Response to chemical emergencies Computerized expert systems can provide police and fire ojicials with tools for taking safe, effective action
Judith M.Hushon Computer Systems Division Bolt Beranek ana' N e w m ~ Arlington Vn. 22209
In 1983, there were more than 5700 transportation incidents in the United States involving chemicals ( I ) . Most of them, 4829, took place on highways; 851 involved railways, 66 happened aboard aircraft, and 13 Occurred during water transport. In most cases, the first on the scene at such emergencies are local police, sheriffs, and firefighters, who often lack the specialized training to assess the severity of the problem correctly and to take appropriate action. Several training programs for first responders are available, but because there are more than 5 million police (private as well as public) and 175,000 firefighters, only a limited number can be trained properly. Although courses can provide information about response techniques and strategies, they do not offer familiarity with environmental chemistry and toxicology. In various incidents, first responders to chemical emergencies took action based on incomplete information. The result was injury or damage that would not have occurred had more complete information been available earlier. In 1980, one such incident occurred in the Boston and Maine Railroad switching yard in Somerville, Mass., and involved the release of about 13,000 gal of phosphorus trichloride (2). Firefighters used water, first to try to prevent entry of the chemical into the sewer system and later to try to stop its evaporation. This action resulted in the creation of clouds of toxic fumes. Some 23,000 persons were evacuated, 418 were treated at the local hospital. A similar incident occurred in December 1985 on a ramp to the Capital Beltway surrounding Washington, D.C., when a truck carrying 4000 gal of femc chloride overturned. The tank NpNred and began to release the chemical and toxic fumes. In this case, danger was averted because no water was used to control the fumes. Nevertheless, the highway was closed for several hours (3). 118 Environ. Sci. Tshnol..
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When a dangerous incident occurs, local responders can request assistance from state and federal agencies. EPA and the Centers for Disease Control (CDC) in Atlanta, Ga., have organized regional emergency response teams, which are headquartered in each of the
10 EPA regional offices. Because these teams must serve regions of as many as eight states, several hours may elapse before team members can reach the scene of an accident. The problem is that their expert aid is needed during the first minutes after the accident.
W13-938W86/09M01181.W0
0 1986 American Chemical Society
Little contact with experts First responders have access to much necessary and useful information. They are often unable, however, to make contact with experts who can rapidly integrate information from a variety of sources, concerning a large number of chemical, physical, and biological variables, to reach the conclusions .necessary to recommend appropriate action. Moreover, no system that does contain information about large numbers of chemicals can integrate information concerning the chemicals to identify which is the most toxic or to predict whether a mixture of chemicals is likely to react. This is the kind of knowledge that can be provided only by a team of experts, normally including a toxicologist, an environmental chemist, and perhaps an analytical chemist and an environmental biologist. The emergency response teams in the EPA regional offices try to provide assistance, but they too must use valuable response time to collect and evaluate relevant chemical data before taking action. There is also a certain reluctance on the part of many local first responders to call in outsiders from the federal government. They usually believe that they can deal with an emergency unassisted. Systems for rapid response One potential answer to this need is to provide first responders with access to an expert system that can take the place of the professional experts. Such a system could provide rapid response to emergencies by supplying accurate assessments of problems and situations and by suggesting solutions.
Expert systems are “man-machine systems with specialized problem-solving expertise” (4). They possess data bases of information about a particular domain or discipline, understanding of the problems addressed within that domain, and skill at solving these problems. Expert systems generally are considered a branch of artificial intelligence; with their knowledge base, these systems can function as experts, making high-level decisions based on multiple and varying inputs. Expert systems are distinguished from traditional data processing systems in several ways. First, they carry out difficult tasks usually reserved for human experts. Second, they emphasize problem-solving strategies. Third, they use a certain amount of self-inspection to evaluate how they reached their conclusions. Finally, they solve problems involving interpretation, pre-
diction, diagnosis, debugging, design, planning, monitoring, repair, instruction, and control. The development of expert systems has been closely tied to the availability of computing power. Several were developed in the early 1960s, but they were focused on narrowly defined a p plications and relatively simple problems (4). By the mid-l970s, work had begun on a number of systems that have formed the historical basis for the current generation of expert systems. One major area in which several expert systems have been developed is medical diagnosis. The MYCIN, PUFF-VM, Internist, and CASNET systems are among the best known (511).Expert systems also have been developed for other applications. Examples include Xcon, for designing and configuring computer systems ( 1 2 , l J ) ; Prospector (14) and Drilling Advisor,
