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CS has gained wide acceptance as a means of controlling and subduing riotous crowds. However, its widespread use has raised questions about its safety. Most published studies have concluded that, if used correctly, the irritant effects of exposure are shortlived and do not cause permanent damage.511 However, there have been isolated reports of fatalities from the use of riot control agents. The most common reports involve deaths attributed to the use of riot control agents by American military personnel in Vietnam.512 Additionally, other reports involve injury and death from the use of CS in Chile, Panama, South Korea, and the Gaza Strip and West Bank of Israel.513 It has been unclear from these reports, however, whether the riot control agent used was CS or another, more toxic, agent.514 Of particular concern, however, has been the indiscriminate use of riot control agents in enclosed and indoor spaces where it is feared that resulting high concentrations may have resulted in harmful levels of exposure. Severe injuries from exploding tear gas grenades as well as deaths from the toxicity of riot control agents used in confined, indoor spaces have been reported.

511 The most thorough study of the use of CS agent against humans is the Himsworth Report, which investigated the use of CS agent in Northern Ireland in 1969. It concluded that exposure to CS did not produce long-term injury or death in humans. Home Office, report of the enquiry into the Medical and Toxicological aspects of CS (Ortho-chlorobenzylidene malononitrile), Part II: Inquiry into Toxicological Aspects of CS and its use for Civil Purposes (1971) [hereinafter Himsworth Report]. A recent study of the use of CS on 1,500 persons in a confined area space made the same findings. P.J. Anderson et al., Acute effects of the potent lacrimator ochlorobenzylidene malonitrile (CS) tear gas, 15 Hum. & Experimental Toxicology 461, 464-465


512 The United States used large amounts of CS during the Vietnam War in both offensive and defensive military operations. The basic doctrine for the use of CS weapons by U.S. sources is summarized in the following passage taken from a 1969 Army training circular:

The employment of riot-control agents (CS, CN) in Counterguerrilla operations is most feasible in tactical situations characterized by close combat in which rapidly responding systems are essential and permanent effects are undesirable. Riot-control munitions can be used tactically to temporarily disable hostile troops, to suppress their fire, or to cause them to abandon their position. Offensively, riot-control agents can be used to "flush out" unprotected enemy troops from concealed positions or to reduce their ability to maneuver or use their weapons. Defensively, riot-control munitions can be integrated into defensive perimeters to provide rapid CS delivery in case of enemy attack.

CS was employed for defensive purposes such as in the event of a surprise attack from superior enemy forces, and to help secure helicopter extractions of combat units or downed airman. It was used extensively in area-denial operations to render terrain uninhabitable by the enemy. CS was also used routinely in direct engagement of the enemy during offensive combat operations.

U.S. forces were issued gas masks to protect themselves against use of CS and other tear gases by the enemy. According to one U.S. evaluation, the North Vietnamese had only a limited supply of tear gas, but they used it to good effect. During the conflict, the general service respirator was replaced by a lighter mask, which went through a number of further modifications. The protection which it conferred was adequate but not complete, because dense CS aerosols can have a strong irritant effect on bare skin, especially in hot and humid conditions when the skin is moist.

513 See generally, H. Jack Geiger & Robert M. Cook-Deegan, The Role of Physicians in Conflicts and Humanitarian Crises, Case Studies from the Field Missions of Physicians for Human Rights, 1988 to 1993, 270 JAMA 616 (1993).

514 In a 1989 report, the General Accounting Office noted that the group Physicians for Human Rights had conducted a factfinding trip to investigate allegations of deaths from the use of CS in the occupied territories but that the members of the group could not confirm that any of the reported deaths were attributable to tear gas inhalation. See e.g., U.S. General Accounting Office, Israel: Use of U.S.-Manufactured Tear Gas in the Occupied Territories 3 (1989) (citing Physicians for Human Rights, "The Casualties of Conflict: Medical Care and Human Rights in the West Bank and Gaza Strip," Report of a Medical Fact Finding Mission by Physicians for Human Rights (1988)). The GAO report also noted that while Amnesty International had reported concerns over a "pattern of death [that] appeared to follow expose to high concentrations of tear gas" they also stated that "Amnesty International noted that it was in no position to

Critics of the use of these agents argue that the available toxicological data is insufficient to describe with any confidence the potential for long-term pulmonary, carcinogenic, and reproductive effects. One recently published review of the toxicological data on riot control agents concluded that relatively little has been published in the mainstream medical literature and that epidemiologic studies following tear gas use under actual field conditions are almost nonexistent. The author of this review wrote:

There is clearly a great need for openly conducted research illuminating the full health consequences of exposure to riot-control agents including outcomes such as tumor formation, reproductive effects, and pulmonary disease. Consideration must be given to the possible effects of these agents on the young, the elderly, and other persons who might have increased susceptibility.515



All riot control agents, including CS, produce intense sensory irritation even in the most minute concentrations. For most of these agents, the eye is the most sensitive organ, with pain arising rapidly, accompanied by conjunctivitis, excessive tearing, and uncontrolled blinking. The inside of the mouth and nose experience a stinging or burning sensation, and there is usually excessive discharge of nasal mucus. Chest tightness and burning are accompanied by coughing, sneezing, and increased secretions from the respiratory passageways. A burning sensation is felt on the skin, often followed by inflammation and redness, and in some cases, actual burning of the skin occurs. Tear gas exposure may also irritate the stomach, leading to vomiting and possibly diarrhea. In addition to the physical symptoms, panic and severe agitation are common among those individuals with no prior experience of exposure to tear gas.


