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DoD experienced threats to range sustainability and effective military training, decreased access to resources, and potential increases in weapon system costs — all from a draft risk assessment that was the subject of significant scientific debate. The perchlorate experience highlights the need for process reform to ensure that agency actions on emerging contaminants, achieve real public benefits without unintended adverse impacts on national security.

Historical compliance-based risk management strategies have proven insufficient to balance compliance with operational mission requirements. A reactive approach that limits itself to complying with regulations and standards after they are developed leaves little to no room for nimbly addressing new, unregulated contaminants and may result in financial and operational costs that are not supported by commensurate human health or environmental benefit. Significant changes in risk assessment policy and practice, including the strategic investment and use of chemical and site risk assessments, are required to transform a regulatory compliance-based environmental and occupational health management strategy into an operational capability/asset management strategy. DoD’s risk assessment policies require review and revision to ensure that DoD programs and service components cost-effectively assess the life-cycle risks posed by emerging chemicals to operational requirements. Such approaches can lead to both short- and long-term decreases in DoD’s costs of operating responsibly with respect to environment, safety and occupational health and to minimize cleanup costs.

The field of microbial perchlorate reduction has clearly advanced significantly in a very short period from a poorly understood metabolism to a burgeoning scientific field of discovery. As outlined above, there is now a much greater appreciation of the microbiology involved and the application of the knowledge to the successful treatment of contaminated environments. Overall, the future is promising even though research in this field is still in its infancy. Nothing is known of the evolutionary root of this metabolism. From a biogeochemical perspective, a better understanding of how perchlorate is formed in the natural environment and what geochemical conditions are required for its formation might give some insight into plotting the metabolism against a realistic evolutionary timeline. From a microbial perspective, it will be important to look for this metabolism in more extreme environments such as hypersaline or hyperthermophilic environments to obtain DPRB isolates across a broader phylogeny to establish a broad-base molecular chronometer. With the development of this field comes a better understanding of the ideal electron donors available and the individual factors which truly control the activity of the these organisms in-situ allowing for the design of more effective and robust enhanced in situ bioremediation technologies.

The identification and analysis of the genes encoding perchlorate reductase and chlorite dismutase has provided not only a building block for pathway understanding, but has also provided a tool for bioremediative and phylogenetic studies. On-going genome sequencing will further facilitate transcriptional profiling under perchlorate-reducing conditions via microarray analyses. This analysis will give a more inclusive look into transcriptional expression patterns associated with the perchlorate metabolism. While further advancements in the genetic analysis of perchlorate-reducing bacteria continue, the recent development of a genetic system in will provide an invaluable tool for corroborating microarray results and solidifying hypotheses regarding microbial perchlorate metabolism.

The frequency of detection of perchlorate impacts to soil, groundwater and surface water, unrelated to military activities, is likely to increase as water utilities analyze for this constituent as part of their UCMR monitoring programs. Based on emerging product and process information, perchlorate is present (intentionally or not) in many more products and processes than initially understood. Furthermore, evidence exists that perchlorate can be formed naturally in evaporate deposits and through atmospheric mechanisms.

The U.S. DOD, NASA and related defense contractors are likely to be the most significant domestic users of perchlorate in North America, and as such, a significant percentage of identified groundwater perchlorate impacts are attributable to DOD, NASA, and related defense contractor facilities. However, cases exist, and many more are likely to surface, where perchlorate impacts result from combinations of military, non-military, and/or natural inputs.

DoD experienced threats to range sustainability and effective military training, decreased access to resources, and potential increases in weapon system costs — all from a draft risk assessment that was the subject of significant scientific debate. The perchlorate experience highlights the need for process reform to ensure that agency actions on emerging contaminants, achieve real public benefits without unintended adverse impacts on national security.

Historical compliance-based risk management strategies have proven insufficient to balance compliance with operational mission requirements. A reactive approach that limits itself to complying with regulations and standards after they are developed leaves little to no room for nimbly addressing new, unregulated contaminants and may result in financial and operational costs that are not supported by commensurate human health or environmental benefit. Significant changes in risk assessment policy and practice, including the strategic investment and use of chemical and site risk assessments, are required to transform a regulatory compliance-based environmental and occupational health management strategy into an operational capability/asset management strategy. DoD’s risk assessment policies require review and revision to ensure that DoD programs and service components cost-effectively assess the life-cycle risks posed by emerging chemicals to operational requirements. Such approaches can lead to both short- and long-term decreases in DoD’s costs of operating responsibly with respect to environment, safety and occupational health and to minimize cleanup costs.

This work provides a proof-of-principle demonstration that Ti(III)-catalyzed electrochemical techniques could potentially be used for reduction of ClO in small waste streams, such as the regeneration of selective anion-exchange resins that are loaded with ClO. The technique may not be directly applied for the treatment of large volumes of ClO-contaminated water at relatively low concentrations because of its slow reaction kinetics and the use of chemical reagents. Further studies are needed to optimize the reaction conditions in order to achieve a complete reduction of ClO and the regeneration of spent resin beds. Alternative complexing and reducing agents may be used to enhance the reaction completeness of sorbed ClO in the resin and to overcome potential clogging of micropores within the resin beads resulting from the precipitation of TiO.

The field of microbial perchlorate reduction has clearly advanced significantly in a very short period from a poorly understood metabolism to a burgeoning scientific field of discovery. As outlined above, there is now a much greater appreciation of the microbiology involved and the application of the knowledge to the successful treatment of contaminated environments. Overall, the future is promising even though research in this field is still in its infancy. Nothing is known of the evolutionary root of this metabolism. From a biogeochemical perspective, a better understanding of how perchlorate is formed in the natural environment and what geochemical conditions are required for its formation might give some insight into plotting the metabolism against a realistic evolutionary timeline. From a microbial perspective, it will be important to look for this metabolism in more extreme environments such as hypersaline or hyperthermophilic environments to obtain DPRB isolates across a broader phylogeny to establish a broad-base molecular chronometer. With the development of this field comes a better understanding of the ideal electron donors available and the individual factors which truly control the activity of the these organisms in-situ allowing for the design of more effective and robust enhanced in situ bioremediation technologies.