Marijuana’s toxic substance, however, is not quickly passed off, and produces harmful effects on the body. Six doctors from Columbia University’s College of Physicians and Surgeons, in a letter to the editor of the New York Times, explained:

“Marijuana contains toxic substances . . . which are only soluble in fat and stored in body tissues, including brain, for weeks and months, like DDT. The storage capacity of tissues for these substances is enormous​—which explains their slow deleterious effects in habitual smokers. Anyone using these substances more than once a week cannot be drug free.”

Marijuana is complex with a persisting effect.” Evidently even the moderate, regular use of marijuana can have bad effects, as the Detroit Free Press notes: “Medical researchers are reporting new discoveries which indicate that marijuana​—and its big brother [hashish]—​are indeed dangerous to physical and mental health when used regularly, even once or twice a week.”