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c Discussion of Health Effects of Non-Lethal Weapons C.1 INTRODUCTION Antipersonnel non-lethal weapons must yield statistically a very small per- centage of permanent damage to people. Yet to be effective, significant amounts of energy, or biological change in the case of chemical systems, must often be imparted. Thus, the dilemma or challenge is to identify susceptibilities of the human to the potential energy forms and to design non-lethal weapons sys- tems that operate within the bounds of effectiveness well short of permanent damage. Initial guidance on the avoidance of permanent damage has been gleaned from the knowledge base for automotive crash tolerance limits for ki- netic-energy weapons and from occupational or public exposure limits that have been developed for lasers, other forms of light, acoustic and electrical sources, chemicals, and microwaves. Exposure limits are based on physiological param- eters, but because the effectiveness of NLWs may result from either physiologi- cal or psychological responses by the targeted human, both areas of human response must be understood. Non-lethal weapons having blunt trauma effects were exploited early because there is considerable history and familiarity with blunt trauma. Other energy sources are now being exploited as well. Address- ing each delivery form in turn, this appendix discusses the type~s) of effects resulting from exposure, the mechanism of damage, current or recent research and available data, and differences among different systems, and gives an as- sessment of the knowledge base. 148

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APPENDIX C 149 C.2 KINETIC ENERGY Effects of Kinetic-Energy Rounds The use of kinetic-energy munitions in NLWs has a long history, beginning with the police baton and the water cannon. A large number of other weapons have been developed to inflict pain on targets for the purposes of area denial and/ or crowd control. Most non-lethal kinetic munitions are blunt objects that are designed to strike the body to inflict temporary pain or discomfort. They can vary in size from a baton round with a mass of 140 gram (g) to plastic pellets with a mass of less than a gram. Their muzzle velocities also have a large range (30 to 500 m/s). For the most part, the risk of causing a fatality is very low. However, the risk of permanent injury is higher to the head, eyes, face, lungs, heart, liver, or ribs, most commonly. (See Section 2.7 for data from the United Kingdom on the use of kinetic rounds in Northern Ireland.) The spectrum of injuries sustained by those struck by kinetic-energy muni- tions relates not only to variations in the types and velocities of these rounds but also to the large variation in human tolerance to blunt impact. Osteoporotic females are more at risk to sustain bone fractures than are young healthy males. It is suspected that ventricular fibrillation of the heart caused by blunt impact may also be related to a pre-existing heart condition. So it is not possible to cite a single number, such as projectile speed, to define human tolerance. Instead, human tolerance needs to be defined in terms of a probability of injury for the population for a given input parameter, such as the force of impact. The current approach is to employ a statistical technique known as Logist analysis, which uses available experimental data to determine the likelihood of injury to the general population. A sample set of Logist curves is shown in Figure C.1, in which the probability of injury as a function of force is depicted. The degree of injury can be selected to produce curves that are non-injurious (effective weapon) to those that cause permanent injuries or death. However, for non-lethal kinetic-energy rounds, there are very few data that can be used to produce such curves, because most of the data on blunt impact have been gener- ated for the automotive crash environment. The difference between these two types of blunt impact is important to recognize in automotive crashes, the speeds are lower than those of kinetic-energy munitions, while the mass or weight of the body segments involved is much higher. Work has been done on interpreting chest injuries at least semiquantitatively. One approach couples the viscous criterion) with a simple mathematical model Piano, David C., and Veng-Kin Lau. 1983. "Role of Impact Velocity and Chest Compression in Thoracic Injury," Aviation, Space and Environmental Medicine, Vol. 54, pp. 16-21. 6

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APPENDIX C non 100 U) 2 c ._ cat o 1r 151 10 Mass (g) 1 000 1 0000 M MCCM Horsch .#23 BR deftec ''. M743 MK close MK standard Sty Baseball eXM1006 + Cooper Automotive FIGURE C.2. Hypothetical study of chest injuries based on the viscous criterion. SOURCE: Lobdell, T.E., C.K. Kroell, D.C. Schneider, W.E. Herring, and A.M. Nahum. 1972. "Impact Response of the Human Thorax," Proceedings of the Human Impact Response Measurement and Simulation Symposium, General Motors Research Labora- tories, October 2-3, Plenum Press, New York-London. seen that there is a possible risk of chest injury from many of the rounds, based on the predictions of the Lobdell model and the VC. An estimate of the toler- ance of the heart to ventricular fibrillation was provided by C.K. Kroell et al.3 It was found that for impacts to the sternum in the range of 12.9 to 30.7 m/s, the critical value for VC for a 50 percent probability of ventricular fibrillation is 1.46 + 0.31 m/s. The values of VC would go up if the fibrillation was accompa- nied by heart rupture. Mechanisms of Injury Derived from Crash Impact Research To understand how a body region is injured by a blunt impact, we resort to the accumulated knowledge in the field of impact biomechanics, a branch of 3Kroell, Charles K., Stanley D. Allen, Charles Y. Warner, and Thomas R. Pert. 1986. "Interrela- tionship of Velocity and Chest Compression in Blunt Thoracic Impact to Swine II," 30th Proceedings of the Stapp Conference, SAE Paper No. 861881, Society of Automotive Engineers, Warrendale, Pa. 5

