More questions than answers about Indian plant accident

India's leak of poisonous gas now must be measured as the world's worst environmental disaster of its kind. Officials acknowledge that despite their efforts, the magnitude of the tragedy means they cannot do nearly enough to aid the victims. At time of writing, Monday's leakage from the Union Carbide insecticide plant in the central city of Bhopal had killed more than 1,600 people; tens of thousands more needed treatment. The number of questions provoked by the leaks is far more abundant than the answers that anyone has been able to provide:

What went wrong?

The alarm system indicating gas was leaking did not go off until two hours and four minutes after the leak began at 56 minutes after midnight.

The local employees and J. Mukund, the factory manager, were unable to stop the leakage of methyl isocyanate gas. A supposedly failsafe system whereby the escaping gas could be diverted into ''scrubbers'' and neutralized with caustic soda, was, for unknown reasons, inoperable that night.

The plant's carbine operators, wearing gas masks, could not plug the leak. Finally, outsiders from another factory, aided by the Army and police, were called in to bring the situation under control.

By then, the deadly gas had been leaking for 55 minutes, covering 25 square miles, from the controversial $25 million factory on the outskirts of Bhopal.

What is to blame for the leak: the tank's design or its maintenance?

According to Indian scientists from the Council of Scientific and Industrial Research, who made an on-the-spot survey, the storage tank containing the leaking gas was ''defective.''

But the argument over culpability between officials of the Indian government and Union Carbide, the American-based parent company of the Bhopal plant, is growing fiercer.

The chairman of Union Carbide, Warren Anderson, arrived in Bombay Thursday, but state government officials denied him entry into the now sealed plant, according to the official United News of India. His arrival coincides with a growing swell of anti-Americanism in the Indian press over the fact that the insecticide factory was one of the few joint ventures in India in which a foreign company held the majority of equity - and, therefore, according to the papers, the majority of responsibility. Union Carbide holds 50.9 percent of the company's shares, as it has since the factory was constructed in 1975.

Were safeguards nonexistent, or, if they existed, were they compromised?

There is little doubt that the state authorities of Madhya Pradesh violated the carefully laid-down guidelines of India's Department of the Environment when they permitted the plant's construction in 1975.

The department's guidelines are clear: Before any plant producing a deadly gas can be constructed, a study must be undertaken to predict population growth in the area over the next 10 years. No plant can be located within a minimum of 50 kilometers (31 miles) from the heart of any projected population center.

In 1969, when it was first decided to build the plant, the Kali Parade area of Bhopal was beyond the city's limits. However, by 1975, communities had already been developed on all sides of the plant. By the time of the disaster, 170,000 people lived within the 25 square miles that the gas covered before the leak was sealed.

For the past four years the state's largest circulation newspaper, Dainik Bhaskar, had been campaigning against the plant. The Hindi-language newspaper has charged that the plant's 1,000 workers had not been adequately trained, that its safety and maintenance were sloppy, and that the company's doctors did not even know if there was an antidote for the deadly methyl isocyanate.

Members of the state assembly had raised a similar cry. But they were overruled by the state's Congress Party government in a December 1982 debate, when then-Labor Minister Mahendra Karma said that ''the factory is not a small stone which can be shifted elsewhere. There is no danger to Bhopal,'' he said with confidence, ''nor will there be.''

This was the fifth known gas leak at the Union Carbide plant since 1978, leading many critics to ask: Why was the production of such a pesticide allowed, given that its manufacture produced such a deadly gas as a by-product?

India relies heavily on agricultural insecticides to sustain its ''green revolution,'' which has made the country nearly self-sufficient in food.

There are six major pesticide plants in the country, but Union Carbide's Bhopal plant was the only one making a pesticide from its basic stage. The other plants, including ''Tata-Fison'' (a joint venture with Britain's Fison company) and the German company Hoescht, import the chemicals and only formulate them here.

Union Carbide was also the only company producing methyl isocyanate gas and, by the time the plant went into full production in 1979, environmentalists, members of the state assembly, and newspapers were charging that there was no need for India to produce such a potentially devastating insecticide.

Who bears responsibility - the Bhopal plant or Union Carbide in the United States?

Despite Union Carbide charges that India's regulations are either weak or nonexistent, Indian officials counter that the responsibility rests with Union Carbide. The Indians say that the Americans constructed the plant and that the Indians had sought iron-clad safety assurances. Pending the outcome of the investigation, the Indian officials were not willing to say what assurances were given.

(The government of Madhya Pradesh State filed a criminal suit Thursday against the owners of the Bhopal factory, Reuters reported.)

In the meantime, Bhopal staggers under the weight of its personal tragedy. And the Congress Party chief minister, Arjun Singh, a protege of Prime Minister Rajiv Gandhi, must clearly be concerned about its impact during the campaign for the Dec. 24 parliamentary poll.

Perhaps that explains the comment of G. K. Moopanar, the party's general secretary, that ''sabotage cannot be ruled out.''