This month’s technical discussion is written by S. Bruce King our regular author of “Let's Take a PEEK at the PEAC Software. We’ll just have to wait till next month, for those expecting another of Dr. Nordin’s definitive articles

The latest PEAC-WMD software release (version 5) will have several new features, two of which will be discussed here. The new release will contain greatly expanded information on bio‑toxins, radiological isotopes, chemical warfare agents as well as toxic industrial chemicals. The latest version will include additions on vapor cloud modeling, chemical reactivity, the ability for the user to incorporate their own data files, information on symptoms of exposure, and additional information chemical exposure guidelines.

During the next several issues of the newsletter, we will introduce different features of the PEAC-WMD v5 release and provide a short discussion behind the intent and purpose of the feature and how it can benefit the First Responder.

Two features to be discussed in this article that were suggested by the military and civilian response community and will be included in the PEAC WMD v5 application are: (1) identifying a class of agent that creates mass casualties based on symptoms and (2) providing an integrated search routine of the database. These features provide an extra dimension not previously offered in the PEAC application. We will call the new features (1) NBC Indicator Matrix and (2) word search engine.

NBC^* Indicator Matrix

A question AristaTek tackled internally was the technical pros and cons of providing identification of a class of agent that creates mass casualties based on symptoms in the PEAC application. Scientists and engineers at AristaTek always wrestle with the advisability of providing a methodology that provides limited certainty.

The availability of an authoritative reference or source of the analysis of symptoms of agents to provide unequivocal guidance is a major concern to AristaTek. A reference was found developed by DOD back in the 1990’s that is referred to as the NBC Indicator Matrix. It provides a methodology by using symptoms exhibited by the casualties or other indicators exhibited in a chemical or biological dispersion area that may assist in identifying the class of agent but not the specific agent. The NBC Indicator Matrix breaks the types of agents into eight classes:

1.Nerve agents,

2.Blister agents,

3.Blood agents,

4.Choking agents,

5.Irritating agents,

6.Incapacitating agents,

7.Biological agents, and

8.Radiological agents.

The concern is that users might not recognize the limitations of subjective evidence used to identify agents in any database and might over extend the method for which it was intended. Therefore AristaTek recommends the user understand that using symptoms to identify a class of agent can be misleading or deceptive for multiple reasons. For example, more than one class of agent commonly exhibits a symptom or symptoms, so a single symptom or partial set of symptoms will not be found for a single class of agent. Another reason this type of subjective evidence can be a problem is the fact that not all symptoms appear at the same time after exposure, therefore some may take longer to be exhibited than others. Related to this fact is the dose of exposure an individual may receive will impact which symptoms are exhibited and how long it takes for these different symptoms to be exhibited. An obvious problem is also the variability between individuals and their susceptibility to the agent released. Because the NBC Indicator Matrix could provide assistance in some terrorist events, AristaTek has decided to discuss these issues in the PEAC User’s Guide to caution the use of this method. The primary concern is that individuals using this Matrix understand the limitations and know that sensor/detector systems or other qualitative procedures are the better and more reliable methods to determine what agent has been released to cause mass casualties.

First Responders will always don chemical protective clothing and respiratory protection before proceeding into a suspect toxic NBC atmosphere to identify the hazardous material with sensors/detectors, search for and collect a sample for analysis or assess the area for possible causes. Attempting to identify the possible agent simply by symptoms is uncertain, but is provided simply as another resource in the responder’s toolbox.

Figures 1-3 provide samples of three of the eight symptom screens provided for the user to indicate symptoms observed in casualties. Figure 4 provides a summary page of the results from the NBC Indicator Matrix where the agent was identified as most likely a Nerve Agent.

Notice, the NBC Indicator Matrix only provides the class of agent, not the specific agent. As shown in Figure 4, the PEAC application displays the results and the most likely agent in the Data Display Box plus it also provides the next most probable agent, in this example a Biological Agent. In addition, when the NBC Indicator Matrix results are displayed, the possible agents that are included in the most likely class are displayed in the List Box on the left portion of the screen.

Word Search Engine

The second feature discussed here is the ability to search the descriptive fields in the PEAC database for specific words or terms. This is provided simply as a resource or tool to assist the user and should not be construed as a methodology to identify a material by its color, odor or appearance. AristaTek and the author are convinced, based on their academic training and experience, the First Responder should not believe a computer search feature will reliably “identify” an unknown substance. Our recommendation is that the three best methods to identify an unknown material are: (1) from a label, shipping papers, placard, or other identification markings, (2) on‑scene sensor or detector system, or (3) laboratory analysis methods.