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152 s s APPENDIX C science that applies the basic principles of mechanics to biological systems, such as the human body. One of the branches of impact Biomechanics is the study of injury mechanisms, that is, how the injury is caused. It is beyond the scope of this appendix to go into a detailed discussion of injury mechanisms from head to foot. The reader is referred to the work of Albert I. King4 for what is known about automotive-related impact injury mechanisms. Several examples illustrate biomechanical aspects of blunt impact injury. Ribs can fracture when a non-lethal round impacts the chest or when the torso impacts a steering wheel. In both cases, the rib is bent and the inside surface of the rib goes into tension. Since bone is weak in tension, fracture of the rib will begin on the inside surface when the deflection of the rib reaches about 70 mm. Similarly, in high-speed blunt impacts to the chest (more than 30 m/s), the heart can go into ventricular fibrillation (ineffective pumping of blood) if the impact occurs at or just prior to the T-wave of the electrocardiogram cycle; that is, after the main signal has been sent to the ventricle to contract and to expel blood into the aorta, the heart muscle goes into a refractory state for a short time, the period of the T-wave. If the heart receives an impact at that time, the signal to the ventricle is blocked for the next cycle and the ventricle goes into fibrilla- tion. In a study of 24 cases of baseball-related impacts to the chest, mostly against young children, none of the victims who went into ventricular fibrillation could be revived, even if immediate cardiopulmonary resuscitation (CPR) was administered. The probability of this happening with a non-lethal munition is very low, but not zero. The exact mechanism as to why the conduction of the signal for the ventricle to contract is interrupted is still being debated. If due to a direct impact to the heart by the chest wall, then the condition can be prevented by the use of a chest protector. However, if the mechanism of injury is the passage of a pressure wave through the organ, the injury can be prevented only by attenuating the wave before it reaches the heart. Laceration of the lung can be due to contact of the lung with the broken end of a rib, while contusion of the lung is more likely due to the same pressure wave effect described above. However, the relationship between pressure magnitudes and severity of lung injury is not fully known or understood. Other examples of injury mechanisms consider brain injury, abdominal in- jury, and spinal injury. For the brain, a blunt impact to the head causes local deformation of the skull and movement of the head. This movement can be in the form of a translational, or linear, acceleration and/or a rotational, or angular, acceleration of the head. Current knowledge regarding mild traumatic brain 4King, Albert I. 2000. "Fundamentals of Impact Biomechanics: Part IBiomechanics of Head, Neck, and Thorax," Annual Review of Biomedical Engineering, Vol. 2, Eds. Martin L. Yarmush, Kenneth R. Diller, and Mehmet Toner, Annual Reviews, Palo Alto, Calif., pp. 55-81; King, Albert I. 2001. "Fundamentals of Impact Biomechanics: Part II Biomechanics of the Abdomen, Pelvis, and Extremities," Annual Review of Biomedical Engineering, Vol. 3, Ed. Roselyn Lowe-Webb, Annual Reviews, Palo Alto, Calif., pp. 27-55.