Most of the symptoms are felt within 10 to 30 seconds after exposure to the agent. After cessation of exposure, however, most symptoms continue to persist for a period of minutes before subsiding and disappearing.517 The effects of expose vary among individuals. Additionally, weather conditions, such as temperature and humidity, can heighten the potency of these agents.518


A review of the scientific literature concerning the use of CS indicates that limited conclusions as to the toxicity and lethality of CS are known. It seems generally accepted by the scientific community that the concentration of CS agent which is noticeable by humans and which will provoke physical responses in humans is 4 milligrams per cubic meter (4 mg/m3).519 While no studies on humans

515 Hu, supra note 508, at 284-285.

516 See generally Id. at 276; Anderson, supra note 511, at 461.

517 Hu, supra note 508, at 276.

518 Id. at 277.

519 Bryan Ballantyne, Riot Control Agents, Biomedical and Health Aspects of the Use of Chemicals in Civil Disturbances 27 (1977); Hu, supra note 508, at 279.

have been conducted concerning the lethality of CS, several studies have projected the concentrations at which CS is lethal to humans from the effects of studies performed on animals. Those studies estimate that the concentration of CS agent which would prove lethal to 50 percent of any given human population ranges from as low as 25,000 520 to as high as 150,000 mg-min/m3.521 Recent estimates by the U.S. military, however, estimate that the lethal concentration for humans is 61,000 mg-min/m3.522 That study projects that the concentrations which would be injurious to the health of approximately 50 percent of any human population range from between 10-20 mg-min/m3.523

It is important to note, however, that there are no published studies which find that any human death has been caused by exposure to CS agent. While a number of unverified reports of human deaths can be found in the literature, in all of these reports it is unclear precisely whether CS or some other, more toxic, riot control agent was used or whether some other circumstance could have caused the deaths. The most extensive study of the use of CS agent on humans, by United Kingdom forces in Northern Ireland in the late 1960's, found that no deaths (and no long-term injuries) resulted from the widespread use of CS agent there.524 The only other documented study of the effects of CS used on a large number of humans confirms this finding.525

Some people may find curious the fact that all of these studies (and similar studies on the effects of chemical agents) uniformly give estimates of the level at which CS is lethal or injurious to 50 percent of a given population of humans. It appears from the literature that the effect of CS on humans (and on other animals) is not "linear," i.e., that proportionately greater concentrations do not have equally proportionate increases in effect. While scientists can estimate the levels which would prove lethal to 50 percent of a given population, it would be incorrect to presume that half of that quantity would kill 25 percent of that population. In fact, the most well-known study of the effects of CS on humans estimates that the likelihood of death after exposure to a dose of CS that is one-tenth the estimated lethal dose is less than 1 in 100,000.526 Accordingly, any analysis of the lethality of the CS agent used in the concentrations that resulted on April 19 can only be performed in light of the 50 percent lethality estimates.

Even when the quantities of CS riot control agent used do not reach lethal toxic levels, there are, nevertheless, significant physical consequences that occur from exposure to CS, and often severe emotional reactions caused by the symptoms brought on from exposure to CS. As discussed above, one recent study of the use of large quantities of CS against a population unable to leave the area in which the CS was used indicated that first, second, and even third

520 Dow Chemical Co., Material Data Safety Sheet (1988); Ballantyne, supra note 519. 521 Id.

522 Headquarters, Departments of the Army, Navy, and the Air Force, Potential Military Chemical/Biological Agents and Compounds 59 (1989).

523 Id.

524 Himsworth Report, supra note 511, at 23-25.

525 Anderson, supra note 511, at 464–465.

526 Himsworth Report, supra note 511, at 55-56; Ballantyne, supra note 519, at 30.

degree burns are possible when skin is exposed to CS.527 Additionally, some studies have shown that exposure to CS can cause allergic contact dermatitis.528 Other studies have shown that when CS can cause severe gastroenteritis when ingested, whether directly or as a result of ingesting mucus secretions containing CS from oral inhalation.529

Additionally, some studies on animals have suggested that exposure to CS might cause cancer and genetic abnormalities.530 Some studies have stated that exposure to high concentrations of CS for prolong periods could result in inflammatory changes in the respiratory tract that might be conducive to secondary respiratory infection.531 And it is believed that CS may exacerbate existing medical conditions of persons with bronchitis or asthma, although no reports of death from these conditions exist.