Existing tools for first responders First responders generally have access to several sources of information: Guides or handbooks commonly carried in emergency vehicles include the Emer. gency Response Guidebook (Department of Transportation), Chemical Hazard R e spnse Information System Reference Manual (US. Coast Guard), Fire Protection Guide on Hazardous Materiels (National Fire Prevention Association), Emergenc) Handling of Hazardous Materials in Surface Transport (Association of American Rail. roads), Handbook of Toxic and Hazardous Chemicals (Marshall Sittig, Noyes Data Corporation, Park Ridge, N.J.), and the Pocket Guide to Chemicals (National lnstitut6 of Occupational Safetyand Health and Occupational Safety and Health Administra. tion). Reference libraries often contain guides or handbooks; access is possible by tele phone. These libraries often contain more complete information consisting of manu facturers’ safety data sheets, medical emergency procedures, and environmenta references. Emergency response centers respond to telephone inquiries by searching paper oi microfiche files or contacting industry An example is CHEMTREC, which is operatec around the clock by the Chemical ManufacturersAssociation (CMA) in Washington D.C. CHEMTREC contains information on 55,000products and can supply industr) contacts appropriate for use in case of an emergency. CMA cannot, however, makt judgments or supply more informationthan is located on its reference cards. Regional and national emergency response centers have access to commerciall! available information resources that contain factual, numeric, and bibliographic infor mation. First responders can have direct access to this information. In an emergenc) the factual and numeric data bases are the most helpful. The systems of major benefi to emergency responders are Ohm-tads (Chemical Information System [CIS]), Ha2 ardous Substances Data Bank (HSDB) of the National Library of Medicine (NLM) Hazardline (Occupational Heakh Service [OHS], BRS, MEAD), and RTECS (NLM CIS). A new software product called the Micro-CSIN Workstation is currently unde joint development by the Council on Environmental Quality, EPA, and NLM to facilitah emergency access to these factual and numeric data bases. The HSDB is a recently updated and expanded version of the NLM Toxicology Dat; Bank and is located on Toxnet, a network that is separate from the rest of the NLh files. Information on Toxnet and HSDB can be obtained from Bruno Vasta (301-496 Information on the Micro-CSIN Workstation is obtainable from Judith Hushoi 24-4870). a files stored in microcomputers are another source of emergency information Two current vendors are Resources Databases (Brentwmd, Tenn.), which markets thi Chemtox Database, and the British National Emergency Centre (Abingdon, England for the Chemdata file. Chemtox contains 41 fields of data on 2500 chemicals. It i accessible through the use of Revelation data base management software. Thi Chemdata file contains emeraenw fire and cleanup data on 14,000chemicals. Information on Chemtox can bebbtained from Jim Wood (615-373-5040)Informc tion on the Chemdata file can be obtained from Bob Cumberland. British Nationi (Abmdm124141 Fxt.3110U. bner(iency-m Environ. Sci. Technol.. Val. 20,NO. 2. 1986 119
for assisting with the evaluation of mineral and drilling data and problems; MolgedGenesis, which aids in genetic engineering (15); Dendral, for the solution of complex molecular design problems (1618); and Sophie (19), Delta/ Cats-1 (2Q, and Steamer (21), for the diagnosis of electronic and mechanical malfunctions. Most of these systems have been developed and revised over a number of years, with changes brought about by the augmentation of available computing power, new logical structures and relationships, refinements of the decision-making abilities of the, experts (such as learning from past mistakes), expansion of the knowledge base, and addition of related areas of knowledge. The stages in construction of an expert system are system design, system development, formal evaluation of performance, formal evaluation of acceptance by those users for whom the system was designed, extended use in a prototype environment, development of maintenance plans, and system release (its marketing and use) (22). A small
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number of expert systems have gained commercial acceptance; among these are Xcon and DeltaKats-l .
System components Building expert systems involves two different approaches-one uses a tural-language processor, which permits the use of natural English to convey information to the system; the other does not (Figure 1) (23). All systems have some sort of interface between the user and the system. The natural-Ianguage interface systems have a parser, which is a component that breaks the user’s input down into a series of statements that the expert system can understand. The second kind of system uses an interface that permits the user either to enter specific commands or to select menu options. The commands are then fed to an inference engine that provides a mechanism for interpreting the commands and gaining access to the knowledge base, which consists of data and rules for combining the data. An inference engine is a set of rules that governs the ability of the system to draw
conclusions. The knowledge base is generally compiled by human experts in applicable subject areas. The advantage of the natural-language front end is obvious: The user can use English and does not need to learn a new computer command language. Such parsers, however, require large amounts of data storage space for their dictionaries and their grammatical algorithms. Therefore, most expert systems employ a user interface and a knowledge engine (an inference engine combined with a data base) rather than a natural-language front end.
