It was not until late 2007 that the Army began issuing FR Army Combat Uniforms (ACUs) to dismounted soldiers being deployed to Afghanistan and Iraq to reduce burn injuries when IEDs became a major threat. In 2009, the FR Army Combat Shirt was issued to provide soldiers with improved comfort as well as FR protection. Recently, Congress recommended that all military uniforms have FR capabilities. Unlike Nomex, which is an inherently flame-resistant fiber – the flame resistance is part of the polymer chemistry – current FR systems (clothing and equipment) focus on chemically treated fibers or fabrics, or the blending of inherently FR fibers with chemically treated fibers/yarns. Current FR materials often include polybrominated diphenyl ethers (PBDE), which have been shown to persist in the environment and bioaccumulate in the food chain.
FR chemicals are “activated” by intense heat producing char and gases which inhibit combustion. Flame retardant products may represent a health and environmental hazard as the result of gaseous acidic combustion products - hydrogen chloride, hydrogen cyanide, nitric oxides, hydrogen sulfur oxides, and other combustion constituents being generated and released in the form of gasses and/or particulates. Little is known about the operational exposure risks for the Warfighter from off-gassing from FR materials during a fire event. At combustion temperatures (800°F), Nomex releases carbon dioxide, carbon monoxide, and sometimes traces of hydrogen cyanide and nitrogen oxides. Under less stringent heating conditions (below 800°F), Nomex degrades very slowly, releasing small quantities of organic compounds. The investigation into the health and immediate environmental issues associated with both Nomex and FR-treated materials merits further study, as well as their lasting impact on the environment such as disposal and biodegradability of these materials.
Industry is shifting away from brominated chemicals and is moving towards organophosphate flame retardants (OPFRs), such as triphenyl phosphate (TPHP), tris (1,3 dichloro-2-propyl) phosphate (TDCIPP) and tris (2-chloroethyl)phosphate (TCEP). However, there is evidence that inhalation exposure may be greater for OPFRs than for the PBDEs. Preliminary studies have found OPFRs transfer from products to users’ hands and leach from products during normal product use.
Mosquito-borne diseases are a significant health concern with over two billion people, primarily in tropical countries, at risk for diseases such as malaria, hemorrhagic dengue and yellow fevers, and filariasis (elephantiasis). Given the U.S. Military’s presence in tropical regions, this risk is a considerable threat that could have adverse effects on personal health of the Warfighter, and negative implications for military operations. There are a number of synthetic chemicals that are currently used as insect repellents, with N, N-diethyl-m-toluamide (DEET) being commonly used for civilian and military insect repellent due to effectiveness at repelling mosquitoes and permethrin as a contact insecticide. Despite the wide-spread use of DEET, there are compelling studies that show negative health implications as a result of exposure to DEET. In humans, DEET can be irritating to skin and mucosal surfaces; in addition, toxic encephalopathy has been reported following skin exposure and ingestion. Studies have also shown that a small proportion of mosquitoes is not repelled by DEET, indicating that mosquitoes are beginning to display a resistance to the repellant.
Military personnel training in endemic areas may be instructed to treat their uniforms with permethrin. Currently, permethrin is only approved for use on outer garments, because direct exposure to permethrin can cause skin irritation and rash. It is also persistent in the environment and is toxic to multiple aquatic and terrestrial species, including fish (fresh and saltwater), bees and other beneficial insects and birds. Permethrin is currently the only insecticide that is approved by the EPA for use as a textile treatment and has been shown to persist on the textile even after extended laundering. Durability and replenishing spatial repellents (even in the case of DEET, since treatment must be reapplied multiple times for continued efficacy) has been an issue for the deployed Warfighter. Once applied, the spatial repellent is active and during subsequent laundering cycles would be reactivated, efficacy would be improved with every laundering. In the past, laundering has been the major reason for loss of repellent efficacy (especially in the case of permethrin treated ACUs). Wash-in spatial repellents treatments or direct incorporation of spatial repellants into the fibers could then be applied to all deployed Warfighters’ garments providing protection against vector-borne illnesses and diseases. Additionally, synthetic chemicals used for control of vectors are causing irreversible damage to the ecosystem, as some of them are non-degradable in nature.
Combat clothing such as flight suits and gloves should be manufactured from novel sustainable fiber blend fabrics and evaluated by the military user community for durability, comfort and overall performance in an operational environment. Legacy flight suits and the Army Combat Glove are fabricated from aramid fibers which are solution spun. Replacing half of those fibers with green and sustainable fiber could reduce military use of aramid fiber by up to 50 percent for these items.
The Weapons Systems and Platforms Program Area supports development of technologies and processes that are associated with the manufacture, operations, and maintenance of military equipment, weaponry, and munitions. These life cycle stages of a system may impact workers, the environment, and surrounding communities. Increasing the sustainability of these systems offers opportunities to identify and manage these impacts to lower associated life cycle costs and improve mission readiness. DoD’s Sustainability Analysis uses a life cycle approach to evaluate potential impacts associated with costs, ecosystem quality, human health, and resource availability