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APPENDIX C 153 injury (MTBI) indicates that the cause is a combination of both forms of accelera- tion, which can generate shear and pressure in the brain tissue. The precise mechanism as to how these factors produce MTBI, including concussion and mental confusion, is still being studied. Injuries to the solid organs of the abdomen, such as the liver, occur as the result of compression of the organ by the abdominal wall or rib cage. The velocity of the abdominal wall is also a factor in causing the organ to rupture. In contrast, the risk of spinal injury is very low; in fact, it is virtually impossible to rupture an intervertebral disc in the neck or lumbar spine with any kind of a single impact to the body unless there is a massive fracture of vertebral bodies immedi- ately adjacent to the disk.5 Because of the eye's fragile structure and high deformability, any increase in ocular pressure due to impact by a blunt projectile can cause permanent injury to several different parts of the eye. In particular, the vitreous humor (a gel-like material) in the rear of the eye, which is in contact with the retina, can produce retinal laceration and detachment if deformed. Retinal injuries are frequently permanent and non-restorable. From these limited examples, it can be seen that even after 60+ years of automotive safety research in impact biomechanics, the mechanisms of injury of many body regions are not fully known or well understood. Non-lethal kinetic- energy weapons add a new dimension to the problem because the speeds in- volved are much higher and the masses involved are much lower. - ., it Recent and Current Human Effects Research on Kinetic-Energy Munitions Experimental Studies Research on the human effects of kinetic-energy rounds has been conducted over the past two decades by many investigators in the United States, the United Kingdom, and elsewhere (see below, Cooper and Maynard, 1986~.6 Among the kinetic-energy munitions that have been studied, rubber-coated steel balls and sponge grenades have been assessed in animal studies. Penetration of the thorax and abdomen of the pig was investigated using these munitions. Animal studies on the fracture risk of the mandible and ribs as well as on the potential of injury to the heart, lungs, and intestines have also been conducted. Cadaveric studies on the effects of baton rounds on the chest and of kinetic-energy rounds on brain contusion and skull fracture have either been completed or are ongoing. A SKing, Albert I. 1993. "Injury to the Thoraco-Lumbar Spine and Pelvis," Accidental Injury: Biomechanics and Prevention, Eds. Alan Nahum and John W. Melvin, Springer-Verlag, New York. pp. 441-443. 6Cooper, G.J., and R.L. Maynard. 1986. "An Experimental Investigation of the Biokinetic Prin- ciples Governing Non-Penetrating Impact to the Chest and the Influence of the Rate of Body Wall Distortion Upon the Severity of Lung Injury," Proceedings of the IRCOBI European Impact Bio- mechanics Conference, Zurich, Switzerland.

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154 o.s - 0.8 - 0.7 - U) 0. 0.6- o it, 0.5- - Q 0.4- lo 0 3 - 0.2 - 0.1 n- APPENDIX C - 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 7 7.5 8 VC max FIGURE C.3 Logist analysis of lung contusion as a function of VC. SOURCE: Cooper, G.J., and R.L. Maynard. 1986. "An Experimental Investigation of the Biokinetic Princi- ples Governing Non-Penetrating Impact to the Chest and the Influence of the Rate of Body Wall Distortion upon the Severity of Lung Injury," Proceedings of the IRCOB1 European Impact Biomechanics Conference, Zurich, Switzerland. human-surrogate rib cage, called the three-rib device, has been developed for testing other types of blunt munitions of equivalent kinetic-energy levels. At the present time, a study using the three-rib device to assess the response of the rib cage to a variety of munitions, including the sponge grenade, the beanbag, and other munitions, is in progress. The impact of sting balls (light plastic balls) on porcine eyes is also being studied. It is not clear if accurate biomechanical measurements are being made along with the study of injury potential. The early work of Cooper and Maynard studied the effect of blunt projectiles on the lung. A large series of porcupine experiments (43 tests) was conducted to evaluate lung contusion, which was defined in terms of an increase in lung weight. A 50 percent increase in weight was considered unacceptable. A Logist plot in terms of VC is shown in Figure C.3. Ventricular fibrillation tests were conducted on swine by Kroell et al.7 In the 41 tests conducted at impact speeds ranging from 9.7 to 30.7 m/s, with impactors ranging in mass from 4.9 to 21 kg, there were 11 cases of ventricular fibrillation 7Kroell, Charles K, Stanley D. Allen, Charles Y. warner, and Thomas R. Pert. 1986. ``Interrelation- ship of Velocity and Chest Compression in Blunt Thoracic Impact to Swine II," 30th Proceedings of the Stapp Conference, SAE Paper No. 861881, society of Automotive Engineers, Warrendale, Pa.

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APPENDIX C 1 - o.s - 0.8 - 0.7 - . ~ 06 o.s .4- 0.3 - 0.2 0.1 O 1 it/ / mar/ P = 1/(1 + exp (22.67 -17.52VCmax)) Chi Square = 7.7, R = 0.58, p = 0.006 1 ,. 1 2.5 3 0 0.5 1 . 1.5 VChlax (m/s) r ~ . - 155 HR: VCmax = 2.69 +/- 0.86 m/s : VF (with HR): VCmax = 2.13 +/- 0.85 m/s VF (AIS 1-3): VCmax = 1.46 +/- 0.31 m/s Sudden Cardiac Attest or Commotio Cordis FIGURE C.4 Logist analysis of ventricular fibrillation (VF) as a function of VC. SOURCE: Kroell, Charles K., Stanley D. Allen, Charles Y. Warner, and Thomas R. Pert. 1986. "Interrelationship of Velocity and Chest Compression in Blunt Thoracic Impact to Swine II," 30th Proceedings of the Stapp Conference, SAE Paper No. 861881, Society of Automotive Engineers, Warrendale, Pa. and 21 cases of heart rupture. In the non-lethal weapons context, ventricular fibrillation is more relevant. A Logist curve for ventricular fibrillation as a function of VC is shown in Figure C.4. As mentioned above, the value of VC for a 50 percent probability of ventricular fibrillation is 1.46 + 0.31 m/s. (Note also the steepness of the transition from no harm to irreversible effect. This is attrac- tive for non-lethal weapons design in allowing a fairly crisp threshold for estab- lishing margins of safety.) Cadaveric tests on the tolerance of the chest to blunt projectile impact (ba- tons) weighing 30 and 140 g and traveling at speeds of 20, 40, and 60 m/s were carried out by Bir.8 A total of 13 cadavers was used and a total of 21 tests was conducted, with a maximum of 3 tests on any given cadaver. If a rib fracture was 8Bir, Cynthia A. 2000. "The Evaluation of Blunt Ballistic Impacts of the Thorax," Ph.D. disserta- tion, Wayne State University, Detroit, Mich.

