Before the dangers can be assessed, the population at risk must be defined. Viewing the public health picture on a large scale, the United States in 1972 may still be considered fortunate with regard to marihuana usage. While it is the third most popular recreational drug, behind alcohol and tobacco, it has not been institutionalized and commercialized.

Most of the Americans who have used marihuana have been merely experimenting with it. As noted in Chapter 1, there are 24 million Americans who have tried marihuana at one time or another, with 8.3 million still using it. Of those who have quit, most say they have simply lost interest in it. The same Survey shows that experience with marihuana peaks in the 18-to-25-year-old group and falls off sharply thereafter. A fact of some significance is that at least 71% of all adults (18-years and older) and 80% of youth (12-to-17-years) have never used marihuana at all.*

The Survey also indicates that the majority of those youth and adults who continue to use marihuana do so intermittently, that is, between one and 10 times a month. These individuals are classified as intermittent marihuana smokers who use the drug for its socializing effects. They are, for the most part, ordinary Americans who are either in school or are employed.

About 2% of those who have ever used marihuana, or 500,000 people, now use the drug heavily. They use the drug several times a day. These individuals use marihuana for its personal drug effects in addition to its socializing effects. Generally, their life styles, values, attitudes, behaviors and activities are unconventional. Marihuana plays an important role in their lives. Because the risk of psychological, and perhaps physical, harm from marihuana increases with the frequency quantity and duration of its use, these heavy marihuana users constitute the greatest at-risk population in the United States today.

The heavy marihuana user presents the greatest potential concern to the, public health. It is the Commission's opinion that these heavy marihuana users constitute a source of contagion within American society. They actively proselytize others into a drug-oriented way of life. The effectiveness of peer group pressure has been described earlier in Chapter II

We anticipate that this at-risk population would increase in number should a policy of institutionalized availability be adopted toward marihuana. Although marihuana is readily available illicitly in the United States today, a policy permitting its legal distribution could be expected to bring about an increase in users, with some percentage of them becoming heavy users. It is the availability of the drug, coupled -with a governmental policy of approval or neutrality, that could escalate this group into a public health and welfare concern. While this is speculative, it is a concern which cannot be dismissed. The experience with the rise in the use of tobacco and alcohol makes clear the probable consequences of commercial exploitation.

Another concern of the Commission is the experience of other countries which have large heavy user populations. While the pattern of behavior in one country is not automatically similar to a pattern of behavior in another country, the existence of heavy user populations constitutes a serious public health concern which must be avoided in this country. The availability of the drug alone does not seem to determine increased usage; supply and governmental inaction appear to tip the balance toward increased use. The proportion of our population susceptible to this pattern of use is conjectural but good preventive public health requires limiting the number to an irreducible minimum.

*In the self-administered instrument, several separate questions were utilized to elicit the respondent's experience with marihuana. This technique permitted an analysis of consistency of responses, and also minimized the possibility of nonresponse. Nevertheless, 14% of the adults and 6% of the youth did not respond to enough of these questions to ascertain whether they had ever tried marihuana or not.

Percentage who- Adult Youth

Ever used ------------------------------------- 15 14

Never used ------------------------------------ 71 so

No response ----------------------------------- 14 6