Since the terror attacks of September 11, 2001, policymakers have been attempting to decreasethe vulnerability of the United States to the terrorist use of weapons of mass destruction. This reportdescribes the different types of high-threat chemical agents. It also discusses their availability,treatment, and detection, and possible policy approaches to reducing the threat posed by them. Terrorist use of chemical agents is widely believed to be an event that has low probability, but potentially high consequences. While there is still debate over whether terrorist groups have anincreased interest in chemical acquisition and use, the domestic vulnerability of the United Statesto chemical attack remains high. Policy approaches to reducing chemical vulnerability havegenerally treated chemical agents as a group, rather than addressing specific agents. Additionally,military and civilian chemical agent detection have developed with little coordination, so thatcivilian toxic industrial chemical kits and military chemical weapons detectors having varyingsensitivities and detection capabilities. Treatments for chemical exposure vary as well, dependingon the type of chemical, and so must be addressed on a chemical by chemical basis. Becausecomparatively few individuals have been exposed to modern chemical weapons, practical experiencein treatment of chemical casualties is limited, especially among civilian health care providers. Whilenational efforts to reduce vulnerability to terrorist chemical agent use continue, it is not clear whetherspecific agents that pose the greatest danger are being adequately addressed as general vulnerabilitiesare being reduced. High-threat chemical agents are, for the purpose of this report, chemicals posing exceptionallethality and danger to humans. (1) Some may havebeen developed and used for commercial purposes. Others may have been used or developed by militaries as chemical weapons. Different chemical weapons cause different symptoms in and injuries to their victims. Because of this range of potential symptoms, it can be difficult to know what treatment will be most effectivefor a victim until the chemical or chemical type has been identified. Also, chemical weapons mayproduce their effects by different exposure routes, for example, by skin contact or by inhalation. Asa consequence, depending on what chemical is encountered, different protective equipment must beemployed; for example, a gas mask alone is not sufficient protection against chemicals which candamage through skin contact. Military planners categorize such agents into four classes: nerve, blister, choking, and bloodagents. (2) This categorization groups chemicals bythe effects they cause to those exposed to them. While the nerve and blister agents are predominantly only manufactured and used by militaries asweapons, both choking agents and blood agents include chemicals widely used in industrialprocesses. Chemical weapons affecting the nervous system are called nerve agents. Nerve agents do not occur naturally. Rather, they are manmade compounds that require manufacture and isolation forhigh toxicity and purity. Most nerve agents belong to a group of chemicals called organophosphates. Organophosphates have a wide range of toxicity, and some are commercially employed asinsecticides, though these are significantly less toxic than those developed as chemical weapons. (3) Nerve agents are mainly liquids. Production. The first nerve agent developed for military use, called Tabun or GA, was made in Germany in the 1930s. (4) Following this discovery,a series of nerve agents similar to Tabun were developed. This series, known as the G-series, includethe weapons Sarin (GB) and Soman (GD). In the late 1940s, another series of nerve agents, theV-series, was invented in England. Both the British and the United States chemical weaponsprograms investigated these compounds. The United States manufactured and stockpiled VX. (5) Arelated compound, V-gas, was manufactured and stockpiled by the Soviet Union. Military use ofnerve agents has been rare. Nerve agents were not used during World War I or World War II. During the 1980 -- 1988 Iran-Iraq war, Iraq reportedly used nerve agents against Iranian troops andlater against members of its Kurdish population in northern Iraq. (6) National chemical weapons programs have produced nerve agents for decades. The technological barriers for a terrorist group to synthesize these agents might be overcome by usingcommercially available equipment, though there would be appreciable danger to the manufacturerdue to the extreme toxicity of these compounds. Nerve agent production requires the use of toxicchemicals during synthesis and specialized equipment to contain the nerve agent produced. Of thenerve agents, VX has been identified as the most difficult to manufacture. (7) Effects. Nerve agents are extremely dangerous and can enter the body through the lungs or by skin contact, though for the G-series nerve agents, theinhalation toxicity is significantly greater than the dermal toxicity. Of the nerve agents, VX is themost deadly and Tabun is the least deadly, though all are exceedingly toxic. Nerve agents interfere with the nervous system, causing overstimulation of muscles. Victims may suffer nausea and weakness and possibly convulsions and spasms. At high concentration, lossof muscle control, nervous system irregularities, and death may occur. The action of nerve agentscan be irreversible if victims are not quickly treated. Treatment. Two drugs, atropine and pralidoxime chloride, are used as antidotes for nerve agents. (8) Atropine prevents muscle spasm and allows thebody time to clear the nerve agent. Pralidoxime chloride limits the effects of nerve agent exposureby reversing the agent's action. Both of these drugs were issued to U.S. troops during the PersianGulf War in the form of an antidote kit called the Mark I. Diazepam (Valium) may be used to reduceconvulsions and seizures brought on by exposure to nerve agents. (9) The treatment window for nerve agent exposure is agent-dependent. Some agents quickly and irreversibly react to enzymes within the body, while others require a much longer time topermanently bind to these enzymes. The most effective treatment occurs before such permanentbinding has taken place. Soman, for example, is permanently bound within minutes, while Tabunis not and can be treated up to several hours after exposure. Prophylactic use of some compounds,such as pyridostigmine bromide, may create