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HOUSTON (AP) — A poisonous gas leak that killed four workers at a Houston-area chemical plant in November can be traced to the design of a network of pipes and valves inside the facility, federal investigators said Thursday.
The DuPont chemical plant in LaPorte, Texas, had a faulty ventilation system that exposed workers to a highly toxic and flammable chemical typically used in insecticides, officials from the U.S. Chemical Safety Board said.
The plant's vents system had several links to the supply line for the chemical, methyl mercaptan, the board said.
Liquid routinely built up inside the building's vents due to the system's flawed design. That required workers to manually drain the system, potentially exposing them to whatever chemicals had accumulated inside, the board said.
Board Chairman Rafael Moure-Eraso said that even if ventilation system fans had been working, the building's design may not have protected workers from the chemical being released into the air.
DuPont said more than 23,000 pounds of methyl mercaptan were released during the Nov. 15 accident.
Moure-Eraso said Thursday that chemical accidents such as the LaPorte incident have several common factors: faulty designs and safety systems, weak regulations, and industry standards that were too permissive.
"The latest accident at DuPont is one of many incidents investigated by the CSB where we believe it will become clear that the process design was not as safe as possible," Moure-Eraso said in remarks released by the board.
The board investigates industrial and chemical accidents. While it has no regulatory authority, it makes recommendations on how to prevent future accidents.
DuPont said in a statement that it "appreciated the opportunity to engage in constructive discussions with the agency."
"DuPont is responding to this tragic incident in a way that reinforces our absolute focus on safety," the company said.
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