LA PORTE, TX -- DuPont officials said Sunday it's still not clear what caused a toxic chemical to leak from a valve at their LaPorte plant, killing four workers and injuring a fifth.
Company spokesman Aaron Woods said DuPont is investigating the cause of the leak of methyl mercaptan. The chemical is used to create crop-protection products such as insecticides and fungicides.
The workers were exposed early Saturday while responding to the leak that started around 4am and took about two hours to contain. They all were working there as part of their normal shift when the leak happened, Woods said.
The four workers died at the plant and a fifth was transported to a nearby hospital. The Medical Examiner's Office released the names of the victims as Crystle Wise, Wade Baker, Gilbert Tisnado and according to relatives, Gilbert's brother Robert Tisnado.
The injured worker has been released from the hospital.
Woods said company officials are cooperating with local, state and federal authorities in the investigation.
A team from the U.S. Chemical Safety Board, an independent federal agency that investigates industrial chemical accidents, arrived in the Houston area on Sunday to start its probe. The agency said in a news release that five of eight team members planned to receive a briefing from company officials Sunday evening, while the full team will begin work Monday.
Don Holmstrom, director of CSB's Western Regional Office in Denver, is leading the investigation team along with Investigation Supervisor Johnnie Banks. CSB Managing Director Daniel Horowitz is accompanying the team.
Methyl mercaptan also is used to odorize natural gas - which has no odor - for safety purposes.
The La Porte plant has 320 DuPont employees. Four other companies are also tenants at the complex.
Jeff Suggs, emergency management coordinator for La Porte, said the chemical release was not toxic for those living nearby, but that it caused a smell similar to rotten eggs.
DUPONT STATEMENT ON DELAY IN NOTIFICATION OF LA PORTE FATALITIES
After receiving an official determination by the Medical Examiner of four confirmed employee fatalities, we began notifying the employees' families immediately. Unfortunately, we were dealing with a contaminated unit that no qualified medical personnel could enter until deemed safe, because they were not trained in the use of the personal protective equipment (PPE).
Our non-medically trained personnel who initially responded before 7 a.m. Central Time (CT) with the proper equipment reported the employees as non-responsive and likely fatalities. It was on that basis that the unit was barricaded for investigation just before 8 a.m. (CT).
The incident scene was deemed safe to enter just before noon and the fatalities were confirmed by the Medical Examiner around 1:30 p.m. (CT) and we immediately began to inform families thereafter.