The 2008 explosion at the West Virginia Bayer plant, which stemmed from a fire within the production unit, resulted in the deaths of two employees and extensive damage to nearby structures. Debris from the blast hit the shield surrounding a storage tank for MIC -- a volatile, highly toxic chemical used in the production of agricultural and residential pesticides. The liquid and vapor forms of MIC can be harmful when inhaled or ingested, or when eyes or skin are exposed to it. In 1984 a cloud of MIC gas from an explosion in Bhopal, India, killed nearly 3,800 people. Although the storage container at the West Virginia plant avoided damage, an investigation by the U.S. Chemical Safety and Hazard Investigation Board found that debris could have struck a relief valve vent pipe resulting in the release of MIC into the atmosphere. Bayer intended to restart production of the pesticides involving MIC after plant modifications were complete, but last year announced it would cease production. Nevertheless, under the congressional mandate, the Research Council study examined the use and storage of MIC at the Bayer facility and possible alternative production processes.
Inherently Safer Process Assessments
The Occupational Safety and Health Administration (OSHA) process safety management regulations require companies to follow evaluative and organizational procedures to ensure a safe chemical manufacturing process. Companies must meet OSHA's requirements, but are not limited to them, and additional hazard control methods are available. One of these additional methods is an "inherently safer process" assessment, which aims to minimize or eliminate the hazard. These assessments will not always result in a clear, well-defined, and feasible path forward. Although one process may be inherently safer with respect to a specific hazard, the process may present other hazards, such as an increase risk of fire or more severe environmental impacts. For instance, changing from a flammable solvent in a process to a non-flammable one will eliminate a fire hazard, but if the new solvent is toxic, then using it introduces a new hazard that must be controlled. Moreover, judgments about what constitutes an inherently safer process varies among professionals, and the chemical industry lacks a common understanding and set of practice protocols for identifying safer processes.
The committee found that Bayer did incorporate some aspects of risk reduction that are associated with inherently safer process principles. However, the inherent safety considerations were not explicitly stated in Bayer's process safety management guidelines and were dependent on the knowledge base of the individual facilitating the particular activity, such as a process hazard analysis. Moreover, Bayer and the previous owners of the plant performed hazard and safety assessments and made business decisions that resulted in MIC inventory reduction, elimination of above ground MIC storage, and adoption of various measures, but these assessments did not incorporate some of the key principles of the inherently safer process. The committee said that without an emphasis on incorporating inherently safer process assessments into process safety management, it is unlikely that these concepts would become part of corporate memory, and therefore could be forgotten or ignored over time. It suggested that Bayer formally incorporate inherently safer process assessments into the company's process safety management system and training, and to record such assessments as part of its audit and review processes.
Alternative Methods for Producing MIC and Pesticides
In reviewing Bayer's assessment of four alternative processes for the manufacture of MIC, the committee said that no method out-performed all others in every category. Bayer also evaluated trade-offs among the alternatives -- considering costs and benefits such as risk, expense, quality of final product, and community perception -- but excluded factors that could have been important in the decision, from the perspectives of both the company and the community. Although it posed higher risks to the surrounding community due to the volume of MIC stored at the facility, the process Bayer ultimately chose decreased the amount of wastewater produced compared with other methods, which in turn decreased the potential damage to local surface waters. The previous owners identified other possible methods that could have resulted in a reduction in MIC production and inventory but determined several limitations prohibited their implementation.
Inherently Safer Processes in Industry
A company's consistent application of inherently safer process strategies could decrease the required scope of organizational emergency preparedness programs by decreasing the vulnerable zones around its facilities. However, a potential concern with using inherently safer process analysis is that it may become too narrowly focused, and as a consequence, may overlook certain outcomes. Even when multiple outcomes are recognized, they may be inappropriately weighted.
The committee recommended that the U.S. Chemical Safety Board or other entity convene a working group to chart a plan for incorporating decision theory frameworks into inherently safer process assessments. The group should identify obstacles to employing methods from the decision sciences, options for tailoring these methods to the chemical process industry, and incentives that would encourage their use.
Provided by National Academy of Sciences
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