The Science Behind Pepper Spray

Pepper spray has been in the news a lot lately as it has been the weapon of choice against the Occupy protesters.  Some think it is a comparatively innocuous  relative of the pepper we use in Chili and other kitchen preparation. Judy Stone at the Scientific American Magazine blogs discusses this misconception when she goes looking for trials of its safety and efficacy.

There are reports of the efficacy of capsaicin in crowd control, but little regarding trials of exposures. Perhaps this is because pepper spray is regulated by the Environmental Protection Agency, as a pesticide and not by the FDA.

The concentration of capsaicin in bear spray is 1-2%; it is 10-30% in “personal defense sprays.”

While the police might feel reassured by the study, “The effect of oleoresin capsicum “pepper” spray inhalation on respiratory function,” I was not. This study met the “gold standard” of clinical trials, in that it was a “randomized, cross-over controlled trial to assess the effect of Oleoresin capsicum (OC) spray inhalation on respiratory function by itself and combined with restraint.” However, while the OC exposure showed no ill effect, only 34 volunteers were exposed to only 1 sec of Cap-Stun 5.5% OC spray by inhalation “from 5 ft away as they might in the field setting (as recommended by both manufacturer and local police policies).”

By contrast, an ACLU report, “Pepper Spray Update: More Fatalities, More Questions” found, in just two years, 26 deaths after OC spraying, noting that death was more likely if the victim was also restrained. This translated to 1 death per 600 times police used spray. (The cause of death was not firmly linked to the OC). According to the ACLU, “an internal memorandum produced by the largest supplier of pepper spray to the California police and civilian markets” concludes that there may be serious risks with more than a 1 sec spray. A subsequent Department of Justice study examined another 63 deaths after pepper spray during arrests; the spray was felt to be a “contributing factor” in several.

The difference in potency between pepper and Capsaicin Spray is  considerable.The Scoville Scale used as a measure of ‘hotness’ in peppers begins with sweet bells at 0 and heads up to 350,000 for the habaneros and up to 800,000 to 1,000,000 for the Bhut Jolokia pepper. Pure capsaisin is between 15 to 16 million units.

A 2004 paper, on the Health Hazards of Pepper Spray stated

The capsaicinoid content of extracts used in pepper sprays varies widely among manufacturers, from 1.2% to 12.6%. Since the concentration of extract in pepper sprays also varies (5-15%), the potential risks associated with capsaicinoid exposure may vary by as much as 30-fold among brands of OC spray.

Depending on brand, an OC spray may contain water, alcohols, or organic solvents as liquid carriers; and nitrogen, carbon dioxide, or halogenated hydrocarbons (such as Freon, tetrachloroethylene, and methylene chloride) as propellants to discharge the canister contents.(3) Inhalation of high doses of some of these chemicals can produce adverse cardiac, respiratory, and neurologic effects, including arrhythmias and sudden death. The health effects of solvents and propellants are beyond the scope of this article, but they too need to be considered in evaluating potential hazards and effects of exposure to specific brands of OC spray.

During the past decade, OC sprays have become popular with law enforcement and corrections personnel as non-lethal deterrent agents. But there is no real scientific basis for the claim that OC sprays are relatively safe. In fact, a number of reports have associated serious adverse sequelae, including death, with legitimate use, as well as misuse and abuse, of these sprays.

and concluded:

Serious adverse health effects, even death, have followed the use of OC sprays. These sprays should be regarded as poisons or weapons and kept away from children and teenagers.(17) The risks of OC spray use by adults for self defense has not been studied, and its effectiveness as a crime deterrent is unknown.





The use of OC Spray has been ubiquitous in the campaign against the occupy movement, and so far I am not aware of any deaths from, these products. However, it is much more than a “food product” as it was described on a Fox TV  newscast.

There have been numerous cases of extraordinary police violence against protestors, the press, and even non-participants. Some of these have resulted in severe injuries and hospitalizations.

It is very reasonable for police to use non-lethal force as a first line against violent perpetrators. It is not reasonable for police to use tasers, OC Spray, or rubber bullets in situations where no one is being threatened. They are not tools to be used for non-compliance with police directives.

Although the problems are much worse in the US, there is certainly room for more accountability  in the way Canadian police handle different situations. The most obvious was the death by taser of Robert Dziekanski in 2007. However, there have been many problems with the treatment of First Nations Peoples in general and protesters at both the G20 Summit and the Occupy Movements.




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