LESS THAN LETHAL WEAPONS – The medical effects of non-lethal weapons -a review1

In   Issue .

A.G. Robertson2


Non-lethal weapons have seen increasing use in the police forces and, more recently, the military forces of various countries around the world. With  increased use in military  operations in areas such  as Panama and Somalia,  there is an increasing  likelihood of military health  service officers coming  in contact with the medical effects of these weapon systems. This review summarises the physiological and psychological effects of these weapons, weapons which will be of increasing interest in the future.


Non-lethal weapons have seen increasing use in the police forces and, more recently, the military  forces of various countries around the world. Defined as those weapons which ‘have a reversible effect on their human targets’, the  term  non-lethal weapons is a misnomer as there will always be an element  of risk associated with the use of any weapon system.l Historically,  these weapons have been classified by their effects, principally whether they disable, disorient, discourage, demobilise or deceive.1The medical effects of these weapons do not easily fall into  this taxonomy.  Any discussion of these effects needs to be based on the target  organ  system  or the specific psychological effect. Some non-lethal technologies aimed  at weapon or communication systems may have peripheral effects on personnel. These may include bums from high powered microwaves or supercaustics, or falls on areas  coated  with very low friction  substances. These collateral effects are not included in this review.

The medical effects of non-lethal weapons may be

broadly categorised into:

  • blunt trauma  effects
  • eye effects
  • auditory effects
  • electrophysiological effects
  • toxicological/pharmaceutical effects
  • psychological effects.


Non lethal riot control ammunition uses rubber, timber or plastic  projectiles to deliver a numbing blow and temporarily incapacitate the target. There  are two main groups: unconventional ammunition fired from conventional weapons (eg stun  bags)  and large slow projectiles  fired from riot guns  and grenade launchers.!These projectiles aim to produce the maximum release of blunt  trauma  to the body without killing. This shock  consists  of impact shock and neurogenic shock.  Impact shock  is the mechanical effect of the blow and is caused by the elastic impact of the projectile. It produces localised bruising and, depending on the range, may cause fractures  and ruptures of internal organs. Neurogenic shock  is due to a temporary partial or complete  blockage  of the nervous system  from high frequency shock waves spreading from the point of contact.l

Plastic bullets  cause fewer serious injuries to face and chest,  although the laryngeal framework is particularly susceptible to injury because of its relatively unprotected position.2  Plastic bullets, however, produce more serious  injuries to skull and brain, and  therefore cause more deaths than rubber bullets.2    Wooden  ‘Broomstick’ rounds may produce internal injury or death at close range and may leave splinters in the  target at greater ranges.3

Stun bag ammunition may cause serious skull injury, liver damage or death3 at less than 5 metres, produces contusions and broken bones at 5 – 10 metres  and is ineffective over 20 metres.  Large slow projectiles  have a similar effect to stun  bags at close range but only distract at long range.l

Other  non-lethal weapons systems  utilise water, lasers or sound to produce  blunt  trauma  effects. High pressure  water sprays, used  to knock  down targets, may produce blunt  trauma.4

Pulsed chemical lasers may be used to produce plasma in front of a target. This will create a blast wave and subsequent blunt trauma  to the target with a stun effect.5,6  Acoustic bullets use  a high  frequency non-  penetrating sound wave to produce a plasma in front of the target, which creates an impact wave that produces incapacitation by blunt  object trauma  to the target.5, 7


An anti-eye laser weapon  has two main applications: temporary visual disablement, such  as flashblinding at night, dazzle or veiling glare, or more permanent eye damage  (partial or total blindness).8, 9 Low-energy lasers can be used to dazzle and  temporarily blind targets.1, 10  More powerful lasers can be used to permanently blind human targets.11  The eye magnifies any laser light hitting  the eye by a factor of approximately 100,000. Given that only a low level of energy density is required at the retina  to cause severe damage, lasers may produce extensive  retinal damage and blindness. If the macula is affected, the target will become functionally blind. Even laser  eye hits from oblique angles may produce  retinal bleeding into  the eyeball and subsequent blindness.8

Pyrotechnic Flash devices are devices are formulated to produce  intense  flashes of temporarily blinding light of 1 to 6 million candela. As 10 million candela  is required for temporary  blindness, the current devices will only temporarily  dazzle  targets.1 There are, however, more powerful devices. These are the optical  munitions. There are two types of optical munition. The Omni-directional Radiator or Isotropic Radiator produces  a very bright multidirectional broadband burst  of visible light. The directional radiator  produces a similar intensity uni-directional light.5   These systems may produce  the dazzle, temporary  blindness,8 or, rarely, permanent blindness,1,12 seen with laser weapons.