a larger window for effective treatments for some nerveagents. (10) Blister agents, also known as vesicants, are chemicals that cause painful blistering of the skin. While such blistering is not generally lethal, the excruciating pain caused by blister agents requiresfull body protection against these chemicals. Militarily, blister agents produce casualties and reducethe combat effectiveness of opposing troops by requiring them to wear bulky protective equipment. (11) The most common blister agent is mustard agents, which includes nitrogen- and sulfur-basedcompounds. Mustard agents are oily liquids which range in color from very pale yellow to darkbrown, depending on the type and purity, and have a faint odor of mustard, onion or garlic. (12) Theseliquids evaporate quickly, and their vapors are also injurious. Blister agents are not naturally occurring compounds. Mustard agents, for example, were first developed in the late 1800s. During World War I, both sides in the conflict used these weaponsagainst their enemies, and the mustard-type blister agent produced the greatest number of chemicalcasualties during World War I, though fewer than 5% of these casualties died. Many countries havestockpiled blister agents in their chemical weapon inventories. Mustard agent was also reportedlyused in the Iran-Iraq war. (13) The United States iscurrently destroying its stockpile of blister agents. Production. Production of blister agents is considered less complicated than that of nerve agents. (14) Likenerve agents, it requires the use of some toxicchemicals and specialized equipment to contain the agent produced. The most common blisteragents have many different methods for their production published in the open literature. (15) Effects. Blister agents can enter the body through the lungs or by contact with the skin or eyes. Some can penetrate through normal clothing material,causing burns in areas that were covered by cloth. While blister agents react quickly upon skincontact, their symptoms may be delayed. In the case of mustard agent, damage occurs within 1-2minutes of exposure, but symptoms do not manifest for several hours. (16) As even low concentrationof vaporized blister agent quickly causes damage, it is unlikely that agents will be removed from theskin prior to injury. The initial symptoms of blister agent exposure are a reddening of the skin, resembling sunburn, combined with pain in the effected area. Swelling, blisters, and lesions may then develop dependingon the degree of exposure. Systemic symptoms such as malaise, vomiting, and fever may alsodevelop in extreme cases. (17) Exposure to largeamounts of liquid mustard agent may prove fatal. (18) The eyes are also very sensitive to blister agents. At high vapor exposures, great pain, corneal damage, and scarring between the iris and lens may occur. The most severe eye damage is oftencaused by liquid agent, either from contact with airborne droplets or by self-contamination of theeyes from contaminated clothing or body parts. (19) Victims inhaling blister agents may suffer damage to their lungs. While a single, low-level exposure will likely produce only temporary impairment, high concentrations or repeated exposuresmay cause permanent damage. Inhalation victims may have symptoms ranging from mild bronchitisto blistering of the lungs. (20) Treatment. Damage from blister agent exposure, lesions and other skin irritations, is symptomatically treated. Hospitalization may be required forrespiratory tract injuries. Victims who suffer severe lung damage may require mechanicalventilation. An additional complication after exposure to large amounts of mustard agent is ageneral weakening of the whole immune system. Because of these systemic effects, specialprecautions must be taken against opportunistic infections in the case of exposure to highconcentration of mustard agent. (21) Chemicals that act on the lungs, causing difficulty in breathing and, potentially, permanent lung damage are known as choking agents. Examples of choking agents include chlorine, ammonia, andphosgene. Choking agents have historically been used during wartime, and are sometimesencountered during industrial accidents. (22) Choking agents are generally gases that have markedodors and may color the surrounding air. Production. Many choking agents are dual-use chemicals with both a civilian and a military purpose. Chlorine and ammonia are both used in largequantities for commercial applications, while phosgene is used within the chemical industry. Methods for producing choking agents are well known, but may be technically challenging. Chokingagents require specialized equipment to produce, compress, and contain them. Choking agents werealso manufactured for wartime use, and were extensively used during World War I. The first major,successful, chemical attack of the war used chlorine gas at Ypres in 1915. (23) Chlorine gas was latersupplemented by phosgene use, which caused greater casualties. (24) Effects. Choking agents injure their victims through inhalation, with a comparatively mild effect on the skin. Exposure to low chemical concentrationscauses chest discomfort or shortness of breath, irritation of nose and throat, and tearing eyes. Highagent concentrations may quickly cause swelling of the lungs, respiratory failure, and possibly death. Symptoms of lung damage can occur up to 48 hours after inhalation of moderate concentrations, andoften do not manifest themselves until the lungs are aggravated by physical effort. (25) Treatment. Victims of choking agents are generally treated symptomatically. Because lung damage may be exacerbated by exercise, victims are kept atrest until the danger of fluid in the lungs is past. Symptoms such as tightness of the chest andcoughing are treated with immediate rest and comfort. Shallow breathing and insufficient oxygenmay require supplemental oxygen. (26) Swelling and accumulation of fluids in the lungs are likely after exposure to a high dose of choking agent. Administration of corticosteroids has been recommended in cases of fluidaccumulation, but their beneficial effects have not been proven. (27) Rest, warmth, sedation, andoxygen are still the primary treatments, even in the case of marked edema. Blood agents are chemicals that interfere with oxygen utilization at the cellular level. Hydrogen cyanide and cyanide salts are agents in this group. Hydrogen cyanide is a very volatile gas, smellingof almonds, while cyanide salts are odorless solids. Hydrogen cyanide was