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156 Cal 11 0.7- O) 0.6 I: 0.5- o ~ 0.4 - ._ Q 0.3 O 0.2 Cot 0.1 1 0.9 0.8 o APPENDIX C - Logistic regression model: X2 = 11.279 p = 0.0008 R=.82 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 VCmax FIGURE C.5 Logist analysis of rib fracture tolerance as a function of VC. SOURCE: Bir, Cynthia A. 2000. "The Evaluation of Blunt Ballistic Impacts of the Thorax," Ph.D. dissertation, Wayne State University, Detroit, Mich. i. detected either by x-ray or by palpation, testing on that cadaver was discontinued. A Logist curve for rib fracture (less than 3) as a function of VC is shown in Figure C.5. The tolerance in terms of a 50 percent probability of no more than two rib fractures is O.8 m/s. Although there are claims of data on brain contusion, skull fracture, maxilla fracture, and liver laceration, no tolerance curves were presented to the commit- tee, and none were found in the open literature. The impact of sting balls on pig eyes is also being studied. Research on intestinal injury due to a pressure wave has been conducted by Yu et al.9 Mathematical and Mechanical Models The only mathematical model used extensively by the military for the predic- tion of human effects due to kinetic-energy rounds is the Interim Total Body Model developed by Jaycor for the Army. It is an outdated spring-mass-damper 9Yu, James H., Edward J. Vasel, and James H. Stuhmiller. 1990. "Modeling of the Non-Auditory Response to Blast Overpressure~astrointestinal Tract Blast Injury Laboratory Test Techniques," Annual/Final Report to U.S. Army Medical Research and Development Command, Fort Detrick, Frederick, Md., Contract No. DAMD17-85-C-5238, by Jaycor, San Diego, Calif. (Accession No. 90 07 2037).

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APPENDIX C 157 model that was popular some 25 to 30 years ago.~ How the model was devel- oped or how the data were obtained to populate the model parameters was not described to the committee. It also appears that no attempt to validate the model against experimental data has been made. Nevertheless' it is claimed that the model is capable of predicting injuries to the brain, eyes, face, lungs, heart, liver, spleen, hollow abdominal organs, and pelvic organs. Differences in Munitions . - The many types of kinetic-energy weapons described above call for a con- certed research effort to try to understand the human effects of these rounds on various body regions. It can be seen from the previous sections that only a few body regions have been studied in detail and that even fewer regions have toler- ance curves, and then only for a limited number of projectiles. The potential combinations of the many critical body regions with at least half a dozen different types of kinetic-energy munitions call for the development of a unifying method of tackling this problem, such as the formulation of a comprehensive finite ele- ment model of the human body, capable of simulating impacts by these muni- tions. During the development of such a model, the needed material parameters would be identified, and running portions of the model to simulate regional impact would identify the types of experiments needed to generate the necessary data for the material constants and for validation of the model. The proposed approach would not only reduce the number of animal and cadaveric tests needed to achieve this goal, but also make such tests more useful. At the same time, the experimental data can be used to obtain Logist curves to define human tolerance to impacts by these munitions. Of major concern are head and brain injuries. Grenade and mortar casing fragment velocities have been measured at approximately 100 m/s; this poses a risk to both the brain and the chest. ~ ~ It should be pointed out that there is no need to create a new finite element model of the head and brain. One already exists, and it can be adapted to kinetic-energy projectiles.l2 Tolerance of the eye to impact by munitions of different shapes and sizes, traveling at different veloci- ties, has not been established. Perhaps a VC-type criterion could be developed to minimize the risk of permanent eye injury. Again, modeling to simulate the iOMayorga, Col Maria, USA, "Interim Total Body Model," briefing to the committee, June 12, 2001, Walter Reed Army Institute of Research, Department of the Army, Silver Spring, Md. 1 1Bir, Cynthia A. 2001. "Thoracic Injury Assessment of the Modular Crowd Control Munition (MCCM)," Final Report, Wayne State University, Bioengineering Center, Detroit, Mich., Contract No. DAAE30-99-M-0222, National Institute of Justice. 12Zhang, L. 2001. "Computational Biomechanics of a Traumatic Brain Injury: An Investigation of Head Impact Response and American Football Head Injury," Ph.D. dissertation, Wayne State University, Detroit, Mich.

