Inspectors from the US Chemical Safety Board (CSB) arrived Monday morning at the DuPont insecticide plant in LaPorte, Texas to begin their investigation into the causes of a chemical leak at the plant that killed four workers on November 15.
The workers died after inhaling methyl mercaptan released into air at the plant.
A fifth worker at the plant was hospitalized and released.
“Our initial investigation plans are to examine the accident site (and) conduct initial interviews with witnesses, if any, as well as key operators and managers,” said Dr. Daniel Horowitz, the leader of the investigating team. “(We’ll) request documentation on a range of relevant activities, such as maintenance histories of key equipment, training, and work schedules.”
The CSB is an independent federal agency charged with investigating industrial chemical accidents.
According to CSB, the agency has investigated DuPont plants before. In 2010, it investigated a flammable vapor explosion at the DuPont plant in Buffalo, New York. Also in 2010, the agency investigated three leaks that took place during a 33 hour period at the company’s plant in Belle, West Virginia.
During one of the leaks in Belle, a worker was overcome and killed by phosgene gas. The gas was released when a hose carrying it burst open and sprayed the deadly gas into the air.
A CSB report issued in 2011 on the incident said that there were “preventable safety shortcomings” at the plant including “failure to maintain the mechanical integrity of the a critical phosgene hose.”
Phosgene, which was used as poisonous gas during World War I and remained in use afterwards as an agent used in making insecticides, is a corrosive that can cause leaks and fraying in hoses unless the hoses are replaced regularly.
CSB said that the kind of hoses used at the Belle plant should have been replaced once a month, but they weren’t.
“I would hope the DuPont officials are examining the safety culture company-wide,” said the then CSB Director John Bresland at the time that the report was released.
In a press statement about the phosgene leak in 2010, CSB said that back in 1987, the company realized the dangers involved in using the stainless steel hoses lined with Teflon that were carrying phosgene at the plant.
The company considered switching to hoses line with Monel, a strong metal alloy much better at resisting corrosion than Teflon.
DuPont, however, decided not to do so because the Monel coated hoses cost more.
The company also considered increasing safety at the plant by enclosing the area where phosgene was handled and venting the enclosed area by using a scrubber system that eliminates phosgene that escapes into the air.
DuPont, according the press statement, decided that taking these safety steps was too expensive.
“Documents show that the company calculated the benefit ratio of potential lives saved compared to cost and decided not to make the safety improvements,” said the CSB in its statement.
Regarding the more recent worker deaths in Texas, CSB said that its investigation and final determination of the causes of the worker deaths could take up to a year but that the agency would release key information and facts about the deaths as they come to light.
CSB doesn’t have the authority to levy fines for safety violations; it can only make recommendations for preventing future safety failures.