considered for use as a chemical warfare agent, but was rarely used in military situations because its effectiveness was limited by its quick dispersion. The Frenchmanufactured hydrogen cyanide as a military agent during World War I. (28) Hydrogen cyanide wasused in other situations though; the principle agent used to kill individuals in German World WarII concentration camps, Zyklon B, used hydrogen cyanide as its active agent. (29) Hydrogen cyanideuse has been attributed to both sides during the Iran-Iraq war. (30) Production. Hydrogen cyanide and cyanide salts are now used as industrial chemicals, having application in the chemical, electroplating, and miningindustries. As with choking agents, methods for producing blood agents are relatively well-known. However, the gaseous nature of hydrogen cyanide complicates production and storage. Effects. Blood agents act through inhalation or ingestion and impair cellular oxygen use. (31) Thecentral nervous system is especially susceptible tothis effect, and blood agents usually cause death through oxygen starvation of brain cells. Thesymptoms of blood agent exposure depend upon the agent concentration and the duration ofexposure. In mild cases, there may be headache, dizziness, and nausea for several hours, followedby complete spontaneous recovery. Higher concentration or longer exposure may additionally causeconvulsions and coma. Very high concentrations may lead to powerful gasping for breath, violentconvulsions, and cardiac failure within a few minutes. (32) Treatment. The effects of blood agents are reversed through treatment with specific antidotes: either amyl or sodium nitrite combined with sodiumthiosulfate. The combination of these two chemicals removes cyanide, the active compound in bloodagents, from the body. When symptoms such as convulsion or depressed breathing are present,ventilation with oxygen and administration of anticonvulsants are used. Cyanide is metabolizedmore readily than most chemical weapons; with prompt treatment, victims may recover fromotherwise-fatal doses. (33) Protection against chemical agents is predominantly achieved through physical, rather thanmedicinal, means. Physical protections limit exposure by protecting the eyes, lungs, and/or skinfrom chemical contact. Physical protection against chemical agents includes gas masks and special protective clothing. Gas mask filters equipped with chemical filters are effective against inhaled chemical agents, butmay not provide sufficient protection against chemical agents active on skin contact, such as VX ormustard agents, or high concentrations of other nerve agents. Gas mask filters are normally constructed from layers of activated charcoal and fine porous material to remove particles and chemicals from the airstream. The activated charcoal bindschemicals, preventing them from being inhaled. Each gas mask filter has a finite capacity,proportional to the amount of unbound activated charcoal remaining, and so has a limited lifetimeonce put into operation. (34) For those chemical weapons that cause effect upon skin contact, a protective garment is required. These garments range in complexity and protective ability. Hazardous materials suits aretypically suits made of layered rubber with activated charcoal. In comparison, military battle dressovergarments designed to protect against chemical weapons in the battlefield are generally cloth,sometimes treated to resist absorbing liquids, containing a layer of charcoal-impregnated foam. (35) The rubber in protective equipment is impermeable to most chemical agents, while the activatedcharcoal acts in a manner similar to a gas mask filter. The combination of mask and suit providesfull protection against most chemical exposures. There are few examples of medical prophylaxis against chemical weapons. Unlike some biological pathogens, there are no vaccines to provide immunity from the effects of these weapons. However, some protection against the nerve agent Soman can be achieved by the pre-exposure useof pyridostigmine bromide. Pyridostigmine bromide acts to supplement post-exposureadministration of the nerve agent antidotes atropine and pralidoxime chloride. Use of pyridostigminebromide prevents permanent binding of nerve agents within the nervous system. Pyridostigminebromide use is recommended only when there is a high imminent threat of chemical weapon use, asit has noticeable side effects. (36) As an added protection against chemical weapons which cause their effects through skin contact, the U.S. Army Medical Research Institute of Chemical Defense has developed a chemicalresistant topical skin cream. The Skin Exposure Reduction Paste Against Chemical Warfare Agents,also known as SERPACWA, is designed to complement chemical protective equipment providedto soldiers in the field. (37) Decontamination, where chemicals are removed from the victims, usually through washing the eyes and skin with water and (against some chemical agents) a dilute bleach solution, is an essentialprotection against secondary chemical exposure. (38) In addition to stopping the victim's exposure tothe chemical agent, this procedure prevents those treating the victim from becoming victimsthemselves, and avoids contamination of treatment facilities. (39) Decontamination is especiallyimportant in those cases where victims have encountered liquid chemical agents, and may havesignificant amounts of chemical agent trapped in their garments. In events with gaseous agents,decontamination may be less critical. After decontamination is completed, treatment of the victimsoccurs, in some cases with agent-specific antidotes while in others, symptomatic treatment isperformed. Chemical weapons detection has been predominantly an area of concern for military planners,although the manufacture of some of these agents for commercial use requires detection capabilitiesat manufacturing plants and by hazardous- materials first responders. While some military unitshave equipment designated for chemical weapon detection, civilian first responders use a variety ofcommercial equipment to detect and identify a wide range of chemicals. Because of the wide spectrum of chemical agents, the development of a portable, integrated instrument which quickly detects all chemical agents remains an area of research and development. The Department of Defense currently employs a series of technologies to detect and identifychemical agents, including personal sensors, automated atmospheric sampling, and field-adaptedlaboratory