Phosgene leak could have crossed river, CSB says
CHARLESTON, W.Va. -- Dangerous levels of the poisonous chemical phosgene may have escaped the DuPont Co. Belle plant and drifted across the Kanawha River as part of a January 2010 leak that killed a DuPont worker, federal investigators revealed Thursday.
U.S. Chemical Safety Board officials used computer models to estimate a "threat zone" from the phosgene leak.
CSB investigators found potentially harmful levels of the chemical -- amounts that could cause serious and irreversible health effects if exposures lasted an hour -- reached at least 0.4 miles from the plant.
Phosgene concentrations on the Kanawha River may have reached the level known as "immediately dangerous to life and health," or the IDLH concentration, the CSB said.
"Lower concentrations could have traveled across the river," the CSB said in a detailed report.
Only two pounds of phosgene were released in the hose leak that killed plant worker Danny Fish, but CSB officials said their computer modeling showed how dangerous the material -- used as a chemical weapon in World War I -- is to plant workers and the public.
"With a very small release of phosgene, there was the potential for an IDLH concentration," said John Bresland, a longtime chemical plant manager and CSB member.
Phosgene is a valuable building block for making other chemicals, and DuPont had used it at Belle to produce various crop protection chemicals. But it is also extremely toxic, and is considered dangerous even in very tiny amounts.
As little as 2 parts per million of phosgene is considered "immediately dangerous to life and health" by the National Institute for Occupational Safety and Health. Phosgene can cause coughing and watery eyes, but can also lead to heart failure and to pulmonary edema, a buildup of fluid in the lungs that can be fatal.
CSB investigators believe that Fish received a lethal dose of phosgene in less than a tenth of a second when he was sprayed in the face and chest from a worn-out chemical hose.
At the time of the incident, DuPont said in a media statement that "there was no off-site exposure or material environmental impact" from the phosgene release or two other incidents that occurred within a 33-hour period at the Belle plant.
Maya Nye, spokeswoman for a new Kanawha Valley group called People Concerned About Chemical Safety, said she was concerned after learning what the CSB found when it modeled the phosgene leak.
"This just goes to show that we can't always believe what [the chemical companies] say," Nye said.
"The CSB report underscores the need for additional oversight," Nye said. "This is the kind of thing that a local oversight body could and should look into and handle."
DuPont plant manager Jim O'Connor said the company doesn't believe the CSB modeling is accurate.
"We have to take exception to what the CSB presented," O'Connor said. "We don't have any evidence that indicates that there were harmful levels that left the site."
As pointed out in the CSB report, the modeling used weather data from Yeager Airport, not from the plant site itself. The CSB noted that the model doesn't account for topography or terrain, and that after the incident there were no reports of any plant neighbors experiencing symptoms of phosgene exposure.
DuPont did not conduct any of its own modeling to project phosgene levels that might have left the plant, O'Connor said.
O' Connor said the CSB's report did include accurate figures for the phosgene concentrations shown on company fence-line monitors on the plant's border with the Kanawha River.
Those figures showed phosgene levels of up to 0.27 parts per million, greater than the amount considered safe for an exposure of an hour or more, the CSB report said.
O'Connor said DuPont's goal is to prevent the release of any amount of phosgene.
"We would never consider the release of phosgene to be acceptable," he said.
Reach Ken Ward Jr. at firstname.lastname@example.org or 304-348-1702.