Chemistry International Vol. 21, No. 6, November 1999 1999, Vol. 21 No. 6 (November) .. 40th Council Highlights .. IUPAC: 2000 and Beyond .. 37th IUPAC Congress .. Chemistry in Today's Brazil .. News from IUPAC:    Biodegradation of    Chemical Warfare    Agents .. Other Societies .. New Books and Publications .. Provisional Recommendations .. Awards .. Conference Announcements .. Conferences Download the November issue in pdf format. (627K) Download the November cover in pdf format. (117K) CI Homepage

Chemistry International Vol. 21, No. 6 November 1999 News from IUPAC Biodegradation of Chemical Warfare Agents Newer CW Biodegradation Research Efforts Show Progress Several Approaches to Biodegrading Nerve Agents Other Microorganisms with CW Hydrolytic Enzymes Identified Strategies for Degrading Bulk Agents Biodegrading the Blistering Agents HD and HT Strategies for Degrading Organo-arsenical Blistering Agents Unanswered CW Degradation Questions Require Further Research Acknowledgments Suggested Reading Strategies for Degrading Organo-arsenical Blistering Agents Although substantial progress has been made toward biodegrading other CW agents, treating the arsenic-containing agents such as adamsite, lewisite, and mustard-lewisite mixtures is problematic because arsenic is toxic. To overcome this problem, Alexander Boronin and his colleagues at the Institute of Biochemistry and Physiology of Microorganisms in Pushchino, Russia developed a three-stage, laboratory-scale process for destroying arsenic-containing CW agents. For example, their process for treating lewisite entails initial hydrolysis to form 2-chlorovinyl arsine oxide (CAO). Because the remaining high arsenic inhibits further biodegradation, they treat the mixture by electrolysis and electrocoagulation (EC), yielding formate, acetate, and arsenous and arsenic acids; subsequently, during the EC step, arsenic precipitates from solution, reducing its concentration by four orders of magnitude. The remaining organic acids are mineralized in a fluidized bed reactor using a natural consortium of microorganisms immobilized on activated carbon. A similar approach is also effective in destroying mustard-lewisite mixture (MLM) and adamsite, according to Boronin. Destroying the arsenic-containing CW agents in the Russian stockpile will generate thousands of tons of arsenic. Although this material might prove useful in the microelectronics, optics, and solar power industries, safe storage facilities are needed. Victor Petrov and coworkers at the Russian Institute of Applied Mechanics suggest that converting free arsenic into arsenic sulfide provides a means for safely storing this bulk material. Unanswered CW Degradation Questions Require Further Research Despite the progress in developing procedures for destroying CW agents, significant gaps in our knowledge of these compounds limit development of alternative technologies and slow progress on destroying them, according to Joseph Bunnett, an organic chemist at the University of California at Santa Cruz, who has served on a variety of international scientific panels examining CW agent destruction. For example, in 1982, officials in the U.S. Army identified incineration as the best technology to use for this purpose, he points out. Yet, 16 years later, complete reliance on this incineration-based "chemical demilitarization" program has resulted in little destruction of agents and remains stymied because of strong political opposition to incineration. Citizen opposition to incineration stems in part from a widely held belief that small amounts of intact chemical warfare (CW) agents will be released to accumulate as a "toxic load" in the environment. However, although traces of CW agents released into the atmosphere are likely to be rapidly destroyed by photolysis, hydrolysis, and oxidation, little if any research has been done to document the atmospheric half-lives of most CW agents, according to Bunnett. Several major CW munitions stockpiles need to be destroyed: the Russian stockpile, most of the U.S. stockpile, the Japanese CW munitions abandoned in China in 1945, and the German munitions that were dumped into the Baltic Sea. Although biodegradation could play a role in destroying these chemical agents, both fundamental and practical questions need to be addressed before even successful laboratory-scale degradative processes can be taken into field-scale use. Yet, unless the pace of research accelerates to meet the deadlines specified by the Chemical Weapons Convention, current gaps in knowledge will sharply limit any use