methods for battlefield use. Detection of chemical agents can serve many purposes. One is to provide warning of a chemical attack, allowing additional time to react to a terror event. Another is to identify thechemical agent used in an attack. This might provide for better treatment and more effectiveresponse. Finally, determining when an area is clear of chemical agents after a terror attack requiressensitive post-event detection. There are techniques for detecting chemical agents that are based on sampling the local environment. Detection paper, tickets, and tubes are examples of such techniques. Detection paperis absorbent paper impregnated with special dyes. When a drop of chemical agent is absorbed bythe paper, it dissolves one of the pigments, causing the paper to change color. Detection tickets areused in a manner similar to detection paper. The ticket is waved in the air or used with a hand pumpto determine if chemical agents are present. Detection tubes use a similar technology, but rely ona hand pump to draw air samples through the tube, which discolors in the presence of an agent. Adisadvantage to these techniques is that other substances can also dissolve these pigments, causingfalse positives. (40) The pigments involved can bespecific to a type of agent, so an array of papers,tickets, or tubes may be required to identify the exact agent encountered. Handheld detectors, such as the Chemical Agent Monitor (CAM), are able to detect some chemical agents, namely mustard agents and nerve agents, at levels that are below the lethalthreshold, but above the acceptable daily exposure limit for civilians. (41) Automatic sampling devices,such as the Automatic Chemical Agent Detector/Alarm (ACADA), are also employed to provideautomated, constant atmospheric sampling. (42) These devices sometimes use a technique called ionmobility spectroscopy to detect the presence of chemical agents. Much of the above equipment is commercially available, and could be used by hazardous material response teams to assess potential terrorist activity. Typically, hazardous material responseteams are equipped with detection paper, tickets, or tubes, but these teams have differingrequirements regarding equipment standardization. (43) The President has requested FY2004 fundingfor the Department of Homeland Security for research on standards for first responder detectionequipment. (44) To aid first responders in choosingthe best or most appropriate system for their use,the National Institute of Justice has provided guidelines to assess various types of detectors. (45) Supplementing first responders is the Metropolitan Medical Response System, a federal program toenhance local capabilities in the event of a terrorist incident. (46) Ninety-seven metropolitan areas areinvolved in this system and maintain additional chemical detection, treatment, and decontaminationequipment. (47) Another way of detecting a chemical terrorism event would be through the public health system. The sudden arrival of chemical casualties in local hospitals will quickly alert health careprofessionals. Since September 11, 2001 increases in public health networking has improvedinformation sharing between localities. (48) Thismay increase the likelihood of identifying, forexample, a covert release of blister agent through identification of symptoms. Public healthmonitoring also may aid in forensic investigations following a covert event, especially if symptomsare delayed. Such public health monitoring may also provide opportunities to identify terrorists whomay have self-inflicted chemical weapon injuries. Additionally, the Laboratory Response Networkhas been established, which links together diagnostic laboratories for the identification of chemicalagents, as well as disease outbreaks. (49) Many experts believe that it would be difficult for terrorist groups to use chemical agents asweapons of mass destruction. Even VX, the most lethal of nerve agents, would require tons, spreaduniformly and efficiently, to kill 50% of the people in a 100 km 2 area. (50) On the other hand, chemicalagents might be effectively used as weapons of terror in situations where limited or enclosed spacemight decrease the required amounts of chemical. That is, the use of the weapon itself, even ifcasualties are few, could cause fear that would magnify the attack's effect beyond what would beexpected based solely on the number of casualties. There have been few examples of successful chemical terror attacks. In 1995, Aum Shinrikyo, a Japanese apocalyptic cult, used Sarin on the Tokyo subway. The attack killed 12 people and sentmore than 5,000 to the hospital with some degree of injury. (51) This same cult reportedly carried outan attack in Matsumoto as well, where 7 people were killed and over 200 injured. (52) Both of theseattacks used G-series nerve agents, which are more toxic through inhalation than by contact. V-series agents employed in a similar manner might have caused greater fatalities. In comparison, blister agents would likely be less lethal, but more injurious, if used in a similar manner. Blister agents are dermally active, so inhalation of the agent would not be necessary tocause injury. Additionally, since mustard agent vapor penetrates most fabrics, victims near the pointof release might suffer grievously. Blister agents, while not likely to cause mass destruction, mightcause mass terror and injury. Choking agents are no longer considered to be useful military weapons, as chemical suits and masks provide high protection. As a weapon of mass destruction used against civilians, thecomparatively low lethality of choking agents complicates their use as a weapon of mass destruction,since very large volumes would be needed. (53) Onthe other hand, the industrial availability of somechoking agents provides opportunities for acquisition and subsequent use of potentially very largevolumes of such agents. For example, the United States produces approximately 1 billion poundsof chlorine a year for use in water treatment facilities. The potential vulnerability of chlorine-filledrail tank cars, by which chlorine is primarily transported, has been noted. (54) Terrorist attack onindustrial stores at chemical or water treatment facilities or during shipment has been raised asanother potential source of concern. (55) Blood agents may be difficult to employ as weapons of mass destruction for many of the same reasons as choking agents. The quick dispersal of blood agents, combined with the large