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158 APPENDIX C various types of munitions should be attempted. Other areas of concern are the face (disfigurement), the ear, the thorax, the abdomen, and the genital organs. One of the difficulties encountered in assessing the injury potential of ki- netic-energy rounds is the variability of conditions under which they may be used. For example, a certain round has a design range of 50 m; that is, it can cause enough temporary pain to effectively dissuade a perpetrator from advanc- ing toward a defending force at this range. However, if the weapon is fired at a target only 25 m away or hits an unintended target that is only 25 m away, the impact may cause not only severe pain but also possibly permanent injury. A weapon system equipped with a rangefinder and an adjustable firing pressure will help solve the problem if the tolerance of the body region is known. In a different example, a long-range kinetic-energy mortar can be made to explode over a crowd assembling several hundred meters away. The munition used could be lightweight, high-velocity pellets that are unlikely to cause perma- nent injury. The canister carrying the munition can cause head injuries, however, unless it is made into harmless shards itself or lands by means of a parachute as the munition is released. Another concern is injury to the eye. When pellets are dispersed indiscrimi- nately over a crowd, there is again a non-zero probability that one of the pellets will hit someone's eye. The chances are very small, because the eyes constitute 0.1 percent of the frontal body surface, but policy or field command must decide if a 0.1 percent probability of a permanent eye injury is worth the risk. . 6 Deficiencies in the Current Program It appears that the development of kinetic NLWs is well ahead of the re- search on human effects. Only a few of these munitions have been tested on live animals and human cadavers, and there is no overall understanding regarding human tolerance as a function of the mass and velocity of a round. In fact, the scaling of tolerance data from the animal to the human has not been very success- ful in low-velocity blunt impacts simulating automotive collisions; cadaveric data were found to be much more reliable in defining human tolerance. Patho- physiological responses cannot be obtained from cadavers, yet reliable numbers on tolerance cannot be deduced from animal data. Research has been concen- trated on the torso (chest and abdomen), where most of the rounds are expected to strike, but these munitions can also cause permanent and critical injuries when they strike the head, face, or eyes. A coordinated effort to study the injury potential of non-lethal kinetic-energy munitions using both animals and cadavers is needed to ensure that one truly has NLWs that fit the requirements of DOD Directive 3000.1. The present structure does not allow for any control over the development of these weapons inasmuch as human effects are not a primary consideration when a weapon is designed and developed.

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APPENDIX C in 159 Another method of assessing the mechanical effects of a kinetic munition on the human body is to use computer models to simulate the impact. The interim total body model currently in use by Army personnel, who are the leading Service expertise in this area, is outdated. In the face of a large multitude of munitions of varying mass and velocity, it is necessary for the non-lethal weapons community to develop a more sophisticated computer model that could simulate a wide range of blunt impacts. One promising approach is to take an existing finite element model of the human body used in automotive safety research and adapt it to simulate the impact of kinetic-energy munitions. Examples of these models can be found in the impact biomechanics literature (Stapp Car Crash Journal and the Proceedings of the Stapp Car Crash Conference). Finite element models can simulate a variety of impacts by different munitions at varying velocities. How- ever, all models need to be validated against experimental data. New data using cadaveric subjects should be acquired. Alternately, animal data can be used, but finite element models of the animals would have to be developed for validation purposes. Moreover, the models need to be validated over a range of munitions fired at varying speeds. It is concluded that although kinetic-energy munitions are not as sophisti- cated and versatile as some of the newer types of NLWs under development, they still have several advantages. The principal advantages are the relatively low cost of the munitions and the adaptability to existing guns and mortars. A need for weapons that can be deployed rapidly at close range to defuse a suddenly devel- oping situation is also still important. After the tolerance of the human to impacts of kinetic-energy munitions has been determined, improvements to the weapon systems can be made. These include new projectiles and rangefinders on weap- ons that can control the speed of the projectile so that the target is impacted at a relatively safe speed even if it is right at the muzzle. C.3 CHEMICAL NON-LETHAL WEAPONS HEALTH EFFECTS Chemical antipersonnel NLWs are intended to dissuade, temporarily inhibit, incapacitate, or otherwise impede individuals and crowds from taking certain actions while causing them no lasting serious side effects. Pepper spray (OC) and tear gas (CS) are common chemical riot control agents; malodorants and calm- atives are also potentially useful within the non-lethal weapons arsenal. These two riot control agents and malodorants act by being so unpleasant, either by irritation/inflammation or stench, that people leave an area. The mechanism of actions for the riot control agents are fairly well studied. Calmatives operate by depressing the central nervous system, but while they offer some opportunity for crowd control, additional research will be required to develop substances that provide reliable human response so as to achieve coop- erative behavior changes versus physiological depression. Increasing concentra-

