pepper spray

Pepper spray (also known as capsicum spray) is a lachrymatory agent (a chemical compound that irritates the eyes to cause tears, pain, and temporary blindness) used in policing, riot control, crowd control, and self-defense, including defense against dogs and bears. Its inflammatory effects cause the eyes to close, taking away vision. This temporary blindness allows officers to more easily restrain subjects and permits people in danger to use pepper spray in self-defense for an opportunity to escape. It also causes temporary discomfort and burning of the lungs which causes shortness of breath. Although considered a less-than-lethal agent, it has been deadly in rare cases, and concerns have been raised about a number of deaths where being pepper sprayed may have been a contributing factor.

The active ingredient in pepper spray is capsaicin, which is a chemical derived from the fruit of plants in the genus Capsicum, including chilis. Extraction of oleoresin capsicum (OC) from peppers requires capsicum to be finely ground, from which capsaicin is then extracted using an organic solvent such as ethanol. The solvent is then evaporated, and the remaining waxlike resin is the oleoresin capsaicin.
An emulsifier such as propylene glycol is used to suspend OC in water, and pressurized to make it aerosol in pepper spray. High performance liquid chromatography (HPLC) is used to measure the amount of capsaicin and major capsaicinoids within pepper sprays.
Determining the strength of different manufacturers of pepper sprays can be confusing and difficult. Statements a company makes about their product strength are not regulated. A method using the capsaicin and related capsaicinoids (CRC) content of the product is unreliable as well, because there are six different types of capsaicinoids, causing different levels of irritation. Manufacturers do not state which particular type of capsaicinoids are used. Personal pepper sprays can range from a low of 0.18% to a high of 3%. Most law enforcement pepper sprays use between 1.3% and 2%. The federal government of the United States has determined that bear attack deterrent sprays must contain at least 1.0% and not more than 2% CRC. CRC does not measure the amount of OC within the formulation. Instead, CRC is the pain-producing component of the OC that produces the burning sensation.
The federal government of the United States makes no mention of Scoville heat units (SHU) or OC in their requirements, only CRC (only for bear attack deterrent sprays). But, there are countries (Italy, Portugal and Spain - see below, under "Legality") and a few states within the US that do mention OC limitations. Some manufacturers may show a very high percentage of OC and, although OC is the active ingredient within the formulation, it does not indicate pepper spray strength. High OC percentage also indicates that a spray has more oil content; which, can possibly use lower grade pepper oils (but, more of it), or lower grade capsaicinoids (within the major CRCs) and also has less ability to soak and penetrate skin than a formula with a less, but higher-quality, pepper oil, because oil has hydrophobic properties.
The OC percentage measures only the amount of chili oil extract contained in the defense spray, not the strength, pungency or effectiveness of the product. Other companies may show a high SHU. The SHU is a measurement of the base resin compound and not what comes out in the aerosol. The rated irritant effect of the resin may be diluted depending on how much of it is put in the can.

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