This is partly due to the fact that poorer neighborhoods lack the social capital needed to resist open-air drug markets. But it also reflects the deleterious effects of our mandatory minimum sentencing policies, discussed below. Finally, drug problems are distributed over time. Musto argues that drug epidemics are dampened by a generational learning process in which new cohorts observe the harmful results of a drug on older users. Building on this idea, Caulkins and his colleagues have developed sophisticated models of how interventions may provide less or greater leverage at different points in a drug epidemic. They argue, for example, that supply reduction measures will be more effective in the early stages of an epidemic but relatively ineffective in a large, mature, established market. Conversely, prevention and treatment may have limited effectiveness early in an epidemic – prevention because its effects are so lagged, and treatment because it interferes with generational learning about drug harms. This work is necessarily fairly speculative at present; we lack enough long term time-series data to permit serious testing of such hypotheses. But their analyses are valuable in encouraging another dimension of more strategic thinking. In 2005, about 46 percent of Americans aged 12 and older had used an illicit drug at least once in their lifetime; 14 percent had done so in the past year, and 8 percent in the past month. Because illicit drug use is so often a fleeting encounter in adolescence,hydroponic system for cannabis drug policy analysts usually view past-month prevalence use as a more meaningful indicator than lifetime prevalence. The 2007 Monitoring the Future annual school survey has the longest running consistently measured time series for substance use in the US. Figure 1 shows trends in past-month prevalence for selected substances for 12th graders .
Several patterns are apparent. First, alcohol remains the most common psychoactive substance among high school seniors. Second, in the most recent year , monthly alcohol and cigarette use each reached their lowest recorded levels. Third, past-month marijuana use reached its peak around 1979, hit a low in 1992, and has stabilized near 20 percent for the past decade. Finally, recent use of cocaine, MDMA, or methamphetamine is fairly rare among high school seniors. MDMA use seems to have peaked at 3.6 percent in the year 2000, cocaine use has remained fairly stable at around 2 percent, and methamphetamine has dropped from 1.9 percent in 2000 to 0.9 percent in 2006. Table 1 shows past-month prevalence of various substances by age category, from the household-based 2006 National Survey on Drug Use and Health . For each substance, young adults were the most frequent recent users, with one exception – heroin. New heroin initiation is rare; the US heroin problem mostly involves an aging cohort of addicts who initiated use in their youth. The overall methamphetamine rates obscure the fact that prevalence remains considerably higher in the Western US than in the Midwest and South and the Northeast , and is higher among whites and Latinos than among African Americans . For a decade there have been claims that methamphetamine, originally a West Coast biker drug, is spreading east, but if so, the diffusion has been fairly slow, and there is no evidence that use is significantly increasing. The fact that someone has used a drug in the past month does not mean they use the drug frequently. As seen in Figure 2, cigarette users tend to be daily users, but most recent users of cocaine and the hallucinogens did so only once or twice in the past month. About a third of marijuana users use almost every day; surprisingly, only half as many alcohol users do so.The prevalence of drug use provides a distorted picture of the actual health and safety harms posed by psychoactive drugs. There are several reasons for this. First, because drug use is only probabilistically related to drug harm, most harms to self and others are attributable to heavy users, and for most substances , a minority of users account for a majority of the quantity consumed. Second, school- and household-based surveys under represent hard core users, who are more likely to be truants, school dropouts, homeless, or institutionalized.
To track the harmful consequences of drug use, analysts generally rely on three types of indicators: Drug mentions in emergency room records, treatment statistics, and drug use among recent arrestees and prisoners. Table 2 shows recent data on the relative impact of the major illicit drugs on these harm indicators. Another major category of drug-related harm is the transmission of HIV. Injection drug use accounts for about a third of all AIDS cases in the US , and non-injection use is associated with an elevated risk of unsafe sexual practices. But there is no reliable way to attribute some fixed percentage of AIDS cases to cocaine use, to marijuana use, and so on. In keeping with our general analytical framework, recall that total harm is the product of prevalence x quantity x average harm. Thus, marijuana – by far the most prevalent illicit – accounts for a sizeable share of all three harm indicators. But relative to their much lower prevalence, it is clear that heroin, cocaine, and methamphetamine are disproportionately harmful substances. A 2007 Lancet article by David Nutt and colleagues offers what is to date the most sophisticated attempt to rate psychoactive substances by their “intrinsic” health and behavioral harms. In decreasing order of harmfulness, the worst five drugs were heroin, cocaine, the barbituates, street methadone, and alcohol. Tobacco was ninth, cannabis eleventh, LSD fourteenth,cannabis drying racks and MDMA eighteenth. If one were starting a society from scratch, it is unclear where one might paint a bright line separating licit from illicit substances, but it is difficult to see why alcohol and tobacco would be more accessible than cannabis or MDMA. But of course, we are not starting a society from scratch. The data in Table 2 are misleading if one wants to rank the intrinsic psychopharmacological harms of drugs – marijuana looming too large – but they are valid indicators if one wants to know the contributions of different substances to social harm under the current regime and with current patterns of use. These kinds of indicators tells us little about how harmful each substance might be in a regime of regulated legal access. Average harm per use might approximate the rating levels in Nutt et al. , though heroin use would become a lot safer per dose. Total harm might differ, if for example legal LSD were to become massively popular. But this might be a short term effect; societies seem to learn from experience and scale back on drugs that are obviously dysfunctional .