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160 APPENDIX C lions of calmatives in the body can lead to a loss of consciousness and, ultimately, death. Ideally, the level of exposure between an "effective dose" and death would be a factor as high as 103 to 104. Major R&D issues involving the use of calmatives will be (1) characterizing and quantifying the safety of the chemicals, and (2) obtaining the method of delivery that will Provide the croner dose. ~ rear C.4 DIRECTED ENERGY This section addresses directed-energy NLWs based on radio-frequency elec- tromagnetic fields or photons either as laser light or as non-coherent light. Radio Frequency . ~ . - 6 Radio-frequency energy, spanning direct current to gigahertz, interacts with biological tissues primarily in conversion of the energy to heat. This thermal bioresponse produces the desired effect in the current and near-term RF non-lethal weapons systems. For example, in VMADS, the first NLW that uses millimeter waves, energy is deposited within a fraction of a millimeter into the skin. This top layer is heated within a few seconds, stimulating the pain receptors but not inducing permanent damage. At present, the JWNLD program is evaluating human responses to VMADS as a function of distance. Technical reports have been published on skin heating and corneal damage in a laboratory setting. Because the millimeter wave- length that VMADS uses is not associated with an existing radar system, little prior information was developed on the safety aspects of the particular weapon concept. The fraction of energy absorbed from the beam depends on the frequency of the energy, the size and shape of the target, and the dielectric characteristics of the target, which varies significantly from tissue to tissue. For humans, these relation- ships and time-averaged power absorption form the basis for establishing the limits of exposure to continuous RF to avoid burning. Recent developments in broadening the bandwidth of RF generators and the development of systems capable of producing very short pulses and very high peak power provide a glimpse into the vast, unexplored region of biological effects or human susceptibilities and potential avenues for NLWs. With such new technologies, the body would be exposed to both low- and high-frequency energy as well as to very high peak powers at some frequencies. The conven- tional measure, the time-averaged absorbed power, would not be a good predictor of relative safety with these systems, and it is not clear just which independent parameters should be associated with safety regulations. Pulsed RF fields are observed to produce a variety of effects that are not understood. Moreover, leap-ahead technologies will require a much more thor- ough knowledge of RF interactions with the human body than currently exists. Such progress will require a prolonged effort by a multidisciplinary team of researchers skilled in a wide range of disciplines.

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APPENDIX C 161 Lasers Lasers are used in the non-lethal sense to function as both physiological and psychological weapons. In the former, the goal is to obscure vision, either di- rectly by interfering with eyesight or indirectly by light scatter. In the latter, the laser is used as an illuminator to let adversaries know that they are targeted. (The latter function was used successfully in tactical situations in Somalia.) Laser weapons may be continuous or pulsed. The method for obscuring vision can be by dazzling or by producing a form of flash blindness by photoreceptor cell saturation. This results in "afterimaging," which gradually fades with time. Only wavelengths in the visible spectrum (400 to 780 nm) produce glare and flash blindness. The eye can also be obscured by using a high-frequency laser that excites the lens to cause fluorescence within the lens. Safety issues have been and continue to be a strong focus of research because of the increasing utility of lasers in commerce, professional use, and within military circles. The potential for a specific laser to produce ocular dam- age depends on the type of laser, the distance from the laser to the target, the energy of the laser, and total exposure time. Laser wavelength is one of the most important characteristics for under- standing effects. Wavelengths from 400 to 1,400 nm, known as the retinal hazard region, are transmitted through the cornea and are focused on the retina. The visible spectrum includes wavelengths from 400 to 780 nm and the near-infrared includes wavelengths from 780 to 1,400 nm. The cornea and lens are capable of concentrating laser energy 100,000 times before it reaches the retina. Lasers operating in the visible or near-infrared spectra are therefore capable of produc- ing severe photochemical and thermal choroidal or retinal damage. Lasers oper- ating in the ultraviolet spectrum (200 to 400 nm) are also capable of producing eye damage, but the retina is usually spared because of the high absorption of ultraviolet in the outer part of the eye. Other lasers operate in the far-infrared with wavelengths above 1,400 rim and are also absorbed by the cornea and lens. These lasers may produce corneal burns or cataracts, but no energy is transmitted to the retina. Sufficient data are available for the American National Standard for safe use of lasers to be promulgated for continuous and pulsed (down to the nanosecond time frame) systems that operate at wavelengths between 180 rim and 1 mm. To exploit lasers for use as NLWs to their maximum potential, specific programs will be required to evaluate the susceptibilities of humans to a wide range of modalities at eye-safe light intensities. This type of work follows devel- opment of guidelines on eye safety for well-studied systems but may require additional study for unexplored modalities. While the phase space requiring exploration for lasers may not be as great as that for RF systems, there is still a significant region of unknowns. It will be necessary to understand the potential for visual disruption as a function of the photon wavelength, use of multiple wavelengths, pulse shapes, interexposure intervals, and the effects of cofactors.

