Once existing marihuana, policy was cast into the realm of public debate, partisans on both sides of the issue over-simplified the question of the effects of use of the, drug on the individual. Proponents of the prohibitory legal system contended that marihuana, was a, dangerous drug, while opponents insisted that it was a harmless drug or was less harmful than alcohol or tobacco.

Any psychoactive drug is potentially harmful to the individual, depending on the intensity, frequency and duration of use. Marihuana is no exception. Because the particular hazards of use differ for different drugs, it makes no sense, to compare the harmfulness of different drugs. One may compare, insofar as the individual is concerned, only the harmfulness of specific effects. Is heroin less harmful than alcohol because, unlike alcohol, it directly causes no physical in-jury? Or is heroin more harmful than alcohol because at normal doses its use is more incapacitating in a behavioral sense?

Assessment of the relative dangers of particular drugs is meaningful only in a wider context which weighs the possible benefits of the drugs, the comparative scope of their use, and their relative impact on society at large. We consider these questions in the next Chapter, particularly in connection with the impact on public health.

Looking only at the effects on the individual, there, is little proven danger of physical or psychological harm from the experimental or intermittent use of the natural preparations of cannabis, including the resinous mixtures commonly used in this country. The risk of harm lies instead in the heavy, long-term use of the drug, particularly of the most potent preparations.

The experimenter and the intermittent users develop little or no psychological dependence on the drug. No organ injury is demonstrable.

Some moderate users evidence a degree of psychological dependence which increases in intensity with prolonged duration of use. Behavioral effects are lesser in stable personalities but greater in those with emotional instability. Prolonged duration of use does increase the probability of some behavioral and organic consequences including the possible shift to a heavy use pattern.

The heavy user shows strong psychological dependence on marihuana and often hashish. Organ injury, especially diminuation of pulmonary function, is possible. Specific behavioral changes are detectable. All of these effects are more apparent with long-term and very long-term heavy use than with short-term heavy use.

The very heavy users, found in countries where the use of cannabis has been indigenous for centuries, have a compulsive psychological dependence on the drug, most commonly used in the form of hashish. Clear-cut behavioral changes and a greater incidence of associated biological injury occur as duration of use increases. At present, the Commission is unaware of any similar pattern in this country.