Is the US chemical industry safe? The US chemical industry, which claims to be one of the safest, is trying to improve methods for handling hazardous substances and, at the same time, to refurbish its tarnished image. First of two articles below.

To chemical industry executives, the United States chemical industry is a paragon of safety. ``We are the safest industry in America,'' states George J. Sella, chairman of American Cyanamid Corporation.

To its critics, the industry is fraught with risks to the public welfare.

``No one has any real doubt we've been lucky that this country hasn't experienced a major incident at a chemical plant that has killed many people,'' says Roger J. Batstone, a chemical engineer at the World Bank. Major changes ``have to be made because our good fortune won't hold out forever.''

This debate is taking place against a backdrop of incidents such as the one that took place recently at Kerr-McGee Corporation's Sequoyah uranium processing facility near Gore, Okla. On Jan. 4, an explosion ripped apart a containment tank, killing one worker and injuring eight others. The ruptured tank released a plume of toxic hydrofluoric acid. Eventually, authorities say, 103 people required medical treatment.

This accident came a year after the December 1984 incident in Bhopal, India, where a leak from a Union Carbide pesticide plant killed more than 2,000 people.

By at least one measure, the chemical industry is the safest in the US. In 1984, the latest year for which figures are available from the US Bureau of Labor Statistics (BLS), lost workdays from occupational injury or illness in the chemical industry ran about 2.3 incidents per 200,000 man-hours. Comparable figures for manufacturing generally and the entire field of private-sector employment run at about 4.5 and 3.7 per 200,000 man-hours, respectively. And despite a substantial increase in lost workdays in other fields, the chemical industry figure actually decreased from the 1983 level. Chemical industry officials frequently cite these data when claiming their industry poses no significant additional hazard to the health and well-being of the general public.

``People are going to come to realize that the odds of being struck by lightning . . . or hurt in a chemical plant accident are very, very slim,'' says Harold J. Corbett, senior vice-president for health, safety, and environment at Monsanto Company. ``Serious accidents are very rare, so when they do occur, they become big news events and receive wide attention.''

Chemical companies are reluctant to reveal the types of chemicals they use because they don't want to tip trade secrets to competitors. Moreover, there are no federal statutes controlling the release of many chemicals or mandating certain types of safety equipment or worker training. The combination of these two factors is ``an invitation for these sorts of incidents to happen,'' says Margaret Seminario, a safety analyst for the AFL-CIO, referring to chemical-plant leaks. ``You cannot simply leave safety up to the manufacturers.''

Ms. Seminario charges that BLS figures used by the industry do not adequately reflect the hazards posed by modern chemical-plant operations.

``Those statistics look at accidents on the job, and most accidents on the job come from operating heavy equipment, which you don't see as much of . . . in a chemical plant as in, say, a steel mill,'' she says.

Chemical hazards are not limited to employees. An Environmental Protection Agency (EPA) survey of chemical mishaps of all sizes over the past five years lists nearly 7,000 incidents. Roughly 420 million pounds of toxic chemicals were released, mostly from chemical plants, but also during the transportation of chemicals and in other situations. The accidents killed 139 people and injured 1,478; more than 217,000 people were evacuated -- and the EPA survey was incomplete.

New York Assemblyman Maurice Hinchey, who began hearings on the state's chemical industry last week, says of the chemical industry, ``It's really in its infancy. Basically it's been built up since just after the war. We live under the threat of some very tragic mistakes as [the industry] learns.''

Still, the chemical industry has been taking dramatic and often costly steps to hone its safety procedures, sharpen employee training programs, and rebuild public confidence in its system.

Many of the programs place heavy emphasis on employee training, which experts have charged has been an Achilles' heel in the safety efforts of many companies. Others are attempting to upgrade equipment or the technologies used in safety devices.

The Chemical Manufacturers Association (CMA) has started a Community Awareness and Emergency Response program that helps companies develop emergency-response plans with local governments. The American Institute of Chemical Engineers has launched a Center for Chemical Plant Safety to provide technical information to chemical companies.

For all these efforts, industry executives concede that any credibility gap with the public has been dramatically widened by recent chemical-plant mishaps. ``It may never be closed,'' says Mr. Sella, the American Cyanamid chairman, who is also CMA chairman. ``We have our work cut out for us.''

First of two articles. Tomorrow: Defining the federal role in regulating chemical-plant safety.

ACCIDENTS at chemical plants rarely happen for the same reason. This complicates the task of safety experts, who try to ensure that equipment functions properly and that mishaps are never repeated. Two recent examples in the United States:

Institute, W.Va. On Aug. 11, 1985, three gaskets on a tank at a Union Carbide plant ruptured, releasing a cloud of aldicarb oxime into the air. Six plant employees and 135 nearby residents were injured in the incident. The image of Union Carbide, already seriously damaged by the December 1984 leak from a similar plant in Bhopal, India, that killed more than 2,000 people, was wrecked.

Paradoxically, the incident came on the heels of an intense inspection of the chemical plant. The Institute facility was the only one in the US involved with the production of methyl isocyanate, or MIC -- the extremely toxic compound that escaped from the Bhopal plant. After the Bhopal incident, federal investigators scrutinized every aspect of the Institute plant's MIC operation, finding it sound in some areas and wanting in others. Union Carbide invested more than $5 million in safety improvements. But the system that broke down on that Sunday in August was separate from the plant's MIC unit. A host of unexpected problems, including an inadequate computer system, equipment breakdown, and employee error, contributed to the mishap.

Bayway, N.J. On Oct. 21, 1985, a storage tank at an Exxon Corporation facility leaked diluted hydrogen sulfide, a substance on the federal Environmental Protection Agency's list of hazardous chemicals, over hundreds of square miles. No one was seriously hurt, but at one point or another the air throughout much of the state of New Jersey and part of Pennsylvania smelled of rotten eggs. New Jersey slapped Exxon with $145,000 in fines, which Exxon is now appealing. The incident raised a few alarming questions. Warning devices, such as pressure and temperature gauges, that could have alerted workers to a problem were reportedly not connected to the control room. Safety mechanisms did not work as designed. Experts have noted strong similarities between such incidents and the Bhopal tragedy, in which inadequate instruments, training, relief procedures, emergency plans, and other shortcomings resulted in a disaster.