Strobing lights, particularly in the red and blue wavelengths, can effect the target’s brain alpha patterns. This can create disorientation, vertigo and nausea  (Bucha Effect).1J2  Epileptic seizures may be induced in susceptible personnet12  Bright lights can also be used, in conjunction with noise, to prevent rest.1 They may also be used to disorient a crowd at night by temporarily  immobilising their night  vision.3


Stun grenades  produce  temporary  hearing loss, aural pain and stunning effect by single or multiple blasts of loud  noise.  These devices generate  noise in the range 140 -170 decibels. Confined spaces, however, may amplify the noise and may produce ruptured ear drums and other inner ear damage at levels above 180 decibels.1

High intensity ultra-low frequency sound may disable by producing body organ resonance. The infrasound may be manipulated to produce distress and anxiety,6  or to produce   temporary incapacitation from disorientation, vertigo, nausea,  vomiting,  bowel spasms or diarrhoea.10, l3 At frequencies between 50 to 100  Hertz and intensity up to 153 dB, nausea, subcostal discomfort, cutaneous flushing  and tingling may be produced. At 60 and 73 Hz, coughing, severe substernal pain, choking, salivation, and pain on swallowing can be produced.1 At very high intensity with prolonged duration, death may result.14   The effects cease on turning off the generator.15   Other effects can also be produced by manipulating sound. Given sufficient intensity, ultrasound may be used to rupture internal organs.16


ELECTROPHYSIOLOGICAL  EFFECTS Electrical Stun Guns are weapons which fire electrodes into  a target  to stun but not kill. The electrodes discharge up to 50 kV at low amperage.  This electrical discharge overloads and temporarily disables the peripheral nervous system. A single shock will disable a limb briefly, a one second burst  will drop a person  to the ground and a 5 second burst will disable a person for up to 15 minutes.1 These weapons may have effects  on cardiac  rhythm  and respiratory function.17 In addition, they produce  a round erythematous rash, with  or without central paleness, which may be accompanied by circumferential abrasions.18


These  effects include those produced by tranquillisers, soporifics, lachrymators, sternutators and incapacitants. Dart guns, injecting up to 3 ml of tranquilliser, have been  developed. The effect is not instantaneous and depends on the route  of administration with intramuscular routes  being faster than subcutaneous routes. 1Other routes for administering tranquillisers are less successful. Opiates and strong sedatives are too dangerous on account of their low margin of safety and milder  tranquillisers cause little  actual loss of performance capability.19

Soporifics  are sleep inducing or sedative drugs which, when mixed with a solvent  like dimethyl sulphoxide (DMSO),  are rapidly absorbed through skin or lungs.1,12  These  may be variations of currently available compounds, like Lysergic Acid Amide  (a milder  form of LSD), or tailored synthetic neuroactive peptides,19, 20  like  Delta Sleep-inducing Peptide analogues.21

Lachrymators are irritants characterised by a very low toxicity (chronic or acute) and a short duration of action.22  Litde or no latent period  occurs after exposure. Orthochlorobenzylidene malononitrile (CS) is the most commonly used irritant for riot control purposes. Chloracetophenone (CN) is also used in some countries for this purpose in spite  of its higher toxicity.  A newer agent is dibenzoxazepine (CR) with which  there is litde  experience.

CS is used as a riot control agent in many countries. The limit of perception by taste ranges from

0.25-0.5  mg.m3.  The minimal irritant concentration ranges from 0.1-1.0  mg.m3  , the ICt 50 from 5-10 mg.m3 and  the LCt 50 for man very much larger, estimated as 60,000  mg.min.m3. This provides a high margin  of safety in its use.  The  CS cloud  is white at the point  of release and for several seconds after release. Exposure is associated with a pepper-like odour, the presence  of intense eye effects, dyspnoea, coughing and rhinorrhoea. During exposure an individual is incapable  of effective concerted action.

CR is similar in its effects to CS, but  the minimum effective concentration is lower and the LCtSO is higher. CN has a minimal irritant concentration is 0.3 mg.m3. It has been estimated from experimental data that the LCt 50 for man is 7000  to 14000 mg.min.m3, but inhalation of 350 mg.m3 for 5 minutes may be dangerous. The ICt 50 is 20 to 40 mg.min.m3.  CN is more  toxic than  CS.  Exposure to CN primarily affects the eyes, producing a burning sensation, lacrimation, inflammation and oedema of the eyelids, blepharospasm, photophobia and, at high concentrations, temporary blindness.23 The severest of these symptoms is reached in a few minutes and then gradually decreases. After about  one or two hours all symptoms disappear. High concentrations can cause irritation of the upper respiratory tract, inflammation of the skin with vesicle formation, visual impairment and pulmonary oedema. Drops or splashes in the eye may cause  corrosive  bums, corneal opacity  and even permanent visual impairment. Drops or splashes  on the skin  may cause papulovesicular dermatitis and superficial skin bums. Ingestion of food or water contaminated with  CN causes nausea, vomiting and  diarrhoea.