amountsnecessary to cause mass casualties, make such agents difficult to use on a mass scale. Even thoseblood agents which are industrially manufactured are often used on-site without being shipped. However, terrorist groups seem to be increasingly interested in these agents, perhaps because ofcriminal use of them. (56) Ramzi Yousef, convicted of the 1993 World Trade Center bombing, stated he had intended to include sodium cyanide in that bomb, in order to create a cloud of cyanide gas. (57) While a smallamount of cyanide was found in the supplies of the bombers, there was no evidence that this hadbeen done. In 1995, following the Sarin attack, members of Aum Shinrikyo attempted an attack inTokyo by setting fire to a plastic bag of sodium cyanide positioned next to a bag of an acid. Asimilar combination of chemicals was discovered the following month in another station. Bothdevices were successfully disarmed. (58) In 2002,Italian police arrested four Moroccan men possessingpotassium ferrocyanide. It was reported that the men arrested planned to poison the water supplyusing the potassium ferrocyanide. It is questionable how effective this would have been, consideringthe volume of the water supply and the amount of potassium ferrocyanide found in their possession. (59) A group calling itself September 11 threatened the use of cyanide to disrupt the America's Cup boatrace in New Zealand. (60) It is believed that the al Qaeda terrorist group has produced and developed plans for the employment of chemical weapons, including hydrogen cyanide. Osama bin Laden has stated thatal Qaeda has a chemical capability. (61) AhmedRessam, convicted in a plot to bomb the Los Angelesairport, testified he had received training in the use of hydrogen cyanide in Afghanistan at an alQaeda training camp. (62) The training describedincluded the production of hydrogen cyanide usingcyanide salts and acids, demonstrations of the effectiveness of the agent by exposing dogs to it, andintroducing the agent into building ventilation systems by placing a source near the air intakes. (63) CNN also located and retrieved videotapes from Afghanistan which portray the results of testing ofunknown chemical agents on dogs. It has been suggested that the chemical agent used in thosevideotapes was a blood agent, most likely hydrogen cyanide. (64) Treaties and multinational agreements are used to control international proliferation of chemical weapons. These multinational programs inhibit proliferation by increasing the technical barriers toweapon production and the difficulties of obtaining required precursor chemicals. Examples of suchmultilateral controls include the Wassenaar Arrangement, the Chemical Weapons Convention, (65) andthe Australia Group. (66) The Chemical WeaponsConvention provides lists of chemicals which areto be controlled through national export regulation. These chemicals include chemical weaponsthemselves and select precursor chemicals which might be used to develop chemical weapons. Inconjunction with these lists for export controls are criteria and a mechanism for inspection visits offacilities suspected of being used to develop chemical weapons. (67) U.S. export controls aimed atcreating proliferation barriers include Export Administration Regulations and International Trafficin Arms Regulations. (68) Other mechanisms, including voluntary governmental programs, increased contacts between suppliers and purchasers, and industrial best practices, are currently used to monitor sale of dual-usechemicals. The Department of Treasury developed a program called "Operation Shield America,"where Customs agents visit U.S. firms manufacturing or distributing technologies and materialswhich may interest terrorist groups. (69) Theseagents provide firms with information about U.S. exportcontrols and request that vendors notify the Customs Service if they are approached by customerslooking to acquire and export their products illegally. (70) Some industries, such as parts of thechemical and pharmaceutical industries, are developing best practices programs to limit potentialmisuse of dual-use equipment, equipment with both a civilian and military use. These practicesinclude higher physical security of laboratory and production facilities. (71) Members of some industries have also developed security plans and self-regulatory mechanisms. For example, the American Chemistry Council, a chemical industrial group, requiresits members to adhere to its Responsible Care Security Code. This code has multiple phasesincluding: prioritizing facilities; assessing the physical security procedures at each facility;developing and implementing any identified flaws or risks; and conducting external and internalaudits of facility security programs. (72) The GeneralAccounting Office has stated that the extent ofsecurity preparedness at chemical facilities is unknown and that such voluntary efforts only reacha fraction of the total number of chemical facilities. (73) Federal agencies currently involved in research and development related to chemical weapons countermeasures include the Department of Health and Human Services, the EnvironmentalProtection Agency, the Department of Energy, and the Department of Defense. Research beingperformed in areas related to chemical weapons includes: biomedical research; increasing detectorsensitivity; and obtaining better scientific understanding of the behavior of chemical releases. The Department of Homeland Security's Science and Technology Directorate will fund research and development activities against chemical terrorism. The FY2004 budget request contains $65million for Chemical/High Explosives Countermeasures, which includes developing bettertechnologies for chemical detection in air and water, chemical weapons forensics, and civilianchemical defense systems; and $25 million for a Standards Program, part of which will develop testand evaluation criteria for first responder detection equipment. (74) Biomedical Research. The United States government continues defensive research into chemical weapons. This research includes enhancingand improving medical treatments for victims of chemical weapon exposure and increasingunderstanding of the fundamental mechanisms of chemical weapon action. Some of this researchis carried out by the Department of Defense, coordinated by the Defense Threat Reduction Agency. (75) The U.S. Army Medical Research Institute of Chemical Defense and U.S. Army Soldier andBiological Chemical Command perform research and development