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62 APPENDIX C The use of cofactors might be considered in the search for synergistic effects of directed-energy systems. Confusion, the influence on temporary memory, and additional stages of neural disruption might be assisted by the application of multiple stimuli, properly timed. The demonstrated psychological effects related to illuminating human targets in Somalia illustrate the desirability of an accompa- nying psychological line of study. C.5 ACOUSTIC NON-LETHAL WEAPONS - Non-lethal acoustic weapons have been discussed at great length in the literature as having the potential for being able to change behavior. The gross effects often described as effecters are pain, presence of irritating/ aggravating noise, or the production of uncomfortable internal organ condi- tions. Several acoustic technologies fit under the label of non-lethal, but might be more appropriately considered in the realm of psychological tools or communication technologies, depending on the use to which they are put. Although repeated attempts have been made to develop high-intensity sound generators capable of eliciting desired results, a consistent set of reliable data, demonstrating aversive effects while not producing deafness, has not been forthcoming. A technology of this type, useful for the same kind of applications, is that derived by sending two separate ultrasonic signals that are above the human hearing range of about 20 kilohertz (kHz). These two signals can be aimed at an individual or reflecting surface to constructively mix and produce normal audible signals, such as voice and music. Two commercial companies offer systems that could be evaluated for operational effectiveness. Combined use of these two acoustic signal technologies offers the potential for synergy, principally in the psychological arena. C.6 ELECTRICAL NON-LETHAL WEAPONS The class of weapons known as lasers (aka stun guns) are NLWs acting by injection of electrical current into the human. Tasers operate either by direct contact from the weapon or by means of darts with wires attaching to the weapon. Once the dart contacts the human, high-voltage but low-amperage electrical cur- rent is discharged. The actual mechanism of action is not well studied, but the commercial devices are effective. Proposals to develop wireless lasers are intriguing because of the potential for significant standoff.~3 Mechanisms of action must be understood and safety 13A reviewer of this report suggested a laser that includes a substantial round with a soft front end and a couple of darts to shoot into the clothing and convey an elecrical shock. The round could contain a capacitor charged before the round is fired.

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APPENDIX C 163 tolerances must be developed because such a weapon, if developed, could be applied at distances that would make it difficult to identify some potential recipi- ents. Such tolerances must be known in order to develop rules of engagement for this type of weapon, since there may be a range of tolerances depending on the age, size, gender, and other physical conditions. C.7 BARRIERS AND ENTANGLEMENTS Effect of Barriers and Entanglements Most barriers and entanglement systems are designed for area denial to personnel and/or vehicles, including ships and boats. Barriers that present con- cerns regarding human effects include caltrops, concertina wires, webshots and entanglement grenades, tire spikes, and portable vehicle arresting barriers (PVABs). Caltrops and concertina wires are designed to deny pedestrian entry into an area by the obvious injury that will be incurred if entry is attempted. Webshots and entanglement grenades are designed to stop fleeing individuals by firing a net over them and entrapping them long enough for the pursuer to reach them. Tire spikes and PVABs are designed to stop fleeing vehicles, and injury may result if there is a crash or if the PVAB fails. Mechanisms of Injury Caltrops and concertina wires can cause lacerations and punctures, particu- larly to the extremities. The injuries are rarely unintended, unless an innocent civilian wanders into the restricted area at night and fails to notice the presence of the barriers. The injuries are not expected to be permanent, however, unless the individual is determined to break through the barrier. Webshots and entangle- ment grenades are not expected to cause major or permanent injuries unless the fugitive happens to hit his or her head on a hard surface during a fall. The probability of that happening is expected to be low. Other injuries can include twisted ankles and wrists and bruises and contusions, none of which is perma- nent. As for tire spikes, the only risk is the loss of control of the vehicle after the tires are blown, particularly if only one is blown. The vehicle may crash into some other barrier, injure nearby pedestrians, cyclists, or vehicular occupants, or roll over. It may also crash into a building, injuring its occupants. Thus, the site of deployment needs to be carefully selected. The risk of serious or fatal injury to the occupants of the fleeing vehicle also needs to be considered, especially since fugitives are not likely to use belted restraints. Fatalities can occur when unbelted occupants are ejected in a rollover. PVABs have been tested at 45 mph. A risk exists for head and neck injuries to unbelted occupants at that speed. The system has not been tested at higher speeds, and the resulting injuries are unknown but are expected to be more severe than at 45 mph. If there is failure of the PVAB system before arresting the vehicle, a crash may occur.