The FY2008 national drug control budget allocates 36 percent of drug funding for interdiction and source-country controls, 28 percent for domestic drug law enforcement, 23 percent for treatment, and 12 percent for prevention . We can only offer a whirlwind tour of the empirical literature on these interventions. Readers can find comprehensive assessments in recent monographs by Boyum and Reuter and the National Academy of Sciences . The drug policy literature is enormous and yet remarkably thin, in that rigorous program evaluations are rare. There are some valuable cost-effectiveness analyses , but these are limited by the available descriptive data and some daunting problems of causal inference , and many of the available evaluations were conducted by program developers, raising concerns about intellectual and financial conflicts of interest. In a classic analysis, Reuter and colleagues explained why we should not expect big impacts of efforts to thwart drug production and trafficking. First, it is not possible to completely “seal the borders” against relatively small packages of chemicals that will be sold at very high prices; there are too many possible smuggling routes and tactics, and dealers are very adaptive. Second, the price structure of illicit markets is such that bulk drug products in source countries are “dirt cheap” compared to the high retail street prices in the US. At the source, the economic value is low by US standards but high by local standards. But most of the markup in US prices occurs in the last few links of the distribution chain, within US borders. For example, Caulkins and Reuter note that the wholesale price of cocaine or heroin in a source country is only about 1 percent of its US retail street price. For example $1500 of cocaine in Colombia may be worth $15,000 at the US border, and $110,000 in the US retail street market. Thus even very large seizures in other countries are unlikely to have big effects on local prices. In recent years, defense analysts have used time-series data to argue that interdiction and source-country campaigns actually do have a significant impact on street prices and US demand. But these analyses have been debunked by a National Academy panel , arguing that the apparent correlations are spurious and amplified by selective focus on certain source-country interventions that happened to precede short-term price drops. It does not follow, however, that we could eliminate these programs entirely without a detectable effect. Most analysts believe that interdiction risks do raise prices; it is just that there are probably steeply declining marginal returns to such efforts. Presumably, these programs serve other US political, diplomatic, and economic goals beyond drug policy, laudable or otherwise. But we could probably cut back significantly on these efforts without seeing an increase in US drug consumption. It is estimated that we now have about a half a million drug offenders in state and federal prisons . The staggering increase in the federal prison population, and the role that drug offenses played in that increase, are shown in Figure 3; state prisons show a similar pattern. Drug arrest rates have remained stable for in recent years, so much of the growth in the prison population has been fueled by declining parole rates. What has this massive social experiment bought us? Early in the growth period, around 1992, one could argue that it was correlated with a considerable drop in drug use relative to the late 1970s . But this period of optimism was short-lived. By 1996, about half of the gains were gone, and levels of use have remained fairly stable since then, even as the drug prison population continued to rise. In fact, illicit drug prices have plummeted during a period when massive law enforcement sought vigorously to make drugs more expensive . This is troubling, because prices do matter; contrary to widespread belief, even addicts have been shown to be sensitive to drug prices . From the perspective of prevalence and quantity reduction, falling prices are a serious problem. But conceivably, falling prices may be beneficial from the perspective of harm reduction, because addicts might be expected to conduct fewer income-generating crimes to feed their habit. This is another illustration of the need to confront hard trade offs in thinking about drug policies. The harshness of US marijuana enforcement has long received considerable criticism, and indeed it is difficult to defend . But Caulkins and Sevignywarn against exaggerated concerns about unlucky marijuana smokers rotting away in a prison cell. Although 38 percent of state and federal incarcerations for drug offenses involved simple possession, “for only 2 percent of imprisoned drug-law violators was there no reason whatsoever to suspect possible involvement in distribution…depending on how strict a definition one preferred, one might argue that anywhere from 5,380 to 41,047 people were in prison in the United States solely for their drug use.” On the other hand, many who avoid time in prison do spend time in jail – as much as a third of arrestees in a study of three counties in Maryland . More troubling is the disproportionate imprisonment of African American men.A major factor is the differential severity of mandatory minimum sentences for crack vs. powder cocaine. Under these laws, a dealer would have to sell 500 grams of powder cocaine but only 5 grams of crack cocaine to receive the same five-year sentence. Since crack is more likely to be sold in African American communities, this has greatly widened the racial gap in sentencing.