activities, while other researchaspects are performed through outside contracts. (76) Increasing Detector Sensitivity. There are a range of programs engaged in developing new or improved detectors for chemical weapons. Improvementsare sought in sensitivity, speed, applicability, and other factors. These programs are located in theDepartment of Defense, the Department of Energy, and the Environmental Protection Agency. The Department of Defense is developing the next generation of chemical agent detectors. It has funded the development and testing of the Joint Chemical Agent Detector, a sensitive,multi-agent detection system intended for individual use or networked as perimeter detection. (77) Other research, performed at Department of Energy laboratories, has resulted in the ChemLabsystem, a portable, hand-held device incorporating "lab on a chip" analysis systems. (78) These devicesare in the development and production stages. Better Understanding of Chemical Releases. Chemical releases may be modeled using powerful computer programs. This ability may aid indetermining the potential extent of contamination, areas of likely effect, and the need for evacuation. Additionally, the science of particle/droplet formation, diffusion and dispersal, and technologies forcloud-monitoring and identification are areas where research continues to be funded. (79) There are numerous federal response teams which could be deployed in the event of chemical terrorism. In general, these teams would support local responders in detection, decontamination, ortreatment roles. A selection of these teams will be described below. One response team is the DOD's Chemical/Biological Incident Response Force (CBIRF). (80) CBIRF can be deployed to aid in consequence management after a chemical or biological terrorattack. It possesses both decontamination and treatment facilities and can be deployed domesticallyor internationally at short notice. This rapid response force was deployed at the Atlanta Olympicsand is equipped with state of the art equipment for chemical and biological threats. It is located atIndian Head, Maryland, and could be deployed in the case of chemical terrorism. (81) The Federal Bureau of Investigation maintains a Hazardous Materials Response Unit which, in response to crimes involving chemical weapons, would be available to analyze and identifychemicals and threats present. This unit provided site-safety assessments during the September 11,2001 attacks. (82) The U.S. Army Technical Escort Unit conducts chemical detection, decontamination, and remediation of chemical devices or hazards worldwide. While typically deployed to handle andsecure discovered chemical munitions, they also have been used to provide support to other largenational events. (83) As part of the National Disaster Medical System, Disaster Mortuary Operational Response Teams, Disaster Medical Assistance Teams, and four National Medical Response Teams areavailable to be deployed to the scene of a national emergency. This program was transferred to theDepartment of Homeland Security and is now located within the Emergency Preparedness andResponse Directorate. (84) The National Guard supports several Weapons of Mass Destruction Civil Support Teams. They were established to support local resources in determining the nature and extent of an attack orincident. These teams are able to deploy within four hours of a given alert. There are several areas where policymakers may wish to further address the danger posed byterrorist acquisition and use of high-threat chemical agents: the availability of such chemical agents;the availability of chemical detectors, their sensitivity, and their use; the ability of first respondersand diagnostic laboratories to detect, respond to, and resolve a chemical attack; the development ofnew treatments and prophylaxis; and determining whether an appropriate amount of funds andfederal attention is being given to this topic. Chemical agent availability varies greatly. Some chemicals, notably those with commercial or industrial use, are available for over-the-counter purchase from chemical suppliers. Because thesechemicals have a legitimate civilian use, there is little oversight of such sales. Consequently, thesechemicals may be available for purchase or theft in large quantities. (85) Regulatory mechanisms designed to increase the barriers to illicit acquisition of dual-use chemical agents, such as mandatory identity or use verification for domestic purchases, might reducethe relative threat. Such a proposal might add a significant burden to chemical manufacturers anddistributers, as well as end-users of these chemicals, since verification paperwork and procedurescould increase manufacturing and overhead costs. Additionally, increasing acquisition barriers viapurchase of such agents would not address the threat posed by theft of these agents. Dual-use chemical agents are transported, and occasionally stored, in large quantities, and it is possible that they might be stolen, or even intentionally damaged while in transit, as part of a terrorattack. Some have advocated that the transport and storage of these chemicals be regulated withgreater strictness, with their transport limited to less populated areas and the amounts transportedor stored limited, (86) and that such facilities be mademore secure. (87) Others have pointed to effortstaken by water officials to reduce on-site stockpiles of chemicals and to use alternate purificationmethods as a model for reducing vulnerability. (88) Such proposals raise the question of what an acceptable threshold for stored or transported chemical agents might be. Railcars may contain up to ninety tons of chemical, while other storagefacilities may contain comparable amounts. Anhydrous ammonia used for refrigerant purposes issometimes stored in fifty to one hundred ton amounts. Proposals involving increasing security orlimiting the size of allowed transfer or storage of chemicals might have significant economic costs. Additional security at manufacturing and transport facilities may increase the cost of these chemicals,while requiring end-user security improvement may prove impractical. Assessing the success ofsuch plans may also be complicated. Legislation has been introduced in the 108th Congress toaddress some of these issues. (89) The availability of actual chemical weapons is severely limited. Facilities where they are kept have high security, and access to chemical weapons is strictly controlled. (90) Chemical