DuPont: 23K pounds of toxic gas escaped from plant

About 23,000 pounds of a flammable, acidic, toxic chemical escaped in the building where four DuPont workers recently died at a pesticide plant in La Porte, the company reported Friday.

That amount of gas could quickly displace the air in an enclosed space, leading to asphyxiation, which medical examiners identified as the cause of the workers' deaths. Although the company has not disclosed how quickly the liquid material escaped and vaporized, it's enough that, if it happened at once, it could fill two Olympic-sized swimming pools.

"The displacement of oxygen would be very severe and very quick," said a former DuPont engineer familiar with the plant and who spoke on the condition of anonymity, adding "within the time it takes you to take a couple of breaths ... that's how quick it is, and you have no idea what's happening to you. Just all of the sudden you're unconscious."

The company was required to submit the report to the Texas Commission on Environmental Quality. Although DuPont disclosed the amount of gas in a three-paragraph news release, it declined to release the full report. Commission offices were closed Friday.

The Nov. 15 release of methyl mercaptan, a foul-smelling gas that, besides its use in pesticide production, is sometimes used to odorize natural gas, is under investigation by the U.S. Chemical Safety and Hazard Investigation Board.

While details of the accident are still emerging, a Chronicle investigation found the pesticide production facility had been plagued with recurring maintenance problems and that workers lacked quick access to breathing equipment that would have given them a better chance at survival.

Those killed included Crystle Rae Wise, 53, the first to alert others of a leak; Wade Baker, 60, a longtime supervisor; and brothers Gilbert and Robert Tisnado, 48 and 39, respectively.

Family members and their attorneys said some of the workers who died were trying to help the others escape. They and the company have indicated a faulty valve may have been involved in the release. The gas escaped from pipes and vessels inside the pesticide unit, DuPont spokesman Aaron Woods said.

That methyl mercaptan leaked and killed workers was a tragic irony in a plant that was upgraded years ago to curb the hazards of what's considered a much deadlier chemical: methyl isocyanate, or MIC. It's the chemical responsible for initially killing more than 2,200 people after escaping an Indian pesticide plant in 1984, causing lingering injuries and deaths for thousands more in the world's worst industrial disaster. Even tiny concentrations of the chemical can be deadly.

DuPont engineers won an industry award for upgrades that allowed the company to produce and consume small batches of MIC, eliminating the need to store and transport it.

Methyl mercaptan, on the other hand, had always been viewed as a "pussycat chemical" by comparison, the former engineer said. The La Porte plant routinely contained tens of thousands of pounds of the mercaptan, according to government documents.

Outdoors, it poses the least threat. County officials monitoring air around La Porte after the release detected none of the gas, although residents could smell it because the human nose detects it at levels so small instruments cannot.

Woods said the gas that built up inside the pesticide building dissipated over time as it escaped through openings in the structure. Once released to air, it rapidly degrades, he said.