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New Methodology to Assess Health and Environmental Impact of Flame Resistant (FR) Textiles
Dr. Timothy Lawton | US Army Natick Soldier Research Development and Engineering Center (NSRDEC)
Little is known about the operational exposure risks for the Warfighter from off-gassing from flame resistant (FR) uniforms during a fire event. It has been shown that Nomex, when heated to temperatures from 150 to 370°C in air, can evolve toxic chemicals such as benzene, aniline, diamino benzene, benzoic acid, benzonitrile, dicyanobenzene, diphenylamine, and cyanophenylbenzene. However, for newer FR fabrics that incorporate ammonium polyphosphate, the National Research Council could identify only one inhalation toxicity study for fabrics incorporating this material.
The objective of this effort is to develop a method for rating fibers, textiles, and impregnated fabrics based upon the toxicity and volume of hazardous chemicals evolved during combustion. This will be done utilizing techniques available to researchers and designers who develop, specify, and acquire FR uniforms for the military. The ratings system will take into consideration the types and relative amounts of these products and assign a score to the material. The ratings developed during this project are not meant to define the absolute toxicity or hazard of the materials; it will rate current and future materials against each other. The results may be used to help guide Department of Defense (DoD) acquisition personnel as well as researchers developing novel FR materials.
The approach will involve three major efforts. The first will be to develop the techniques required to assess toxic combustion products. These will be developed using instrumentation available to DoD personnel researching and selecting materials. Specifically the research team plans to utilize pyrolysis gas chromatography with mass spectroscopy (PyGCMS) and thermogravimetric analysis with mass spectroscopy (TGA-MS) in order to determine the identity and relative amount of these products. In parallel, a method will be prepared to assign a toxic combustion product rating to fabrics based on the results from this testing. This rating system will consider the types and relative amounts of these products and assign a score to the fabric based on the acute toxicity rating of the compounds as defined by the Globally Harmonized System of Classification and Labeling of Chemicals. Finally, many of the standard FR materials utilized within the DoD will be tested and a database with ratings for each of these materials will be prepared. This database will be made available to the Army acquisition and research personnel for its potential use as a tool to guide the selection and development of FR materials.
Successful completion of this effort will yield a test protocol and rating system for FR fabrics based on toxic combustion products, enabling current and developmental materials to be easily compared based on their potential impact. This will help guide policy makers and acquisition personnel when selecting FR materials for given applications and enable DoD and industry researchers to utilize this as one of the factors for further materials development and acceptance.