Chloroethane is used as an anesthetic, refrigerant, aerosol propellant, and blowing agent for foam packaging. It is also used to diagnose dead teeth by placing it on suspect teeth - if the tooth is dead, it will not respond to the chloroethane. Chloroethane was historically used to produce tetraethyllead as an anti-knock additive for gasoline. It is not considered carcinogenic but high concentrations starting at 9-12% can be toxic, affecting heart rate.