Testimony before the subcommittees presented contradictory evidence on the effects of CS riot control agent. The published literature described above, however, is more consistent in the conclusions drawn. While it cannot be concluded with certainty, it is unlikely that the CS riot control agent, in the quantities used by the FBI, reached lethal toxic levels. The evidence presented to the subcommittees does indicate, however, that CS insertion into the enclosed bunker at a time when women and children were assembled inside that enclosed space could have been a proximate cause of or directly resulted in some or all of the deaths attributed to asphyxiation in the autopsy reports.

In order to answer the question of whether the quantities of CS agent inserted into the residence might have reached lethal levels, the subcommittees attempted to determine the concentrations that were present in the residence under the "worst-case" circumstances. To make this determination, a number of assumptions must be made. Many of these assumptions were overstated solely for the purpose of calculation in order to place the greatest scrutiny on the government's actions.

In each of the first two phases of insertion into the Branch Davidian residence, a total of 180 grams (180,000 mgs) of CS was delivered.532 For the purposes of analysis, the subcommittees assumed an "extreme case" scenario, where all 180 grams were delivered into the building by the two CEV's at the same instant, and that one-quarter of the Ferret rounds fired at the residence were fired at the precise moment that the CS delivered by the CEV's entered the residence.533 If so, then during the first and second

527 Anderson, supra note 511, at 463–464.

528 Hu, supra note 508, at 280.

529 Id.

530 Id.

531 Ballantyne, supra note 519, at 30.

532 CEV-1 emptied its four 30-gram cylinders while CEV-2 emptied the contents of its two 30-gram cylinders. The total delivered was thus (4 x 30) + (2 x 30) = 180 grams.

533 Each Ferret round carried 3.7 grams of CS agent. A total of 400 Ferret rounds were fired at the residence. Thus, the total quantity of CS agent in one quarter of the Ferret rounds used

phases of the CS operation, 550 grams (550,000 mgs) of CS were delivered to the residence.534 During the first and second phases, therefore, the total concentration of CS delivered into the compound was 108.92 mgs/m3.535 During the third and fourth phases, due to the mechanical failure of the second CEV, only 490 grams (490,000 mgs) of CS agent was delivered into the residence.536 During each of the third and fourth phases the total concentration at the (assumed) moment of insertion was 97.04 mgs/ m3.537

Assuming the Branch Davidian residence been air-tight, so that none of the CS agent escaped the building (which was not the case), the total amount of CS agent delivered present in the building would have been 411.92 mgs/m3.538 This concentration is far below the 61,000 mgs/m3 amount projected to be lethal to 50 percent of a given population of humans. Stated in another way, it would take a concentration of CS 148 times greater than the greatest amount that could have been present at the Branch Davidian residence on April 19 to reach that lethal level.

In reality, the concentrations of CS inside the Branch Davidian residence did not reach even these levels. The Branch Davidian residence was a poorly constructed structure which allowed for air to move in and out of the residence continuously. The air circulation carried some of the CS agent out of the building. Adding to the air circulation inside the Davidians residence that day was the fact that the FBI began to use the CEV's to ram openings into the building, ostensibly to create a means of escape for the Davidians and, later, to "deconstruct" portions of the structure in an effort to prevent the Davidians from occupying those areas of the residence. These actions greatly enhanced the circulation into the residence and further depleted the concentration of CS agent inside the residence. Additionally, on April 19th, the winds were gusting up to 25 mph.539 This fact greatly enhanced the air circulation inside the residence, adding to the dissipation of the concentration of CS agent in the residence. Thus, the actual levels of CS inside the Davidian residence were less than those calculated above.

Some who have contacted the subcommittees have suggested that the above analysis is flawed because it does not allow for the possibility that some CS agent was concentrated in certain areas of the residence rather than being evenly distributed throughout the entire structure. The subcommittees believe that it is important to address that possibility.

Because the largest group of bodies recovered after the fire was found in the area of the residence commonly known as the gun

534 On each of the first two phases, 180 grams of CS agent was delivered by the CEV's and approximately 370 grams was delivered by Ferret Rounds. This totals 550 grams, or 550,000 milligrams.

535 The Branch Davidian residence contained approximately 178,310 cubic feet of living area. Converted into meters, the volume of the residence was 5,049.7 cubic meters. The concentration inside the building, therefore, was 108.92 mgs/m3 (550,000 mgs/5,049.7m3 108.92 mgs/m3). 536 The 180 grams from CEV-1 and the approximately 370 grams from 100 of the Ferret Rounds totals 490 grams, or 490,000 milligrams.


537 490,000 mgs/5049.7 m3 = 97.04 mgs/m3.

538 The concentration inside the building, therefore, was 108.92 mgs/m3 + 108.92 mgs/m3 + 97.04 mgs/m3 + 97.04 mgs/m3 = 411.92 mgs/m3).

539 The National Oceanic and Atmospheric Administration recorded high winds beginning at noon on April 18, 1993. The winds continued through April 19. At 11:52 a.m. on April 19, winds

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