Sternutators22 produce strong pepper-like irritation in the upper  respiratory tract with  irritation of the eyes and lacrimation. They cause violent uncontrollable sneezing, cough,  nausea,  vomiting and a general  feeling of bodily  discomfort.  The principal agents in  this group are diphenylchlorarsine (DA), diphenylaminearsine chloride (Adamsite  (DM)) and diphenylcyanarsine (DC). They are dispersed  as aerosols and  produce  their effects by inhalation or by direct action on the eyes.  The onset of symptoms may be delayed  for several minutes after initial exposure (especially with  DM); effective exposure may, therefore, occur  before the presence  of the smoke  is suspected. Inhalation is followed by a burning sensation in  the nose and throat,  hypersalivation, rhinorrhea, coughing, sneezing, nausea  and vomiting. Mental  depression may occur  during  the progression of symptoms. The paranasal sinuses are irritated and fill with secretions and severe frontal  headache results. Prolonged exposure may cause retrostemal pain, dyspnoea and  asthma like symptoms. Symptoms reach their climax after 5 to 10 minutes and disappear  one to two hours after cessation  of exposure. Effects on the eyes are slight  and are restricted to a burning sensation and  lacrimation.  Exposure  of the skin  to high concentrations will cause erythema  and itching, proceeding to a burning sensation and vesicle formation. Ingestion of food and water contaminated by sternutators may cause nausea, vomiting, diarrhoea (sometimes bloodstained) and weakness  and dizziness have been reported.

High concentrations are not expected  in the open owing  to movement of air, but may be met within enclosed  spaces  (shelters, tents etc),  and under these circumstances the skin may show vesicle formation, capillary  damage and localised  swelling, while corneal necrosis and  pulmonary oedema are possible results. Unsteady gait and a positive  Romberg sign have been reported.  Other  neurological results of severe e”-posure include hyperaesthesia, anaesthesia and paraesthesia, especially  in the legs. Loss of consciousness has been reported.

Incapacitants22 are chemical  agents which produces a temporary disabling  condition that persists for hours to days after exposure to the agent has occurred. There  are two major categories:  CNS depressants (anticholinergics) and CNS stimulants (LSD). CNS depressants produce  their effects by interfering with  transmission of information across central  synapses. An example of this type of agent is BZ (3-quinuclidinyl benzoate). Small doses of BZ  cause sleepiness and  diminished alertness. Diagnosis can be made by noting increased heart rate, dry skin and lips, drowsiness and a progressive  intoxication in the untreated individual as follows:

  • 1-4 hours
  • Tachycardia, dizziness, ataxia, vomiting, dry mouth, blurred vision, confusion, sedation progressing to stupor.
  • 4-12 hours
  • Inability to respond to the environment effectively or to move about.
  • 12-96 hours
  • Increasing activity, random unpredictable behaviour with delusions and  hallucination.

The principal CNS stimulant is LSD. The clinical manifestations of LSD (D-lysergic acid diethylamide) intoxication often include an early stage of nausea followed 45-60 minutes after dosage  by a confused state  in which  delusions and hallucinations are common but not always experienced. Subjects intoxicated with LSD show evidence of sympathetic stimulation (rapid  heart  rate, sweating palms, pupillary enlargement, cold extremities) and mental excitation (nervousness, trembling or spasms, anxiety, euphoria and inability  to relax or sleep).

Hyperthermia has been  reported. Subjectively,  feelings of tension, heightened awareness, exhilaration, kaleidoscopic imagery, emotions of every  type, hilarity and  exultation are characteristic.  Paranoid ideas and more  profound states of terror  and ecstasy  may also occur, especially in highly  suggestible individuals. True hallucinations are rare, as is homicidal or suicidal behaviour.

Foul smelling gases may be used  to dispel crowds. Hydrogen Sulphide and  NaS8  have been  proposed. Hydrogen sulphide, however, is a powerful asphyxiant in moderate doses. At lower doses,  it may produce nausea, eye irritation, respiratory irritation and pulmonary oedema_10, 19


The  psychological effects of non-lethal weapons may vary depending on the physical context in which  it is used, whether the target  is a crowd or an individual, whether the target is trained or not  trained to expect or counter the effects of such weapons or whether it is used in a crowd control, counter-terrorist or battlefield situation. Camouflage and psyops are not  part of the non-lethal weapons  area as they are conceptually and operationally different.24

The use of blinding lasers will have significant psychological  impact  once personnel realise that observing  the terrain as well as looking towards the enemy may entail a significant  risk of being blinded.8 Mter  an attack, medical companies can expect to handle  many personnel who think they have been hit by lasers when  they have not.9   These psychological casualties may be reduced by appropriate training.

