Presented June 02, 2016- Presentation Slides
“Development of Environmental Health Criteria for Insensitive Munitions” by Dr. Mark S. Johnson
New insensitive energetic formulations are being developed to improve soldier survivability. Some components of these new formulations, such as 2,4-dinitroanisole (DNAN), nitroguanidine (NQ) and 3-nitro-1,2,4-triazol-5-one (nitrotriazalone (NTO)), have limited toxicity information and possess some chemical properties that suggest environmental sustainability could be an issue. This project involved reproductive/developmental tests using NTO in rodent, avian and amphibian models, and acute and subchronic toxicity tests using DNAN in aquatic animal models in a controlled laboratory environment to assist the development of safe exposure benchmarks to support environmental decision making. Rodents were exposed to NTO through drinking water in an extended one-generation design to determine probability for reproductive and/or developmental effects to subsequent generations. Japanese quail were exposed by gavage to NTO in water in a similar extended generational design. NTO was also tested in frogs to understand the probability for effects to a sentinel species within sensitive life stages. Following hatching, larvae (tadpoles) of Northern leopard frogs (Lithobates pipiens) were exposed to NTO until development. Studies were also conducted in aquatic species (Pimphales promelas, Ceriodaphnia dubia) in acute and chronic exposure designs. Results and implications of these studies were discussed.
“Dissolution of NTO, DNAN and Insensitive Munitions Formulations and Their Fates in Soils” by Dr. Katerina Dontsova
The objective of this project was to measure the dissolution, photodegradation and soil adsorption properties of DNAN, NTO and insensitive munitions formulations that contain them (IMX-101, IMX-104, and PAX-21) to determine their environmental fate. Particles of DNAN, NTO, IM formulations and detonation residues were characterized, and their dissolution and phototransformation were measured when exposed to simulated and natural rainfall and light. Particles were imaged using X-ray microtomography to determine their 3D structure before and after dissolution. Data from these efforts was used to model the dissolution mechanics of DNAN and NTO and how these change when the compounds are in formulations. Adsorption and transformation of IM compounds in a range of soils was also determined to identify soil properties that influence soil interactions. Together, these data are used to develop and validate the predictive capability of a mathematical model (HYDRUS-1D) for simulating the environmental fate of IM explosives. This project addresses DoD need for better predicting IM dissolution, photodegradation, soils interactions, data critical to determining exposure potential, and, consequently, risk.
“Biodegradation of Insensitive Munitions Compound NTO to Mineral Products via 3-amino-1,2,4-triazol-5-one (ATO) as the Central Intermediate” by Dr. Jim A. Field
Very little is known about the environmental fate of NTO. NTO may enter soil, groundwater and surface water via activity on firing ranges and through discharges of waste effluents at munitions production facilities. Bacteria have been shown to degrade and biotransform nitroaromatic compounds, and biotransformations catalyzing the reduction of nitro-groups or demethylation of methoxy groups have been reported to create reactive intermediates that are subject to oxidative coupling and formation of bound residue. In order to better understand the environmental fate of NTO, this project evaluated the interaction of biological and abiotic processes in soil that collectively contribute to their conversion and attenuation under a range of soil conditions. Studies showed that NTO is readily reduced under anaerobic conditions in soil to an amine-containing daughter product, ATO. The successful conversion of NTO to ATO under anaerobic conditions required the addition of electron donating co-substrates to the soil, such as hydrogen gas or pyruvate. ATO was not further metabolized under anaerobic conditions, but under aerobic conditions, microorganisms in some soils are able to biodegrade ATO. Project results taken as a whole indicate that a sequence of reductive and oxidative events can convert NTO to environmentally-benign mineral end products.
Dr. Mark S. Johnson is the Director of Toxicology at the U.S. Army Public Health Center, Aberdeen Proving Ground, Maryland. He has worked extensively on evaluating the toxicity of military unique compounds and developing and evaluating sensitive indicators of stress (e.g., immunotoxicity) for use in field applications and toxicity testing. He has broad experience in risk assessment and has developed and tested new methods on improving exposure/effects relationships. His current work involves the development of a phased approach to gather toxicity data for new compounds under development (ASTM E-2552). Other work has included the development of a process to derive toxicity reference values for terrestrial wildlife. Dr. Johnson has authored over 100 peer-reviewed publications, book chapters and technical reports. He has been a member of Society of Environmental Toxicology and Chemistry (SETAC) since 1997 and a member of Society of Toxicology (SOT) since 2009. Within SETAC, Dr. Johnson is a Steering Group Member of the Wildlife Toxicology World Advisory Group, vice-chair of the Ecological Risk Assessment World Advisory Group, and a member of the Science Committee for SETAC North America. He is the Chair of the Tri-Service Toxicology Consortium (TSTC), Steering Committee Chair of the Joint Army-Navy-NASA-Air Force (JANNAF) Propulsion Committee, Subcommittee on Safety and Environmental Protection, and the past chair of the Terrestrial Toxicity Subcommittee of the Biological Fate and Effects Committee of the American Society for Testing and Materials (ASTM). He is also the current President of the American Board of Toxicology (ABT).
Dr. Katerina Dontsova is an Associate Research Professor at the University of Arizona in Tuscon. Dr. Dontsova’s current work, started in 2012, is sponsored by SERDP and focuses on insensitive munitions. She and her collaborators study dissolution of insensitive munitions formulations, phototransformation of their constituents in solid and dissolved form, as well as their interactions with soils, such as adsorption and phototransformation. Previously, she designed and performed multiple studies that examined fate and transport of energetic compounds in soils, including traditional explosives and propellants. She employs numerical modelling to quantitatively characterize dissolution, adsorption and transformation of these compounds. Dr. Dontsova authored and co-authored multiple publications that examine the fate of munitions in soils. She graduated from the Ukrainian Agricultural University in Kyiv in 1995 with a degree in soil science, and completed her master’s (1998) and doctoral (2002) degrees in soil chemistry at Purdue University.
Dr. James Field is a Professor at the Department of Chemical and Environmental Engineering at the University of Arizona, Tucson. In 2014, he received a 50% appointment as Assistant Dean to the College of Engineering, responsible for graduate education. Prior to that, Dr. Field was an Associate Professor and Department Head for five years. From 1992 to 2000, he was assistant professor in a combined appointment with the Department of Environmental Technology and the Division of Industrial Microbiology. Dr. Field conducts research in the areas of bioremediation, biotransformation and biodegradation of hazardous environmental contaminants. Among his current topics is the environmental fate of the insensitive munitions, NTO and DNAN. Dr. Field has published 245 peer-reviewed journal publications which collectively have been cited more than 12,300 times. He has published 10 peer-reviewed journal articles on the biotransformation/biodegradability of DNAN and NTO. He obtained his bachelor’s and master’s degrees from the Virginia Polytechnic Institute (Virginia Tech) and his doctoral degree from the Department of Environmental Technology at Wageningen University, The Netherlands.