The U.S. Chemical Safety Board (CSB) today voted to initiate an investigation of recent accidents at the DuPont chemical complex in Belle, West Virginia, following a release of highly toxic phosgene on Saturday that fatally injured a veteran operator, according to a CSB press release.

DuPont officials told the CSB that a braided steel hose connected to a one-ton capacity phosgene tank suddenly ruptured, releasing phosgene into the air. An operator who was exposed to the chemical was transported to the hospital, where he died the following day.

The phosgene release followed two other accidents at the same plant this week, including an ongoing release of chloromethane from the plant’s Hexazinone unit, which went undetected for several days, and a release of sulfur dioxide from a spent sulfuric acid unit. The plant announced over the weekend that it would be shutting down a number of process units immediately for safety checks.

Speaking for the three-member board, Member William E. Wright said: “The Board is concerned by these releases, which had tragic consequences, and will proceed with an investigation to understand why these unfortunate events occurred.” Mr. Wright cautioned that the new case would likely delay efforts to complete other investigations that are being conducted by same investigative team, including those at the Bayer CropScience facility in Institute, West Virginia, and an Ohio environmental services company. Including DuPont, the CSB has 17 open investigations, the largest number in its 11-year history.

In voting to approve the investigation, the Board noted that the CSB was aware of six other releases from the plant since December 2006. The DuPont Belle complex is a large facility that is regulated under the EPA Risk Management Program and the OSHA Process Safety Management standard because of the volume and hazards of the materials it handles and the potential risk to workers and the community.

CSB investigator Johnnie Banks will lead the four-member team which is expected at the site on Tuesday.