With  regard to other  non-lethal weapons agents, obscuration foams may induce  panic from a perceived difficulty in breathing coupled with restriction  in sight and hearing.1 There is little documented on the psychological effects of other non-lethal weapons and further research is required  in this area.


This paper  has reviewed  the physiological and psychological  effects of non lethal weapons. The definition and classification of non-lethal weapons remains unclear. Many authors use the  term Non  Lethal Weapons, and other similar  terms, to include weapons  that affect both weapon, and command and control  systems,  where there is little  or no human element involved. The taxonomy  used for military  effects does  not fit easily with physiological effects and further  clarification  of both  the definition of non-lethal weapons  and its categories is required. The·health effects vary in severity from the temporary disabling effects of lachrymators, infrasound and stun grenades to the potentially permanently disabling effects of blinding lasers and non-lethal projectiles. In most  areas, the information on physiological  and psychological effects is limited and further research is required to delineate both short  term and long term effects of these weapon  modalities.

The Wall Street Joumal notes that the  ‘move into nonlethality could  pry open a Pandora’s box of chemical, biological, and nuclear  weaponry that diplomats have spent much  of the 20th century trying to keep  closed.’ 16  The majority of the chemicals cited  are in contravention of the Chemical Weapons Convention and several of the other  technologies would  probably  contravene the Inhumane Weapons Convention because  of their indiscriminate effects. Further research is required to identify the legality of these weapon systems in the Australian  context.




  1. Gillman G. Non lethal anti-personnel weapons. DSTO: 1995: 1-24.
  1. 2. Ordog Management of gunshot wounds. Elsevier: New York; 1988.
  1. 3. Deane-Drummond A. Riot RUSI:London; 1975.
  1. 4. Lewer Non-lethal weapons. Med War 1995, ll, 78-90.
  1. Tapscott M, Atwal K. New weapons that win without killing on DOD's horizon. Def Electronics 1993, 25(2), 41-46.
  1. 6. Barry J , Morganthau T. Soon, 'Phasers on stun'. Newsweek 1994; 08 Feb: 54-56.
  1. Starr B. Non-lethal weapon puzzle for US Army. Internat  Def Rev 1993; (4): 319-320.
  1. 8. Anderberg B, Wolbasht Blinding lasers: The nastiest weapon? Mil Tech 1990; (3): 58-62.
  1. Jacobson MR. Lasers on the modern battlefield. Infantry 1994; 84(6): 15-16.
  1. Starr B. Less than lethal. Internat Def Rev 1994; 27(7): 29-39.
  1. Fridling BE. Blinding lasers: The need for control. USN!Proceed 1988; (10): 151-156.
  1. 12. Evancoe Non-lethal technologies enhance warrior's punch. National Def; 78(493): 26-29.
  1. Aftergood S. The soft-kill fallacy. Bull Atom Sci 1994; 50(5): 40-45.
  1. 14. Davis How to win wars without actually killing. Asia-Pac Def Report 1994; 20(10): 36-37.
  1. 15. Kiernan War over weapons that can't kill. New Scient 1993; ll December:
  1. Neven TE. Nonlethal weapons: Expanding our options. Marine Corps Gaz 1993; 77(12): 61-62.
  1. Fish R. Electric shock, Part Ill: Deliberately applied electric shocks and the treatment of electric injuries. J Emerg Med 1993;11(5):
  1. 18. Ikeda N, Harada A, Suzuki T. Homicidal manual strangulation and multiple stun-gun Amj Forensic Med Pathol1992;
13(4): 320-3.  
  1. 19. Finkel Hamilton and Hardys' Industrial Toxicology. (4th Ed.). PSG Inc.: Boston; 1983.
  1. Abdullah RG. Strategic psychopharmacology in modern warfare. Asian Defence J 1994; (10): 54-55.
  1. Myers RD. Neuroactive peptides: unique phases in research on mammalian brain over three decades. Peptides 1994; 15(2),
  1. AMEDP6. NATO handbook on the medical aspects of NBC defensive operations. 1990.
  1. 23. Rengstorff RH. Tear gas and riot control agents: A review of eye effects. EASP 100-71; 197
  1. DPSYCH-A Minute 1402/95 173-3-6 dated 01 Sep 95.