Diethyl ether (ether) had been widely used for anesthesia until the 1960s despite its explosive properties and toxicity to both humans and animals. Diethyl ether still serves a role today as an effective inhalation agent. Newer inhalation agents have replaced ether completely and open drop delivery systems have been exchanged for complicated vaporizers and monitoring systems. Anesthesia in the developing world, however, still closely resembles primitive anesthetics.