"In summary, current evidence does not support the hypothesis that MML passage is associated with increased marijuana use prevalence among adolescents in states that have passed such laws up until 2014. Based on this evidence, we recommend several steps to advance the understanding of current and future marijuana policy effects. First, continued exploration of the effects of these state policies on different measures of use among adolescents is warranted.

"The perceived availability of cigarettes continued a long-term decline in 8th and 10th grade to historic low levels, with a significant decline in 10th grade. (Availability of cigarettes in 12th grade was first asked this year, so trend data are not yet available). After holding fairly steady at very high levels for some years, perceived availability reported by 8th and 10th graders began to decline modestly after 1996, very likely as a result of increased enforcement of laws prohibiting sale to minors under the Synar Amendment and FDA regulations.

"Although availability of alcohol among 12th grade students is near its lowest level recorded since first measured in 1999, at 86% it is still very high.

"Marijuana has been the most consistently available illicit drug and has shown only small variations over the years (see Figure 9-5a). What is most noteworthy is how little change has occurred in the proportion of 12th graders who say that marijuana is fairly or very easy to get. By this measure, marijuana has been readily available to the great majority of American 12th graders (from 80% to 90%) since 1975.

"Inhalants rank second among the illicit drugs in lifetime prevalence for 8th graders (8.9%) and third for 10th graders (6.1%); but they rank seventh for 12th graders (4.9%). Inhalants also rank second-highest in 30-day prevalence among the illicit drugs for 8th (2.1%) and third (1.1%) among 10th graders, but they rank much lower for 12th graders (0.8%). Note that the youngest respondents report the highest levels of use; this is the only class of drugs for which current use declines with age during adolescence.³"

"Annual marijuana prevalence peaked among 12th graders in 1979 at 51%, following a rise that began during the 1960s. Then use declined fairly steadily for 13 years, bottoming at 22% in 1992—a decline of more than half. The 1990s, however, saw a resurgence of use. After a considerable increase (one that actually began among 8th graders a year earlier than among 10th and 12th graders), annual prevalence rates peaked in 1996 at 8th grade and in 1997 at 10th and 12th grades. After these peak years, use declined among all three grades through 2007 or 2008.

"Teen users are at significantly higher risk of developing an addictive disorder compared to adults, and the earlier they began using, the higher their risk. Nine out of 10 people who meet the clinical criteria for substance use disorders involving nicotine, alcohol or other drugs began smoking, drinking or using other drugs before they turned 18. People who begin using any addictive substance before age 15 are six and a half times as likely to develop a substance use disorder as those who delay use until age 21 or older (28.1 percent vs. 4.3 percent)."

"For a number of years, 12th grade African-American students reported lifetime, annual, 30-day, and daily prevalence levels for nearly all drugs that were lower – sometimes dramatically so – than those for White or Hispanic 12th graders. That is less true today, with levels of drug use among African Americans more similar to the other groups. This narrowing of the gap between African Americans and other racial/ethnic groups is also seen in 8th and 10th grade, indicating that this narrowing in 12th grade is almost certainly not due primarily to differential dropout rates.

"Nationwide, 35.6% of students had used marijuana (also called grass, pot, or weed) one or more times during their life (Supplementary Table 106). The prevalence of having ever used marijuana was higher among black (42.8%) and Hispanic (42.4%) than white (32.0%) students, higher among black female (44.9%) and Hispanic female (42.7%) than white female (32.1%) students, and higher among black male (40.5%) and Hispanic male (42.1%) than white male (31.7%) students.

"• In 2017, 46% of 8th graders and 63% of 10th graders thought that cigarettes would be fairly easy or very easy for them to get if they wanted some.