Issue Date: March 9, 2009
Chlorine Spill Offers Insights
LESSONS ARE STILL being learned four years after a 2005 train crash spread a toxic plume of chlorine gas through the small mill town of Graniteville, S.C., killing nine people, injuring hundreds, and forcing thousands of residents to evacuate their homes.
Chlorine gas, widely used in water treatment and industrial manufacturing, has been designated a "chemical of concern" by the U.S. Department of Homeland Security. Officials fear that terrorists could target a storage tank or rail shipment of chlorine in a high-density area and cause thousands of fatalities and serious injuries.
Researchers believe an analysis of the after-effects of the South Carolina accident could help larger metropolitan areas prepare emergency response systems for an accidental or terrorist release of the deadly gas.
"Public health agencies and hospitals across the country can learn a lot from this disaster and be better prepared to help in the next emergency," says James J. Gibson, state epidemiologist and director of the Bureau of Disease Control at the South Carolina Department of Health & Environmental Control (DHEC).
"This is one of the largest community exposures to chlorine gas since World War I," says David Van Sickle, a Robert Wood Johnson Foundation Health & Society Scholar at the University of Wisconsin's School of Medicine & Public Health. "It was a tragic disaster that shows us what a significant challenge a large-scale chlorine gas release poses to health care facilities."
Van Sickle was part of a team from the U.S. Centers for Disease Control & Prevention (CDC) and the South Carolina DHEC that examined the health effects resulting from the accident. Their findings were published in the January 2009 issue of the American Journal of Emergency Medicine (2009, 27, 1).
Before dawn on Jan. 6, 2005, a Norfolk Southern Railway freight train pulled out of Macon, Ga., destined for Columbia, S.C. That morning, the train's two locomotives were pulling 42 cars, among them three tankers loaded with 270 tons of liquefied compressed chlorine. Shortly after entering Graniteville, an improperly set railroad switch diverted the train off the mainline track onto a side spur where it slammed into an unoccupied, parked locomotive. The collision and subsequent derailment ruptured one of the tankers, releasing approximately 60 tons of chlorine.
THE TRAIN'S ENGINEER and seven other people died at the scene of the accident, which occurred near a large Avondale Mills textile complex, where 180 people were working the overnight shift. A ninth person died later. All of the fatalities were due to inhalation of chlorine gas, according to the National Safety Transportation Board. More than 850 people sought medical treatment after the train wreck and 72 were hospitalized. Local businesses and schools were closed, and an estimated 5,400 residents within a mile of the crash site were forced to evacuate their homes for up to two weeks while cleanup crews decontaminated the area.
"There has been concern that something like this could happen in a large urban area," Van Sickle says. "Our study shows that we just can't underestimate the magnitude of the potential for a hazmat rail incident, either deliberate or accidental, to cause devastating health effects and to really overwhelm health care facilities with people who are seriously injured."
While small, accidental, and on-the-job exposures to chlorine are not unusual, Van Sickle and his colleagues used the South Carolina disaster to learn as much as possible about the health effects from widespread exposure to chlorine gas. "We also wanted to understand how physicians treated the patients, how quickly they recovered, and what resources hospitals would need to respond effectively in the future," Van Sickle remarks.
According to the study, many of the 72 hospitalized patients showed evidence of severe lung damage. More than a third were admitted to intensive care, and 10% required mechanical ventilation. Van Sickle says hospitals need to be able to quickly recognize the signs of chlorine exposure and have a sufficient supply of ventilators and other equipment on hand.
"One lesson we can take from this is that we need to do a better job of figuring out the best way to approach chlorine poisoning from a medical standpoint. That needs to be standardized so that if this happens again, the optimal kind of treatment is delivered to everybody who's affected," Van Sickle says. "That's something to aim for."
Despite the severity of their injuries, most patients were discharged within a week, the study indicates. "The good news is that many patients came in seriously injured, but then with appropriate support and attention, they recovered fairly quickly in most cases," Van Sickle notes. "So there is a silver lining."
Although most of those who were injured made a speedy recovery, many residents are experiencing chronic health effects from the spill, including breathing problems and emotional issues, says Erik Svendsen, a researcher at the University of South Carolina's School of Public Health. "Many of the victims are still concerned about their health, both right now and in the future. There are still many unanswered questions about the long-term health effects of chlorine gas injury," says Svendsen, who is also an environmental epidemiologist at DHEC's Bureau of Disease Control.
The initial focus following the emergency response, he says, was to establish an area health registry and to screen people who had been exposed to the toxic gas. "We're interested not just in the science and in measuring what happened; we are trying to help the people who were victims as well," Svendsen says. "After a disaster, science isn't the most important thing—the people are."
South Carolina health authorities continue to monitor the after-effects of the accident through the Graniteville Recovery & Chlorine Epidemiology project. "The goals of the project are to reduce the impact of the event on the community, identify people who need medical care, and get them to local physicians for the care they need," Svendsen says. "As long as the community needs help, the health department is there to help them as much as it can. We'll continue this until we believe the community has recovered."