weapons inthe United States are controlled in military facilities. (91) On the other hand, some chemical weaponprecursors, such as thiodiglycol, can be domestically purchased from chemical companies in limitedquantities. Some companies have instituted a greater degree of identity and use verification for thesepurchases. There are many potential manufacturing methods for chemical weapons, and so it ispossible to make them from simpler, unregulated compounds. However, this process would increasethe manufacturing complexity and time required for production. Legislation has been introduced inthe 108th Congress to address some of these issues. (92) Policymakers may wish to direct or increase research efforts in developing reliable, sensitive chemical agent detectors. Detection of chemical agents at low levels is a challenging task which hasnot yet been uniformly achieved. The current generation of Chemical Agent Monitors is not capableof detecting chemical weapons at the acceptable exposure threshold limit. (93) This greatly complicatesthe efforts of hazardous materials first responders in assessing safety. One of the trade-offs in developing sensitive chemical detectors is the risk of detecting a chemical similar to a chemical agent and incorrectly registering it as an agent. In a civilian system,such false positives may lead to great disruption and uncertainty. (94) In contrast, false negatives, wherethe detector signals the absence of a chemical agent when one is actually present, might endangercivilians. How chemical weapon detectors are to be employed in civilian society is open to question. Currently detectors are used on a case-by-case basis, generally in response to an emergency. Chemical weapon detectors are used to determine the extent of a hazardous release and the degreeof contamination of the air and surrounding materials. (The atmosphere is not generally monitoredfor chemical weapons.) This prevailing approach is being assessed to determine if it is the mostappropriate use of such equipment. At least one real-time chemical detection system has been installed in public transit in Washington, DC, to detect potential chemical attacks in the Washington Metropolitan TransitSystem. Information about the extent of the system and its sensitivity is not publically available, butsuch a prototype system might be further expanded to provide greater detection coverage within theWashington Metropolitan Transit System or installed in other public transit systems to providechemical detection ability. (95) Expansion of sucha system might prove costly, both in initial costs andin maintenance. An assessment of how effective the current prototype system has been, includingwhether it has an appreciable number of false signals or the degree of testing the system hasundergone in identifying compounds at appropriately low concentrations, is not publicly available. The Environmental Protection Agency has a nationwide system of air quality detectors which it uses to monitor certain compounds, such as ozone and common pollutants. A prototype systemfor detecting biological agents has been added to selected detectors, with the goal of identifyingcovert biological weapon release. (96) Whether asimilar system could be developed to detect covertchemical weapon release may be of interest to policymakers. Any such system would need to besensitive and provide timely data, while also providing detector coverage for an appreciable outdoorarea. In the prototype biological detection system being implemented, samples are taken back to alaboratory and there tested for biological material. This may be an effective method for testing forbiological weapons, as there is usually a multi-day incubation period for infection. In contrast tobiological weapons, chemical weapons cause their effects quickly. Any detector system designedto monitor ambient air would need to respond immediately, a key criterion in a "detect-to-warn"system. A chemical weapon's effects would be detected through the arrival of victims in hospitalsbefore a laboratory test of detector samples could be performed. Additionally, the utility of such a detection grid might be in question if the system is unable to detect small, but effective, amounts or releases which occur within enclosed spaces. Developmentand maintenance of such a system may prove costly, both in initial capital and in maintenance costs. Determining the density and location of such monitors may also pose a difficult policy issue. Thecriteria used for locating air quality monitors may not be equally appropriate for chemical agentdetection. First responder equipment is currently not standardized, with each jurisdiction purchasing its own equipment. Whether all first responders should have standardized equipment may be a topicof Congressional interest. (97) Some first responderteams feel well-equipped and prepared for apotential chemical attack, while others do not yet have necessary equipment. (98) While the NationalInstitute of Justice has provided a manual outlining the criteria by which chemical equipment mightbe assessed, (99) some first responders have claimedthat the federal government has not providedenough oversight and direction regarding such esoteric purchases. (100) Advocates of allowing eachcommunity to choose what equipment to provide to first responders point out that the needs of onecommunity may not be the same as the next, and, because of location, population, or previousexpenditures, mandating specific equipment purchases may not meet locality needs. (101) TheDepartment of Homeland Security's Standards Program will develop test and evaluation criteria andconduct analyses for first responder detection equipment to help provide more guidance. (102) Theadequacy of current first responder equipment and its availability, whether proper guidance has beengiven by the federal government to state and local authorities regarding this equipment, and whatsteps may be required, through oversight or legislation, to properly equip first responders, are alsotopics of potential interest to policymakers. Another area where equipment and methodologies are not standardized is the testing of environmental samples. State public health laboratories, which might be reasonably expected tohandle analysis of samples from potentially contaminated sites or perform confirmatory tests as tothe identity of a chemical used in an attack, have reported a lack of funding and planning regardingthis topic. (103) The Chemical Terrorism