Lachrymatory agent

A lachrymatory agent or lachrymator (from lacrima meaning "a tear" in Latin) is a chemical compound that stimulates the corneal nerves in the eyes to cause tears, pain, and even temporary blindness. Several commonly used chemicals are lachrymators; for example, bromoacetone, benzylchloride, thiophene, xylyl bromide, chlorine, and bromine.

Effects
Tear gas works by irritating mucous membranes in the eyes, nose, mouth and lungs, and cause tearing, sneezing, coughing, etc. Lachrymators are thought to exert their action through the inhibition of sulphydryl enzymes but this is not completely understood.

Usage
Lachrymatory agents that are commonly used as riot control agents and chemical warfare agents. For example, tear gas and pepper spray are commonly used for riot control. During World War I more toxic lachrymatory agents were used albeit in much smaller amounts than dangerously poisonous gases such as phosgene(a compound of chlorine).

Certain lachrymatory agents are often used by police to assist in bringing offenders under control, most notably tear gas, but also in some countries (Finland & Australia, also the USA) another issued substance is Mace (chloracetophenone) which is used as a personal attack repellent. All of these substances have basically the same chemical formulation, but often very subtle differences in their make-up.