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164 Recent and Current Studies APPENDIX C The injuries that can be caused by caltrops and concertina wires have not been studied. The obviousness of their injury potential does not justify any re- search. While webshots and entanglement grenades appear to present a very low probability of permanent injury, prevention of a severe head injury is neverthe- less difficult in this situation and the state of the art in computer modeling of this event is currently unable to simulate human muscular response, particularly since it is totally unpredictable. The injury mechanisms involved in the use of tire spikes and PVABs are the same as those observed in automotive crashes. Un- belted occupants are more at risk than belted ones, regardless of whether the vehicle is equipped with airbags or not. The severity of the injury depends on the crash velocity and increases with older and smaller vehicles. C.8 PSYCHOLOGICAL EFFECTS The main purpose of NLWs is to change the behavior of opponents while minimizing collateral damage. For this reason, psychological and behavioral studies are an important adjunct to the development of NLWs. Studies should seek to understand the behavioral responses to NLWs and the psychological effects and effectiveness of these weapons. An example of the kind of behavioral effects that are important to understand might be the response of a crowd to the use of VMADS. What might be the response of subjects caught in the VMADS beam with others close by? Given this information, techniques that it would be possible to develop would most likely cause people to move away from the target area as opposed to panicking. Similarly, it would be useful to have more understanding of the response of people from different cultures to specific malodorants and when exhibiting dif- ferent levels of aggression. Because NLWs are applied with the intent of clearing, dissuading, blocking, or otherwise causing peaceful changes in behavior, it is important to thoroughly understand people's responses to them and behaviors as individuals or in the context of the crowds and confined spaces likely to be encountered in missions. Recent developments in broadening the bandwidth of RF generators and the development of systems capable of producing very short pulses and very high peak power provide a glimpse into the vast unexplored region of biological effects or human susceptibilities and potential avenues for NLWs. Single pulses of RF energy have been associated with stun and seizure, decreased spontaneous animal activity, microwave-induced whole body movements, thermal sensations, and startle modification. Some of these effects may be associated with the activation of specialized nerve endings and/or may be only partially mediated by heating. Little evidence has been identified to suggest that a bioelectromagnetics program exists to explore the vast domain of RF energy for application to NLWs.

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APPENDIX C 165 The present VMADS system and those under development are based on knowl- edge initially gained decades ago. Leap-ahead non-lethal weapons technologies will require a much more thorough knowledge of RF interactions with the human body than is in existence or can be envisioned within the current programmatic plans of the JNLWD. Such an effort would require a prolonged effort by a multidisciplinary team of researchers skilled in a wide range of disciplines. Likewise, to exploit lasers for use as NLWs to their maximum potential, specific programs would be required to evaluate the susceptibilities of humans to eye-safe light intensities. It will be necessary to understand the potential for visual disruption as a function of the photon wavelength, use of multiple wave- lengths, pulse shapes, interexposure intervals, and the effects of cofactors. The use of cofactors might be considered in the search for synergistic effects of directed-energy systems. Confusion, temporary memory, and additional stages of neural disruption might be assisted by the application of multiple stimuli, properly timed. The demonstrated psychological effects related to illuminating human targets in Somalia demonstrate the need for an accompanying psychologi- cal line of study. The main purpose of any weapon is to change the behavior of an opponent. Given the non-lethal weapons goal of changing behavior while minimizing col- lateral damage, opportunities must be sought to understand how to optimize psychological effects toward change of behavior within the context of available and desired NLWs. Only cursory consideration is now given to the use of existing weapons systems for psychological advantage, but it seems within the realm of possibility that systems might be developed with that in mind. Examples of psychological effects were identified in the preceding sections on specific health effects. Much opportunity seems possible using systems that are explicitly designed to enhance communication, since information exchange is a principal medium of psychological effects. Notable among these were the acoustic technologies that provide communication through vastly different means. In addition to the intended targeting of psychological effects are the effects that might be associated with kinetic-energy, directed energy, or chemical systems. Of- ten these are applied with the intent of clearing, dissuading, blocking, and so on. Unless these weapons systems are thoroughly studied in the context of crowds as well as of individuals in both open and confined spaces, there could easily be unintended consequences as a result of undesirable psychological responses. it /