Pepper Spray

Oleoresin Capsaicin (OC) Sprays



There is a need in the law enforcement community for a nonlethal weapon that will safely decrease an aggressive, hostile individual’s “edge” (i.e., his ability to respond quickly and effectively to a threat) or to incapacitate him without causing acute or long-term injury.  A spray containing oleoresin capsaicin (OC), which is an organic solvent extract of Capsicum (pepper) spp., was introduced under the brand name Cap-Stun in 1976. Pepper or OC spray is designed to be sprayed on the eyes, nose, and mouth. The acute effects last 5-10 minutes, with relatively complete recovery within 60 minutes.  The OC sprays contain varying amounts of OC. 
The sprays that are available for civilians contain 5% OC, while the sprays available for law enforcement officials contain 10-15% OC and the sprays that are designed for controlling animals contains 15-17% OC.  But, it is important that you understand that while the relative OC concentration is important, it is the amount of the active agent in the OC that determines its effectiveness. The amount of active agent contained in the OC can vary from manufacturer to manufacturer and even from canister to canister from a single manufacturer (see below).  The active agents in oleroresin capsaicum are capsaicinoids.  Capsaicin is the most common capsaicinoid. 
The capsaicinoids contained in the spray: 1) stimulate nociceptors (pain receptors) in the mucus membranes and skin to cause moderate to severe pain; 2) cause blepharospasm (blinking and 'intense' closure of the eyelids), lacrimation (tearing of the eyes), and conjunctivtis (swelling of the 'third' eyelid over the eye), as well as miosis (contraction of the pupil), which all interfere with normal vision; and 3) interfere with normal breathing.
Oleoresin capsicum is prepared by extracting ground, fresh or dried, Capsicum spp, with solvents. The capsaicinoid concentration of varies depending on the type of pepper that is used in the extraction.  Mild Capsicum spp contain as little as 0.1-0.2% capsaicinoid, while hot peppers, such as the Jalapeno or the Habanero, contain as much as 0.6-1.4% capsaicinoids . It also depends on what parts of the pepper are used in the extraction.  The membranes holding the seeds (that is, dissepimeat and placenta) contain about 90% of capsaicinoid, while the seeds contain about 10%.  The pericarp, the outer wall of the pepper contains negligible amounts of capsaicinoids.  Therefore, if the whole or dried pepper is extracted the OC will contain less capsaicinoid then if the pericarp was discarded and only the membranes and seeds were extracted.  Last, but certainly not least, the solvent used to make the extraction will determine the final concentration of capsaicinoid in the OC.  It is important to remember that OC is an extraction of a natural product and thus contains at least 100 different chemicals, including alcohols, carbonyls, carboxylic acid, esters, terpenes, toluene, and xylene. OC also contains a number of phenolic components that may interfere with the useful effects of the capsaicinoids. The effects of pepper spray are determined by the concentration of OC, the concentration of capsaicinoids and other active agents in the OC, the solvent, the spray pressure, and the parts of the body the spray touches.
The propellant for OC spray is nitrogen gas under pressure, rather than chlorofluorocarbons, which is the solvent and propellant for Mace (see box).  A typical formulation of OC contains 0.2 to 0.4 % by weight OC.  The OC is dissolved in a mixture of 10-18%, by weight, glycol and 33-37%, by weight, ethyl alcohol and this mixture is dissolved in water, 46-54%, by weight (see U.S. Patent 5217708: Capsicum Lachrymator). 
The world biomedical literature from 1966 to 1999 contains more 4000 references dealing with capsaicin. Most of these papers deal with the unique pharmacology of capsaicin when it is administered by injection. For example, if a laboratory animal is injected with a large dose of capsaicin, its body temperature will rapidly drop (hypothermia) and it will take several hours for its body temperature to return to normal. Further, after capsaicin treatment these animals are not able to thermoregulate.  For example, if these animals are exposed to high ambient temperatures, their body temperature will increase to potentially lethal levels. Their body temperature will also increase to potentially lethal levels if they are exposed to painful stimuli. And these effects on thermoregulation appear to be irreversible.  Capsaicin injections also permanently disrupt the activity of certain pain sensors in the skin.  It is important for you to understand that these effects occur only when the capsaicin is injected, these effects do not occur when peppers are eaten or OC or capsaicin is applied to the skin and mucous membranes.
The literature dealing with pepper or OC spray is small, fragmented, and contains just a handful of publications.  We have not been able to find any papers describing the effects of OC spray under controlled conditions. This is important because it means that all of the information that we have in the scientific literature about the effects of OC spray describe the post-exposure effects of OC spray and the methods use to treat people exposed to OC spray. For example, Watson and his colleagues provide an analysis of the symptoms of people exposed to OC that were brought to the Truman Medical Center from June, 1991 to July, 1994, while Haas and his colleagues describe their comparison of two formulations of OC spray.  Patel and Steffee and his colleagues describe in-custody deaths that have been associated with the use of pepper spray. Tominack and Spyker describe how hot peppers were used in a child abuse case. Busker and his colleagues provide an overview of OC spray and the discuss the risks associated with its use by the Dutch police force.  Edwards and his colleagues report the results of a National Institute of Justice study of pepper or OC spray use by the Baltimore County Police Department’s from July, 1993 to March, 1994.  During this time period, there were 194 uses of OC spray, 174 against humans and 20 against animals.  Approximately 90% of these exposures were successful in taking away the ‘edge’ of the aggressive individual, where the OC apparently had no effect on 7subjects.  These subjects appeared to either be intoxicated with drugs or had significant emotional problems.
Although controversial, it has been suggested that hog tying a violent subject; that is, handcuffing the hands behind the back, shackling the feet together, and then attaching the handcuffs and shackles together with a short chair, causing the legs to be bent at the knees, especially if the subject is forced to lay on his stomach, may be associated with an increased risk of injury or death following an OC exposure. Aggressive or hostile subjects that are intoxicated with drugs, especially stimulants; have asthma; bronchitis; or other upper respiratory problems are at greater risk for injury or death than subjects without these problems.
The uses and particularly the abuses of OC spray has received a good deal of coverage by the media.  For example, Steve James reported in Reuters (6/18/95) that the California ACLU found that there were reports of more than 26 deaths associated with the use of OC spray in California.  Arming Women Against Rape & Endangerment webpage (http://www.aware.org/rcapstun.htm) recommends Cap-Stun as a protective aid for women who must be out alone at night or in other threatening circumstances.  The Covert Action Quarterly webpage (http://caq.com/CAQ56pepper.htlm) by Lynne Wilson displays a picture of what appear to be police or private guards spraying what appears on a crowd of what appear to be labor protestors. 
FOR FURTHER READING
Busker, R. W. and van Helden, H. P.,  Toxicologic evaluation of pepper spray as a
possible weapon for the Dutch police force: risk assessment and efficacy. 
American Journal of Forensic Medical Pathology 1998, 19: 309-16

