In the aftermath of last year's tragic chemical leak at a Union Carbide pesticide plant in Bhopal, India, the United States chemical industry has embarked on a major review of its safety practices. ``Every company I know of . . . is conducting major reviews of safety programs,'' says Geraldine Cox, vice-president of the Chemical Manufacturers Association (CMA), which represents most of the nation's medium-size and large chemical companies.
James Gideon, an expert on control technology for the National Institute of Occupational Safety and Health (NIOSH), likens the current reaction to the period of introspection the nuclear industry went through after the accident at the Three Mile Island nuclear reactor.
``It's the `deep-pockets theory,' '' Dr. Gideon says. ``The concept that one accident can bankrupt even a large company is making them go back and seriously review their safety procedures.''
In Gideon's view, the issue of safety at the nation's chemical plants is less a matter of needing new technology and procedures than of making sure that companies are doing the things they know they should.
Major US chemical companies deserve high but not perfect marks on the engineering controls and safety-related technology they design into their facilities, says the NIOSH scientist, who has visited and studied many of the plants. He illustrates this point by describing what he saw on a recent visit to a Union Carbide plant in Georgia that handles methyl isocyanate (MIC), the volatile, toxic chemical that killed about 2,000 people in the Indian accident.
The MIC handling facility was a 50-foot-square pad of concrete, isolated from the main plant and surrounded by a concrete dike, he says. Handlers were dressed in ``spacesuits'' with bottled air. The tanks containing the dangerous chemical were underneath a roof equipped with a sprinkler system that could deluge the area. A second chemical (a caustic) was available in ample quantities to chemically deactivate all the MIC on hand. In addition, there was a bin of activated charcoal nearby, which could be shoveled onto any of the chemical that was spilled, absorbing and neutralizing it.
``We came away convinced that there was little chance of a major accident,'' Gideon says. This picture stands in stark contrast to some press reports on the operations of the Union Carbide plant in Bhopal.
The NIOSH expert ranks Union Carbide's Georgia plant as about average, compared with other US companies, in its concern for safety. On the other hand, he rates the Du Pont Company as the most fanatic in its care. Du Pont divides safety issues into three major categories, explains E. Neil Helmers, the company's air quality manager. These are problem avoidance, problem detection, and problem response.
``Hazard avoidance starts with the design of the facilities,'' Dr. Helmers explains. A number of times during the process, plans are subject to formal ``hazard design reviews,'' in which safety specialists examine the blueprints and suggest safety-related improvements.
In the last five years this process has become considerably more sophisticated, Helmers says. Du Pont and a number of other chemical companies have adopted formalized risk-analysis techniques from the aerospace and nuclear industries. These allow safety engineers to compare quantitatively the relative odds and potential consequences of hundreds of accident possibilities.
Processes that involve highly toxic materials are generally designed to run in tightly sealed compartments. They are also built with considerable redundancy -- with completely independent backup controls, valves, and piping systems -- so that if one system fails, another can take over. With advances in computer technology, plants are becoming increasingly automated, both in routine operation and in safety response.
This growing complexity has brought with it a new problem, however. It is known as the ``Christmas-tree effect.'' The new control rooms have so many lights, dials, and warning buzzers that when something goes wrong, operators can easily become confused for a while before they start to figure out what is really going on.
To combat this problem, chemical companies are turning to special computer programs called expert systems. These have proved their worth in medical diagnosis, mineral prospecting, and a number of other areas. Installed in a chemical-plant control room, the expert system would receive all the signals from the plant and present the operator with an almost instant diagnosis of the situation were a problem to arise. If the operator were unsure about the computer program's conclusion, he could request that it explain the basis of its recommendations, then either accept or reject them.
The ability to measure small quantities of chemicals in the air or water has improved tremendously within the last decade, experts say. And this improved instrumentation is being used by the chemical industry to detect leaks and spills.
The incorporation of microelectronics in instruments has also allowed an increasing amount of ``real-time monitoring.'' Measurements are transmitted to the control room in a matter of seconds. Traditional methods, on the other hand, involve periodic sample collections and laboratory analyses, processes not suited to emergency conditions. NIOSH's Gideon says the industry should move more aggressively in this area.
A big problem has been instrument reliability, an apparent factor in the Bhopal leak. To counter this problem, many companies are beginning to deploy sensors in sets of three. A computer periodically ``polls'' the three instruments and compares their readings. When a sensor begins giving results that differ from its companions, it is scheduled for testing and maintenance.
Should a leak occur, the chemical plant generally has a number of defenses, depending on the substance. A common practice for flammable gases is ``flaring,'' channeling the gas through a vent, where it is burned. Another option is venting through a chamber containing another chemical that deactivates the substance. In the case of water-soluble vapors, plants may have strategically placed water cannons (high-pressure water hoses) to wash the chemical out of the air, or water curtains, which act to contain the material's spread.
When all these precautions fail, then the surrounding area must be evacuated. Sophisticated new computer systems are being installed in many plants that promise to help in this difficult process. They take into account weather conditions and the amount and type of chemical released to project the shape and the intensity of the plume that will form. The computer systems also contain the phone numbers of local officials, for rapid notification when necessary.
No matter how sophisticated the technology, in the long run it is the attitude of plant workers that is most important, Du Pont's Helmers acknowledges. That is why his company has tried so hard to foster a safety-conscious attitude above everything else, he says.
One way that companies like Du Pont try to maintain safety awareness is by conducting safety audits, in which a team from corporate headquarters periodically inspects each plant. A 1981 survey by the Chemical Manufacturers Association found that three-fourths of its member companies conducted audits of this type.
Despite efforts of this sort, ``we've found considerable variation in safety consciousness among plants, even within the same company, depending on the attitude of the manager,'' Gideon observes.
Nevertheless, the chemical industry in the US has a relatively good safety record. According to the National Safety Council, the chemical industry ranked first in the nation last year, having the lowest incidence of employee days away due to work accidents and deaths. One person out of every 100 working in the industry has a safety- or environment-related job, says the CMA's Cox.
Gideon agrees that chemical companies ``have a pretty good record when you consider the amount of material they have processed, the number of plants, and the period of time involved.'' But he points out that legitimate questions are being raised about chronic, low-level worker exposures to a number of chemicals. The industry has also had a serious problem with fires and explosions, he notes.
Still, Gideon says, ``I think a case like Bhopal was an anomaly for a major US chemical company. A similar incident in the US would most likely come from a user of chemicals, rather than a manufacturer.''
What has been reported about the Bhopal case -- that safety equipment was disconnected and safety procedures not followed -- was considerably below what he has witnessed in US chemical plants, Gideon says.