The Canadian Controlled Products Regulations (part of the Workplace Hazardous Materials Information System (WHMIS) describes technical criteria for identifying materials which are classified as dangerously reactive. A dangerously reactive material can react vigorously: 1. with water to produce a very toxic gas; 2. on its own by polymerization or decomposition; or, 3. under conditions of shock, or an increase in pressure or temperature. | The American National Standards Institute (ANSI) defines a dangerously reactive material as one that is able to undergo a violent self-accelerating exothermic chemical reaction with common materials, or by itself. | A dangerously reactive material may cause a fire, explosion or other hazardous condition. It is very important to know which conditions (such as shock, heating or contact with water) may set off the dangerous reaction so that appropriate preventive measures can be taken. | See also the U.S. OSHA HAZCOM definitions for unstable (reactive) and water reactive.