THC has an LD50 (dose killing half of the research subjects) value of 1270 mg/kg (male rats) and 730 mg/kg (female rats) administered orally dissolved in sesame oil.[21] The LD50 value for rats by inhalation of THC is 42 mg/kg of body weight.[21] One estimate of THC's LD50 for humans indicates that about 1,500 pounds (680 kg) of cannabis would have to be smoked within 14 minutes.[22] This estimate is supported by studies which indicate that the effective dose of THC is at least 1000 times lower than the estimated lethal dose (a "therapeutic ratio" of 1000:1). This is much higher than alcohol (therapeutic ratio 10:1), cocaine (15:1), or heroin (6:1).[23]