Assessing expert systems To evaluate a number of the existing expert systems, a group of scientists undertook an exercise to moeram a specific problem in several IkGagesEMYCIN. KAS. EXPERT. OPS5. HEARSAY Ill, RLL, and ROSIE (24): The problem involved a chemical spill at a specific site within a government compound. The expert systems were asked to determine the source of the spill from the available monitoring data. This exercise illustrates the problems faced by first responders to chemical emergencies in that it required knowledge about chemicals involved in the accident and their potential behavior under spill conditions. The questions the systems were designed to ask, however, were very different from those that would be asked by a generalized first responder’s system. The system used for this problem was set up to contain much site-specific knowledge. Therefore, none of the designs from this exercise meet first responders’ needs for expert guidance in the event of a chemical emergency. Rather, the exercise was undertaken to compare the abilities of the expert system software currently available for defining and solving problems. Several expert systems have been developed for use at plant sites to determine the location of an emergency and to predict danger to the environment and community health that could result from atmospheric chemical releases. An example is the Hazard Assessment System for Toxic Emissions (HASTE), developed by Environmental Research & Technology (Concord, Mass.) (25). This system, however, is specific to a plant site and therefore not appropriate for public emergency response personnel, such as police and firefighters, who often must cover large areas and numerous accidents involving many more chemicals than the number expected to exist at a specific plant site. First responders’ system criteria Because existing expert systems technology is inadequate to meet the
needs of first responders to chemical emergencies, a new expert system must be created. Such a system should consist of a data base that contains chemical-specific information and a set of rules for combining site-specific information with information from the data base to enable the first responders to draw appropriate conclusions. It also should contain a user interface that queries the user for site-specific and accident-specific information and delivers the best possible response. Such an expert system can help first responders make decisions based on answers to a number of questions: Which of the chemicals present represents the greatest human health hazard? What is the critical exposure route? If there is a fire, what is the best extinguishing material? What equipment should be worn by personnel to protect against the chemicals present? Should population evacuation be considered, and, if so, what is the longest distance recommended by the Department of Transportation? Is there a possibility of explosion? What are the likely symptoms of chemical poisoning from the substances present? The above list is not complete, but it does indicate the responses the expert system should be expected to provide. It also will serve as a guide to the information that must be included in the data base. To be maximally useful to first responders, the expert system must be able to operate with inexpensive and readily available microcomputer hardware. It must be user friendly and prompt the user for the required information, and it must provide unambiguous answers quickly. The first expert system likely to be available to first responders to chemical emergencies will be centralized. Emergency responders will call in and p r e vide details concerning the site and the nature of the chemical emergency (for example, the chemicals involved, the presence of a fire, any injuries, and the distance to the closest population). The central operator will enter these data and run the expert system program. The results can then be communicated to the scene of the emergency orally or electronically. This approach will enable emergency response personnel to respond more appropriately and rapidly. It is even possible tl.at a preliminary action plan could be plipared with the aid of the expert system, on the basis of information from the initial accident report, and then be refined as details become available. The ability to formulate an inci-
dent-specific accident response plan while the emergency response team is en route to the scene has obvious advantages. It may even be possible to have the expert system computer installed in the emergency vehicle. The drawbacks to this approach are the expense involved and the inability of some emergency response personnel to operate computers. The microcomputer hardware needed to run such an expert system costs about $5000; the software probably will cost several thousand dollars more. This expense will make it difficult for most small jurisdictions to acquire systems, and it will tend to encourage centralization. An alternative approach involves a central multiuser system accessed through small, inexpensive, portable terminals on emergency vehicles. This would raise the central hardware cost to $40,000-$50,000,but it would lower the cost per vehicle to $500-$700.
System under development Because of the obvious need, an expert system for first responders to chemical emergencies is under development; a prototype for testing can be expected by late 1986. The objective is to design a system that can be operated on a commonly available microcomputer with a hard disk. It is hoped that such a system will be available commercially shortly thereafter. There are, however, issues of liability to be dealt with first. For example, if the system makes recommendations That are followed, but injuries still result, the system’s developer can be sued. Moreover, it is almost impossible to obtain insurance to cover the potential defendant in such a suit, and what insurance is available is prohibitively expensive. Also, it is unclear whether the centralized or distributed approach to making this expert system available to first responders would work best.
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Acknowledgment Before publication, this article was reviewed for suitaL lity as an ES&T feaNre by Barbara Goldsmith of Environmental Research and Technology, Concord, Mass. 01742; and Steven Eisenreich, University of Minnesota. Minneapolis, Minn. 55455. References ( I ) “Transportation Accidents by Mode”: U S . Department of Transportation: Washington, D.C.. 1984. (2) ”Special Investigation Report: Phosphorus Trichloride Release in Boston and Maine Yard 8 During Switching Operations. Somerville, Mass.. April 3. 1980.” NTSBHZM-81-1: National Transportation Safety Board, Department of Transportation: Washington. D.C.. 1981. (3) 7?w Wushingrun Pmr. Dec. 23. 1985. p. BI. (4) Hayes-Roth, F.; Waterman, D. A,; Lenat. D. B. Buildinx E r p m Sysrems: Addison
Judilh M. Hushon is a senior scienrisr wirh BBN Lobomrories. a subsidiary of Bolr Beranek and Newman, w,here she i5 the manager of rhe Research Svsrem Deparrmenrk Washingron, D.C., ojice. She has managed numerous projecrs relared 10 obraining and rvaluaring chemical informalion. Her work o,~rxperr sprems is being carried our in connecrion wirh rhe acquisir i m of a docroml degree in munagemmi of informarion s.ssrems rechrtolog? ai rhr George Washingrun Uniwrsiq. Environ. Sci. Technal.. Vol. 20, NO.2, 1986 121