of this promising technology. Two critical questions need to be addressed soon. One is how well laboratory-scale procedures will perform under field conditions, particularly in settings where partly degraded materials contain a mix of chemical contaminants, as well as an ill-defined range of indigenous microorganisms. Researchers, who typically have tested their processes only on highly purified starting materials, will need access to CW agents from munition stockpiles to see if biodegradative processes will work on complex mixtures. A second, more fundamental question to address is whether new microbial consortia can be selected or developed that are better suited for carrying out biodegradation of CW agents. One research approach will be to conduct a comprehensive screening of organisms from anaerobic sites or from highly acidic, hypersaline, or metal-contaminated aerobic environments. In conducting this research, it is crucial that international collaborative efforts be continued and expanded. Although individual nations naturally have a domestic focus when deciding on national research priorities, chemical weapons are an international legacy, and their inappropriate disposal by any nation may have long-lasting consequences. By sharing ideas and resources, the international community stands the best chance of developing and implementing appropriate technology worldwide to prevent further contamination by these dangerous compounds. Acknowledgments The IUPAC Ad Hoc Committee on Chemical Weapons Destruction Technologies sponsored this review. We gratefully acknowledge NATO for funding Russian-American linkage grants and for funding the Advanced Research Workshop on Chemical and Biological Technologies for the Detection, Destruction, and Decontamination of Chemical Warfare Agents (12-15 May 1996, Russia). We thank Dr. Steve Harvey for his careful reading of the manuscript and Dr. Joe DeFrank for his suggestions and for calculating the values shown in Table 1. Suggested Reading Cheng, T.C., L. Liu, B. Wang, J. Wu, J. J. DeFrank, D. M. Anderson, V. K. Rastogi, and A. B. Hamilton. 1997. Nucleotide sequence of a gene encoding an organophosphorus nerve agentdegrading enzyme from Alteromonas haloplanktis. J. Ind. Microbiol. Biotechnol. 18:49-55. DeFrank, J. J., and T.C. Cheng. 1991. Purification and properties of an organophosphorus acid anhydrolase from a halophilic bacterial isolate. J. Bacteriol. 173:1938-1943. Harvey, S. P., L. L. Szafraniec, W. T. Beaudry, D. K. Rohrbaugh, M. V. Haley, and C. W. Kurnas. 1997. Sequencing batch reactor biodegradation of HT: a detailed comparison of the results of two different approaches. U.S. Army Armament Munitions Chemical Command. ERDECTR, in press. Kolakowski, J. E., J. J. DeFrank, S. P. Harvey, L. L. Szafraniec, W. T. Beaudry, K. Lai, and J. R. Wild. 1997. Enzymatic hydrolysis of the chemical warfare agent VX and its neurotoxic analogues by organophosphorus hydrolase. Biocatal. Biotransform. 15:297-312. NATO, Scientific and Environmental Affairs Division. Abstracts of the advanced research workshop on chemical and biological technologies for the detection, destruction, and decontamination of chemical warfare agents (May 12-15, 1996, Russia). Rainina, E., J.W. Kim, E. Efremenko, C. R. Engler, and J. R. Wild. 1997. Degradation of thiodiglycol, the hydrolysis product of sulfur mustard, with bacteria immobilized within poly(vinyl) alcohol cryogel. Biotechnol. Lett., in press. U.S. Congress, Office of Technology Assessment. Disposal of chemical weapons: alternative technologiesbackground paper, OTABP095, June 1992. U.S. Government Printing Office, Washington, D.C. U.S. General Accounting Office. Chemical weapons disposal: plans for nonstockpile chemical warfare materiel can be improved, GAO/NSIAD9555, Dec. 1994. U.S. Government Printing Office, Washington, D.C. U.S. General Accounting Office. Chemical weapons and materiel: key factors affecting disposal costs and schedule, GAO/NSIAD9718, Feb. 1997. U.S. Government Printing Office, Washington, D.C. Yang, Y.C., L. L. Szafraniec, W. T. Beaudry, and J. R. Ward. 1988. Kinetics and mechanism of the hydrolysis of 2chloroethyl sulfides. J. Org. Chem. 53:3293-3297.

IUPAC

News and Notices - Organizations and People - Standing Committees Divisions - Projects - Reports - Publications - Symposia - AMP - Links Page last modified 1 October 2001. Copyright © 1999-2001 International Union of Pure and Applied Chemistry. Questions or comments about IUPAC, please contact the Secretariat. Questions regarding the website, please contact [email protected]