|Laurie E. Locascio, Ph.D. chaired the Sampling Standard Task Group that developed this standard. She is the chief of the Biochemical Science Division at the National Institute of Standards and Technology and is the chair-elect of the American Chemical Society, Division of Analytical Chemistry.
A Speedy Response
The development, validation, and approval of ASTM International standard E 2458 was put on a fast track due to the urgency and obvious need for standards of this type. From start to finish, the standard was completed and adopted by both ASTM International and AOAC International in approximately one year. It is anticipated that future standards will address even more difficult and pressing issues associated with biological agent detection, including sampling for suspected biological contamination without visible powder present, sampling for biological cleanup and decontamination, and sampling to make decisions regarding clearance and safety following a known biological attack.
Department of Homeland Security and Committee E54 Lead the Way
Standards Developed for Visible Powder Collection
Following the 2001 anthrax attacks in Florida, Washington, D.C., and New York, N.Y., the number of suspected biological incidents increased so rapidly that response teams and the laboratories that could handle biological samples for the federal government were quickly overwhelmed with the sheer volume of work. Complicating that fact, at that time there were no coordinated, validated methods available for the response teams to follow when collecting biological samples for laboratory analysis. As a result, critical forensic samples of suspected biological agents were collected and sent to the laboratories in large dirty garbage bags, adhered to duct tape, and in various other unusual and unusable ways that made the samples impossible to analyze. In other cases, valuable samples were not collected and sent to the laboratory, but rather, were entirely consumed in the process of trying to make a field identification using on-site analytical methods or technologies.
In cases where there is a high risk of a biological incident, there are several competing considerations and viewpoints that come into play:
• Local decision-makers want immediate confirmation of a biological incident to determine how to respond;
• Law enforcement investigators need to have all evidence protected and preserved;
• Health officials need absolute and definitive confirmation regarding the biological agent in order to inform and protect the public, minimize exposure, and mitigate health risks.
It is understandable that pressure exerted on first responders by government decision-makers during these incidents can be high. Without standardized, validated methods in place, mistakes are more likely to be made in the field during sample acquisition, handling, and screening. In a federal government analysis of the anthrax response,1 it was noted that standards and validated methods were desperately needed for sample collection, detection, and analysis, and the Department of Homeland Security was charged to lead the way.
In mid-2005, following the distribution of the federal government report, the Department of Homeland Security’s Office of Standards called on other agencies to unite in an effort to develop standard validated methods that would become crucial in responding to a potential biological attack. The National Institute of Standards and Technology and AOAC International, partnering under the direction of the DHS, created a consortium of members representing key federal, state and local stakeholders including the Centers for Disease Control and Prevention’s National Institute of Occupational Safety and Health; the Federal Bureau of Investigation; DHS; the Department of Defense’s U.S. Army Medical Research Institute for Infectious Diseases, Dugway Proving Ground, Edgewood Chemical and Biological Center, the Environmental Protection Agency, the International Association of Fire Chiefs, the National Guard, the New York State Department of Health, NIST and many others to develop the first standard. A recently approved ASTM standard, developed by Committee E54 on Homeland Security Applications, is the first step toward the goal of developing a suite of standards designed to help the first responder community respond to a possible biological attack or biological accident.
Standard for Sample Collection of Visible Powders
ASTM Standard E 2458, Practices for Bulk Sample Collection and Swab Sample Collection of Visible Powders Suspected of Being Biological Agents from Nonporous Surfaces, describes methods for collecting and packaging visible powder samples that are suspected biological agents. Validation studies were organized by AOAC and conducted at Dugway Proving Ground under the direction of Bruce Harper. AOAC International, known for publishing the AOAC Official Methods, simultaneously approved and adopted the ASTM International standard, representing a unique opportunity to obtain broad consensus among standards organizations on issues related to homeland security.
This new standard provides guidance for the first responder on how to proceed when a powder that is a suspected biological agent is found on a hard surface such as a desktop, tile or wood floor, vinyl chair or stainless steel machinery. The sample collection standard procedure is performed after an initial risk assessment for explosive, radiological, and chemical hazard is conducted according to accepted procedures and regulations, and a visible powder is deemed a credible biological threat. The responder is first instructed to collect and package the bulk powder sample before using any prescreening technologies that might be available, such as field portable immunoassays, immunoassay tickets, or field portable polymerase chain reaction equipment.
The reasons for collecting the bulk sample before biological screening is performed may not be obvious to those collecting samples in the field who are under significant pressure to get an immediate answer to the question “Is this a real attack?” The standard is specifically written to ensure that a sufficient quantity of powder is collected and transported for definitive laboratory analysis even when a very small quantity is present. The importance given to acquiring and preserving as much powder as possible is based on three factors:
• Definitive identification and characterization of a biological agent by a Laboratory Response Network-approved laboratory is essential for guiding critical public health decisions regarding treatment and prophylaxis of potential victims.
• Significant quantities of powder are required for forensic analysis, which may be critical to the identification of a source or perpetrator and to the prevention of further attacks.
• On-site biological screening methods cannot provide the degree of certainty required for public health decisions, and have great potential for giving false negatives, particularly when the target analyte is either unknown or uncharacterized.
In essence, the requirement for accurate laboratory analysis supersedes the need to conduct presumptive field analysis (beyond basic stand-off characterization). If only one or the other is possible, the former must be chosen.
Demonstration of bulk powder sample collection method:
a. Step 1; b. Step 2; c. Step 3
How It’s Done
Bulk powder sample collection is performed using simple tools: a dry swab, laminated card, and a wide-mouth sealable plastic specimen container. Using the swab, the powder is gently pushed onto the laminated card, and the card and powder are placed together in the container and sealed. During validation trials, it was found that this step can be performed rapidly and effectively by trained hazmat teams so that the responders can move quickly to performing other procedures for containment and assessment of the contamination.
Following collection of the bulk powder sample, any residual powder may be used for on-site biological screening if the responders choose to do so. In validation studies using samples collected from the residual powder as prescribed in the sampling standard, it was found that the residual sample contained enough of the biological agent to effectively yield an accurate analysis using a validated on-site biological screening tool, or using a common microbiological technique to quantify the number of organisms (plate counts).
If the responder does not choose to perform on-site biological screening, or if there is additional residue left on the surface following biological screening, the first responder is instructed to pick up the remaining powder using a wet swab. In several published studies, the wet swab has been found to be the most effective instrument for picking up small samples of biological agents from smooth surfaces. Wet swab wiping, as prescribed in the ASTM standard, is recommended independently by several agencies, including CDC-published procedures.
In addition to the collection procedures, the ASTM standard also provides guidance for packaging all collected samples so that they can be delivered safely to a laboratory in the national response network (currently the Laboratory Response Network, or LRN) using appropriate chain of custody procedures.
This standard is the first of its kind for collection of suspected biological agents for homeland security and defense applications, and represents a good faith effort among all partners to promote safe and effective sample handling during a biological incident. As Dr. Bert Coursey, director of the DHS Office of Standards, points out, “The development of this ASTM standard represents an important step towards building consensus between the emergency responder communities and the federal agencies on national standards for responding to possible terrorists attacks.” //
1 GAO-05-493T Anthrax Detection: Agencies Need to Validate Sampling Activities in Order to Increase Confidence in Negative Results.