Obviously if a container has a label or other markings, as hazardous materials transportation containers are required to have, the identification process is usually easy. Sometimes in an accident, the container may not have any markings, or they may not be visible, or shipping papers may not be accessible. There are some important programs being developed that are targeted to eliminate this problem, at least with commercial transportation commodities, e.g., OREIS from Operation Respond Institute (http://www.oreis.org/).

The threat of a terrorist event has influenced increased spending and the introduction of many new products to the emergency response community. If an emergency HAZMAT event is a terrorist event, the First Responder may not have the luxury of a label, placard or a note from the terrorist identifying what has been released. Then the First Responder is going to have to rely on one or more new sensor/detector systems that are being continually evaluated and included in their grant applications.

The following discussion provides further substance to the issue that identifying an unknown by “searching physical characteristics databases” that AristaTek recognizes has some major shortcomings. The descriptive terms associated with a substance found in most databases are developed and based on the typical or most common observed characteristics caused by the substance. The reader should also understand that a material in a database may also exist with slightly different or in some cases substantially different characteristics. For instance, reported colors are typically based on that observed for the pure substance. If this same material has impurities or added chemicals to stabilize it, these can cause the observed color to be different than that reported for the pure material. In many instances a commercial product is produced as a mixture, which can mislead the search for a specific color or odor.

An example could be an unknown material described as a “white dust or powder.” There are numerous materials, some hazardous and most not hazardous, that could fall into this general description. An example of a hazardous material would be anthrax, but there is also the possibility of relatively non-hazardous candidates such as sucrose (sugar), marble dust (a form of Calcium carbonate) or gypsum (Calcium[II] sulfate dehydrate). Anthrax, sucrose, marble dust and gypsum are in the PEAC‑WMD database and would all appear along with numerous other entries if searched on the basis of a description “white dust or powder.”

Odor is also a subjective characteristic since individuals have different sensitivity to odor. Some hazardous materials can saturate an individual’s olfactory sensory receptors causing olfactory fatigue and the individual will no longer be able to perceive the odor.

Physical state can also be deceptive. For instance, a solid material can appear in many forms, which are dependent on how the material is processed. A material that is a solid at room temperature can have the form of flakes, powder, granular or crystalline. Likewise a material, which is normally a liquid at normal ambient conditions, may be absorbed onto a solid substrate and appear as a solid. A common example of this is pesticides and the manner in which they are produced as commercial products. Many pesticides are liquids in their pure state but are absorbed onto a solid and distributed as powders or granular products. Other pesticides may be solids in their pure state but are distributed as a liquid emulsion or solution. As explained earlier, if the material, which may be the active ingredient in a product, is produced as part of a mixture, its characteristics as a pure material may have no semblance to its commercial form.

Therefore, even though the First Response community requests these features be in the PEAC system to help with the identification of hazardous materials, AristaTek is determined to point out the uncertainty and limits inherent in these approaches to identifying NBC agents or hazardous materials in general.

The following figures provide a quick glimpse of the search feature as it is implemented in the upcoming release of the PEAC application. Figure 5 shows the main screen and the Search Icon that can be clicked to display the Search Tool window the user uses to specify the terms or words to be searched for.

The Search feature allows the user to either select terms or words from the categories listed (color, appearance, odor strength and order likeness) or enter terms in the description area field. These terms are searched for in the descriptive fields in the entry records. Likewise, the user can select terms from the symptoms or entry terms or words that will be searched for in the symptoms fields of the entry records. The user can specify that all terms must be found to be included in the results or any terms can be specified.

An example a Search is shown in Figure 6 where all entries were searched, i.e., “Name” was specified in the Lookup By field and the terms searched for were “white” and “solid”.

Upon clicking on the [Search] button, the search is completed and a window is displayed to show the number of entries found. In this case 2794 entries were found that matched the criteria, perhaps some help, but still a long list to be reduced by searching for other characteristics.

By clicking on the [OK] button, the application will create a dynamic list, called the Search Results as shown in Figure 8. This dynamic list is a temporary list that the user can then search for other characteristics to reduce the number to a more workable list. In the example in Figure 8, the Search Results contain the 2794 entries.

*NBC represents Nuclear Biological Chemical