Edwards, S. M., Garnfield, J., and Omnen, J.  The Evaluation of Pepper Spray, National
Institute of Justice, 1997

Haas, J. S., Whipple, R. E., Grant, P. M., Andersen, B. D., Volpe, A. M., and Pelkey, G.
E.  Chemical and elemental comparison of two formulations of olecresin capsicum.  Science and Justice, 197, 37: 15-24

Patel, V.  Deaths in police custody.  British Medical Journal 1996, 312: 7022

Robinson, S. P. Doctors and police custody. Lancet 1993, 341: 8861.

Steffee CH, Lantz PE, Flannagan LM, Thompson RL, Jason DR
Oleoresin capsicum (pepper) spray and "in-custody deaths".
Am J Forensic Med Pathol 1995, 16: 185-92

Tominack, R. L. and Spyker, D. A. Capsicum and capsaicin-A review:  Case report of the
use of hot peppers in child abuse.  Journal of Toxicology and Clinical Toxicology. 1987, 25: 591-601.

Watson, W. A., Stremel,K. R. and Westdrop, E. J.  Oleoresin capsicum (Cap-Stun)
toxicity from aerosol exposure.  Annals of Pharmacotherapy 1996, 30: 733-5
















Chemical Mace, which has effects that are similar, but not identical, to OC contains a liquid based chloroacetophenone (CN).  It was introduced in 1966 by the General Ordance Equipment Co., a division of Smith and Wesson.  A closely related chemical orthochlorobenzalmalononitrile (CS) has also been used since the 60’s. The non flammable carrier agent/solvent for these formulations are the chlorofluorocarbons (CFCs), trichlorotrifluoroethanes 111 and 113.  There has a push to eliminate CFCs since the 1990 and these solvents are carefully controlled.  There does not seem to be a suitable substitute. 
The microscopic particles that are containing the CN remain airborne for some time after the agent is dispensed and the time that they remain airborne depends on the amount of agent that is dispensed, wind speed, local temperature and humidity.  The agent does not appear to ‘work’ when the ambient temperature is less than 50 F and is most effective when the ambient temperature is above 72 F.  People who have a high pain threshold, such as those who are intoxicated, highly agitated, or are mentally ill appear to be less affected by CN.  CN is also relatively ineffective against animals.
CS, which is sometimes called ‘super tear gas’ is apparently absorbed by the mucous membranes and causes tearing of the eyes, runny nose, and persistent coughing and sneezing.  It works over a wider temperature range than CN.  CS is also relatively ineffective against animals.
         Although controversial, some nations would classify these agents as chemical weapons and their use would be banned under the Geneva Protocol (Hu et al., 1989).
Hu, H., Fine, J., Epstein, P., Kelsey, K., Reynolds, P., and Walker, B.  Tear gas-harassing agent or toxic chemical weapon?  Journal of the Americian Medical Association 1989, 262: 660-3.