modeling


techniques. Toxicity


and


physical properties may also be assessed at this stage through the use of rapid, low-cost computer modeling. Tis initial computer modeling assessment is useful for comparing compounds and identifying potential areas of human and environmental health concern. Te modeling assessment is also valuable in prioritizing testing later in development.


As small quantities (i.e., fewer than 10 grams) of


the new substance become


available in the synthesis and testing phases, relatively low-cost in vitro assay techniques can be used to predict likely toxic endpoints, such as acute oral toxicity, aquatic toxicity and mutagenicity. Te researcher usually has down-selected to two or three possible candidates by this point in the development process.


Candidates chosen for further develop- ment and formulation will proceed to the demonstration and validation phase, involving the first, more definitive whole- animal testing such as acute oral toxicity studies (to determine the median lethal dose, LD50), 90-day oral


subchronic


studies or inhalation toxicity testing. Tus, longer-term studies take place only after considerable preliminary screening and assessment.


Te phased approach to toxicity assess- ment has enabled researchers to select more environmentally sustainable ener- getic materials for the 2.75-inch Hydra rocket, one of the most extensively used munitions in the Army, a significant source


of toxic constituents released


on training ranges and one of the most environmentally problematic munitions in its current configuration. Te M274 training warhead for the rocket con- tains perchlorate, and the M275 rocket motor propellant contains lead as a burn-rate modifier.


FIGURE 3


ASTM Standard E2552, “Standard Guide for Assessing the Environmental and Human Health Impacts of New Energetic Compounds,” is a useful tool with applicability well beyond the develop- ment of energetic materials. The standard calls for various types of toxicity testing, matched here with the various stages of development. (SOURCE: AIPH)


Te phased approach to environmental assessment was used during the effort to evaluate and replace the various com- ponents of the Hydra rocket, with the components now entering the final stages of RDT&E. New formulations were evaluated based on ESOH data, show- ing empirically that the new materials are more environmentally sustainable than the current ones.


Meanwhile, perchlorate-containing


simulators—the M115A2 Ground Burst Artillery and M116A1 artillery and hand grenade simulators, and the M117/M118/M119 family of booby trap simulators—were identified as one of the largest sources of potential perchlo- rate contamination on Army training ranges. In fact, in 1997, the Environ- mental Protection Agency ordered a training shutdown at the Massachusetts Military Reservation (MMR) and Camp Edwards because of perchlorate and other


munition-constituent contamination of the primary aquifer beneath MMR, the main source of drinking water for the residents of Cape Cod.


To maintain operations nate a source of and elimi- future environmental


contamination, OEP officials, in con- junction with the assistant chief of staff of


the Army for installation manage-


ment and the U.S. Army Environmental Command, initiated the perchlorate elimination program that continues to this day. OEP investigators developed environmentally benign substitutes for the perchlorate-based fuels in the simu- lators. Final formulations were selected based on performance, cost and poten- tial environmental impact, as evaluated using the ASTM process.


In a measure of the success of this program, a replacement for the M116 hand grenade simulator was approved for use at MMR


ASC.ARMY.MIL 55


ACQUISITION


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