by Elizabeth Grossman
On Sunday August 21, a cleaning process designed to make tomatoes safe for customers eating marinara sauce, pizza topping, and canned tomatoes resulted in a release of chlorine dioxide gas that sent 43 workers at the Pacific Coast Producers plant in Woodland, California to area hospitals. According to Pacific Coast Producers vice president Mona Shulman, a malfunction of sanitizing equipment caused an “overdosing” of chlorine dioxide, causing the chemical to off-gas to the atmosphere. Chlorine dioxide gas was also drawn into a building through the ventilation system. “The building was immediately evacuated,” said Shulman. The incident, which prompted the evacuation of about 300 people, was described by local authorities as a “mass casualty” and “hazardous materials release” event. Those affected had symptoms that included difficulty breathing, itchy throats, and water eyes. The next day, all but two of those treated at hospitals had been released back to work.
In response, the California Department of Occupational Safety and Health (Cal/OSHA) has issued an order prohibiting Pacific Coast Producers’ use of the equipment involved until information can be provided showing it can be operated safely. “It’s not common to issue such an order unless equipment poses an imminent danger,” explained Cal/OSHA spokesperson Erika Monterroza. Cal/OSHA has also initiated what it calls a “multiple employer” investigation of the event, one that currently involves Pacific Coast Producers and RUSH Personnel, a California-based employment agency that hires workers for the Woodland plant. The sanitizing equipment that caused the chlorine dioxide release is “owned by a vendor,” International Dioxcide, Inc., Shulman told me. “Our employees don’t operate the injection system,” she said.
A gas with explosive potential
International Dioxcide, Inc. is also known as DuPont Water Technologies, and is part of DuPont’s chlorine dioxide division. (DuPont purchased the Rhode Island-based company in 2000. In 2006 International Dioxcide paid a fine levied by the US Environmental Protection Agency for selling and distributing pesticides – a disinfectant product – with outdated labels that lacked key safety information.) DuPont describes chlorine dioxide as “an ideal choice to meet the microbial and oxidative challenges of today’s environmentally concerned world.” A DuPont fact sheet notes that chlorine dioxide produces “no hazardous residues” and offers an efficient way to sanitize food processing equipment, water used in food processing, and produce itself. DuPont Public Affairs spokesperson Janet E. Smith replied to my questions about the process by email, noting that, “Chlorine dioxide disinfects by way of oxidation, whereas chlorine itself disinfects by way of chlorination. Chlorine dioxide is an ideal replacement for chlorine, providing the same benefits and more, while minimizing the potential concerns of chlorinated by-products.” At Pacific Coast Producers, she explained, “chlorine dioxide is generated on-site using equipment and sodium chlorite supplied by International Dioxcide, as well as hydrochloric acid and bleach supplied by other companies.”
While chlorine dioxide, a synthetic gas used widely to disinfect water (in both drinking water systems and food preparation), may minimize occurrence of chlorinated by-products, it has its own hazards. High levels of chlorine dioxide can be severely irritating to the nose, eyes, throat, and lungs. Acute exposure can cause pulmonary edema, headache, and vomiting, while ongoing exposure can lead to chronic bronchitis and emphysema. A very reactive compound, chlorine dioxide breaks down quickly in air and sunlight into oxygen and chlorine gas, and in water forms chlorite. The Occupational Health and Safety Administration (OSHA) “Safety and Health Guidelines” for chlorine dioxide describe the compound as “a very unstable material even at room temperatures [that] will explode on impact, when exposed to sparks or sunlight, or when heated rapidly to degrees C (212 degrees F). Airborne concentrations greater than 10 percent may explode.” OHSA also notes that “Chlorine dioxide reacts with water or steam to form toxic and corrosive fumes of hydrochloric acid,” and that it may cause fire or explosions if it comes into contact with hydrocarbons (i.e., petroleum products) or dust.
Not a one-time problem
Pacific Coast Producers has been using chlorine dioxide to sanitize tomatoes for a number of years, said Shulman. But this is not the first time the company has had trouble with chlorine dioxide gas. In 2007 equipment supplied by another vendor (not International Dioxcide, Shulman explained) also malfunctioned when a sensor failed after the system became clogged with organic matter. The continued pumping of chlorine dioxide and subsequent off-gassing caused 39 employees at the Woodland plant to experience severe respiratory symptoms. Thirty-five workers were hospitalized, two overnight who were treated for pulmonary edema and bronchial inflammation. The initial fine from OSHA was $47,805, but the negotiated settlement came to $21,000.
Pacific Coast Producers is a privately owned company. My request to read the company’s 2010 annual report was denied, but Shulman told me that in the last fiscal year annual revenues were $499 million. About half that revenue is from tomato products, 85 to 95% of which are grown within fifteen miles of Woodland, California, the rest in northern California. The company’s Woodland facility employs approximately 130 people full time and 800 to 1,000 seasonal workers. Company-wide, Pacific Coast Producers has about 600 permanent and 3,500 or so seasonal employees. The company makes a variety of canned tomato products that include whole, diced, and pureed tomatoes and sauces. “We are a grower owned agricultural cooperative, and are a private label supplier for most major retailers in the U.S.,” wrote Shulman. “We do carry environmental insurance, and we observe all laws and regulations with respect to hazardous materials and waste, including safety training for employees.” Shulman said the company was continuing work using an alternate sanitizing process.
Pacific Coast Producers is not the only company to have had problems with chlorine dioxide gas releases. According to OSHA inspection reports, in 2009 another vegetable processing operation, Earthbound Farm Holdings in San Juan Bautista, California also experienced a release of chlorine dioxide gas that affected 17 workers who were treated and released by local hospitals. Additional OSHA records over the past ten years show that chlorine dioxide is also widely used in the pulp and paper industry, water treatment, and in meat processing. While OSHA statistics record illness and injury rates, they do not indicate how many people were put at risk by chlorine dioxide accidents, whether workers at plants like Pacific Coast Producers or communities like those in Washington state affected in 2002 by a chlorine dioxide leak at Weyerhaeuser pulp plant. A report prepared for the Environmental Protection Agency in 2000 ranked chlorine dioxide as among the chemicals with the highest annual rates of accidents between 1994 and 1999.
Given the concerns about contaminated food, the frequency of such incidents, and the great number of people that can be affected by a single batch of tainted processed food, sanitizing food processing operations is absolutely necessary. But might there be a way to do so that does not involve substances so hazardous that they risk harming the health of those working to keep our food safe?
Elizabeth Grossman is the author of Chasing Molecules: Poisonous Products, Human Health, and the Promise of Green Chemistry, High Tech Trash: Digital Devices, Hidden Toxics, and Human Health, and other books. Her work has appeared in a variety of publications including Scientific American, Salon, The Washington Post, The Nation, Mother Jones, Grist, and the Huffington Post. Chasing Molecules was chosen by Booklist as one of the Top 10 Science & Technology Books of 2009 and won a 2010 Gold Nautilus Award for investigative journalism.