2000 1800 1600 1400 '" "0 c 1200 5 c. '0 ~ 1000 c ill :J ~ 800 t- 600 400 200 o~--~--~--~--~--~--~--~ 69 70 71 72 73 74 Year Removals of marihuana by USA federal authorities (domestic and foreign cooperative). (In order to roughly estimate the amounts consumed, the amounts removed are usually multiplied by six.) From "Hearings of the U.S. Senate Committee on the Judiciary (Subcommittee on Internal Security): Marihuana-Hashish Epidemic, Part II, The Continuing Escalation, May 8, 1975," U.S. Government Printing Office, Washington, D.C., 1975. then indicated that accumulation of these foreign molecules did not seem to affect permanently any of the vital functions over weeks and as "tolerance" to their use developed. months At the same time, studies by several cell biologists were published in close succession: Zimmerman, the Leuchtenbergers,