What Happened At Bhopal

By Philip Elmer-DeWitt

After poisonous vapors spewed from a Union Carbide pesticide plant in Bhopal, India, last December, killing some 2,000 people and injuring another 200,000, Chairman Warren Anderson flew halfway around the world to make a dramatic appearance at the site, promising to find out what had gone wrong. Last week, at a press briefing near the company's Danbury, Conn., headquarters, he made good his promise. The world's worst industrial accident had been caused, he said, by gross violations of established safety procedures. "That plant," Anderson declared, "should not have been operating."

Union Carbide's investigation in Bhopal focused on a partially buried tank holding more than 10,000 gal. of methyl isocyanate (MIC), a highly toxic chemical used in the manufacture of Sevin, Temik and other pesticides. The sealed tank was designed to keep the deadly MIC refrigerated and isolated from the environment. But on the night of Dec. 2, a series of runaway chemical reactions heated the interior of the tank to 400 degreesF, causing an escape valve to burst open and release a lethal cloud of vapor over the slums of Bhopal.

What triggered the reaction? Analyzing residue from the bottom of the tank, Union Carbide investigators determined that the culprit "with high probability" was water. Either by accident or design, they said, a large quantity of water had been poured into the holding tank, reacting with the MIC to produce enough heat and pressure to pop the valve. One possible source: a utility station where a pipe marked "water" is located next to one marked "nitrogen" (used to pressurize the tank). Most likely, the investigators suggested, someone connected the wrong pipe to the tank, allowing as much as 240 gal. of water to mix with the MIC.

Even then, tragedy might have been averted were it not for an extraordinary series of mishaps and oversights. A refrigeration unit that might have kept temperatures in the tank at a manageable level had broken down more than five months earlier and never been repaired. A temperature alarm, which would have alerted workers to the trouble, had not been properly set. A flare tower that could have destroyed some of the escaping gas was out of commission. And a "scrubber," designed to neutralize toxic vapors, was not turned on until after the reaction had raced out of control.

These lapses, said Anderson, were the real cause of the tragedy. The company had provided the necessary safeguards, he insisted; if the Indians neglected to put them in effect, then they must be held accountable. "Safety is the responsibility of the people who operate our plants," said Anderson. "You can't be there day in and day out."

Indian officials were quick to dispute the report. "How can Union Carbide disown its own subsidiary?" H.R. Bharadwaj, India's Minister of State for Law and Justice, asked in an interview with the New York Times. (The company holds a 50.9% stake in Union Carbide India Ltd.) "We expected the company would try to palm off the blame," Kamal Pareek, an engineer familiar with the plant, told the paper. "But Union Carbide cannot escape responsibility." Indeed, suits totaling more than $250 billion have been filed against the firm on behalf of the residents of Bhopal.

Union Carbide last week moved to ease public concern over its MIC plant at Institute, W. Va., which was closed down immediately after the Bhopal tragedy. Conducting a press tour of the facility, it showed off the results of a $5 million program to improve safety measures. Some environmentalists were not entirely reassured. Says A. Karim Ahmed, a scientist with the Natural Resources Defense Council in New York City: "It remains to be seen whether they learned the lesson of Bhopal."