A major advance has been a quantification of dose of THC in relation to clinically observable phenomena. This has been extensively studied over a wide dose range for marihuana (Rodin and Domino, 1970; Melges et al., 1970; Tinklenberg et al., 197O; Weil et al., 1968; Meyer et al., 1971; Clark and Nakashima, 1968; Clark et al., 1970; Jones and Stone, 1970; Mayor's Committee, 1944; Manno et al., 1970) and Delta 9 tetrahydrocannabinol (Isbell et al., 1967; Waskow et al., 1970; Hollister et al., 1968; Perez-Reyes and Lipton, 1971; Lemberger et -al., 1971; Dornbush and Freedman, 1971).

Investigations by Isbell et al. (1967), Kiplinger et al. (1971) and Renault et al. (1971) have clearly demonstrated that when reliable quantities of smoked marihuana or THC are delivered to the subject, a reproducible linear dose-dependent effect occurs on indices of physiologic, psychomotor, and mental performance as well as on mood and subjective experiences over a dose range of 12.50 to 200 micrograms of Delta 9 THC per kilogram of body weight.

In a 154 pound man this is comparable to consuming 0.88 to 17.5 milligrams of Delta 9 THC or 88 to 150 milligrams of marihuana containing one percent Delta 9 THC. It is generally assumed that good quality marihuana available in the United States contains 1% Delta 9 THC and an average marihuana cigarette consists of 500 milligrams of marihuana; thus, 5 milligrams of Delta 9 THC (Hollister, 1971).

As with most drugs, the larger the dose taken, the greater the psychopharmacologic effect. Isbell et al. (1967) noted that clinical syndromes vary from a mild euphoric feeling of relaxation at low doses (25 micrograms per kilogram) to an intensive hallucinogenic-like experience at high doses (250 micrograms per kilogram).

Probably the duration of use will vary considerably depending on cultural acceptance or rejection (McGlothlin, 1972).