BY CHARLES A. ZONA
SINCE SEPTEMBER 11, 2001, first responders across the country have had to embrace new assumptions when responding to hazardous materials incidents. They now must consider that a substance might be a biological or chemical weapon intentionally planted to cause harm not only to the public but also to first responders.
Until recently, first responders had limited methods for quickly and accurately determining whether a suspect material at an incident site was harmless or dangerous. Under previous protocols, an unknown sample was usually collected and sent to a remote laboratory for identification, a very slow procedure that could compromise safety on-scene. Even today, other technology available on-site is limited in generating quick and accurate information. Both scenarios hinder the haz-mat team’s ability to secure the area and neutralize the unknown material.
In many instances, local fire departments are now the first to be called to investigate suspect powder incidents, whereas previously calls went to the National Guard’s Weapons of Mass Destruction/Civil Support Teams (WMD/CST). As a result, many fire departments are developing and modeling their haz-mat teams after the WMD/CST. Fire departments are acquiring similar equipment and training their first responders in identifying suspect materials on-site. Over the past year, protocols have been changed to incorporate the polarized light microscope (PLM) as the first analytical step in the protocol. The PLM enables responders to characterize and identify suspicious powders based on their unique properties.
Cleveland response unit. In 2006, the Cleveland (OH) Fire Department was the first fire department to use a polarized light microscope in its emergency response vehicle as its prime analytical tool. In addition, to ensure personnel safety, it also was the first to house its microscope in a Class III Biological Safety Cabinet (BSC).
 Photo courtesy of Cleveland (OH) Fire Department. |
The Class III BSC/Microscope system, developed by The McCrone Group, is a negative-pressure glovebox system designed to house the microscope as well as protect the analysts from chemical hazards.
The custom-designed glovebox consists of three isolated chambers. The first chamber is the sample insertion/pass-through chamber, accessible to first responders outside the vehicle when the exterior door is closed (photo). A sample of a suspect material can be inserted directly into the Class III BSC from curbside without personnel having to enter the vehicle. This ensures that the integrity of the environment within the vehicle is maintained. The sample is then moved to the second chamber, where the sample is prepared for testing. The third chamber contains the microscope and is accessed from the second chamber through a sealed door. All sample preparations and analyses are performed in the safe, sealed confines of the Class III BSC.
The Cleveland vehicle is equipped with a modified Olympus BX51 polarized light microscope with fluorescence capabilities housed within the McCrone-designed glovebox. The microscope system also includes other accessories, including a specialized sample collection tool, a micro-transport device, and a specially designed haz-mat thermal microscope stage.
Sample collection and preparation. The suspect powder is collected using a standard protocol such as American Society for Testing and Materials (ASTM) E2458-06, Standard Practices for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces. The sample is then placed into the specially designed transport device. Once loaded, the lid on the microtransport device is closed and sealed, and the entire device is decontaminated. The transporter is then placed directly into the glovebox’s sample insertion chamber from the curbside of the vehicle. A first responder (analyst) then moves the transport device into the second chamber of the glovebox within the vehicle without contaminating it or compromising the integrity of the samples.
Sample analysis. After following the sequence above, the transport device containing the unknown samples is moved into the microscope chamber; the quartz dishes holding the samples are then removed and placed on the microscope stage for analysis. The polarized light microscope can rapidly show diagnostic characteristics of unknown powders, such as size, shape, and appearance unique to a particular compound. The first responder can use this information to identify the material or compare the information obtained using the microscope with the Atlas of Microscopic Particles, McCrone’s on-line atlas of more than 1,000 images of unknown substances.
Rapidly identifying suspicious powders at the site of a haz-mat incident enables first responders to better manage the incident and their responses. The polarized light microscope is the first step in the analysis protocol. The data collected complement data from other analytical instruments first responders use. Housing the microscope within a Class III BSC (glovebox) ensures safety for first responders (analysts inside the vehicle) while they analyze the suspicious powders.
CHARLES A. ZONA is a vice president of The McCrone Group in Westmont, Illinois, and dean of its College of Microscopy.
