ≥70% predicted → Do methacholine challenge; after each concentration of 

methacholine, readminister spirometry

if FEV1 is >80% of baseline FEV1 → go to next higher concentration of methacholine 

solution or stop if at last concentration.

OR

if FEV1 is below 80% of baseline FEV1 → administer bronchodilator and readminister 

spirometry after 10 minutes, if FEV1 is within 90% of baseline FEV1 subject is 

finished, otherwise administer bronchodilator again, wait 10 minutes and check 

spirometry again.

 OR

 b. If baseline FEV1 <70% predicted → administer bronchodilator and readminister spirometry 

after 10 minutes. We define reversible obstruction as an increase in FEV1 of 12% and at least 

200 mL.

If, after all rounds of methacholine challenge, participants were unable to achieve an FEV1 below 80% 

of baseline, they were classified as nonresponders to the methacholine challenge test and classified as 

not having asthma. A positive methacholine challenge test (decrement of FEV1 below 80% of baseline) 

indicates bronchial hyperresponsiveness, consistent with asthma. Depending on the dose of methacholine, 

the test can indicate mild, moderate, and severe hyperresponsiveness. If during baseline spirometry they 

had a baseline less than 70% predicted FEV1, and responded to bronchodilators by improving 12% and 

at least 200 mL, then those participants were also classified as having bronchial hyperresponsiveness 

consistent with asthma. Otherwise, they were classified as not having asthma. Participants were notified in 

writing, in their primary language, of their test results. 
Page 21 Health Hazard Evaluation Report 2011-0128-3166

Appendix C: Occupational Exposure Limits and Health Effects

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 2012]. WEELs have been established for some chemicals “when 

no other legal or authoritative limits exist” [AIHA 2012].

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 
Health Hazard Evaluation Report 2011-0128-3166 Page 22

Appendix C: Occupational Exposure Limits and Health Effects

 (continued)

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.

Below we provide the OELs for chlorine, as well as a discussion of the potential health effects from 

exposure to chlorine gas.

Chlorine

Chlorine is a greenish-yellow gas and has a pungent smell, with an odor threshold of approximately 

0.3–0.5 ppm. Chlorine gas was the first chemical used in modern warfare. It was used by the Germans in 

Ypres, Belgium, on April 22, 1915, resulting in 5,000 pulmonary casualties [Evans 2004].

Chlorine is moderately water soluble, so it can enter the upper and lower respiratory tract and often affects 

mucus membranes, eyes, and the lower respiratory tract. It forms hydrochloric and hypochlorous acid 

upon contact with water in the eyes, mucus membranes, and lower respiratory tract [Das and Blanc 1993].
Page 23 Health Hazard Evaluation Report 2011-0128-3166

Appendix C: Occupational Exposure Limits and Health Effects

 (continued)

Table C1. Chlorine gas concentration and health effects

Concentration Effect on human health

1–3 ppm Mild irritation of mucous 

membranes

>5 ppm Eye irritation

>15 ppm Throat irritation

15–30 ppm Cough, choking, burning

>50 ppm Chemical pneumonitis

430 ppm Death after 30 minutes exposure

>1000 ppm Death within minutes

The current OSHA PEL for chlorine is 1 ppm (3 mg/m3) as a ceiling limit. A worker's exposure to 

chlorine shall at no time exceed this ceiling level [29 CFR 1910.1000, Table Z-1]. NIOSH has established 

a REL for chlorine of 0.5 ppm (1.5 mg/m3) as a TWA for up to a 10-hour workday and a 40-hour 

workweek and a STEL of 1 ppm (3 mg/m3) [NIOSH 1992]. The ACGIH TLV is 0.5 ppm (1.5 mg/m3) as 

a TWA for a normal 8-hour workday and a 40-hour workweek and a STEL of 1.0 ppm (2.9 mg/m3) for 

periods not to exceed 15 minutes. Exposures at the STEL concentration should not be repeated more 

than four times a day and should be separated by intervals of at least 60 minutes [ACGIH 2012].

References

ACGIH [2012]. 2012 TLVs® and BEIs®: threshold limit values for chemical substances and physical 

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

Industrial Hygienists.

AIHA [2012]. AIHA 2012 Emergency response planning guidelines (ERPG) & workplace environmental 

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

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

Federal Register.

Das R, Blanc R [1993]. Chlorine gas exposure and the lung: a review. Toxic Industr Hlth 9(3):439–455.

Evans RB [2004]. Chlorine: State of the Art. Lung 183(3):151–167.

NIOSH [1992]. Recommendations for occupational safety and health: compendium of policy documents 

and statements by Dames BL. 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. 92-100.
Health Hazard Evaluation Report 2011-0128-3166 Page 24

Appendix C: Occupational Exposure Limits and Health Effects

 (continued)

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: September 2012. 
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Health Hazard Evaluation Report 2011-0128-3166 Page 26

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 Francisco Meza, Charles Mueller, and 

Bradley King of HETAB. Field assistance was provided by Walter 

Alarcon, Diana Ceballos, Elizabeth Garza, Melody Kawamoto, 

Rachel Weintraub, Sandy Hainline, Williamina Bing, Jim Wilson, 

Ashley Whitlow, and Kenny Boaz. Health communication 

assistance was provided by Stefanie Evans. Editorial assistance was 

provided by Ellen Galloway. Desktop publishing was performed by 

Mary Winfree and Greg Hartle.

Copies of this report have been sent to employee and management 

representatives at the poultry plant, the 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 at 5825 Port Royal Road, 

Springfield, Virginia 22161.

Acknowledgments and

Availability of Report
Below is a recommended citation for this report:

NIOSH [2012]. Health hazard evaluation report: evaluation of health effects of a 

chlorine gas release in a poultry processing plant – Arkansas. By Meza F, Mueller 

C, King B. 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. 2011-0128-3166.

To receive NIOSH documents or information about 

occupational safety and health topics, contact NIOSH at:

1-800-CDC-INFO (1-800-232-4636)

TTY: 1-888-232-6348

E-mail: cdcinfo@cdc.gov

or visit the NIOSH web site at: www.cdc.gov/niosh.

For a monthly update on news at NIOSH, subscribe to 

NIOSH eNews by visiting www.cdc.gov/niosh/eNews.

Delivering on the Nation’s promise:

Safety and health at work for all people

through research and prevention.

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Safety and Health