Homeland Security Research

Research Highlights

The Pathogen Information Catalog (PI Cat) Tool to Support Dose-Response Assessments

Information derived from microbial dose-response assessment is being used to support risk-based cleanup goals

Figure 1. PI Cat Tool start-up screen for initial data population. Users begin with entering new data source information (e.g. report title, author, publication date) in the "Bookkeeping" form to assign the reference an identification number (RMID). The dose-response data and associated experimental details are then populated in the subsequent entry forms under the "Test and Product Data" form associated with the new RMID.

There are many challenges in assessing health risks from the exposure to microorganisms. Quality human dose-response data is limited or, in many cases, nonexistent. In order to recommend risk-based cleanup levels, as well as analytical detection limits and environmental decontamination efficacies, there is a need to characterize microbial dose-response relationships. EPA and the United States Army Public Health Command (Provisional) initiated a meta-analysis project to develop an innovative approach that re-evaluates historical experimental animal dose-response studies and extrapolates these data to more realistic estimates of human exposures.

To this end, the Pathogen Information Catalog (PI Cat) Tool was created using Microsoft® Access. This tool structures and organizes dose-response data with the corresponding experimental details, facilitating subsequent statistical analysis. Users can set up custom queries in Microsoft® Access or export their data into a spreadsheet format to facilitate any number of statistical comparisons for the populated data. For example, to determine a no adverse effect level (NOAEL), a query may be created to identify the occurrence and frequency of experimental dose groups that survived the challenge dose. Although the PI Cat Tool was originally developed to organize microbial inhalational exposure data, it is thought that the PI Cat Tool can be expanded and modified to address other exposure routes, as well as chemical and radiological agents of concern.

The available PI Cat Tool (without populated data) is composed of nine individual tables. These tables organize and link experimental details (parameters), dose level, and response data. Figure 1 shows the PI Cat Tool start-up screen for initial data input, and the following text provides a short description of each data table currently included in the database.

• Test Table:  Information pertaining to the experimental conditions of each test including parameters such as chamber size, environmental conditions (temperature, relative humidity, and season), delivery mechanism, detection equipment, etc.
• Test Product Table:  Information about the specific characteristics of the test products including details on preparation, source strength, decay rates, wet/dry products, treatments, etc.
• Particle Size Table:  Information on particle size, quantity recovered, aerosol sampler utilized.
• Lethal Dose Statistics Table:  Information on statistical dose-response relationships such as the lethal dose at 50% (LD₅₀) or probit slope values.
• Host Response Table:  Information regarding the test animals’ characteristics and responses to the exposures including data on species, body weight, calculated inhalational doses, breathing rates, etc.
• Regression Table:  Information on calculations and extrapolations performed during data population to estimate specific inhaled doses.
• Laboratory Analysis Table:  Details on the purpose of the performed tests and any statistical analyses conducted.
• Bookkeeping Table:  Particulars on the physical location of each report and basic experimental details (e.g., test name, date).
• Quality Assurance/Quality Control Table:  Information regarding subject matter expert reviews and data entry.

The U.S. Army Public Health Command (Provisional) has been formed from select missions of the U.S. Army Center for Health Promotion and Preventive Medicine and the U.S. Veterinary Command.