Pepper spray, also known as OC spray (from "Oleoresin Capsicum"), OC gas, and capsicum spray, is a lachrymatory agent (a chemical compound that irritates the eyes to cause tears, pain, and even temporary blindness) that is used in riot control, crowd control, and personal self-defense, including defense against dogs and bears.

Although considered a less lethal agent, it may be deadly in rare cases, and concerns have been raised about a number of deaths where being pepper sprayed may have been a contributing factor.^[1]

The active ingredient in pepper spray is capsaicin, which is a chemical derived from the fruit of plants in the Capsicum genus, including chilis. Extraction of oleoresin capsicum from peppers involves finely ground capsicum, from which capsaicin is extracted in an organic solvent such as ethanol. The solvent is then evaporated, and the remaining waxlike resin is the oleoresin capsicum. An emulsifier such as propylene glycol is used to suspend the OC in water, and pressurized to make it aerosol in pepper spray.

The US Army concluded in a 1993 Aberdeen Proving Ground study that pepper spray could cause "Mutagenic effects, carcinogenic effects, sensitization, cardiovascular and pulmonary toxicity, neurotoxicity, as well as possible human fatalities. There is a risk in using this product on a large and varied population".^[8] However, the pepper spray was widely approved in the US despite the reservations of the US military scientists after it passed FBI tests in 1991. As of 1999, it was in use by more than 2000 public safety agencies.^[9]

The head of the FBI's Less-Than-Lethal Weapons Program at the time of the 1991 study, Special Agent Thomas W. W. Ward, was fired by the FBI and was sentenced to 2 months in prison for receiving payments from a peppergas manufacturer while conducting and authoring the FBI study that eventually approved pepper spray for FBI use.^[7][10][11] Prosecutors said that from December 1989 through 1990, Ward received about $5,000 a month for a total of $57,500, from Luckey Police Products, a Fort Lauderdale, Florida-based company that was a major producer and supplier of pepper spray. The payments were paid through a Florida company owned by Ward's wife.^[12]