Projectof the Association of Public Health Laboratories hasdeveloped a series of recommendations for improving the ability of public health laboratories torespond to chemical terrorism. (104) Thus, theremay be interest in determining whether federalagencies are fulfilling their role in providing validated testing methods for diagnostic laboratories,whether appropriate support is available for testing equipment for state laboratories, and what rolethe federal government should play with respect to state laboratories. Because of the rarity of chemical weapon exposure, there has been little civilian market for new treatments and prophylactics against them. Development and identification of medications againstchemical weapons is thus an area of limited private sector research. Some have argued that withoutfederal sponsorship of such research, advances in this area will be very slow, and new treatments willnot be sufficiently developed. They assert that the federal government should commit to purchasingfixed quantities of a successful new treatment in order to boost private-sector funding of thisresearch. (105) They point out that without anassured market, the private sector will not be willing tospend research and development money on products. Others believe that committing to the purchaseof unproven treatments will not yield the best treatments and prophylaxis possible. Finally, someassert that improvements should be made to the general public health system, rather than targetinglow probability events. The possible use of federal response teams to augment local first responder capabilities provokes differing responses. An investigation by the General Accounting Office in 2000 found that"Federal response teams do not duplicate one another." (106) On the other hand, the varied teamsestablished by these agencies have been called redundant. (107) Also, the general structure ofestablishing regional teams has been questioned, since there would be a delay in response due torequired travel time for a team. (108) Others haveadvocated that parallel civilian and military responseteams may be necessary, since military teams might not be available to civilians during wartime. CRS Report RL31332, Weapons of Mass Destruction: The Terrorist Threat , by SteveBowman. CRS Report RL31831 , Terrorist Motivations for Chemical and Biological Weapons Use: Placing the Threat in Context , by [author name scrubbed]. CRS Report RL31669 , Terrorism: Background on Chemical, Biological, and Toxin Weapons and Options for Lessening Their Impact , by [author name scrubbed]. CRS Report RL31475, First Responder Initiative: Policy Issues and Options , by Ben Canada. CRS Report RL31853 , Food Safety Issues in the 108th Congress , by [author name scrubbed]. CRS Report RL31791, Emergency Management Funding for the Department of Homeland Security: Information and Issues for FY2004 , by [author name scrubbed], Coordinator, Rob Buschmann, Ben Canada,Wayne Morrissey, [author name scrubbed], and [author name scrubbed]. CRS Report RL31530 , Chemical Plant Security , by [author name scrubbed]. CRS Report RL30169, Export Administration Act of 1979 Reauthorization , coordinated by Ian F.Fergusson. CRS Issue Brief IB94029, Chemical Weapons Convention: Issues for Congress , by Steven R.Bowman. CRS Report RL31559 , Proliferation Control Regimes: Background and Status , by Sharon A.Squassoni, Coordinator, Steven R. Bowman, and, [author name scrubbed].

Summary: Terrorist use of chemical agents has been a noted concern, highlighted after the Tokyo Sarin gas attacks of 1995. The events of September 11, 2001, increased Congressional attention towardsreducing the vulnerability of the United States to such attacks. High-threat chemical agents, whichinclude chemical weapons and some toxic industrial chemicals, are normally organized by militaryplanners into four groups: nerve agents, blister agents, choking agents, and blood agents. While therelative military threat posed by the various chemical types has varied over time, use of thesechemicals against civilian targets is viewed as a low probability, high consequence event. High-threat chemical agents, depending on the type of agent used, cause a variety of symptoms in their victims. Some cause death by interfering with the nervous system. Some inhibit breathingand lead to asphyxiation. Others have caustic effects on contact. As a result, chemical attacktreatment may be complicated by the need to identify at least the type of chemical used. Differencesin treatment protocols for the various high-threat agents may also strain the resources of the publichealth system, especially in the case of mass casualties. Additionally, chemical agents trapped onthe body or clothes of victims may place first responders and medical professionals at risk. Protection from and detection of chemical agents is an area of much concern. The range of protection and detection equipment available to first responders has led to questions regardingequipment standardization and state and local preparedness. Whether terrorist groups are capable of using chemical agents as weapons of mass destruction is unclear. Some have asserted that the volumes of chemicals required to cause mass casualtieswould make that scenario unlikely. They claim that chemical terrorism is more likely to be smallin scale. Others have suggested that there has been an increase in terrorist interest regardingchemical agents, and that this interest could lead to their use in terrorist attacks. Current policies seek to reduce the proliferation of chemicals that could be transformed into chemical weapons, prevent unrestricted access to large amounts of toxic chemicals, provide federalassistance to locations that are affected by chemical terrorism, and support research and developmentactivities. It is expected that the Department of Homeland Security will take a major role in federalpolicy efforts. Additional measures suggested for addressing potential chemical terrorism vulnerabilities include further restricting domestic access to precursor chemicals and technologies required tomanufacture high-threat chemical agents; directing continued research and development intoselective, sensitive chemical agent detectors; implementing air monitoring equipment to detectchemical releases in, for example, public transportation or urban spaces; and overseeing furtherresearch into protective equipment, prophylaxis, and treatment against high-threat chemicals. Thisreport will be updated as circumstances warrant.