A chlorine gas leak that sickened nearly 200 people at a Tyson Foods plant in Arkansas last year happened because a worker who couldn't read the English-language label on a barrel of chemicals inadvertently poured bleach into it, the Centers for Disease Control and Prevention said in a report released Thursday.
Tyson Foods disputed the report, saying federal investigators misidentified the worker who caused the accident. Company spokesman Gary Mickelson told The Associated Press the worker who mixed the chemicals speaks English as his primary language and was able to read the label, but didn't.
In its Morbidity and Mortality Weekly Report, the CDC recommends that industries adopt safety training tailored to its employees' language skills. It found that, at Springdale, Ark., in June 2011, a Spanish-speaking worker poured sodium hypochlorite, which is bleach, into a 55-gallon drum that had been left in the wrong place and that contained a residual solution of an acidic antimicrobial agent, creating chlorine gas.
"The worker who mixed the sodium hypochlorite with the leftover acidic solution told investigators he knew such a mixture was dangerous but did not recognize the drum and could not read the label to ascertain its contents," the CDC wrote of the June 27, 2011, incident.
Workers scurried from the poultry plant after being exposed to the poisonous gas, which can cause a range of respiratory problems, from irritated tissue to sudden death from narrowing of the upper airway.
Of the 600 workers who were at the plant, the CDC said investigators from its National Institute for Occupational Safety and Health interviewed 545. Of those, 195 said they sought medical help and 152 of those were hospitalized. Three workers developed irritant-induced asthma, the agency said.
"This chlorine release and its resultant health effects were preventable," the CDC said. It noted an earlier study that said Hispanics are killed on the job at a higher rate than other workers and that training programs should ensure employees understand hazards. "All communication, training, and signage in the workplace should be easy-to-read and provided in languages understood by workers."
Tyson Foods said the report was based on a false premise — that a Hispanic worker who couldn't read English caused the accident — but that corrective measures were already in place.
"Since mid-2011, we've put additional controls in place to limit access to chemicals in the plant and we've continued to emphasize training for those authorized to handle such chemicals," Mickelson said in a statement.
He said NIOSH "incorrectly identifies the employee who accidentally mixed the chemicals as being Spanish-speaking. The worker responsible is not Hispanic and his primary language is English. In addition, this employee had previously received hazardous chemical training."
"We believe he failed to look at the label on the drum," Mickelson said. He said the company had left messages with several NIOSH officials regarding the discrepancy.
NIOSH spokeswoman Christina Spring said the agency stood by the report.
Acidic solutions of antimicrobial agents are used throughout the food industry to prevent or retard spoilage. According to the CDC report, Tyson Foods normally stores the acidic solution that reacted with the bleach in larger containers at its Springdale plant, but a sample drum had been inadvertently left in the area where the bleach was kept.
The CDC noted that while more than two-thirds of the plant's workers spoke Spanish as their primary language and 12 percent primarily spoke Marshallese, a language spoken in the Marshall Islands, material safety data sheets are written in English at a college reading level.
"To help overcome language and literacy obstacles, employers should actively engage workers in hands-on training," the CDC said, citing a 1992 study that explored safety education for workers with limited English skills. It also supports the use of symbols and simple text to highlight chemical hazards.
Mickelson said the company paid a $2,500 fine to settle a citation filed by the Occupational Safety and Health Administration, retrained workers and re-evaluated the plant's emergency response plan.