Svendsen is trying to obtain a federal grant for a long-term health study of the 7,000-person community of Graniteville. "We know there was a short-term epidemic of injuries resulting from the event. But we know that people are still sick," he notes. "In any disaster event, you have a surge of people that end up in the hospital. In the case of exposure to irritant chemicals, there can be longer-term health complications after the initial acute illness has been resolved. Receiving additional funding to study the health of this community is a way to track their future health problems and to potentially help answer some of those yet-unanswered questions."
But Svendsen says it has been difficult to get much assistance from Washington, D.C. The federal disaster response system, he says, is "geared toward saying you're recovered when the lights are back on and people are back in their houses. It really is shortsighted in how it addresses the full scope of disaster recovery. We've seen that with Katrina, obviously, and we've seen it at Graniteville. When the dust settles after the initial response, who is there to take care of the people? There's a big disconnect."
After Hurricane Katrina devastated New Orleans and much of the Gulf Coast region in August 2005, Svendsen says, "the CDC people who were out helping us in Graniteville were recalled, and they've never come back. That's not to fault them. They have limited resources and priorities. That's just one of the systematic issues. "
AN ESTIMATED 13 MILLION to 14 million tons of chlorine are produced in the U.S. each year, and much of it is transported by rail, often through densely populated areas. Rail accidents involving chlorine and other toxic inhalation hazards have been exceedingly rare, but the Graniteville crash was particularly alarming because it raised concerns that the federal government wasn't doing enough to protect heavily populated regions from chemical spills or terrorist attacks.
Two sweeping new federal regulations on the transport of hazardous rail cargo seek to prevent a similar disaster in a major metropolitan area. On Jan. 12, the Department of Transportation finalized new standards to strengthen the design of tank cars used to haul the most dangerous chemicals (C&EN, Jan. 19, page 8). "Strengthening rail hazmat tank cars will reduce the risk of spills and increase public safety should a train accident occur," former DOT secretary Mary E. Peters remarked in announcing the rule.
Beginning this month, newly constructed tank cars are required to have a combination of thicker inner shells and outer jackets to improve puncture resistance in side impact accidents. Each end of the car must be equipped with special safety devices called head shields, and stronger, more accident-resistant top fittings are required to protect the valves and nozzles used in loading and unloading the tankers. The rule also imposes a 50-mph speed limit on trains hauling extremely toxic chemicals.
Bulk shipments of chlorine and anhydrous ammonia account for about 80% of the materials railroads handle that are poisonous if inhaled. Such chemicals constitute the greatest public safety risk because they are transported under pressure and create vapor clouds if released. "Shipping these critical materials by rail is one of the safest modes of transportation, and this new rule will make it even safer," says Arthur Dungan, president of the Chlorine Institute, an industry trade association.
The new standards will sharply reduce the likelihood that dangerous chemicals will be released during accidents, adds Edward R. Hamberger, president of the Association of American Railroads (AAR), a trade group that represents the freight rail industry. "The number one priority for the nation's freight railroads is safety, both that of the communities we serve and of our employees," Hamberger says. According to a study conducted for AAR by the University of Illinois, the new standards will reduce the likelihood of substance release during an accident by up to 73%, depending upon the specific commodity.
DOT initiated the changes in tank car construction after the Graniteville disaster, which was the third in a string of deadly rail accidents in recent years that involved chemical releases. In June 2004, three people died when a Union Pacific train struck a Burlington Northern Santa Fe train in Macdona, Texas, rupturing a chlorine tank car. In January 2002, a Canadian Pacific Railway train derailed in Minot, N.D., splitting five tank cars open and releasing about 200,000 gal of anhydrous ammonia—the largest spill of that chemical in U.S. history. One resident was killed and more than 1,400 were injured.
IN NOVEMBER, DOT issued a related rule that requires railroads to select the "safest and most secure" routes to transport hazardous cargo (C&EN, Nov. 24, 2008 page 28). Under that regulation, by March 31, 2010, freight carriers must analyze a minimum of 27 risk factors that could affect the possibility of a catastrophic release along a specific route, assess alternative routing options, and select the most appropriate pathway.
However, critics say the rule will allow railroads to continue hauling dangerous chemicals through densely populated areas rather than taking longer routes that bypass cities. "This rerouting policy leaves our cities vulnerable to attacks on trains carrying hazardous rail cargoes," says Brent Blackwelder, president of Friends of the Earth, a Washington, D.C.-based environmental group.
Environmental activists have supported efforts by the governments of 11 major cities, including St. Louis, Buffalo, Chicago, and Washington, D.C., to ban or restrict the movement of hazardous materials through their communities. But DOT made it clear that it has no intention of forcing railroads to reroute shipments. "We continue to believe that rail carriers are in the best position to select the safest and most secure routes," the department states in the regulation.
Shippers and rail companies had expressed concern that onerous local routing requirements could add hundreds of miles to a trip, delay product deliveries, and increase costs significantly while merely shifting the risk from one population to another. "When it comes to routing, it has always been our belief that you need to address this issue at the federal level," says Scott Jensen, a spokesman for the American Chemistry Council, which represents major chemical producers. Conflicting local ordinances, he says, would disrupt interstate rail operations and could shut down the entire system.
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