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. NIOSH received a request for technical assistance from OSHA to evaluate employee health effects after the chlorine gas release. What NIOSH found: 1) labeling in English only and lack of literacy in English contributed to the chlorine gas release; 2) 116 (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; 106 (19%) participants had posttraumatic stress disorder symptoms 4 months after the release. The report…
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.
What NIOSH Did
- investigated the causes of the chlorine gas release.
- interviewed 545 employees during part or all of our evaluation.
- interviewed employees about exposure to the chlorine gas. Interviews were done in English, Spanish, and Marshallese.
- asked about acute symptoms in the days following the chlorine gas release.
- 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
- labeling in English only and lack of literacy in English contributed to the chlorine gas release.
- 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.
- 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.
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. Labeling in English only and lack of English literacy contributed to this incident. Three employees developed RADS, and more than 100 had symptoms of PTSD. 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 the employee who mixed the chemicals 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 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 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.
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