Effects of 35-day exposures to subanesthetic concentrations of halothane, isoflurane, and diethyl ether were measured in mice, rats, and guinea pigs which were in a phase of rapid body growth. Halothane produced a greater decrement in weight gain and a greater incidence of hepatic degenerative changes than isoflurane or diethyl ether despite its administration at lower anesthetic concentrations. Isoflurane results were intermediate between those of halothane and diethyl ether. No consistent injury to any organ other than the liver was found.
