LA PORTE, Texas (AP) — Chemical manufacturer DuPont says about 23,000 pounds of a flammable toxic chemical escaped in the building where four of its workers died two weeks ago at a Houston-area plant.

The Houston Chronicle reports DuPont has disclosed the quantity of the methyl mercaptan that led to the four deaths Nov. 15 but the company has declined to release a more detailed report of its findings delivered to the Texas Commission on Environmental Quality.

Medical examiners say the foul-smelling chemical, used in production of pesticides, caused the asphyxiation deaths of the four workers.

Officials have said a faulty valve may be responsible for the fatal chemical release at the DuPont plant along the Houston Ship Channel in La Porte. The U.S. Chemical Safety Board is continuing its investigation.

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