Cocaine abuse has developed vastly in North America for the past 10 years. Usually, users inhaled a crystalline form of cocaine and only a few heavy users injected it. However, in about 1985 "crack" cocaine was developed, and it has become the most popular form for many cocaine users in the United States. Since 1986, a variety of studies have been made of the extent of crack use in different populations. In addition, many clinical case histories have been reported describing the effects of crack use by mothers and their offspring, as well as cases of serious neurological, psychiatric, cardiac, and pulmonary adverse reactions. Many such reactions are similar to those for other types of cocaine, but some are probably unique to crack. No recent review of survey and clinical case history research on crack seems to be available. Some of the relevant material is in unpublished reports, or letters to journal editors, and hence may not be readily available to those concerned with crack. This paper reviews research on levels of crack use, the characteristics of users, and reported adverse reactions to crack.
Crack is produced by mixing cocaine crystal or powder (cocaine hydrochloride and adulterants) with water and baking soda or sodium) bicarbonate. The mixture is boiled until the water has evaporated and a waxy substance remains in rocks or chunks. It contains alkali and cocaine, and unlike the cocaine powder, it is readily burned to make smoke at moderate temperatures. Usually, crack is smoked in special glass pipes, put on cigarettes, or even into non-tobacco cigarettes. Because crack produces small particles when smoked, it is absorbed rapidly through the lung and produces its peak high about 6-8 minutes after taking it. The effects are similar to those for intravenous doses and appear much more quickly than for the traditional cocaine sniffing. The rapid onset of effects is probably a factor in crack's high level of addictive potential, as well as the adverse reactions often seen.
Sometimes crack is confused with freebase cocaine, especially in papers on adverse effects. Freebase is cocaine from which adulterants have been removed, usually by boiling with an alkali and ether. However, crack is a smokable form of street cocaine from which adulterants have not been removed.
PREVALENCE OF CRACK USE
Because of its relative newness in the drug-taking scene, only a few studies have been made of crack use in large populations or high-risk groups. Table 1 summarizes the available studies; only one of adults seems to be available. Smart and Adlaf found that 0.7% of adults in Ontario had used crack or about 12.0% of those who had tried cocaine in all its forms.
Several studies have been made of crack use among students. Smart and Adlaf found in 1987 that 1.6% of students (aged 13-19) had used crack in Ontario; about 24.2% of all cocaine users had tried crack. Among students in British Columbia aged 14-18, about 1.6% reported crack use. Rates of use were much higher among seniors in American high schools. In 1987, 5.6% had used cocaine in their lifetime, 4.0% in the past year, and 1.5% in the past month. However, rates of use were much lower among college students; only 2.0% had used in the past year. Among high school seniors, about 27.1% of students who reported some cocaine use (lifetime) reported crack use.
Only Johnson et al.'s annual studies of high school seniors give any indication of trends in crack use. Both crack and cocaine use dropped significantly between 1987 and 1988. Crack was not included in the surveys before 1986, and hence data are not available for the early years of the crack epidemic. However, this study did show a large increase in cocaine smoking between 1983 and 1986.
As expected, crack use is very high among high-risk or known drug-using groups. For example, Washton et al found that 32% of cocaine users calling a cocaine hotline had used crack. One study of intensive supervision probationers in Brooklyn showed that 38% had used crack. However, 96% of street youths involved in drugs and crime in Miami used crack, often very heavily, although much of their cocaine use does not involve crack.
In general, crack use rates are low in general populations, far lower than for alcohol, cannabis, or tobacco, and even for the use of cocaine in other forms. However, rates of crack use are much greater in some high-risk groups, although in some a minority of cocaine users have tried crack.
CHARACTERISTICS OF CRACK USERS
Several studies of crack users have established that they share many characteristics with users of other types of cocaine. Typically, they are young males who are heavy users of cocaine and other drugs. For example, the research of adults in Ontario established that most crack users were male, in the age between18-19, as were most other cocaine users. Many of them were heavy users of sleeping pills, cannabis and alcohol.