National Household Survey - Adult Marijuana Use Levels and Trends

The most extensive survey on drug use in the United States is now conducted annually. The National Household Survey is conducted by the National Institute on Drug Abuse and presents an impressive array of data on the prevalence of lifetime, annual, past month, and weekly drug use among various demographic categories and other occasional criteria. The NHS provides the official baseline for estimating the number of marijuana users in the U.S.

Generally the Household Survey indicates that marijuana use was falling steadily since 1979. Indeed, monthly use of marijuana has fallen 60% since then, although this steady decline has just recently reversed.

The number of people who used marijuana in the past year increased from 17.4 million in 1992 to 18.6 million in 1993. Occasional users increased from 8.8 to 9.6 million, and monthly users increased from 8.6 to 9.0 million. Roughly, half of marijuana smokers use marijuana monthly, and half of those use marijuana at least on a weekly basis.

Of those aged 12 - 17, 9.9% use marijuana, up from 8.2% in 1992. Of adults, 8.9% used marijuana in 1993, up from 8.5% the previous year. Over two million kids between the ages of 12 and 17 used marijuana during 1993, a million of then on a monthly basis. These figures are unacceptable to all Americans, and indicate that marijuana's current scheduling under the CSA has not created the "closed system" envisioned by the legislation's authors.

The NHS estimates and reports a) the number of people who have taken any illicit substance, b) the number of people who have taken illicit substances other than marijuana and c) the number of people who have taken marijuana. To discover the number of people who only use marijuana and not other illegal drugs, one has to subtract figure b from figure a. The chart below summarizes this process and also provides a comparison of the number of people who only smoke marijuana to all those who use it.

Table 1. Per cent of marijuana users who only use marijuana.

Source: National Household Survey SAMSHA Advance Report #7, Table 4A

Table 1 supports several arguments. Most users of marijuana do not use other illegal drugs. The more someone identifies themselves with marijuana use, the less likely it is they use any other illegal drug. Over the last ten years, a group ethic against the use of more dangerous drugs has strengthened among regular marijuana users. At best less than one fourth of monthly marijuana users use other illegal drugs as well, hardly sufficient justification for the criminal persecution of all adult marijuana users.

Yet old "truths" die hard. It is true that in the early 1990's the perceived harm of marijuana use dropped among teens and teenage use of the drug increased. While this could mean that kids just haven't got the message yet, it could also just as easily mean they've heard the word and rejected it. Is there a credibility problem with anti-marijuana messages?

Historically, anti-marijuana campaigns have been the subject of ridicule and embarrassment. The classic example is a late 1930's movie, Reefer Madness, which is now a cult favorite on account of its ridiculous portrayal of marijuana's effects on a pair of school age teens. Ever self-conscious of this scurrilous tradition of propaganda, modern efforts are carefully prepared with claims promising faithfulness to the latest scientific evidence.

What percentage of adults report perception of great risk of smoking marijuana occasionally? How does this vary with the development of adult, independent reasoning skills?

Table 2. % of adults perceiving great risk to occasional marijuana use, by age group and educational status, in 1985, 1990, 1991, and 1992.

Source: National Household Survey SAMSHA Advance Report #5 Table 9. 3/94.

The more education an individual has, the less likely they are to believe that the occasional use of marijuana is harmful. This observation holds up for any age group in any year. People find less risk associated with marijuana use as their education and independent reasoning skills increase.

When kids are taught that marijuana users move on to other drugs, they also note the subtle suggestion that if someone likes marijuana, they'll like the other drugs as well, and if they find marijuana exciting, other thrills await. This is the real danger of exaggerating the effects and dangers of marijuana use for adults, if the plan backfires there's no reason to avoid more dangerous drugs.

Many Americans clearly do not think marijuana use is dangerous, but still choose not to use the drug. This data is also available from the Household Survey, but like some of the data above requires a little mathematics. Table 2 presents the percentages of people who perceive harm from occasional marijuana use in various age groups. For each percentage that perceives harm, there is a complementary percentage who do not. For example, if 40% of a group think marijuana is harmful, then 60% of the group do not think it is harmful. Conventional wisdom would suggest that a high percentage of people who do not think occasional use of marijuana is harmful would also be regular users of the drug. Table 3 compares lists percentages obtained by comparing respondents who do not find great risk in occasional marijuana use with those who use the drug monthly.

Table 3. Ratio of percentages of monthly marijuana users to percentages of those who do not perceive great risk in occasional marijuana use, by year and demographic characteristics, with related availability data.

Source: National Household Survey, SAMSHA Advance Report #5, 3/94; #7, 7/74.

If marijuana use drops as perception of great risk increase, then one would expect increased use among those who perceive that the risk not to be great. Table 3 does not confirm that expectation (if it did the percentages would be considerable higher), and supports an argument that other factors than perceived risk contribute to avoidance of marijuana use. Only about 8% of people who do not think marijuana is dangerous use it monthly.

The National Household Survey does indicate that after a steadying decline, marijuana use is beginning to increase again in the United States. However it also demonstrates that nearly 80% of regular marijuana users do not use other illegal drugs, that adults lose confidence in government anti-marijuana information as the age and education increases, and that adults choose not to use marijuana despite a lack of harmful perceptions about the drug.